Terrascript refactor

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/Parser.java

@@ -16,10 +16,10 @@ import java.util.Map;
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
 import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.Executable;
-import com.dfsek.terra.addons.terrascript.parser.lang.Item;
+import com.dfsek.terra.addons.terrascript.parser.lang.Statement;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable.ReturnType;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression.ReturnType;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope.ScopeBuilder;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.BooleanConstant;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.ConstantExpression;
@@ -58,7 +58,7 @@ import com.dfsek.terra.addons.terrascript.parser.lang.variables.assign.VariableA
 import com.dfsek.terra.addons.terrascript.parser.lang.variables.reference.BoolVariableReferenceNode;
 import com.dfsek.terra.addons.terrascript.parser.lang.variables.reference.NumVariableReferenceNode;
 import com.dfsek.terra.addons.terrascript.parser.lang.variables.reference.StrVariableReferenceNode;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.addons.terrascript.tokenizer.Token;
 import com.dfsek.terra.addons.terrascript.tokenizer.Tokenizer;
 import com.dfsek.terra.api.util.generic.pair.Pair;
@@ -66,12 +66,12 @@ import com.dfsek.terra.api.util.generic.pair.Pair;
 
 @SuppressWarnings("unchecked")
 public class Parser {
-    private final String data;
+    private final String source;
     private final Map<String, FunctionBuilder<? extends Function<?>>> functions = new HashMap<>();
     private final List<String> ignoredFunctions = new ArrayList<>();
     
-    public Parser(String data) {
+    public Parser(String source) {
-        this.data = data;
+        this.source = source;
     }
     
     public Parser registerFunction(String name, FunctionBuilder<? extends Function<?>> functionBuilder) {
@@ -93,7 +93,7 @@ public class Parser {
      */
     public Executable parse() {
         ScopeBuilder scopeBuilder = new ScopeBuilder();
-        return new Executable(parseBlock(new Tokenizer(data), false, scopeBuilder), scopeBuilder);
+        return new Executable(parseBlock(new Tokenizer(source), false, scopeBuilder), scopeBuilder);
     }
     
     private Keyword<?> parseLoopLike(Tokenizer tokens, boolean loop, ScopeBuilder scopeBuilder) throws ParseException {
@@ -112,102 +112,102 @@ public class Parser {
         };
     }
     
-    private WhileKeyword parseWhileLoop(Tokenizer tokens, Position start, ScopeBuilder scopeBuilder) {
+    private WhileKeyword parseWhileLoop(Tokenizer tokens, SourcePosition start, ScopeBuilder scopeBuilder) {
-        Returnable<?> first = parseExpression(tokens, true, scopeBuilder);
+        Expression<?> first = parseExpression(tokens, true, scopeBuilder);
-        ParserUtil.checkReturnType(first, Returnable.ReturnType.BOOLEAN);
+        ParserUtil.checkReturnType(first, Expression.ReturnType.BOOLEAN);
         
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_END);
         
-        return new WhileKeyword(parseStatementBlock(tokens, true, scopeBuilder), (Returnable<Boolean>) first, start); // While loop
+        return new WhileKeyword(parseStatementBlock(tokens, true, scopeBuilder), (Expression<Boolean>) first, start); // While loop
     }
     
-    private IfKeyword parseIfStatement(Tokenizer tokens, Position start, boolean loop, ScopeBuilder scopeBuilder) {
+    private IfKeyword parseIfStatement(Tokenizer tokens, SourcePosition start, boolean loop, ScopeBuilder scopeBuilder) {
-        Returnable<?> condition = parseExpression(tokens, true, scopeBuilder);
+        Expression<?> condition = parseExpression(tokens, true, scopeBuilder);
-        ParserUtil.checkReturnType(condition, Returnable.ReturnType.BOOLEAN);
+        ParserUtil.checkReturnType(condition, Expression.ReturnType.BOOLEAN);
         
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_END);
         
         Block elseBlock = null;
         Block statement = parseStatementBlock(tokens, loop, scopeBuilder);
         
-        List<Pair<Returnable<Boolean>, Block>> elseIf = new ArrayList<>();
+        List<Pair<Expression<Boolean>, Block>> elseIf = new ArrayList<>();
         
-        while(tokens.hasNext() && tokens.get().getType().equals(Token.Type.ELSE)) {
+        while(tokens.hasNext() && tokens.current().getType().equals(Token.Type.ELSE)) {
             tokens.consume(); // Consume else.
-            if(tokens.get().getType().equals(Token.Type.IF_STATEMENT)) {
+            if(tokens.current().getType().equals(Token.Type.IF_STATEMENT)) {
                 tokens.consume(); // Consume if.
-                Returnable<?> elseCondition = parseExpression(tokens, true, scopeBuilder);
+                Expression<?> elseCondition = parseExpression(tokens, true, scopeBuilder);
-                ParserUtil.checkReturnType(elseCondition, Returnable.ReturnType.BOOLEAN);
+                ParserUtil.checkReturnType(elseCondition, Expression.ReturnType.BOOLEAN);
-                elseIf.add(Pair.of((Returnable<Boolean>) elseCondition, parseStatementBlock(tokens, loop, scopeBuilder)));
+                elseIf.add(Pair.of((Expression<Boolean>) elseCondition, parseStatementBlock(tokens, loop, scopeBuilder)));
             } else {
                 elseBlock = parseStatementBlock(tokens, loop, scopeBuilder);
                 break; // Else must be last.
             }
         }
         
-        return new IfKeyword(statement, (Returnable<Boolean>) condition, elseIf, elseBlock, start); // If statement
+        return new IfKeyword(statement, (Expression<Boolean>) condition, elseIf, elseBlock, start); // If statement
     }
     
     private Block parseStatementBlock(Tokenizer tokens, boolean loop, ScopeBuilder scopeBuilder) {
         
-        if(tokens.get().getType().equals(Token.Type.BLOCK_BEGIN)) {
+        if(tokens.current().getType().equals(Token.Type.BLOCK_BEGIN)) {
             ParserUtil.checkType(tokens.consume(), Token.Type.BLOCK_BEGIN);
             Block block = parseBlock(tokens, loop, scopeBuilder);
             ParserUtil.checkType(tokens.consume(), Token.Type.BLOCK_END);
             return block;
         } else {
-            Position position = tokens.get().getPosition();
+            SourcePosition position = tokens.current().getPosition();
-            Block block = new Block(Collections.singletonList(parseItem(tokens, loop, scopeBuilder)), position);
+            Block block = new Block(Collections.singletonList(parseStatement(tokens, loop, scopeBuilder)), position);
             ParserUtil.checkType(tokens.consume(), Token.Type.STATEMENT_END);
             return block;
         }
     }
     
-    private ForKeyword parseForLoop(Tokenizer tokens, Position start, ScopeBuilder scopeBuilder) {
+    private ForKeyword parseForLoop(Tokenizer tokens, SourcePosition start, ScopeBuilder scopeBuilder) {
         scopeBuilder = scopeBuilder.sub(); // new scope
-        Token f = tokens.get();
+        Token f = tokens.current();
         ParserUtil.checkType(f, Token.Type.NUMBER_VARIABLE, Token.Type.STRING_VARIABLE, Token.Type.BOOLEAN_VARIABLE, Token.Type.IDENTIFIER);
-        Item<?> initializer;
+        Statement<?> initializer;
         if(f.isVariableDeclaration()) {
             VariableAssignmentNode<?> forVar = parseVariableDeclaration(tokens, scopeBuilder);
-            Token name = tokens.get();
+            Token name = tokens.current();
             if(functions.containsKey(name.getContent()) || scopeBuilder.contains(name.getContent()))
                 throw new ParseException(name.getContent() + " is already defined in this scope", name.getPosition());
             initializer = forVar;
         } else initializer = parseExpression(tokens, true, scopeBuilder);
         ParserUtil.checkType(tokens.consume(), Token.Type.STATEMENT_END);
-        Returnable<?> conditional = parseExpression(tokens, true, scopeBuilder);
+        Expression<?> conditional = parseExpression(tokens, true, scopeBuilder);
-        ParserUtil.checkReturnType(conditional, Returnable.ReturnType.BOOLEAN);
+        ParserUtil.checkReturnType(conditional, Expression.ReturnType.BOOLEAN);
         ParserUtil.checkType(tokens.consume(), Token.Type.STATEMENT_END);
         
-        Item<?> incrementer;
+        Statement<?> incrementer;
-        Token token = tokens.get();
+        Token token = tokens.current();
         if(scopeBuilder.contains(token.getContent())) { // Assume variable assignment
             incrementer = parseAssignment(tokens, scopeBuilder);
         } else incrementer = parseFunction(tokens, true, scopeBuilder);
         
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_END);
         
-        return new ForKeyword(parseStatementBlock(tokens, true, scopeBuilder), initializer, (Returnable<Boolean>) conditional, incrementer,
+        return new ForKeyword(parseStatementBlock(tokens, true, scopeBuilder), initializer, (Expression<Boolean>) conditional, incrementer,
                               start);
     }
     
-    private Returnable<?> parseExpression(Tokenizer tokens, boolean full, ScopeBuilder scopeBuilder) {
+    private Expression<?> parseExpression(Tokenizer tokens, boolean full, ScopeBuilder scopeBuilder) {
         boolean booleanInverted = false; // Check for boolean not operator
         boolean negate = false;
-        if(tokens.get().getType().equals(Token.Type.BOOLEAN_NOT)) {
+        if(tokens.current().getType().equals(Token.Type.BOOLEAN_NOT)) {
             booleanInverted = true;
             tokens.consume();
-        } else if(tokens.get().getType().equals(Token.Type.SUBTRACTION_OPERATOR)) {
+        } else if(tokens.current().getType().equals(Token.Type.SUBTRACTION_OPERATOR)) {
             negate = true;
             tokens.consume();
         }
         
-        Token id = tokens.get();
+        Token id = tokens.current();
         
         ParserUtil.checkType(id, Token.Type.IDENTIFIER, Token.Type.BOOLEAN, Token.Type.STRING, Token.Type.NUMBER, Token.Type.GROUP_BEGIN);
         
-        Returnable<?> expression;
+        Expression<?> expression;
         if(id.isConstant()) {
             expression = parseConstantExpression(tokens);
         } else if(id.getType().equals(Token.Type.GROUP_BEGIN)) { // Parse grouped expression
@@ -230,14 +230,14 @@ public class Parser {
         }
         
         if(booleanInverted) { // Invert operation if boolean not detected
-            ParserUtil.checkReturnType(expression, Returnable.ReturnType.BOOLEAN);
+            ParserUtil.checkReturnType(expression, Expression.ReturnType.BOOLEAN);
-            expression = new BooleanNotOperation((Returnable<Boolean>) expression, expression.getPosition());
+            expression = new BooleanNotOperation((Expression<Boolean>) expression, expression.getPosition());
         } else if(negate) {
-            ParserUtil.checkReturnType(expression, Returnable.ReturnType.NUMBER);
+            ParserUtil.checkReturnType(expression, Expression.ReturnType.NUMBER);
-            expression = new NegationOperation((Returnable<Number>) expression, expression.getPosition());
+            expression = new NegationOperation((Expression<Number>) expression, expression.getPosition());
         }
         
-        if(full && tokens.get().isBinaryOperator()) { // Parse binary operations
+        if(full && tokens.current().isBinaryOperator()) { // Parse binary operations
             return parseBinaryOperation(expression, tokens, scopeBuilder);
         }
         return expression;
@@ -245,7 +245,7 @@ public class Parser {
     
     private ConstantExpression<?> parseConstantExpression(Tokenizer tokens) {
         Token constantToken = tokens.consume();
-        Position position = constantToken.getPosition();
+        SourcePosition position = constantToken.getPosition();
         switch(constantToken.getType()) {
             case NUMBER:
                 String content = constantToken.getContent();
@@ -260,21 +260,21 @@ public class Parser {
         }
     }
     
-    private Returnable<?> parseGroup(Tokenizer tokens, ScopeBuilder scopeBuilder) {
+    private Expression<?> parseGroup(Tokenizer tokens, ScopeBuilder scopeBuilder) {
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_BEGIN);
-        Returnable<?> expression = parseExpression(tokens, true, scopeBuilder); // Parse inside of group as a separate expression
+        Expression<?> expression = parseExpression(tokens, true, scopeBuilder); // Parse inside of group as a separate expression
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_END);
         return expression;
     }
     
-    private BinaryOperation<?, ?> parseBinaryOperation(Returnable<?> left, Tokenizer tokens,
+    private BinaryOperation<?, ?> parseBinaryOperation(Expression<?> left, Tokenizer tokens,
                                                        ScopeBuilder scopeBuilder) {
         Token binaryOperator = tokens.consume();
         ParserUtil.checkBinaryOperator(binaryOperator);
         
-        Returnable<?> right = parseExpression(tokens, false, scopeBuilder);
+        Expression<?> right = parseExpression(tokens, false, scopeBuilder);
         
-        Token other = tokens.get();
+        Token other = tokens.current();
         if(ParserUtil.hasPrecedence(binaryOperator.getType(), other.getType())) {
             return assemble(left, parseBinaryOperation(right, tokens, scopeBuilder), binaryOperator);
         } else if(other.isBinaryOperator()) {
@@ -283,41 +283,41 @@ public class Parser {
         return assemble(left, right, binaryOperator);
     }
     
-    private BinaryOperation<?, ?> assemble(Returnable<?> left, Returnable<?> right, Token binaryOperator) {
+    private BinaryOperation<?, ?> assemble(Expression<?> left, Expression<?> right, Token binaryOperator) {
         if(binaryOperator.isStrictNumericOperator())
             ParserUtil.checkArithmeticOperation(left, right, binaryOperator); // Numeric type checking
         if(binaryOperator.isStrictBooleanOperator()) ParserUtil.checkBooleanOperation(left, right, binaryOperator); // Boolean type checking
         switch(binaryOperator.getType()) {
             case ADDITION_OPERATOR:
-                if(left.returnType().equals(Returnable.ReturnType.NUMBER) && right.returnType().equals(Returnable.ReturnType.NUMBER)) {
+                if(left.returnType().equals(Expression.ReturnType.NUMBER) && right.returnType().equals(Expression.ReturnType.NUMBER)) {
-                    return new NumberAdditionOperation((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                    return new NumberAdditionOperation((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
                 }
-                return new ConcatenationOperation((Returnable<Object>) left, (Returnable<Object>) right, binaryOperator.getPosition());
+                return new ConcatenationOperation((Expression<Object>) left, (Expression<Object>) right, binaryOperator.getPosition());
             case SUBTRACTION_OPERATOR:
-                return new SubtractionOperation((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new SubtractionOperation((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             case MULTIPLICATION_OPERATOR:
-                return new MultiplicationOperation((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new MultiplicationOperation((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             case DIVISION_OPERATOR:
-                return new DivisionOperation((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new DivisionOperation((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             case EQUALS_OPERATOR:
-                return new EqualsStatement((Returnable<Object>) left, (Returnable<Object>) right, binaryOperator.getPosition());
+                return new EqualsStatement((Expression<Object>) left, (Expression<Object>) right, binaryOperator.getPosition());
             case NOT_EQUALS_OPERATOR:
-                return new NotEqualsStatement((Returnable<Object>) left, (Returnable<Object>) right, binaryOperator.getPosition());
+                return new NotEqualsStatement((Expression<Object>) left, (Expression<Object>) right, binaryOperator.getPosition());
             case GREATER_THAN_OPERATOR:
-                return new GreaterThanStatement((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new GreaterThanStatement((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             case LESS_THAN_OPERATOR:
-                return new LessThanStatement((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new LessThanStatement((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             case GREATER_THAN_OR_EQUALS_OPERATOR:
-                return new GreaterOrEqualsThanStatement((Returnable<Number>) left, (Returnable<Number>) right,
+                return new GreaterOrEqualsThanStatement((Expression<Number>) left, (Expression<Number>) right,
                                                         binaryOperator.getPosition());
             case LESS_THAN_OR_EQUALS_OPERATOR:
-                return new LessThanOrEqualsStatement((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new LessThanOrEqualsStatement((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             case BOOLEAN_AND:
-                return new BooleanAndOperation((Returnable<Boolean>) left, (Returnable<Boolean>) right, binaryOperator.getPosition());
+                return new BooleanAndOperation((Expression<Boolean>) left, (Expression<Boolean>) right, binaryOperator.getPosition());
             case BOOLEAN_OR:
-                return new BooleanOrOperation((Returnable<Boolean>) left, (Returnable<Boolean>) right, binaryOperator.getPosition());
+                return new BooleanOrOperation((Expression<Boolean>) left, (Expression<Boolean>) right, binaryOperator.getPosition());
             case MODULO_OPERATOR:
-                return new ModuloOperation((Returnable<Number>) left, (Returnable<Number>) right, binaryOperator.getPosition());
+                return new ModuloOperation((Expression<Number>) left, (Expression<Number>) right, binaryOperator.getPosition());
             default:
                 throw new UnsupportedOperationException("Unsupported binary operator: " + binaryOperator.getType());
         }
@@ -327,7 +327,7 @@ public class Parser {
         Token type = tokens.consume();
         ParserUtil.checkType(type, Token.Type.STRING_VARIABLE, Token.Type.BOOLEAN_VARIABLE, Token.Type.NUMBER_VARIABLE);
         
-        Returnable.ReturnType returnType = ParserUtil.getVariableReturnType(type);
+        Expression.ReturnType returnType = ParserUtil.getVariableReturnType(type);
         
         ParserUtil.checkVarType(type, returnType); // Check for type mismatch
         Token identifier = tokens.consume();
@@ -336,40 +336,40 @@ public class Parser {
             throw new ParseException(identifier.getContent() + " is already defined in this scope", identifier.getPosition());
         ParserUtil.checkType(tokens.consume(), Token.Type.ASSIGNMENT);
         
-        Returnable<?> value = parseExpression(tokens, true, scopeBuilder);
+        Expression<?> value = parseExpression(tokens, true, scopeBuilder);
         ParserUtil.checkReturnType(value, returnType);
 
         String id = identifier.getContent();
 
         return switch(value.returnType()) {
-            case NUMBER -> new NumAssignmentNode((Returnable<Number>) value, identifier.getPosition(), scopeBuilder.num(id));
+            case NUMBER -> new NumAssignmentNode((Expression<Number>) value, identifier.getPosition(), scopeBuilder.num(id));
-            case STRING -> new StrAssignmentNode((Returnable<String>) value, identifier.getPosition(), scopeBuilder.str(id));
+            case STRING -> new StrAssignmentNode((Expression<String>) value, identifier.getPosition(), scopeBuilder.str(id));
-            case BOOLEAN -> new BoolAssignmentNode((Returnable<Boolean>) value, identifier.getPosition(), scopeBuilder.bool(id));
+            case BOOLEAN -> new BoolAssignmentNode((Expression<Boolean>) value, identifier.getPosition(), scopeBuilder.bool(id));
             default -> throw new ParseException("Illegal type for variable declaration: " + type, value.getPosition());
         };
     }
     
     private Block parseBlock(Tokenizer tokens, boolean loop, ScopeBuilder scopeBuilder) {
-        List<Item<?>> parsedItems = new ArrayList<>();
+        List<Statement<?>> statements = new ArrayList<>();
         
         scopeBuilder = scopeBuilder.sub();
         
-        Token first = tokens.get();
+        Token first = tokens.current();
         
         while(tokens.hasNext()) {
-            Token token = tokens.get();
+            Token token = tokens.current();
             if(token.getType().equals(Token.Type.BLOCK_END)) break; // Stop parsing at block end.
-            Item<?> parsedItem = parseItem(tokens, loop, scopeBuilder);
+            Statement<?> statement = parseStatement(tokens, loop, scopeBuilder);
-            if(parsedItem != Function.NULL) {
+            if(statement != Function.NULL) {
-                parsedItems.add(parsedItem);
+                statements.add(statement);
             }
             if(tokens.hasNext() && !token.isLoopLike()) ParserUtil.checkType(tokens.consume(), Token.Type.STATEMENT_END);
         }
-        return new Block(parsedItems, first.getPosition());
+        return new Block(statements, first.getPosition());
     }
     
-    private Item<?> parseItem(Tokenizer tokens, boolean loop, ScopeBuilder scopeBuilder) {
+    private Statement<?> parseStatement(Tokenizer tokens, boolean loop, ScopeBuilder scopeBuilder) {
-        Token token = tokens.get();
+        Token token = tokens.current();
         if(loop) ParserUtil.checkType(token, Token.Type.IDENTIFIER, Token.Type.IF_STATEMENT, Token.Type.WHILE_LOOP, Token.Type.FOR_LOOP,
                                       Token.Type.NUMBER_VARIABLE, Token.Type.STRING_VARIABLE, Token.Type.BOOLEAN_VARIABLE,
                                       Token.Type.RETURN, Token.Type.BREAK, Token.Type.CONTINUE, Token.Type.FAIL);
@@ -384,9 +384,7 @@ public class Parser {
                 return parseAssignment(tokens, scopeBuilder);
             } else return parseFunction(tokens, true, scopeBuilder);
         } else if(token.isVariableDeclaration()) {
-            
             return parseVariableDeclaration(tokens, scopeBuilder);
-            
         } else if(token.getType().equals(Token.Type.RETURN)) return new ReturnKeyword(tokens.consume().getPosition());
         else if(token.getType().equals(Token.Type.BREAK)) return new BreakKeyword(tokens.consume().getPosition());
         else if(token.getType().equals(Token.Type.CONTINUE)) return new ContinueKeyword(tokens.consume().getPosition());
@@ -401,7 +399,7 @@ public class Parser {
         
         ParserUtil.checkType(tokens.consume(), Token.Type.ASSIGNMENT);
         
-        Returnable<?> value = parseExpression(tokens, true, scopeBuilder);
+        Expression<?> value = parseExpression(tokens, true, scopeBuilder);
         
         String id = identifier.getContent();
         
@@ -410,9 +408,9 @@ public class Parser {
         ReturnType type = value.returnType();
         
         return switch(type) {
-            case NUMBER -> new NumAssignmentNode((Returnable<Number>) value, identifier.getPosition(), scopeBuilder.getIndex(id));
+            case NUMBER -> new NumAssignmentNode((Expression<Number>) value, identifier.getPosition(), scopeBuilder.getIndex(id));
-            case STRING -> new StrAssignmentNode((Returnable<String>) value, identifier.getPosition(), scopeBuilder.getIndex(id));
+            case STRING -> new StrAssignmentNode((Expression<String>) value, identifier.getPosition(), scopeBuilder.getIndex(id));
-            case BOOLEAN -> new BoolAssignmentNode((Returnable<Boolean>) value, identifier.getPosition(), scopeBuilder.getIndex(id));
+            case BOOLEAN -> new BoolAssignmentNode((Expression<Boolean>) value, identifier.getPosition(), scopeBuilder.getIndex(id));
             default -> throw new ParseException("Illegal type for variable assignment: " + type, value.getPosition());
         };
     }
@@ -427,11 +425,11 @@ public class Parser {
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_BEGIN); // Second is body begin
         
         
-        List<Returnable<?>> args = getArgs(tokens, scopeBuilder); // Extract arguments, consume the rest.
+        List<Expression<?>> args = getArgs(tokens, scopeBuilder); // Extract arguments, consume the rest.
         
         ParserUtil.checkType(tokens.consume(), Token.Type.GROUP_END); // Remove body end
         
-        if(fullStatement) ParserUtil.checkType(tokens.get(), Token.Type.STATEMENT_END);
+        if(fullStatement) ParserUtil.checkType(tokens.current(), Token.Type.STATEMENT_END);
         
         if(ignoredFunctions.contains(identifier.getContent())) {
             return Function.NULL;
@@ -444,7 +442,7 @@ public class Parser {
                 throw new ParseException("Expected " + builder.argNumber() + " arguments, found " + args.size(), identifier.getPosition());
             
             for(int i = 0; i < args.size(); i++) {
-                Returnable<?> argument = args.get(i);
+                Expression<?> argument = args.get(i);
                 if(builder.getArgument(i) == null)
                     throw new ParseException("Unexpected argument at position " + i + " in function " + identifier.getContent(),
                                              identifier.getPosition());
@@ -455,13 +453,13 @@ public class Parser {
         throw new UnsupportedOperationException("Unsupported function: " + identifier.getContent());
     }
     
-    private List<Returnable<?>> getArgs(Tokenizer tokens, ScopeBuilder scopeBuilder) {
+    private List<Expression<?>> getArgs(Tokenizer tokens, ScopeBuilder scopeBuilder) {
-        List<Returnable<?>> args = new ArrayList<>();
+        List<Expression<?>> args = new ArrayList<>();
         
-        while(!tokens.get().getType().equals(Token.Type.GROUP_END)) {
+        while(!tokens.current().getType().equals(Token.Type.GROUP_END)) {
             args.add(parseExpression(tokens, true, scopeBuilder));
-            ParserUtil.checkType(tokens.get(), Token.Type.SEPARATOR, Token.Type.GROUP_END);
+            ParserUtil.checkType(tokens.current(), Token.Type.SEPARATOR, Token.Type.GROUP_END);
-            if(tokens.get().getType().equals(Token.Type.SEPARATOR)) tokens.consume();
+            if(tokens.current().getType().equals(Token.Type.SEPARATOR)) tokens.consume();
         }
         return args;
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/ParserUtil.java

@@ -13,7 +13,7 @@ import java.util.List;
 import java.util.Map;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.tokenizer.Token;
 
 
@@ -56,31 +56,31 @@ public class ParserUtil {
         throw new ParseException("Expected " + Arrays.toString(expected) + " but found " + token.getType(), token.getPosition());
     }
     
-    public static void checkReturnType(Returnable<?> returnable, Returnable.ReturnType... types) {
+    public static void checkReturnType(Expression<?> returnable, Expression.ReturnType... types) {
-        for(Returnable.ReturnType type : types) if(returnable.returnType().equals(type)) return;
+        for(Expression.ReturnType type : types) if(returnable.returnType().equals(type)) return;
         throw new ParseException("Expected " + Arrays.toString(types) + " but found " + returnable.returnType(), returnable.getPosition());
     }
     
-    public static void checkArithmeticOperation(Returnable<?> left, Returnable<?> right, Token operation) {
+    public static void checkArithmeticOperation(Expression<?> left, Expression<?> right, Token operation) {
-        if(!left.returnType().equals(Returnable.ReturnType.NUMBER) || !right.returnType().equals(Returnable.ReturnType.NUMBER)) {
+        if(!left.returnType().equals(Expression.ReturnType.NUMBER) || !right.returnType().equals(Expression.ReturnType.NUMBER)) {
             throw new ParseException(
                     "Operation " + operation.getType() + " not supported between " + left.returnType() + " and " + right.returnType(),
                     operation.getPosition());
         }
     }
     
-    public static void checkBooleanOperation(Returnable<?> left, Returnable<?> right, Token operation) {
+    public static void checkBooleanOperation(Expression<?> left, Expression<?> right, Token operation) {
-        if(!left.returnType().equals(Returnable.ReturnType.BOOLEAN) || !right.returnType().equals(Returnable.ReturnType.BOOLEAN)) {
+        if(!left.returnType().equals(Expression.ReturnType.BOOLEAN) || !right.returnType().equals(Expression.ReturnType.BOOLEAN)) {
             throw new ParseException(
                     "Operation " + operation.getType() + " not supported between " + left.returnType() + " and " + right.returnType(),
                     operation.getPosition());
         }
     }
     
-    public static void checkVarType(Token token, Returnable.ReturnType returnType) {
+    public static void checkVarType(Token token, Expression.ReturnType returnType) {
-        if(returnType.equals(Returnable.ReturnType.STRING) && token.getType().equals(Token.Type.STRING_VARIABLE)) return;
+        if(returnType.equals(Expression.ReturnType.STRING) && token.getType().equals(Token.Type.STRING_VARIABLE)) return;
-        if(returnType.equals(Returnable.ReturnType.NUMBER) && token.getType().equals(Token.Type.NUMBER_VARIABLE)) return;
+        if(returnType.equals(Expression.ReturnType.NUMBER) && token.getType().equals(Token.Type.NUMBER_VARIABLE)) return;
-        if(returnType.equals(Returnable.ReturnType.BOOLEAN) && token.getType().equals(Token.Type.BOOLEAN_VARIABLE)) return;
+        if(returnType.equals(Expression.ReturnType.BOOLEAN) && token.getType().equals(Token.Type.BOOLEAN_VARIABLE)) return;
         throw new ParseException("Type mismatch, cannot convert from " + returnType + " to " + token.getType(), token.getPosition());
     }
     
@@ -96,11 +96,11 @@ public class ParserUtil {
             throw new ParseException("Expected binary operator, found " + token.getType(), token.getPosition());
     }
     
-    public static Returnable.ReturnType getVariableReturnType(Token varToken) {
+    public static Expression.ReturnType getVariableReturnType(Token varToken) {
         return switch(varToken.getType()) {
-            case NUMBER_VARIABLE -> Returnable.ReturnType.NUMBER;
+            case NUMBER_VARIABLE -> Expression.ReturnType.NUMBER;
-            case STRING_VARIABLE -> Returnable.ReturnType.STRING;
+            case STRING_VARIABLE -> Expression.ReturnType.STRING;
-            case BOOLEAN_VARIABLE -> Returnable.ReturnType.BOOLEAN;
+            case BOOLEAN_VARIABLE -> Expression.ReturnType.BOOLEAN;
             default -> throw new ParseException("Unexpected token " + varToken.getType() + "; expected variable declaration",
                                                 varToken.getPosition());
         };

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/exceptions/ParseException.java

@@ -9,20 +9,20 @@ package com.dfsek.terra.addons.terrascript.parser.exceptions;
 
 import java.io.Serial;
 
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ParseException extends RuntimeException {
     @Serial
     private static final long serialVersionUID = 6744390543046766386L;
-    private final Position position;
+    private final SourcePosition position;
     
-    public ParseException(String message, Position position) {
+    public ParseException(String message, SourcePosition position) {
         super(message);
         this.position = position;
     }
     
-    public ParseException(String message, Position position, Throwable cause) {
+    public ParseException(String message, SourcePosition position, Throwable cause) {
         super(message, cause);
         this.position = position;
     }
@@ -32,7 +32,7 @@ public class ParseException extends RuntimeException {
         return super.getMessage() + ": " + position;
     }
     
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Block.java

@@ -9,22 +9,23 @@ package com.dfsek.terra.addons.terrascript.parser.lang;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.parser.lang.Block.ReturnInfo;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public class Block implements Item<Block.ReturnInfo<?>> {
+public class Block implements Statement<ReturnInfo<?>> {
-    private final List<Item<?>> items;
+    private final List<Statement<?>> items;
-    private final Position position;
+    private final SourcePosition position;
     
-    public Block(List<Item<?>> items, Position position) {
+    public Block(List<Statement<?>> items, SourcePosition position) {
         this.items = items;
         this.position = position;
     }
     
     @Override
-    public ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
-        for(Item<?> item : items) {
+        for(Statement<?> item : items) {
-            Object result = item.apply(implementationArguments, scope);
+            Object result = item.invoke(implementationArguments, scope);
             if(result instanceof ReturnInfo<?> level) {
                 if(!level.getLevel().equals(ReturnLevel.NONE)) return level;
             }
@@ -33,7 +34,7 @@ public class Block implements Item<Block.ReturnInfo<?>> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Executable.java

@@ -14,6 +14,6 @@ public class Executable {
     }
 
     public boolean execute(ImplementationArguments arguments) {
-        return script.apply(arguments, scope.get()).getLevel() != Block.ReturnLevel.FAIL;
+        return script.invoke(arguments, scope.get()).getLevel() != Block.ReturnLevel.FAIL;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Expression.java

@@ -7,7 +7,7 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang;
 
-public interface Returnable<T> extends Item<T> {
+public interface Expression<T> extends Statement<T> {
     ReturnType returnType();
     
     enum ReturnType {

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/ImplementationArguments.java

@@ -8,7 +8,7 @@
 package com.dfsek.terra.addons.terrascript.parser.lang;
 
 /**
- * Arguments passed to {@link Item}s by the implementation
+ * Arguments passed to {@link Statement}s by the implementation
  */
 public interface ImplementationArguments {
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Item.java

@@ -1,25 +0,0 @@
-/*
- * Copyright (c) 2020-2021 Polyhedral Development
- *
- * The Terra Core Addons are licensed under the terms of the MIT License. For more details,
- * reference the LICENSE file in this module's root directory.
- */
-
-package com.dfsek.terra.addons.terrascript.parser.lang;
-
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
-
-
-public interface Item<T> {
-    T apply(ImplementationArguments implementationArguments, Scope scope);
-    
-    default double applyDouble(ImplementationArguments implementationArguments, Scope scope) {
-        throw new UnsupportedOperationException("Cannot apply " + this + " as double");
-    }
-    
-    default boolean applyBoolean(ImplementationArguments implementationArguments, Scope scope) {
-        throw new UnsupportedOperationException("Cannot apply " + this + " as double");
-    }
-    
-    Position getPosition();
-}

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Keyword.java

@@ -7,5 +7,5 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang;
 
-public interface Keyword<T> extends Returnable<T> {
+public interface Keyword<T> extends Expression<T> {
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Scope.java

@@ -6,7 +6,7 @@ import net.jafama.FastMath;
 import java.util.HashMap;
 import java.util.Map;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable.ReturnType;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression.ReturnType;
 import com.dfsek.terra.api.util.generic.pair.Pair;
 
 

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/Statement.java

@@ -7,5 +7,19 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang;
 
-public interface Statement extends Item<Boolean> {
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
+
+
+public interface Statement<T> {
+    T invoke(ImplementationArguments implementationArguments, Scope scope);
+    
+    default double applyDouble(ImplementationArguments implementationArguments, Scope scope) {
+        throw new UnsupportedOperationException("Cannot apply " + this + " as double");
+    }
+    
+    default boolean applyBoolean(ImplementationArguments implementationArguments, Scope scope) {
+        throw new UnsupportedOperationException("Cannot apply " + this + " as double");
+    }
+    
+    SourcePosition getPosition();
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/constants/BooleanConstant.java

@@ -9,13 +9,13 @@ package com.dfsek.terra.addons.terrascript.parser.lang.constants;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BooleanConstant extends ConstantExpression<Boolean> {
     private final boolean constant;
 
-    public BooleanConstant(Boolean constant, Position position) {
+    public BooleanConstant(Boolean constant, SourcePosition position) {
         super(constant, position);
         this.constant = constant;
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/constants/ConstantExpression.java

@@ -8,27 +8,27 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.constants;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public abstract class ConstantExpression<T> implements Returnable<T> {
+public abstract class ConstantExpression<T> implements Expression<T> {
     private final T constant;
-    private final Position position;
+    private final SourcePosition position;
     
-    public ConstantExpression(T constant, Position position) {
+    public ConstantExpression(T constant, SourcePosition position) {
         this.constant = constant;
         this.position = position;
     }
     
     @Override
-    public T apply(ImplementationArguments implementationArguments, Scope scope) {
+    public T invoke(ImplementationArguments implementationArguments, Scope scope) {
         return constant;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/constants/NumericConstant.java

@@ -8,15 +8,15 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.constants;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class NumericConstant extends ConstantExpression<Number> {
     private final double constant;
 
-    public NumericConstant(Number constant, Position position) {
+    public NumericConstant(Number constant, SourcePosition position) {
         super(constant, position);
         this.constant = constant.doubleValue();
     }
@@ -27,7 +27,7 @@ public class NumericConstant extends ConstantExpression<Number> {
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.NUMBER;
+        return Expression.ReturnType.NUMBER;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/constants/StringConstant.java

@@ -7,17 +7,17 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.constants;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class StringConstant extends ConstantExpression<String> {
-    public StringConstant(String constant, Position position) {
+    public StringConstant(String constant, SourcePosition position) {
         super(constant, position);
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.STRING;
+        return Expression.ReturnType.STRING;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/functions/Function.java

@@ -8,12 +8,12 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.functions;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public interface Function<T> extends Returnable<T> {
+public interface Function<T> extends Expression<T> {
     Function<?> NULL = new Function<>() {
         @Override
         public ReturnType returnType() {
@@ -21,23 +21,23 @@ public interface Function<T> extends Returnable<T> {
         }
 
         @Override
-        public Object apply(ImplementationArguments implementationArguments, Scope scope) {
+        public Object invoke(ImplementationArguments implementationArguments, Scope scope) {
             return null;
         }
 
         @Override
-        public Position getPosition() {
+        public SourcePosition getPosition() {
             return null;
         }
     };
     
     @Override
     default double applyDouble(ImplementationArguments implementationArguments, Scope scope) {
-        return ((Number) apply(implementationArguments, scope)).doubleValue();
+        return ((Number) invoke(implementationArguments, scope)).doubleValue();
     }
     
     @Override
     default boolean applyBoolean(ImplementationArguments implementationArguments, Scope scope) {
-        return (Boolean) apply(implementationArguments, scope);
+        return (Boolean) invoke(implementationArguments, scope);
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/functions/FunctionBuilder.java

@@ -9,14 +9,14 @@ package com.dfsek.terra.addons.terrascript.parser.lang.functions;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public interface FunctionBuilder<T extends Function<?>> {
-    T build(List<Returnable<?>> argumentList, Position position);
+    T build(List<Expression<?>> argumentList, SourcePosition position);
     
     int argNumber();
     
-    Returnable.ReturnType getArgument(int position);
+    Expression.ReturnType getArgument(int position);
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/flow/BreakKeyword.java

@@ -11,23 +11,23 @@ import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BreakKeyword implements Keyword<Block.ReturnInfo<?>> {
-    private final Position position;
+    private final SourcePosition position;
     
-    public BreakKeyword(Position position) {
+    public BreakKeyword(SourcePosition position) {
         this.position = position;
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
         return new Block.ReturnInfo<>(Block.ReturnLevel.BREAK, null);
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/flow/ContinueKeyword.java

@@ -11,23 +11,23 @@ import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ContinueKeyword implements Keyword<Block.ReturnInfo<?>> {
-    private final Position position;
+    private final SourcePosition position;
     
-    public ContinueKeyword(Position position) {
+    public ContinueKeyword(SourcePosition position) {
         this.position = position;
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
         return new Block.ReturnInfo<>(Block.ReturnLevel.CONTINUE, null);
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/flow/FailKeyword.java

@@ -11,23 +11,23 @@ import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class FailKeyword implements Keyword<Block.ReturnInfo<?>> {
-    private final Position position;
+    private final SourcePosition position;
     
-    public FailKeyword(Position position) {
+    public FailKeyword(SourcePosition position) {
         this.position = position;
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
         return new Block.ReturnInfo<>(Block.ReturnLevel.FAIL, null);
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/flow/ReturnKeyword.java

@@ -11,23 +11,23 @@ import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ReturnKeyword implements Keyword<Block.ReturnInfo<?>> {
-    private final Position position;
+    private final SourcePosition position;
     
-    public ReturnKeyword(Position position) {
+    public ReturnKeyword(SourcePosition position) {
         this.position = position;
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
         return new Block.ReturnInfo<>(Block.ReturnLevel.RETURN, null);
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/looplike/ForKeyword.java

@@ -9,21 +9,21 @@ package com.dfsek.terra.addons.terrascript.parser.lang.keywords.looplike;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Item;
+import com.dfsek.terra.addons.terrascript.parser.lang.Statement;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ForKeyword implements Keyword<Block.ReturnInfo<?>> {
     private final Block conditional;
-    private final Item<?> initializer;
+    private final Statement<?> initializer;
-    private final Returnable<Boolean> statement;
+    private final Expression<Boolean> statement;
-    private final Item<?> incrementer;
+    private final Statement<?> incrementer;
-    private final Position position;
+    private final SourcePosition position;
     
-    public ForKeyword(Block conditional, Item<?> initializer, Returnable<Boolean> statement, Item<?> incrementer, Position position) {
+    public ForKeyword(Block conditional, Statement<?> initializer, Expression<Boolean> statement, Statement<?> incrementer, SourcePosition position) {
         this.conditional = conditional;
         this.initializer = initializer;
         this.statement = statement;
@@ -32,11 +32,11 @@ public class ForKeyword implements Keyword<Block.ReturnInfo<?>> {
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
-        for(initializer.apply(implementationArguments, scope);
+        for(initializer.invoke(implementationArguments, scope);
-            statement.apply(implementationArguments, scope);
+            statement.invoke(implementationArguments, scope);
-            incrementer.apply(implementationArguments, scope)) {
+            incrementer.invoke(implementationArguments, scope)) {
-            Block.ReturnInfo<?> level = conditional.apply(implementationArguments, scope);
+            Block.ReturnInfo<?> level = conditional.invoke(implementationArguments, scope);
             if(level.getLevel().equals(Block.ReturnLevel.BREAK)) break;
             if(level.getLevel().isReturnFast()) return level;
         }
@@ -44,7 +44,7 @@ public class ForKeyword implements Keyword<Block.ReturnInfo<?>> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/looplike/IfKeyword.java

@@ -14,21 +14,21 @@ import java.util.List;
 import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.util.generic.pair.Pair;
 
 
 public class IfKeyword implements Keyword<Block.ReturnInfo<?>> {
     private final Block conditional;
-    private final Returnable<Boolean> statement;
+    private final Expression<Boolean> statement;
-    private final Position position;
+    private final SourcePosition position;
-    private final List<Pair<Returnable<Boolean>, Block>> elseIf;
+    private final List<Pair<Expression<Boolean>, Block>> elseIf;
     private final Block elseBlock;
     
-    public IfKeyword(Block conditional, Returnable<Boolean> statement, List<Pair<Returnable<Boolean>, Block>> elseIf,
+    public IfKeyword(Block conditional, Expression<Boolean> statement, List<Pair<Expression<Boolean>, Block>> elseIf,
-                     @Nullable Block elseBlock, Position position) {
+                     @Nullable Block elseBlock, SourcePosition position) {
         this.conditional = conditional;
         this.statement = statement;
         this.position = position;
@@ -37,21 +37,21 @@ public class IfKeyword implements Keyword<Block.ReturnInfo<?>> {
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
-        if(statement.apply(implementationArguments, scope)) return conditional.apply(implementationArguments, scope);
+        if(statement.invoke(implementationArguments, scope)) return conditional.invoke(implementationArguments, scope);
         else {
-            for(Pair<Returnable<Boolean>, Block> pair : elseIf) {
+            for(Pair<Expression<Boolean>, Block> pair : elseIf) {
-                if(pair.getLeft().apply(implementationArguments, scope)) {
+                if(pair.getLeft().invoke(implementationArguments, scope)) {
-                    return pair.getRight().apply(implementationArguments, scope);
+                    return pair.getRight().invoke(implementationArguments, scope);
                 }
             }
-            if(elseBlock != null) return elseBlock.apply(implementationArguments, scope);
+            if(elseBlock != null) return elseBlock.invoke(implementationArguments, scope);
         }
         return new Block.ReturnInfo<>(Block.ReturnLevel.NONE, null);
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/keywords/looplike/WhileKeyword.java

@@ -10,26 +10,26 @@ package com.dfsek.terra.addons.terrascript.parser.lang.keywords.looplike;
 import com.dfsek.terra.addons.terrascript.parser.lang.Block;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Keyword;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class WhileKeyword implements Keyword<Block.ReturnInfo<?>> {
     private final Block conditional;
-    private final Returnable<Boolean> statement;
+    private final Expression<Boolean> statement;
-    private final Position position;
+    private final SourcePosition position;
     
-    public WhileKeyword(Block conditional, Returnable<Boolean> statement, Position position) {
+    public WhileKeyword(Block conditional, Expression<Boolean> statement, SourcePosition position) {
         this.conditional = conditional;
         this.statement = statement;
         this.position = position;
     }
     
     @Override
-    public Block.ReturnInfo<?> apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Block.ReturnInfo<?> invoke(ImplementationArguments implementationArguments, Scope scope) {
-        while(statement.apply(implementationArguments, scope)) {
+        while(statement.invoke(implementationArguments, scope)) {
-            Block.ReturnInfo<?> level = conditional.apply(implementationArguments, scope);
+            Block.ReturnInfo<?> level = conditional.invoke(implementationArguments, scope);
             if(level.getLevel().equals(Block.ReturnLevel.BREAK)) break;
             if(level.getLevel().isReturnFast()) return level;
         }
@@ -37,7 +37,7 @@ public class WhileKeyword implements Keyword<Block.ReturnInfo<?>> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/BinaryOperation.java

@@ -7,23 +7,23 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public abstract class BinaryOperation<I, O> implements Returnable<O> {
+public abstract class BinaryOperation<I, O> implements Expression<O> {
-    protected final Returnable<I> left;
+    protected final Expression<I> left;
-    protected final Returnable<I> right;
+    protected final Expression<I> right;
-    private final Position start;
+    private final SourcePosition start;
     
-    public BinaryOperation(Returnable<I> left, Returnable<I> right, Position start) {
+    public BinaryOperation(Expression<I> left, Expression<I> right, SourcePosition start) {
         this.left = left;
         this.right = right;
         this.start = start;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return start;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/BooleanAndOperation.java

@@ -8,13 +8,13 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BooleanAndOperation extends BinaryOperation<Boolean, Boolean> {
-    public BooleanAndOperation(Returnable<Boolean> left, Returnable<Boolean> right, Position start) {
+    public BooleanAndOperation(Expression<Boolean> left, Expression<Boolean> right, SourcePosition start) {
         super(left, right, start);
     }
     
@@ -24,7 +24,7 @@ public class BooleanAndOperation extends BinaryOperation<Boolean, Boolean> {
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/BooleanNotOperation.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BooleanNotOperation extends UnaryOperation<Boolean> {
-    public BooleanNotOperation(Returnable<Boolean> input, Position position) {
+    public BooleanNotOperation(Expression<Boolean> input, SourcePosition position) {
         super(input, position);
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/BooleanOrOperation.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BooleanOrOperation extends BinaryOperation<Boolean, Boolean> {
-    public BooleanOrOperation(Returnable<Boolean> left, Returnable<Boolean> right, Position start) {
+    public BooleanOrOperation(Expression<Boolean> left, Expression<Boolean> right, SourcePosition start) {
         super(left, right, start);
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/ConcatenationOperation.java

@@ -8,13 +8,13 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ConcatenationOperation extends BinaryOperation<Object, Object> {
-    public ConcatenationOperation(Returnable<Object> left, Returnable<Object> right, Position position) {
+    public ConcatenationOperation(Expression<Object> left, Expression<Object> right, SourcePosition position) {
         super(left, right, position);
     }
     
@@ -30,12 +30,12 @@ public class ConcatenationOperation extends BinaryOperation<Object, Object> {
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.STRING;
+        return Expression.ReturnType.STRING;
     }
     
     @Override
-    public Object apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Object invoke(ImplementationArguments implementationArguments, Scope scope) {
-        return toString(left.apply(implementationArguments, scope)) + toString(right.apply(implementationArguments, scope));
+        return toString(left.invoke(implementationArguments, scope)) + toString(right.invoke(implementationArguments, scope));
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/DivisionOperation.java

@@ -8,23 +8,23 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class DivisionOperation extends BinaryOperation<Number, Number> {
-    public DivisionOperation(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public DivisionOperation(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.NUMBER;
+        return Expression.ReturnType.NUMBER;
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/ModuloOperation.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ModuloOperation extends BinaryOperation<Number, Number> {
-    public ModuloOperation(Returnable<Number> left, Returnable<Number> right, Position start) {
+    public ModuloOperation(Expression<Number> left, Expression<Number> right, SourcePosition start) {
         super(left, right, start);
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/MultiplicationOperation.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class MultiplicationOperation extends BinaryOperation<Number, Number> {
-    public MultiplicationOperation(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public MultiplicationOperation(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/NegationOperation.java

@@ -8,13 +8,13 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class NegationOperation extends UnaryOperation<Number> {
-    public NegationOperation(Returnable<Number> input, Position position) {
+    public NegationOperation(Expression<Number> input, SourcePosition position) {
         super(input, position);
     }
     
@@ -24,7 +24,7 @@ public class NegationOperation extends UnaryOperation<Number> {
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/NumberAdditionOperation.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class NumberAdditionOperation extends BinaryOperation<Number, Number> {
-    public NumberAdditionOperation(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public NumberAdditionOperation(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/SubtractionOperation.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class SubtractionOperation extends BinaryOperation<Number, Number> {
-    public SubtractionOperation(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public SubtractionOperation(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/UnaryOperation.java

@@ -7,21 +7,21 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.operations;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public abstract class UnaryOperation<T> implements Returnable<T> {
+public abstract class UnaryOperation<T> implements Expression<T> {
-    protected final Returnable<T> input;
+    protected final Expression<T> input;
-    private final Position position;
+    private final SourcePosition position;
     
-    public UnaryOperation(Returnable<T> input, Position position) {
+    public UnaryOperation(Expression<T> input, SourcePosition position) {
         this.input = input;
         this.position = position;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/statements/EqualsStatement.java

@@ -10,35 +10,35 @@ package com.dfsek.terra.addons.terrascript.parser.lang.operations.statements;
 import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.operations.BinaryOperation;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 import static com.dfsek.terra.api.util.MathUtil.EPSILON;
 
 
 public class EqualsStatement extends BinaryOperation<Object, Boolean> {
     
-    public EqualsStatement(Returnable<Object> left, Returnable<Object> right, Position position) {
+    public EqualsStatement(Expression<Object> left, Expression<Object> right, SourcePosition position) {
         super(left, right, position);
     }
     
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     
     @Override
     public boolean applyBoolean(ImplementationArguments implementationArguments, Scope scope) {
-        Object leftValue = left.apply(implementationArguments, scope);
+        Object leftValue = left.invoke(implementationArguments, scope);
-        Object rightValue = right.apply(implementationArguments, scope);
+        Object rightValue = right.invoke(implementationArguments, scope);
         if(leftValue instanceof Number l && rightValue instanceof Number r) {
             return FastMath.abs(l.doubleValue() - r.doubleValue()) <= EPSILON;
         }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/statements/GreaterOrEqualsThanStatement.java

@@ -8,24 +8,24 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations.statements;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.operations.BinaryOperation;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class GreaterOrEqualsThanStatement extends BinaryOperation<Number, Boolean> {
-    public GreaterOrEqualsThanStatement(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public GreaterOrEqualsThanStatement(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/statements/GreaterThanStatement.java

@@ -8,20 +8,20 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations.statements;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.operations.BinaryOperation;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class GreaterThanStatement extends BinaryOperation<Number, Boolean> {
-    public GreaterThanStatement(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public GreaterThanStatement(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     
@@ -31,7 +31,7 @@ public class GreaterThanStatement extends BinaryOperation<Number, Boolean> {
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/statements/LessThanOrEqualsStatement.java

@@ -8,20 +8,20 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations.statements;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.operations.BinaryOperation;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class LessThanOrEqualsStatement extends BinaryOperation<Number, Boolean> {
-    public LessThanOrEqualsStatement(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public LessThanOrEqualsStatement(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     
@@ -31,7 +31,7 @@ public class LessThanOrEqualsStatement extends BinaryOperation<Number, Boolean>
     }
 
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/statements/LessThanStatement.java

@@ -8,20 +8,20 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.operations.statements;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.operations.BinaryOperation;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class LessThanStatement extends BinaryOperation<Number, Boolean> {
-    public LessThanStatement(Returnable<Number> left, Returnable<Number> right, Position position) {
+    public LessThanStatement(Expression<Number> left, Expression<Number> right, SourcePosition position) {
         super(left, right, position);
     }
     
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     
@@ -31,7 +31,7 @@ public class LessThanStatement extends BinaryOperation<Number, Boolean> {
     }
 
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/operations/statements/NotEqualsStatement.java

@@ -10,28 +10,28 @@ package com.dfsek.terra.addons.terrascript.parser.lang.operations.statements;
 import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.operations.BinaryOperation;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 import static com.dfsek.terra.api.util.MathUtil.EPSILON;
 
 
 public class NotEqualsStatement extends BinaryOperation<Object, Boolean> {
-    public NotEqualsStatement(Returnable<Object> left, Returnable<Object> right, Position position) {
+    public NotEqualsStatement(Expression<Object> left, Expression<Object> right, SourcePosition position) {
         super(left, right, position);
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     
     @Override
     public boolean applyBoolean(ImplementationArguments implementationArguments, Scope scope) {
-        Object leftValue = left.apply(implementationArguments, scope);
+        Object leftValue = left.invoke(implementationArguments, scope);
-        Object rightValue = right.apply(implementationArguments, scope);
+        Object rightValue = right.invoke(implementationArguments, scope);
         if(leftValue instanceof Number l && rightValue instanceof Number r) {
             return FastMath.abs(l.doubleValue() - r.doubleValue()) > EPSILON;
         }
@@ -40,7 +40,7 @@ public class NotEqualsStatement extends BinaryOperation<Object, Boolean> {
     }
     
     @Override
-    public Returnable.ReturnType returnType() {
+    public Expression.ReturnType returnType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/BooleanVariable.java

@@ -7,15 +7,15 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.variables;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BooleanVariable implements Variable<Boolean> {
-    private final Position position;
+    private final SourcePosition position;
     private Boolean value;
     
-    public BooleanVariable(Boolean value, Position position) {
+    public BooleanVariable(Boolean value, SourcePosition position) {
         this.value = value;
         this.position = position;
     }
@@ -31,12 +31,12 @@ public class BooleanVariable implements Variable<Boolean> {
     }
     
     @Override
-    public Returnable.ReturnType getType() {
+    public Expression.ReturnType getType() {
-        return Returnable.ReturnType.BOOLEAN;
+        return Expression.ReturnType.BOOLEAN;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/NumberVariable.java

@@ -7,15 +7,15 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.variables;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class NumberVariable implements Variable<Number> {
-    private final Position position;
+    private final SourcePosition position;
     private Number value;
     
-    public NumberVariable(Number value, Position position) {
+    public NumberVariable(Number value, SourcePosition position) {
         this.value = value;
         this.position = position;
     }
@@ -31,12 +31,12 @@ public class NumberVariable implements Variable<Number> {
     }
     
     @Override
-    public Returnable.ReturnType getType() {
+    public Expression.ReturnType getType() {
-        return Returnable.ReturnType.NUMBER;
+        return Expression.ReturnType.NUMBER;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/StringVariable.java

@@ -7,15 +7,15 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.variables;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class StringVariable implements Variable<String> {
-    private final Position position;
+    private final SourcePosition position;
     private String value;
     
-    public StringVariable(String value, Position position) {
+    public StringVariable(String value, SourcePosition position) {
         this.value = value;
         this.position = position;
     }
@@ -31,12 +31,12 @@ public class StringVariable implements Variable<String> {
     }
     
     @Override
-    public Returnable.ReturnType getType() {
+    public Expression.ReturnType getType() {
-        return Returnable.ReturnType.STRING;
+        return Expression.ReturnType.STRING;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/Variable.java

@@ -7,8 +7,8 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.variables;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public interface Variable<T> {
@@ -16,7 +16,7 @@ public interface Variable<T> {
     
     void setValue(T value);
     
-    Returnable.ReturnType getType();
+    Expression.ReturnType getType();
     
-    Position getPosition();
+    SourcePosition getPosition();
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/assign/BoolAssignmentNode.java

@@ -1,18 +1,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.variables.assign;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BoolAssignmentNode extends VariableAssignmentNode<Boolean> {
-    public BoolAssignmentNode(Returnable<Boolean> value, Position position, int index) {
+    public BoolAssignmentNode(Expression<Boolean> value, SourcePosition position, int index) {
         super(value, position, index);
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyBoolean(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/assign/NumAssignmentNode.java

@@ -1,18 +1,18 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.variables.assign;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class NumAssignmentNode extends VariableAssignmentNode<Number> {
-    public NumAssignmentNode(Returnable<Number> value, Position position, int index) {
+    public NumAssignmentNode(Expression<Number> value, SourcePosition position, int index) {
         super(value, position, index);
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return applyDouble(implementationArguments, scope);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/assign/StrAssignmentNode.java

@@ -1,19 +1,19 @@
 package com.dfsek.terra.addons.terrascript.parser.lang.variables.assign;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class StrAssignmentNode extends VariableAssignmentNode<String> {
-    public StrAssignmentNode(Returnable<String> value, Position position, int index) {
+    public StrAssignmentNode(Expression<String> value, SourcePosition position, int index) {
         super(value, position, index);
     }
     
     @Override
-    public String apply(ImplementationArguments implementationArguments, Scope scope) {
+    public String invoke(ImplementationArguments implementationArguments, Scope scope) {
-        String val = value.apply(implementationArguments, scope);
+        String val = value.invoke(implementationArguments, scope);
         scope.setStr(index, val);
         return val;
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/assign/VariableAssignmentNode.java

@@ -7,25 +7,25 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.variables.assign;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Item;
+import com.dfsek.terra.addons.terrascript.parser.lang.Statement;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public abstract class VariableAssignmentNode<T> implements Item<T> {
+public abstract class VariableAssignmentNode<T> implements Statement<T> {
-    protected final Returnable<T> value;
+    protected final Expression<T> value;
     protected final int index;
-    private final Position position;
+    private final SourcePosition position;
     
     
-    public VariableAssignmentNode(Returnable<T> value, Position position, int index) {
+    public VariableAssignmentNode(Expression<T> value, SourcePosition position, int index) {
         this.value = value;
         this.index = index;
         this.position = position;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/reference/BoolVariableReferenceNode.java

@@ -2,16 +2,16 @@ package com.dfsek.terra.addons.terrascript.parser.lang.variables.reference;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BoolVariableReferenceNode extends VariableReferenceNode<Boolean> {
-    public BoolVariableReferenceNode(Position position, ReturnType type, int index) {
+    public BoolVariableReferenceNode(SourcePosition position, ReturnType type, int index) {
         super(position, type, index);
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         return scope.getBool(index);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/reference/NumVariableReferenceNode.java

@@ -2,16 +2,16 @@ package com.dfsek.terra.addons.terrascript.parser.lang.variables.reference;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class NumVariableReferenceNode extends VariableReferenceNode<Number> {
-    public NumVariableReferenceNode(Position position, ReturnType type, int index) {
+    public NumVariableReferenceNode(SourcePosition position, ReturnType type, int index) {
         super(position, type, index);
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return scope.getNum(index);
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/reference/StrVariableReferenceNode.java

@@ -2,16 +2,16 @@ package com.dfsek.terra.addons.terrascript.parser.lang.variables.reference;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class StrVariableReferenceNode extends VariableReferenceNode<String> {
-    public StrVariableReferenceNode(Position position, ReturnType type, int index) {
+    public StrVariableReferenceNode(SourcePosition position, ReturnType type, int index) {
         super(position, type, index);
     }
     
     @Override
-    public String apply(ImplementationArguments implementationArguments, Scope scope) {
+    public String invoke(ImplementationArguments implementationArguments, Scope scope) {
         return scope.getStr(index);
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/parser/lang/variables/reference/VariableReferenceNode.java

@@ -7,16 +7,16 @@
 
 package com.dfsek.terra.addons.terrascript.parser.lang.variables.reference;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
-public abstract class VariableReferenceNode<T> implements Returnable<T> {
+public abstract class VariableReferenceNode<T> implements Expression<T> {
     protected final int index;
-    private final Position position;
+    private final SourcePosition position;
     private final ReturnType type;
     
-    public VariableReferenceNode(Position position, ReturnType type, int index) {
+    public VariableReferenceNode(SourcePosition position, ReturnType type, int index) {
         this.position = position;
         this.type = type;
         this.index = index;
@@ -28,7 +28,7 @@ public abstract class VariableReferenceNode<T> implements Returnable<T> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/StructureScript.java

@@ -19,7 +19,7 @@ import java.util.Random;
 
 import com.dfsek.terra.addons.terrascript.parser.Parser;
 import com.dfsek.terra.addons.terrascript.parser.lang.Executable;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.builders.BinaryNumberFunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.builders.BiomeFunctionBuilder;
@@ -58,12 +58,12 @@ public class StructureScript implements Structure, Keyed<StructureScript> {
     private final Platform platform;
     
     @SuppressWarnings("rawtypes")
-    public StructureScript(InputStream inputStream, RegistryKey id, Platform platform, Registry<Structure> registry,
+    public StructureScript(InputStream source, RegistryKey id, Platform platform, Registry<Structure> structureRegistry,
                            Registry<LootTable> lootRegistry,
                            Registry<FunctionBuilder> functionRegistry) {
         Parser parser;
         try {
-            parser = new Parser(IOUtils.toString(inputStream, Charset.defaultCharset()));
+            parser = new Parser(IOUtils.toString(source, Charset.defaultCharset()));
         } catch(IOException e) {
             throw new RuntimeException(e);
         }
@@ -76,7 +76,7 @@ public class StructureScript implements Structure, Keyed<StructureScript> {
         parser
                 .registerFunction("block", new BlockFunctionBuilder(platform))
                 .registerFunction("debugBlock", new BlockFunctionBuilder(platform))
-                .registerFunction("structure", new StructureFunctionBuilder(registry, platform))
+                .registerFunction("structure", new StructureFunctionBuilder(structureRegistry, platform))
                 .registerFunction("randomInt", new RandomFunctionBuilder())
                 .registerFunction("recursions", new RecursionsFunctionBuilder())
                 .registerFunction("setMark", new SetMarkFunctionBuilder())
@@ -89,15 +89,15 @@ public class StructureScript implements Structure, Keyed<StructureScript> {
                 .registerFunction("state", new StateFunctionBuilder(platform))
                 .registerFunction("setWaterlog", new UnaryBooleanFunctionBuilder((waterlog, args) -> args.setWaterlog(waterlog)))
                 .registerFunction("originX", new ZeroArgFunctionBuilder<Number>(arguments -> arguments.getOrigin().getX(),
-                                                                                Returnable.ReturnType.NUMBER))
+                                                                                Expression.ReturnType.NUMBER))
                 .registerFunction("originY", new ZeroArgFunctionBuilder<Number>(arguments -> arguments.getOrigin().getY(),
-                                                                                Returnable.ReturnType.NUMBER))
+                                                                                Expression.ReturnType.NUMBER))
                 .registerFunction("originZ", new ZeroArgFunctionBuilder<Number>(arguments -> arguments.getOrigin().getZ(),
-                                                                                Returnable.ReturnType.NUMBER))
+                                                                                Expression.ReturnType.NUMBER))
                 .registerFunction("rotation", new ZeroArgFunctionBuilder<>(arguments -> arguments.getRotation().toString(),
-                                                                           Returnable.ReturnType.STRING))
+                                                                           Expression.ReturnType.STRING))
                 .registerFunction("rotationDegrees", new ZeroArgFunctionBuilder<>(arguments -> arguments.getRotation().getDegrees(),
-                                                                                  Returnable.ReturnType.NUMBER))
+                                                                                  Expression.ReturnType.NUMBER))
                 .registerFunction("print",
                                   new UnaryStringFunctionBuilder(string -> LOGGER.info("[TerraScript:{}] {}", id, string)))
                 .registerFunction("abs", new UnaryNumberFunctionBuilder(number -> FastMath.abs(number.doubleValue())))

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/BinaryNumberFunctionBuilder.java

@@ -11,11 +11,11 @@ import java.util.List;
 import java.util.function.BiFunction;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class BinaryNumberFunctionBuilder implements FunctionBuilder<Function<Number>> {
@@ -27,7 +27,7 @@ public class BinaryNumberFunctionBuilder implements FunctionBuilder<Function<Num
     }
     
     @Override
-    public Function<Number> build(List<Returnable<?>> argumentList, Position position) {
+    public Function<Number> build(List<Expression<?>> argumentList, SourcePosition position) {
         return new Function<>() {
             @Override
             public ReturnType returnType() {
@@ -36,13 +36,13 @@ public class BinaryNumberFunctionBuilder implements FunctionBuilder<Function<Num
             
             @SuppressWarnings("unchecked")
             @Override
-            public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+            public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
-                return function.apply(((Returnable<Number>) argumentList.get(0)).apply(implementationArguments, scope),
+                return function.apply(((Expression<Number>) argumentList.get(0)).invoke(implementationArguments, scope),
-                                      ((Returnable<Number>) argumentList.get(1)).apply(implementationArguments, scope));
+                                      ((Expression<Number>) argumentList.get(1)).invoke(implementationArguments, scope));
             }
             
             @Override
-            public Position getPosition() {
+            public SourcePosition getPosition() {
                 return position;
             }
         };
@@ -54,8 +54,8 @@ public class BinaryNumberFunctionBuilder implements FunctionBuilder<Function<Num
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
-        if(position == 0 || position == 1) return Returnable.ReturnType.NUMBER;
+        if(position == 0 || position == 1) return Expression.ReturnType.NUMBER;
         return null;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/BiomeFunctionBuilder.java

@@ -9,10 +9,10 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.BiomeFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 
 
@@ -25,9 +25,9 @@ public class BiomeFunctionBuilder implements FunctionBuilder<BiomeFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public BiomeFunction build(List<Returnable<?>> argumentList, Position position) {
+    public BiomeFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new BiomeFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new BiomeFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                 (Returnable<Number>) argumentList.get(2), position);
+                                 (Expression<Number>) argumentList.get(2), position);
     }
     
     @Override
@@ -36,9 +36,9 @@ public class BiomeFunctionBuilder implements FunctionBuilder<BiomeFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/BlockFunctionBuilder.java

@@ -10,12 +10,12 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 import java.util.List;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.BooleanConstant;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.StringConstant;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.BlockFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 
 
@@ -28,17 +28,17 @@ public class BlockFunctionBuilder implements FunctionBuilder<BlockFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public BlockFunction build(List<Returnable<?>> argumentList, Position position) {
+    public BlockFunction build(List<Expression<?>> argumentList, SourcePosition position) {
         if(argumentList.size() < 4) throw new ParseException("Expected data", position);
-        Returnable<Boolean> booleanReturnable = new BooleanConstant(true, position);
+        Expression<Boolean> booleanReturnable = new BooleanConstant(true, position);
-        if(argumentList.size() == 5) booleanReturnable = (Returnable<Boolean>) argumentList.get(4);
+        if(argumentList.size() == 5) booleanReturnable = (Expression<Boolean>) argumentList.get(4);
         if(argumentList.get(3) instanceof StringConstant) {
-            return new BlockFunction.Constant((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+            return new BlockFunction.Constant((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                              (Returnable<Number>) argumentList.get(2), (StringConstant) argumentList.get(3),
+                                              (Expression<Number>) argumentList.get(2), (StringConstant) argumentList.get(3),
                                               booleanReturnable, platform, position);
         }
-        return new BlockFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new BlockFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                 (Returnable<Number>) argumentList.get(2), (Returnable<String>) argumentList.get(3), booleanReturnable,
+                                 (Expression<Number>) argumentList.get(2), (Expression<String>) argumentList.get(3), booleanReturnable,
                                  platform, position);
     }
     
@@ -48,11 +48,11 @@ public class BlockFunctionBuilder implements FunctionBuilder<BlockFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            case 3 -> Returnable.ReturnType.STRING;
+            case 3 -> Expression.ReturnType.STRING;
-            case 4 -> Returnable.ReturnType.BOOLEAN;
+            case 4 -> Expression.ReturnType.BOOLEAN;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/CheckBlockFunctionBuilder.java

@@ -9,18 +9,18 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.CheckBlockFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class CheckBlockFunctionBuilder implements FunctionBuilder<CheckBlockFunction> {
     @SuppressWarnings("unchecked")
     @Override
-    public CheckBlockFunction build(List<Returnable<?>> argumentList, Position position) {
+    public CheckBlockFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new CheckBlockFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new CheckBlockFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                      (Returnable<Number>) argumentList.get(2), position);
+                                      (Expression<Number>) argumentList.get(2), position);
     }
     
     @Override
@@ -29,9 +29,9 @@ public class CheckBlockFunctionBuilder implements FunctionBuilder<CheckBlockFunc
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/EntityFunctionBuilder.java

@@ -9,10 +9,10 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.EntityFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 
 
@@ -25,9 +25,9 @@ public class EntityFunctionBuilder implements FunctionBuilder<EntityFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public EntityFunction build(List<Returnable<?>> argumentList, Position position) {
+    public EntityFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new EntityFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new EntityFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                  (Returnable<Number>) argumentList.get(2), (Returnable<String>) argumentList.get(3), platform, position);
+                                  (Expression<Number>) argumentList.get(2), (Expression<String>) argumentList.get(3), platform, position);
     }
     
     @Override
@@ -36,10 +36,10 @@ public class EntityFunctionBuilder implements FunctionBuilder<EntityFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            case 3 -> Returnable.ReturnType.STRING;
+            case 3 -> Expression.ReturnType.STRING;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/GetMarkFunctionBuilder.java

@@ -9,10 +9,10 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.GetMarkFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class GetMarkFunctionBuilder implements FunctionBuilder<GetMarkFunction> {
@@ -22,9 +22,9 @@ public class GetMarkFunctionBuilder implements FunctionBuilder<GetMarkFunction>
     
     @SuppressWarnings("unchecked")
     @Override
-    public GetMarkFunction build(List<Returnable<?>> argumentList, Position position) {
+    public GetMarkFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new GetMarkFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new GetMarkFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                   (Returnable<Number>) argumentList.get(2), position);
+                                   (Expression<Number>) argumentList.get(2), position);
     }
     
     @Override
@@ -33,9 +33,9 @@ public class GetMarkFunctionBuilder implements FunctionBuilder<GetMarkFunction>
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/LootFunctionBuilder.java

@@ -9,11 +9,11 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.StructureScript;
 import com.dfsek.terra.addons.terrascript.script.functions.LootFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.registry.Registry;
 import com.dfsek.terra.api.structure.LootTable;
@@ -32,9 +32,9 @@ public class LootFunctionBuilder implements FunctionBuilder<LootFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public LootFunction build(List<Returnable<?>> argumentList, Position position) {
+    public LootFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new LootFunction(registry, (Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new LootFunction(registry, (Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                (Returnable<Number>) argumentList.get(2), (Returnable<String>) argumentList.get(3), platform, position,
+                                (Expression<Number>) argumentList.get(2), (Expression<String>) argumentList.get(3), platform, position,
                                 script);
     }
     
@@ -44,10 +44,10 @@ public class LootFunctionBuilder implements FunctionBuilder<LootFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            case 3 -> Returnable.ReturnType.STRING;
+            case 3 -> Expression.ReturnType.STRING;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/PullFunctionBuilder.java

@@ -9,10 +9,10 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.PullFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 
 
@@ -25,9 +25,9 @@ public class PullFunctionBuilder implements FunctionBuilder<PullFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public PullFunction build(List<Returnable<?>> argumentList, Position position) {
+    public PullFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new PullFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new PullFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                (Returnable<Number>) argumentList.get(2), (Returnable<String>) argumentList.get(3), platform, position);
+                                (Expression<Number>) argumentList.get(2), (Expression<String>) argumentList.get(3), platform, position);
     }
     
     @Override
@@ -36,10 +36,10 @@ public class PullFunctionBuilder implements FunctionBuilder<PullFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            case 3 -> Returnable.ReturnType.STRING;
+            case 3 -> Expression.ReturnType.STRING;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/RandomFunctionBuilder.java

@@ -9,17 +9,17 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.RandomFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class RandomFunctionBuilder implements FunctionBuilder<RandomFunction> {
     @SuppressWarnings("unchecked")
     @Override
-    public RandomFunction build(List<Returnable<?>> argumentList, Position position) {
+    public RandomFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new RandomFunction((Returnable<Number>) argumentList.get(0), position);
+        return new RandomFunction((Expression<Number>) argumentList.get(0), position);
     }
     
     @Override
@@ -28,8 +28,8 @@ public class RandomFunctionBuilder implements FunctionBuilder<RandomFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
-        if(position == 0) return Returnable.ReturnType.NUMBER;
+        if(position == 0) return Expression.ReturnType.NUMBER;
         return null;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/RecursionsFunctionBuilder.java

@@ -9,15 +9,15 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.RecursionsFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class RecursionsFunctionBuilder implements FunctionBuilder<RecursionsFunction> {
     @Override
-    public RecursionsFunction build(List<Returnable<?>> argumentList, Position position) {
+    public RecursionsFunction build(List<Expression<?>> argumentList, SourcePosition position) {
         return new RecursionsFunction(position);
     }
     
@@ -27,7 +27,7 @@ public class RecursionsFunctionBuilder implements FunctionBuilder<RecursionsFunc
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return null;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/SetMarkFunctionBuilder.java

@@ -9,10 +9,10 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.SetMarkFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class SetMarkFunctionBuilder implements FunctionBuilder<SetMarkFunction> {
@@ -22,9 +22,9 @@ public class SetMarkFunctionBuilder implements FunctionBuilder<SetMarkFunction>
     
     @SuppressWarnings("unchecked")
     @Override
-    public SetMarkFunction build(List<Returnable<?>> argumentList, Position position) {
+    public SetMarkFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new SetMarkFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new SetMarkFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                   (Returnable<Number>) argumentList.get(2), (Returnable<String>) argumentList.get(3), position);
+                                   (Expression<Number>) argumentList.get(2), (Expression<String>) argumentList.get(3), position);
     }
     
     @Override
@@ -33,10 +33,10 @@ public class SetMarkFunctionBuilder implements FunctionBuilder<SetMarkFunction>
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            case 3 -> Returnable.ReturnType.STRING;
+            case 3 -> Expression.ReturnType.STRING;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/StateFunctionBuilder.java

@@ -10,10 +10,10 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 import java.util.List;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.StateFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 
 
@@ -26,10 +26,10 @@ public class StateFunctionBuilder implements FunctionBuilder<StateFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public StateFunction build(List<Returnable<?>> argumentList, Position position) {
+    public StateFunction build(List<Expression<?>> argumentList, SourcePosition position) {
         if(argumentList.size() < 4) throw new ParseException("Expected data", position);
-        return new StateFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new StateFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                 (Returnable<Number>) argumentList.get(2), (Returnable<String>) argumentList.get(3), position);
+                                 (Expression<Number>) argumentList.get(2), (Expression<String>) argumentList.get(3), position);
     }
     
     @Override
@@ -38,10 +38,10 @@ public class StateFunctionBuilder implements FunctionBuilder<StateFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            case 3 -> Returnable.ReturnType.STRING;
+            case 3 -> Expression.ReturnType.STRING;
             default -> null;
         };
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/StructureFunctionBuilder.java

@@ -11,10 +11,10 @@ import java.util.List;
 import java.util.stream.Collectors;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.functions.StructureFunction;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.registry.Registry;
 import com.dfsek.terra.api.structure.Structure;
@@ -31,12 +31,12 @@ public class StructureFunctionBuilder implements FunctionBuilder<StructureFuncti
     
     @SuppressWarnings("unchecked")
     @Override
-    public StructureFunction build(List<Returnable<?>> argumentList, Position position) {
+    public StructureFunction build(List<Expression<?>> argumentList, SourcePosition position) {
         if(argumentList.size() < 5) throw new ParseException("Expected rotations", position);
         
-        return new StructureFunction((Returnable<Number>) argumentList.remove(0), (Returnable<Number>) argumentList.remove(0),
+        return new StructureFunction((Expression<Number>) argumentList.remove(0), (Expression<Number>) argumentList.remove(0),
-                                     (Returnable<Number>) argumentList.remove(0), (Returnable<String>) argumentList.remove(0),
+                                     (Expression<Number>) argumentList.remove(0), (Expression<String>) argumentList.remove(0),
-                                     argumentList.stream().map(item -> ((Returnable<String>) item)).collect(Collectors.toList()), registry,
+                                     argumentList.stream().map(item -> ((Expression<String>) item)).collect(Collectors.toList()), registry,
                                      position, platform);
     }
     
@@ -46,10 +46,10 @@ public class StructureFunctionBuilder implements FunctionBuilder<StructureFuncti
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
-            default -> Returnable.ReturnType.STRING;
+            default -> Expression.ReturnType.STRING;
         };
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/UnaryBooleanFunctionBuilder.java

@@ -11,12 +11,12 @@ import java.util.List;
 import java.util.function.BiConsumer;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class UnaryBooleanFunctionBuilder implements FunctionBuilder<Function<Void>> {
@@ -28,7 +28,7 @@ public class UnaryBooleanFunctionBuilder implements FunctionBuilder<Function<Voi
     }
     
     @Override
-    public Function<Void> build(List<Returnable<?>> argumentList, Position position) {
+    public Function<Void> build(List<Expression<?>> argumentList, SourcePosition position) {
         return new Function<>() {
             @Override
             public ReturnType returnType() {
@@ -37,14 +37,14 @@ public class UnaryBooleanFunctionBuilder implements FunctionBuilder<Function<Voi
             
             @SuppressWarnings("unchecked")
             @Override
-            public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+            public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
-                function.accept(((Returnable<Boolean>) argumentList.get(0)).apply(implementationArguments, scope),
+                function.accept(((Expression<Boolean>) argumentList.get(0)).invoke(implementationArguments, scope),
                                 (TerraImplementationArguments) implementationArguments);
                 return null;
             }
             
             @Override
-            public Position getPosition() {
+            public SourcePosition getPosition() {
                 return position;
             }
         };
@@ -56,8 +56,8 @@ public class UnaryBooleanFunctionBuilder implements FunctionBuilder<Function<Voi
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
-        if(position == 0) return Returnable.ReturnType.BOOLEAN;
+        if(position == 0) return Expression.ReturnType.BOOLEAN;
         return null;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/UnaryNumberFunctionBuilder.java

@@ -10,11 +10,11 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 import java.util.List;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class UnaryNumberFunctionBuilder implements FunctionBuilder<Function<Number>> {
@@ -26,7 +26,7 @@ public class UnaryNumberFunctionBuilder implements FunctionBuilder<Function<Numb
     }
     
     @Override
-    public Function<Number> build(List<Returnable<?>> argumentList, Position position) {
+    public Function<Number> build(List<Expression<?>> argumentList, SourcePosition position) {
         return new Function<>() {
             @Override
             public ReturnType returnType() {
@@ -35,12 +35,12 @@ public class UnaryNumberFunctionBuilder implements FunctionBuilder<Function<Numb
             
             @SuppressWarnings("unchecked")
             @Override
-            public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+            public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
-                return function.apply(((Returnable<Number>) argumentList.get(0)).apply(implementationArguments, scope));
+                return function.apply(((Expression<Number>) argumentList.get(0)).invoke(implementationArguments, scope));
             }
             
             @Override
-            public Position getPosition() {
+            public SourcePosition getPosition() {
                 return position;
             }
         };
@@ -52,8 +52,8 @@ public class UnaryNumberFunctionBuilder implements FunctionBuilder<Function<Numb
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
-        if(position == 0) return Returnable.ReturnType.NUMBER;
+        if(position == 0) return Expression.ReturnType.NUMBER;
         return null;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/UnaryStringFunctionBuilder.java

@@ -10,11 +10,11 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 import java.util.List;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class UnaryStringFunctionBuilder implements FunctionBuilder<Function<Void>> {
@@ -26,7 +26,7 @@ public class UnaryStringFunctionBuilder implements FunctionBuilder<Function<Void
     }
     
     @Override
-    public Function<Void> build(List<Returnable<?>> argumentList, Position position) {
+    public Function<Void> build(List<Expression<?>> argumentList, SourcePosition position) {
         return new Function<>() {
             @Override
             public ReturnType returnType() {
@@ -35,13 +35,13 @@ public class UnaryStringFunctionBuilder implements FunctionBuilder<Function<Void
             
             @SuppressWarnings("unchecked")
             @Override
-            public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+            public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
-                function.accept(((Returnable<String>) argumentList.get(0)).apply(implementationArguments, scope));
+                function.accept(((Expression<String>) argumentList.get(0)).invoke(implementationArguments, scope));
                 return null;
             }
             
             @Override
-            public Position getPosition() {
+            public SourcePosition getPosition() {
                 return position;
             }
         };
@@ -53,8 +53,8 @@ public class UnaryStringFunctionBuilder implements FunctionBuilder<Function<Void
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
-        if(position == 0) return Returnable.ReturnType.STRING;
+        if(position == 0) return Expression.ReturnType.STRING;
         return null;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/builders/ZeroArgFunctionBuilder.java

@@ -10,25 +10,25 @@ package com.dfsek.terra.addons.terrascript.script.builders;
 import java.util.List;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ZeroArgFunctionBuilder<T> implements FunctionBuilder<Function<T>> {
     private final java.util.function.Function<TerraImplementationArguments, T> function;
-    private final Returnable.ReturnType type;
+    private final Expression.ReturnType type;
     
-    public ZeroArgFunctionBuilder(java.util.function.Function<TerraImplementationArguments, T> function, Returnable.ReturnType type) {
+    public ZeroArgFunctionBuilder(java.util.function.Function<TerraImplementationArguments, T> function, Expression.ReturnType type) {
         this.function = function;
         this.type = type;
     }
     
     @Override
-    public Function<T> build(List<Returnable<?>> argumentList, Position position) {
+    public Function<T> build(List<Expression<?>> argumentList, SourcePosition position) {
         return new Function<>() {
             @Override
             public ReturnType returnType() {
@@ -36,12 +36,12 @@ public class ZeroArgFunctionBuilder<T> implements FunctionBuilder<Function<T>> {
             }
             
             @Override
-            public T apply(ImplementationArguments implementationArguments, Scope scope) {
+            public T invoke(ImplementationArguments implementationArguments, Scope scope) {
                 return function.apply((TerraImplementationArguments) implementationArguments);
             }
             
             @Override
-            public Position getPosition() {
+            public SourcePosition getPosition() {
                 return position;
             }
         };
@@ -53,7 +53,7 @@ public class ZeroArgFunctionBuilder<T> implements FunctionBuilder<Function<T>> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         if(position == 0) return type;
         return null;
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/BiomeFunction.java

@@ -10,11 +10,11 @@ package com.dfsek.terra.addons.terrascript.script.functions;
 import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.util.RotationUtil;
 import com.dfsek.terra.api.util.vector.Vector2;
 import com.dfsek.terra.api.util.vector.Vector3;
@@ -22,11 +22,11 @@ import com.dfsek.terra.api.world.biome.generation.BiomeProvider;
 
 
 public class BiomeFunction implements Function<String> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     
     
-    public BiomeFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Position position) {
+    public BiomeFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, SourcePosition position) {
         this.x = x;
         this.y = y;
         this.z = z;
@@ -35,11 +35,11 @@ public class BiomeFunction implements Function<String> {
     
     
     @Override
-    public String apply(ImplementationArguments implementationArguments, Scope scope) {
+    public String invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
         
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()),
+                                                          z.invoke(implementationArguments, scope).doubleValue()),
                                                arguments.getRotation());
         
         
@@ -49,12 +49,12 @@ public class BiomeFunction implements Function<String> {
                                       .toVector3()
                                       .mutable()
                                       .add(Vector3.of(FastMath.roundToInt(xz.getX()),
-                                                      y.apply(implementationArguments, scope).intValue(),
+                                                      y.invoke(implementationArguments, scope).intValue(),
                                                       FastMath.roundToInt(xz.getZ()))).immutable(), arguments.getWorld().getSeed()).getID();
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/BlockFunction.java

@@ -15,12 +15,12 @@ import java.util.HashMap;
 import java.util.Map;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.StringConstant;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.block.state.BlockState;
 import com.dfsek.terra.api.util.RotationUtil;
@@ -30,15 +30,15 @@ import com.dfsek.terra.api.util.vector.Vector3;
 
 public class BlockFunction implements Function<Void> {
     private static final Logger logger = LoggerFactory.getLogger(BlockFunction.class);
-    protected final Returnable<Number> x, y, z;
+    protected final Expression<Number> x, y, z;
-    protected final Returnable<String> blockData;
+    protected final Expression<String> blockData;
     protected final Platform platform;
     private final Map<String, BlockState> data = new HashMap<>();
-    private final Returnable<Boolean> overwrite;
+    private final Expression<Boolean> overwrite;
-    private final Position position;
+    private final SourcePosition position;
     
-    public BlockFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Returnable<String> blockData,
+    public BlockFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, Expression<String> blockData,
-                         Returnable<Boolean> overwrite, Platform platform, Position position) {
+                         Expression<Boolean> overwrite, Platform platform, SourcePosition position) {
         this.x = x;
         this.y = y;
         this.z = z;
@@ -49,7 +49,7 @@ public class BlockFunction implements Function<Void> {
     }
     
     @Override
-    public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
         BlockState rot = getBlockState(implementationArguments, scope);
         setBlock(implementationArguments, scope, arguments, rot);
@@ -57,7 +57,7 @@ public class BlockFunction implements Function<Void> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     
@@ -68,14 +68,14 @@ public class BlockFunction implements Function<Void> {
     
     void setBlock(ImplementationArguments implementationArguments, Scope scope,
                   TerraImplementationArguments arguments, BlockState rot) {
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         try {
             Vector3.Mutable set = Vector3.of(FastMath.roundToInt(xz.getX()),
-                                             y.apply(implementationArguments, scope).doubleValue(),
+                                             y.invoke(implementationArguments, scope).doubleValue(),
                                              FastMath.roundToInt(xz.getZ())).mutable().add(arguments.getOrigin());
             BlockState current = arguments.getWorld().getBlockState(set);
-            if(overwrite.apply(implementationArguments, scope) || current.isAir()) {
+            if(overwrite.invoke(implementationArguments, scope) || current.isAir()) {
                 arguments.getWorld().setBlockState(set, rot);
             }
         } catch(RuntimeException e) {
@@ -84,15 +84,15 @@ public class BlockFunction implements Function<Void> {
     }
     
     protected BlockState getBlockState(ImplementationArguments arguments, Scope scope) {
-        return data.computeIfAbsent(blockData.apply(arguments, scope), platform.getWorldHandle()::createBlockState);
+        return data.computeIfAbsent(blockData.invoke(arguments, scope), platform.getWorldHandle()::createBlockState);
     }
     
     
     public static class Constant extends BlockFunction {
         private final BlockState state;
         
-        public Constant(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, StringConstant blockData,
+        public Constant(Expression<Number> x, Expression<Number> y, Expression<Number> z, StringConstant blockData,
-                        Returnable<Boolean> overwrite, Platform platform, Position position) {
+                        Expression<Boolean> overwrite, Platform platform, SourcePosition position) {
             super(x, y, z, blockData, overwrite, platform, position);
             this.state = platform.getWorldHandle().createBlockState(blockData.getConstant());
         }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/CheckBlockFunction.java

@@ -10,21 +10,21 @@ package com.dfsek.terra.addons.terrascript.script.functions;
 import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.util.RotationUtil;
 import com.dfsek.terra.api.util.vector.Vector2;
 import com.dfsek.terra.api.util.vector.Vector3;
 
 
 public class CheckBlockFunction implements Function<String> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     
-    public CheckBlockFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Position position) {
+    public CheckBlockFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, SourcePosition position) {
         this.x = x;
         this.y = y;
         this.z = z;
@@ -33,11 +33,11 @@ public class CheckBlockFunction implements Function<String> {
     
     
     @Override
-    public String apply(ImplementationArguments implementationArguments, Scope scope) {
+    public String invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
         
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()),
+                                                          z.invoke(implementationArguments, scope).doubleValue()),
                                                arguments.getRotation());
         
         
@@ -46,7 +46,7 @@ public class CheckBlockFunction implements Function<String> {
                                                        .toVector3()
                                                        .mutable()
                                                        .add(Vector3.of(FastMath.roundToInt(xz.getX()),
-                                                                       y.apply(implementationArguments, scope)
+                                                                       y.invoke(implementationArguments, scope)
                                                                         .doubleValue(), FastMath.roundToInt(xz.getZ()))))
                                .getAsString();
         if(data.contains("[")) return data.substring(0, data.indexOf('[')); // Strip properties
@@ -54,7 +54,7 @@ public class CheckBlockFunction implements Function<String> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/EntityFunction.java

@@ -9,12 +9,12 @@ package com.dfsek.terra.addons.terrascript.script.functions;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.ConstantExpression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.entity.Entity;
 import com.dfsek.terra.api.entity.EntityType;
@@ -26,12 +26,12 @@ import com.dfsek.terra.api.util.vector.Vector3;
 
 public class EntityFunction implements Function<Void> {
     private final EntityType data;
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     private final Platform platform;
     
-    public EntityFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Returnable<String> data, Platform platform,
+    public EntityFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, Expression<String> data, Platform platform,
-                          Position position) {
+                          SourcePosition position) {
         this.position = position;
         this.platform = platform;
         if(!(data instanceof ConstantExpression)) throw new ParseException("Entity data must be constant", data.getPosition());
@@ -43,12 +43,12 @@ public class EntityFunction implements Function<Void> {
     }
     
     @Override
-    public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         
-        Entity entity = arguments.getWorld().spawnEntity(Vector3.of(xz.getX(), y.apply(implementationArguments, scope).doubleValue(),
+        Entity entity = arguments.getWorld().spawnEntity(Vector3.of(xz.getX(), y.invoke(implementationArguments, scope).doubleValue(),
                                                                     xz.getZ())
                                                                 .mutable()
                                                                 .add(arguments.getOrigin())
@@ -59,7 +59,7 @@ public class EntityFunction implements Function<Void> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/GetMarkFunction.java

@@ -10,21 +10,21 @@ package com.dfsek.terra.addons.terrascript.script.functions;
 import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.util.RotationUtil;
 import com.dfsek.terra.api.util.vector.Vector2;
 import com.dfsek.terra.api.util.vector.Vector3;
 
 
 public class GetMarkFunction implements Function<String> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     
-    public GetMarkFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Position position) {
+    public GetMarkFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, SourcePosition position) {
         this.position = position;
         this.x = x;
         this.y = y;
@@ -32,13 +32,13 @@ public class GetMarkFunction implements Function<String> {
     }
     
     @Override
-    public String apply(ImplementationArguments implementationArguments, Scope scope) {
+    public String invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         
         String mark = arguments.getMark(Vector3.of(FastMath.floorToInt(xz.getX()), FastMath.floorToInt(
-                                                           y.apply(implementationArguments, scope).doubleValue()),
+                                                           y.invoke(implementationArguments, scope).doubleValue()),
                                                    FastMath.floorToInt(xz.getZ()))
                                                .mutable()
                                                .add(arguments.getOrigin())
@@ -47,7 +47,7 @@ public class GetMarkFunction implements Function<String> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/LootFunction.java

@@ -14,12 +14,12 @@ import org.slf4j.LoggerFactory;
 import java.util.Random;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.StructureScript;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.block.entity.BlockEntity;
 import com.dfsek.terra.api.block.entity.Container;
@@ -35,14 +35,14 @@ import com.dfsek.terra.api.util.vector.Vector3;
 public class LootFunction implements Function<Void> {
     private static final Logger LOGGER = LoggerFactory.getLogger(LootFunction.class);
     private final Registry<LootTable> registry;
-    private final Returnable<String> data;
+    private final Expression<String> data;
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     private final Platform platform;
     private final StructureScript script;
     
-    public LootFunction(Registry<LootTable> registry, Returnable<Number> x, Returnable<Number> y, Returnable<Number> z,
+    public LootFunction(Registry<LootTable> registry, Expression<Number> x, Expression<Number> y, Expression<Number> z,
-                        Returnable<String> data, Platform platform, Position position, StructureScript script) {
+                        Expression<String> data, Platform platform, SourcePosition position, StructureScript script) {
         this.registry = registry;
         this.position = position;
         this.data = data;
@@ -54,20 +54,20 @@ public class LootFunction implements Function<Void> {
     }
     
     @Override
-    public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()),
+                                                          z.invoke(implementationArguments, scope).doubleValue()),
                                                arguments.getRotation());
         
         
-        String id = data.apply(implementationArguments, scope);
+        String id = data.invoke(implementationArguments, scope);
         
         
         registry.get(RegistryKey.parse(id))
                 .ifPresentOrElse(table -> {
                                      Vector3 apply = Vector3.of(FastMath.roundToInt(xz.getX()),
-                                                                y.apply(implementationArguments, scope)
+                                                                y.invoke(implementationArguments, scope)
                                                                  .intValue(),
                                                                 FastMath.roundToInt(xz.getZ())).mutable().add(arguments.getOrigin()).immutable();
             
@@ -97,7 +97,7 @@ public class LootFunction implements Function<Void> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/PullFunction.java

@@ -11,12 +11,12 @@ import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.ConstantExpression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.block.state.BlockState;
 import com.dfsek.terra.api.util.RotationUtil;
@@ -26,11 +26,11 @@ import com.dfsek.terra.api.util.vector.Vector3;
 
 public class PullFunction implements Function<Void> {
     private final BlockState data;
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     
-    public PullFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Returnable<String> data, Platform platform,
+    public PullFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, Expression<String> data, Platform platform,
-                        Position position) {
+                        SourcePosition position) {
         this.position = position;
         if(!(data instanceof ConstantExpression)) throw new ParseException("Block data must be constant", data.getPosition());
         
@@ -41,12 +41,12 @@ public class PullFunction implements Function<Void> {
     }
     
     @Override
-    public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         
-        Vector3.Mutable mutable = Vector3.of(FastMath.roundToInt(xz.getX()), y.apply(implementationArguments, scope).intValue(),
+        Vector3.Mutable mutable = Vector3.of(FastMath.roundToInt(xz.getX()), y.invoke(implementationArguments, scope).intValue(),
                                              FastMath.roundToInt(xz.getZ())).mutable().add(arguments.getOrigin());
         while(mutable.getY() > arguments.getWorld().getMinHeight()) {
             if(!arguments.getWorld().getBlockState(mutable).isAir()) {
@@ -59,7 +59,7 @@ public class PullFunction implements Function<Void> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/RandomFunction.java

@@ -8,18 +8,18 @@
 package com.dfsek.terra.addons.terrascript.script.functions;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class RandomFunction implements Function<Integer> {
-    private final Returnable<Number> numberReturnable;
+    private final Expression<Number> numberReturnable;
-    private final Position position;
+    private final SourcePosition position;
     
-    public RandomFunction(Returnable<Number> numberReturnable, Position position) {
+    public RandomFunction(Expression<Number> numberReturnable, SourcePosition position) {
         this.numberReturnable = numberReturnable;
         this.position = position;
     }
@@ -31,13 +31,13 @@ public class RandomFunction implements Function<Integer> {
     }
     
     @Override
-    public Integer apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Integer invoke(ImplementationArguments implementationArguments, Scope scope) {
         return ((TerraImplementationArguments) implementationArguments).getRandom().nextInt(
-                numberReturnable.apply(implementationArguments, scope).intValue());
+                numberReturnable.invoke(implementationArguments, scope).intValue());
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/RecursionsFunction.java

@@ -11,13 +11,13 @@ import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class RecursionsFunction implements Function<Number> {
-    private final Position position;
+    private final SourcePosition position;
     
-    public RecursionsFunction(Position position) {
+    public RecursionsFunction(SourcePosition position) {
         this.position = position;
     }
     
@@ -27,12 +27,12 @@ public class RecursionsFunction implements Function<Number> {
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         return ((TerraImplementationArguments) implementationArguments).getRecursions();
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/SetMarkFunction.java

@@ -10,22 +10,22 @@ package com.dfsek.terra.addons.terrascript.script.functions;
 import net.jafama.FastMath;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.util.RotationUtil;
 import com.dfsek.terra.api.util.vector.Vector2;
 import com.dfsek.terra.api.util.vector.Vector3;
 
 
 public class SetMarkFunction implements Function<Void> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
-    private final Returnable<String> mark;
+    private final Expression<String> mark;
     
-    public SetMarkFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Returnable<String> mark, Position position) {
+    public SetMarkFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, Expression<String> mark, SourcePosition position) {
         this.position = position;
         this.mark = mark;
         this.x = x;
@@ -34,22 +34,22 @@ public class SetMarkFunction implements Function<Void> {
     }
     
     @Override
-    public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         
         
         arguments.setMark(Vector3.of(FastMath.floorToInt(xz.getX()),
                                      FastMath.floorToInt(
-                                             y.apply(implementationArguments, scope).doubleValue()),
+                                             y.invoke(implementationArguments, scope).doubleValue()),
                                      FastMath.floorToInt(xz.getZ())).mutable().add(arguments.getOrigin()).immutable(),
-                          mark.apply(implementationArguments, scope));
+                          mark.invoke(implementationArguments, scope));
         return null;
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/StateFunction.java

@@ -12,11 +12,11 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.block.entity.BlockEntity;
 import com.dfsek.terra.api.util.RotationUtil;
 import com.dfsek.terra.api.util.vector.Vector2;
@@ -25,12 +25,12 @@ import com.dfsek.terra.api.util.vector.Vector3;
 
 public class StateFunction implements Function<Void> {
     private static final Logger LOGGER = LoggerFactory.getLogger(StateFunction.class);
-    private final Returnable<String> data;
+    private final Expression<String> data;
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     
-    public StateFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Returnable<String> data,
+    public StateFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, Expression<String> data,
-                         Position position) {
+                         SourcePosition position) {
         this.position = position;
         this.data = data;
         this.x = x;
@@ -39,17 +39,17 @@ public class StateFunction implements Function<Void> {
     }
     
     @Override
-    public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         
         
-        Vector3 origin = Vector3.of(FastMath.roundToInt(xz.getX()), y.apply(implementationArguments, scope).intValue(),
+        Vector3 origin = Vector3.of(FastMath.roundToInt(xz.getX()), y.invoke(implementationArguments, scope).intValue(),
                                     FastMath.roundToInt(xz.getZ())).mutable().add(arguments.getOrigin()).immutable();
         try {
             BlockEntity state = arguments.getWorld().getBlockEntity(origin);
-            state.applyState(data.apply(implementationArguments, scope));
+            state.applyState(data.invoke(implementationArguments, scope));
             state.update(false);
         } catch(Exception e) {
             LOGGER.warn("Could not apply BlockState at {}", origin, e);
@@ -59,7 +59,7 @@ public class StateFunction implements Function<Void> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/script/functions/StructureFunction.java

@@ -14,12 +14,12 @@ import org.slf4j.LoggerFactory;
 import java.util.List;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.StructureScript;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 import com.dfsek.terra.api.registry.Registry;
 import com.dfsek.terra.api.structure.Structure;
@@ -31,14 +31,14 @@ import com.dfsek.terra.api.util.vector.Vector2;
 public class StructureFunction implements Function<Boolean> {
     private static final Logger LOGGER = LoggerFactory.getLogger(StructureFunction.class);
     private final Registry<Structure> registry;
-    private final Returnable<String> id;
+    private final Expression<String> id;
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     private final Platform platform;
-    private final List<Returnable<String>> rotations;
+    private final List<Expression<String>> rotations;
     
-    public StructureFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Returnable<String> id,
+    public StructureFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, Expression<String> id,
-                             List<Returnable<String>> rotations, Registry<Structure> registry, Position position, Platform platform) {
+                             List<Expression<String>> rotations, Registry<Structure> registry, SourcePosition position, Platform platform) {
         this.registry = registry;
         this.id = id;
         this.position = position;
@@ -55,20 +55,20 @@ public class StructureFunction implements Function<Boolean> {
     }
     
     @Override
-    public Boolean apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Boolean invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
         
         if(arguments.getRecursions() > platform.getTerraConfig().getMaxRecursion())
             throw new RuntimeException("Structure recursion too deep: " + arguments.getRecursions());
         
-        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = RotationUtil.rotateVector(Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                                          z.apply(implementationArguments, scope).doubleValue()), arguments.getRotation());
+                                                          z.invoke(implementationArguments, scope).doubleValue()), arguments.getRotation());
         
         
-        String app = id.apply(implementationArguments, scope);
+        String app = id.invoke(implementationArguments, scope);
         return registry.getByID(app).map(script -> {
             Rotation rotation1;
-            String rotString = rotations.get(arguments.getRandom().nextInt(rotations.size())).apply(implementationArguments, scope);
+            String rotString = rotations.get(arguments.getRandom().nextInt(rotations.size())).invoke(implementationArguments, scope);
             try {
                 rotation1 = Rotation.valueOf(rotString);
             } catch(IllegalArgumentException e) {
@@ -80,7 +80,7 @@ public class StructureFunction implements Function<Boolean> {
                 return structureScript.generate(arguments.getOrigin(),
                                                 arguments.getWorld()
                                                          .buffer(FastMath.roundToInt(xz.getX()),
-                                                                 y.apply(implementationArguments, scope).intValue(),
+                                                                 y.invoke(implementationArguments, scope).intValue(),
                                                                  FastMath.roundToInt(xz.getZ())),
                                                 arguments.getRandom(),
                                                 arguments.getRotation().rotate(rotation1), arguments.getRecursions() + 1);
@@ -88,7 +88,7 @@ public class StructureFunction implements Function<Boolean> {
             return script.generate(arguments.getOrigin(),
                                    arguments.getWorld()
                                             .buffer(FastMath.roundToInt(xz.getX()),
-                                                    y.apply(implementationArguments, scope).intValue(),
+                                                    y.invoke(implementationArguments, scope).intValue(),
                                                     FastMath.roundToInt(xz.getZ())),
                                    arguments.getRandom(),
                                    arguments.getRotation().rotate(rotation1));
@@ -99,7 +99,7 @@ public class StructureFunction implements Function<Boolean> {
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/LookaheadStream.java

@@ -17,14 +17,14 @@ import java.util.List;
 /**
  * Stream-like data structure that allows viewing future elements without consuming current.
  */
-public class Lookahead {
+public class LookaheadStream {
     private final List<Char> buffer = new ArrayList<>();
     private final Reader input;
     private int index = 0;
     private int line = 0;
     private boolean end = false;
     
-    public Lookahead(Reader r) {
+    public LookaheadStream(Reader r) {
         this.input = r;
     }
     
@@ -88,7 +88,7 @@ public class Lookahead {
         }
     }
     
-    public boolean matches(String check, boolean consume) {
+    public boolean matchesString(String check, boolean consume) {
         if(check == null) return false;
         
         for(int i = 0; i < check.length(); i++) {
@@ -120,11 +120,7 @@ public class Lookahead {
         }
     }
     
-    public int getLine() {
+    public SourcePosition getPosition() {
-        return line;
+        return new SourcePosition(line, index);
-    }
-    
-    public int getIndex() {
-        return index;
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/SourcePosition.java

@@ -7,11 +7,11 @@
 
 package com.dfsek.terra.addons.terrascript.tokenizer;
 
-public class Position {
+public class SourcePosition {
     private final int line;
     private final int index;
     
-    public Position(int line, int index) {
+    public SourcePosition(int line, int index) {
         this.line = line;
         this.index = index;
     }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/Token.java

@@ -10,9 +10,9 @@ package com.dfsek.terra.addons.terrascript.tokenizer;
 public class Token {
     private final String content;
     private final Type type;
-    private final Position start;
+    private final SourcePosition start;
     
-    public Token(String content, Type type, Position start) {
+    public Token(String content, Type type, SourcePosition start) {
         this.content = content;
         this.type = type;
         this.start = start;
@@ -31,7 +31,7 @@ public class Token {
         return content;
     }
     
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return start;
     }
     
@@ -232,6 +232,10 @@ public class Token {
         /**
          * Else keyword
          */
-        ELSE
+        ELSE,
+        /**
+         * End of file
+         */
+        END_OF_FILE
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/Tokenizer.java

@@ -22,14 +22,13 @@ import com.dfsek.terra.addons.terrascript.tokenizer.exceptions.TokenizerExceptio
 public class Tokenizer {
     public static final Set<Character> syntaxSignificant = Sets.newHashSet(';', '(', ')', '"', ',', '\\', '=', '{', '}', '+', '-', '*', '/',
                                                                            '>', '<', '!'); // Reserved chars
-    private final Lookahead reader;
+    private final LookaheadStream reader;
-    private final Stack<Token> brackets = new Stack<>();
+    private final Stack<Token> bracketStack = new Stack<>();
     private Token current;
-    private Token last;
     
     public Tokenizer(String data) {
-        reader = new Lookahead(new StringReader(data + '\0'));
+        reader = new LookaheadStream(new StringReader(data + '\0'));
-        current = fetchCheck();
+        current = tokenize();
     }
     
     /**
@@ -39,8 +38,7 @@ public class Tokenizer {
      *
      * @throws ParseException If token does not exist
      */
-    public Token get() {
+    public Token current() {
-        if(!hasNext()) throw new ParseException("Unexpected end of input", last.getPosition());
         return current;
     }
     
@@ -52,64 +50,66 @@ public class Tokenizer {
      * @throws ParseException If token does not exist
      */
     public Token consume() {
-        if(!hasNext()) throw new ParseException("Unexpected end of input", last.getPosition());
+        if (current.getType() == Token.Type.END_OF_FILE) return current;
         Token temp = current;
-        current = fetchCheck();
+        current = tokenize();
         return temp;
     }
     
-    private Token fetchCheck() {
+    /**
-        Token fetch = fetch();
+     * Whether this {@code Tokenizer} contains additional tokens.
-        if(fetch != null) {
+     *
-            last = fetch;
+     * @return {@code true} if more tokens are present, otherwise {@code false}
-            if(fetch.getType() == Token.Type.BLOCK_BEGIN) brackets.push(fetch); // Opening bracket
+     */
-            else if(fetch.getType() == Token.Type.BLOCK_END) {
+    public boolean hasNext() {
-                if(!brackets.isEmpty()) brackets.pop();
+        return current.getType() != Token.Type.END_OF_FILE;
-                else throw new ParseException("Dangling opening brace", new Position(0, 0));
-            }
-        } else if(!brackets.isEmpty()) {
-            throw new ParseException("Dangling closing brace", brackets.peek().getPosition());
-        }
-        return fetch;
     }
     
-    private Token fetch() throws TokenizerException {
+    private Token tokenize() throws TokenizerException {
-        while(!reader.current().isEOF() && reader.current().isWhitespace()) reader.consume();
+        consumeWhitespace();
         
-        while(reader.matches("//", true)) skipLine(); // Skip line if comment
+        // Skip line if comment
+        while(reader.matchesString("//", true)) skipLine();
         
-        if(reader.matches("/*", true)) skipTo("*/"); // Skip multi line comment
+        // Skip multi line comment
+        if(reader.matchesString("/*", true)) skipTo("*/");
         
-        if(reader.current().isEOF()) return null; // EOF
+        // Reached end of file
+        if(reader.current().isEOF()) {
+            if (!bracketStack.isEmpty()) throw new ParseException("Dangling closing brace", bracketStack.peek().getPosition());
+            return new Token(reader.consume().toString(), Token.Type.END_OF_FILE, reader.getPosition());
+        }
         
-        if(reader.matches("==", true))
+        // Check if operator token
-            return new Token("==", Token.Type.EQUALS_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.matchesString("==", true))
-        if(reader.matches("!=", true))
+            return new Token("==", Token.Type.EQUALS_OPERATOR, reader.getPosition());
-            return new Token("!=", Token.Type.NOT_EQUALS_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.matchesString("!=", true))
-        if(reader.matches(">=", true))
+            return new Token("!=", Token.Type.NOT_EQUALS_OPERATOR, reader.getPosition());
-            return new Token(">=", Token.Type.GREATER_THAN_OR_EQUALS_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.matchesString(">=", true))
-        if(reader.matches("<=", true))
+            return new Token(">=", Token.Type.GREATER_THAN_OR_EQUALS_OPERATOR, reader.getPosition());
-            return new Token("<=", Token.Type.LESS_THAN_OR_EQUALS_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.matchesString("<=", true))
-        if(reader.matches(">", true))
+            return new Token("<=", Token.Type.LESS_THAN_OR_EQUALS_OPERATOR, reader.getPosition());
-            return new Token(">", Token.Type.GREATER_THAN_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.matchesString(">", true))
-        if(reader.matches("<", true))
+            return new Token(">", Token.Type.GREATER_THAN_OPERATOR, reader.getPosition());
-            return new Token("<", Token.Type.LESS_THAN_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.matchesString("<", true))
-        
+            return new Token("<", Token.Type.LESS_THAN_OPERATOR, reader.getPosition());
-        
-        if(reader.matches("||", true))
-            return new Token("||", Token.Type.BOOLEAN_OR, new Position(reader.getLine(), reader.getIndex()));
-        if(reader.matches("&&", true))
-            return new Token("&&", Token.Type.BOOLEAN_AND, new Position(reader.getLine(), reader.getIndex()));
         
+        // Check if logical operator
+        if(reader.matchesString("||", true))
+            return new Token("||", Token.Type.BOOLEAN_OR, reader.getPosition());
+        if(reader.matchesString("&&", true))
+            return new Token("&&", Token.Type.BOOLEAN_AND, reader.getPosition());
         
+        // Check if number
         if(isNumberStart()) {
             StringBuilder num = new StringBuilder();
             while(!reader.current().isEOF() && isNumberLike()) {
                 num.append(reader.consume());
             }
-            return new Token(num.toString(), Token.Type.NUMBER, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(num.toString(), Token.Type.NUMBER, reader.getPosition());
         }
         
+        // Check if string literal
         if(reader.current().is('"')) {
             reader.consume(); // Consume first quote
             StringBuilder string = new StringBuilder();
@@ -121,83 +121,93 @@ public class Tokenizer {
                     continue;
                 } else ignoreNext = false;
                 if(reader.current().isEOF())
-                    throw new FormatException("No end of string literal found. ", new Position(reader.getLine(), reader.getIndex()));
+                    throw new FormatException("No end of string literal found. ", reader.getPosition());
                 string.append(reader.consume());
             }
             reader.consume(); // Consume last quote
             
-            return new Token(string.toString(), Token.Type.STRING, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(string.toString(), Token.Type.STRING, reader.getPosition());
         }
         
         if(reader.current().is('('))
-            return new Token(reader.consume().toString(), Token.Type.GROUP_BEGIN, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.GROUP_BEGIN, reader.getPosition());
         if(reader.current().is(')'))
-            return new Token(reader.consume().toString(), Token.Type.GROUP_END, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.GROUP_END, reader.getPosition());
         if(reader.current().is(';'))
-            return new Token(reader.consume().toString(), Token.Type.STATEMENT_END, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.STATEMENT_END, reader.getPosition());
         if(reader.current().is(','))
-            return new Token(reader.consume().toString(), Token.Type.SEPARATOR, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.SEPARATOR, reader.getPosition());
-        if(reader.current().is('{'))
+        
-            return new Token(reader.consume().toString(), Token.Type.BLOCK_BEGIN, new Position(reader.getLine(), reader.getIndex()));
+        if(reader.current().is('{')) {
-        if(reader.current().is('}'))
+            Token token = new Token(reader.consume().toString(), Token.Type.BLOCK_BEGIN, reader.getPosition());
-            return new Token(reader.consume().toString(), Token.Type.BLOCK_END, new Position(reader.getLine(), reader.getIndex()));
+            bracketStack.push(token);
+            return token;
+        }
+        if(reader.current().is('}')) {
+            if(bracketStack.isEmpty()) throw new ParseException("Dangling opening brace", new SourcePosition(0, 0));
+            bracketStack.pop();
+            return new Token(reader.consume().toString(), Token.Type.BLOCK_END, reader.getPosition());
+        }
+        
         if(reader.current().is('='))
-            return new Token(reader.consume().toString(), Token.Type.ASSIGNMENT, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.ASSIGNMENT, reader.getPosition());
         if(reader.current().is('+'))
-            return new Token(reader.consume().toString(), Token.Type.ADDITION_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.ADDITION_OPERATOR, reader.getPosition());
         if(reader.current().is('-'))
             return new Token(reader.consume().toString(), Token.Type.SUBTRACTION_OPERATOR,
-                             new Position(reader.getLine(), reader.getIndex()));
+                             reader.getPosition());
         if(reader.current().is('*'))
             return new Token(reader.consume().toString(), Token.Type.MULTIPLICATION_OPERATOR,
-                             new Position(reader.getLine(), reader.getIndex()));
+                             reader.getPosition());
         if(reader.current().is('/'))
-            return new Token(reader.consume().toString(), Token.Type.DIVISION_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.DIVISION_OPERATOR, reader.getPosition());
         if(reader.current().is('%'))
-            return new Token(reader.consume().toString(), Token.Type.MODULO_OPERATOR, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.MODULO_OPERATOR, reader.getPosition());
         if(reader.current().is('!'))
-            return new Token(reader.consume().toString(), Token.Type.BOOLEAN_NOT, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(reader.consume().toString(), Token.Type.BOOLEAN_NOT, reader.getPosition());
         
+        // Read word
         StringBuilder token = new StringBuilder();
         while(!reader.current().isEOF() && !isSyntaxSignificant(reader.current().getCharacter())) {
             Char c = reader.consume();
             if(c.isWhitespace()) break;
             token.append(c);
         }
-        
         String tokenString = token.toString();
         
+        // Check if word is a keyword
         if(tokenString.equals("true"))
-            return new Token(tokenString, Token.Type.BOOLEAN, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.BOOLEAN, reader.getPosition());
         if(tokenString.equals("false"))
-            return new Token(tokenString, Token.Type.BOOLEAN, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.BOOLEAN, reader.getPosition());
         
         if(tokenString.equals("num"))
-            return new Token(tokenString, Token.Type.NUMBER_VARIABLE, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.NUMBER_VARIABLE, reader.getPosition());
         if(tokenString.equals("str"))
-            return new Token(tokenString, Token.Type.STRING_VARIABLE, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.STRING_VARIABLE, reader.getPosition());
         if(tokenString.equals("bool"))
-            return new Token(tokenString, Token.Type.BOOLEAN_VARIABLE, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.BOOLEAN_VARIABLE, reader.getPosition());
         
         if(tokenString.equals("if"))
-            return new Token(tokenString, Token.Type.IF_STATEMENT, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.IF_STATEMENT, reader.getPosition());
         if(tokenString.equals("else"))
-            return new Token(tokenString, Token.Type.ELSE, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.ELSE, reader.getPosition());
         if(tokenString.equals("while"))
-            return new Token(tokenString, Token.Type.WHILE_LOOP, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.WHILE_LOOP, reader.getPosition());
         if(tokenString.equals("for"))
-            return new Token(tokenString, Token.Type.FOR_LOOP, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.FOR_LOOP, reader.getPosition());
         
         if(tokenString.equals("return"))
-            return new Token(tokenString, Token.Type.RETURN, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.RETURN, reader.getPosition());
         if(tokenString.equals("continue"))
-            return new Token(tokenString, Token.Type.CONTINUE, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.CONTINUE, reader.getPosition());
         if(tokenString.equals("break"))
-            return new Token(tokenString, Token.Type.BREAK, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.BREAK, reader.getPosition());
         if(tokenString.equals("fail"))
-            return new Token(tokenString, Token.Type.FAIL, new Position(reader.getLine(), reader.getIndex()));
+            return new Token(tokenString, Token.Type.FAIL, reader.getPosition());
         
-        return new Token(tokenString, Token.Type.IDENTIFIER, new Position(reader.getLine(), reader.getIndex()));
+        // If not keyword, assume it is an identifier
+        return new Token(tokenString, Token.Type.IDENTIFIER, reader.getPosition());
     }
     
     private void skipLine() {
@@ -210,9 +220,9 @@ public class Tokenizer {
     }
     
     private void skipTo(String s) throws EOFException {
-        Position begin = new Position(reader.getLine(), reader.getIndex());
+        SourcePosition begin = reader.getPosition();
         while(!reader.current().isEOF()) {
-            if(reader.matches(s, true)) {
+            if(reader.matchesString(s, true)) {
                 consumeWhitespace();
                 return;
             }
@@ -221,15 +231,6 @@ public class Tokenizer {
         throw new EOFException("No end of expression found.", begin);
     }
     
-    /**
-     * Whether this {@code Tokenizer} contains additional tokens.
-     *
-     * @return {@code true} if more tokens are present, otherwise {@code false}
-     */
-    public boolean hasNext() {
-        return !(current == null);
-    }
-    
     private boolean isNumberLike() {
         return reader.current().isDigit()
                || reader.current().is('_', '.', 'E');
@@ -243,5 +244,4 @@ public class Tokenizer {
     public boolean isSyntaxSignificant(char c) {
         return syntaxSignificant.contains(c);
     }
-    
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/exceptions/EOFException.java

@@ -9,7 +9,7 @@ package com.dfsek.terra.addons.terrascript.tokenizer.exceptions;
 
 import java.io.Serial;
 
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class EOFException extends TokenizerException {
@@ -17,11 +17,11 @@ public class EOFException extends TokenizerException {
     @Serial
     private static final long serialVersionUID = 3980047409902809440L;
     
-    public EOFException(String message, Position position) {
+    public EOFException(String message, SourcePosition position) {
         super(message, position);
     }
     
-    public EOFException(String message, Position position, Throwable cause) {
+    public EOFException(String message, SourcePosition position, Throwable cause) {
         super(message, position, cause);
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/exceptions/FormatException.java

@@ -9,7 +9,7 @@ package com.dfsek.terra.addons.terrascript.tokenizer.exceptions;
 
 import java.io.Serial;
 
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class FormatException extends TokenizerException {
@@ -17,11 +17,11 @@ public class FormatException extends TokenizerException {
     @Serial
     private static final long serialVersionUID = -791308012940744455L;
     
-    public FormatException(String message, Position position) {
+    public FormatException(String message, SourcePosition position) {
         super(message, position);
     }
     
-    public FormatException(String message, Position position, Throwable cause) {
+    public FormatException(String message, SourcePosition position, Throwable cause) {
         super(message, position, cause);
     }
 }

common/addons/structure-terrascript-loader/src/main/java/com/dfsek/terra/addons/terrascript/tokenizer/exceptions/TokenizerException.java

@@ -10,7 +10,7 @@ package com.dfsek.terra.addons.terrascript.tokenizer.exceptions;
 import java.io.Serial;
 
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public abstract class TokenizerException extends ParseException {
@@ -18,11 +18,11 @@ public abstract class TokenizerException extends ParseException {
     @Serial
     private static final long serialVersionUID = 2792384010083575420L;
     
-    public TokenizerException(String message, Position position) {
+    public TokenizerException(String message, SourcePosition position) {
         super(message, position);
     }
     
-    public TokenizerException(String message, Position position, Throwable cause) {
+    public TokenizerException(String message, SourcePosition position, Throwable cause) {
         super(message, position, cause);
     }
 }

common/addons/structure-terrascript-loader/src/test/java/structure/LookaheadStreamTest.java

@@ -11,13 +11,13 @@ import org.junit.jupiter.api.Test;
 
 import java.io.StringReader;
 
-import com.dfsek.terra.addons.terrascript.tokenizer.Lookahead;
+import com.dfsek.terra.addons.terrascript.tokenizer.PeekableStream;
 
 
-public class LookaheadTest {
+public class PeekableStreamTest {
     @Test
     public void lookahead() {
-        Lookahead lookahead = new Lookahead(new StringReader("Test string..."));
+        PeekableStream lookahead = new PeekableStream(new StringReader("Test string..."));
         
         for(int i = 0; lookahead.next(i) != null; i++) {
             System.out.print(lookahead.next(i).getCharacter());

common/addons/structure-terrascript-loader/src/test/java/structure/ParserTest.java

@@ -20,11 +20,11 @@ import com.dfsek.terra.addons.terrascript.parser.Parser;
 import com.dfsek.terra.addons.terrascript.parser.exceptions.ParseException;
 import com.dfsek.terra.addons.terrascript.parser.lang.Executable;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class ParserTest {
@@ -35,7 +35,7 @@ public class ParserTest {
         
         parser.registerFunction("test", new FunctionBuilder<Test1>() {
             @Override
-            public Test1 build(List<Returnable<?>> argumentList, Position position) {
+            public Test1 build(List<Expression<?>> argumentList, SourcePosition position) {
                 return new Test1(argumentList.get(0), argumentList.get(1), position);
             }
             
@@ -45,10 +45,10 @@ public class ParserTest {
             }
             
             @Override
-            public Returnable.ReturnType getArgument(int position) {
+            public Expression.ReturnType getArgument(int position) {
                 return switch(position) {
-                    case 0 -> Returnable.ReturnType.STRING;
+                    case 0 -> Expression.ReturnType.STRING;
-                    case 1 -> Returnable.ReturnType.NUMBER;
+                    case 1 -> Expression.ReturnType.NUMBER;
                     default -> null;
                 };
             }
@@ -66,25 +66,25 @@ public class ParserTest {
     }
     
     private static class Test1 implements Function<Void> {
-        private final Returnable<?> a;
+        private final Expression<?> a;
-        private final Returnable<?> b;
+        private final Expression<?> b;
-        private final Position position;
+        private final SourcePosition position;
         
-        public Test1(Returnable<?> a, Returnable<?> b, Position position) {
+        public Test1(Expression<?> a, Expression<?> b, SourcePosition position) {
             this.a = a;
             this.b = b;
             this.position = position;
         }
         
         @Override
-        public Void apply(ImplementationArguments implementationArguments, Scope scope) {
+        public Void invoke(ImplementationArguments implementationArguments, Scope scope) {
-            System.out.println("string: " + a.apply(implementationArguments, scope) + ", double: " +
+            System.out.println("string: " + a.invoke(implementationArguments, scope) + ", double: " +
-                               b.apply(implementationArguments, scope));
+                               b.invoke(implementationArguments, scope));
             return null;
         }
         
         @Override
-        public Position getPosition() {
+        public SourcePosition getPosition() {
             return position;
         }
         

common/addons/terrascript-function-check-noise-3d/src/main/java/com/dfsek/terra/addon/terrascript/check/CheckFunction.java

@@ -12,11 +12,11 @@ import net.jafama.FastMath;
 import com.dfsek.terra.addons.chunkgenerator.generation.NoiseChunkGenerator3D;
 import com.dfsek.terra.addons.chunkgenerator.generation.math.samplers.SamplerProvider;
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.util.RotationUtil;
 import com.dfsek.terra.api.util.vector.Vector2;
 import com.dfsek.terra.api.util.vector.Vector3;
@@ -25,10 +25,10 @@ import com.dfsek.terra.api.world.WritableWorld;
 
 
 public class CheckFunction implements Function<String> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Position position;
+    private final SourcePosition position;
     
-    public CheckFunction(Returnable<Number> x, Returnable<Number> y, Returnable<Number> z, Position position) {
+    public CheckFunction(Expression<Number> x, Expression<Number> y, Expression<Number> z, SourcePosition position) {
         this.x = x;
         this.y = y;
         this.z = z;
@@ -37,26 +37,26 @@ public class CheckFunction implements Function<String> {
     
     
     @Override
-    public String apply(ImplementationArguments implementationArguments, Scope scope) {
+    public String invoke(ImplementationArguments implementationArguments, Scope scope) {
         
         
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
         
         
-        Vector2 xz = Vector2.of(x.apply(implementationArguments, scope).doubleValue(),
+        Vector2 xz = Vector2.of(x.invoke(implementationArguments, scope).doubleValue(),
-                                z.apply(implementationArguments, scope).doubleValue());
+                                z.invoke(implementationArguments, scope).doubleValue());
         
         RotationUtil.rotateVector(xz, arguments.getRotation());
         
         Vector3 location = arguments.getOrigin().toVector3Mutable().add(
-                Vector3.of(FastMath.roundToInt(xz.getX()), y.apply(implementationArguments, scope).doubleValue(),
+                Vector3.of(FastMath.roundToInt(xz.getX()), y.invoke(implementationArguments, scope).doubleValue(),
                            FastMath.roundToInt(xz.getZ()))).immutable();
         
         return apply(location, arguments.getWorld());
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/terrascript-function-check-noise-3d/src/main/java/com/dfsek/terra/addon/terrascript/check/CheckFunctionBuilder.java

@@ -9,9 +9,9 @@ package com.dfsek.terra.addon.terrascript.check;
 
 import java.util.List;
 
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.Platform;
 
 
@@ -24,9 +24,9 @@ public class CheckFunctionBuilder implements FunctionBuilder<CheckFunction> {
     
     @SuppressWarnings("unchecked")
     @Override
-    public CheckFunction build(List<Returnable<?>> argumentList, Position position) {
+    public CheckFunction build(List<Expression<?>> argumentList, SourcePosition position) {
-        return new CheckFunction((Returnable<Number>) argumentList.get(0), (Returnable<Number>) argumentList.get(1),
+        return new CheckFunction((Expression<Number>) argumentList.get(0), (Expression<Number>) argumentList.get(1),
-                                 (Returnable<Number>) argumentList.get(2), position);
+                                 (Expression<Number>) argumentList.get(2), position);
     }
     
     @Override
@@ -35,9 +35,9 @@ public class CheckFunctionBuilder implements FunctionBuilder<CheckFunction> {
     }
     
     @Override
-    public Returnable.ReturnType getArgument(int position) {
+    public Expression.ReturnType getArgument(int position) {
         return switch(position) {
-            case 0, 1, 2 -> Returnable.ReturnType.NUMBER;
+            case 0, 1, 2 -> Expression.ReturnType.NUMBER;
             default -> null;
         };
     }

common/addons/terrascript-function-sampler/src/main/java/com/dfsek/terra/addons/terrascript/sampler/ConstantSamplerFunction.java

@@ -1,28 +1,28 @@
 package com.dfsek.terra.addons.terrascript.sampler;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.noise.NoiseSampler;
 
 
 public class ConstantSamplerFunction implements Function<Number> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
     private final NoiseSampler sampler;
     
     
     private final boolean twoD;
-    private final Position position;
+    private final SourcePosition position;
     
     public ConstantSamplerFunction(NoiseSampler sampler,
-                                   Returnable<Number> x,
+                                   Expression<Number> x,
-                                   Returnable<Number> y,
+                                   Expression<Number> y,
-                                   Returnable<Number> z,
+                                   Expression<Number> z,
                                    boolean twoD,
-                                   Position position) {
+                                   SourcePosition position) {
         this.x = x;
         this.y = y;
         this.z = z;
@@ -32,22 +32,22 @@ public class ConstantSamplerFunction implements Function<Number> {
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        double x = this.x.apply(implementationArguments, scope).doubleValue();
+        double x = this.x.invoke(implementationArguments, scope).doubleValue();
         
-        double z = this.z.apply(implementationArguments, scope).doubleValue();
+        double z = this.z.invoke(implementationArguments, scope).doubleValue();
         
         if(twoD) {
             return sampler.noise(arguments.getWorld().getSeed(), x, z);
         } else {
-            double y = this.y.apply(implementationArguments, scope).doubleValue();
+            double y = this.y.invoke(implementationArguments, scope).doubleValue();
             return sampler.noise(arguments.getWorld().getSeed(), x, y, z);
         }
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/terrascript-function-sampler/src/main/java/com/dfsek/terra/addons/terrascript/sampler/SamplerFunction.java

@@ -3,30 +3,30 @@ package com.dfsek.terra.addons.terrascript.sampler;
 import java.util.function.Supplier;
 
 import com.dfsek.terra.addons.terrascript.parser.lang.ImplementationArguments;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
 import com.dfsek.terra.addons.terrascript.parser.lang.Scope;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.Function;
 import com.dfsek.terra.addons.terrascript.script.TerraImplementationArguments;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 import com.dfsek.terra.api.noise.NoiseSampler;
 
 
 public class SamplerFunction implements Function<Number> {
-    private final Returnable<Number> x, y, z;
+    private final Expression<Number> x, y, z;
-    private final Returnable<String> function;
+    private final Expression<String> function;
     
     private final java.util.function.Function<Supplier<String>, NoiseSampler> samplerFunction;
     
     private final boolean twoD;
-    private final Position position;
+    private final SourcePosition position;
     
-    public SamplerFunction(Returnable<String> function,
+    public SamplerFunction(Expression<String> function,
-                           Returnable<Number> x,
+                           Expression<Number> x,
-                           Returnable<Number> y,
+                           Expression<Number> y,
-                           Returnable<Number> z,
+                           Expression<Number> z,
                            java.util.function.Function<Supplier<String>, NoiseSampler> samplerFunction,
                            boolean twoD,
-                           Position position) {
+                           SourcePosition position) {
         this.x = x;
         this.y = y;
         this.z = z;
@@ -37,23 +37,23 @@ public class SamplerFunction implements Function<Number> {
     }
     
     @Override
-    public Number apply(ImplementationArguments implementationArguments, Scope scope) {
+    public Number invoke(ImplementationArguments implementationArguments, Scope scope) {
         TerraImplementationArguments arguments = (TerraImplementationArguments) implementationArguments;
-        double x = this.x.apply(implementationArguments, scope).doubleValue();
+        double x = this.x.invoke(implementationArguments, scope).doubleValue();
         
-        double z = this.z.apply(implementationArguments, scope).doubleValue();
+        double z = this.z.invoke(implementationArguments, scope).doubleValue();
         
-        NoiseSampler sampler = samplerFunction.apply(() -> function.apply(implementationArguments, scope));
+        NoiseSampler sampler = samplerFunction.apply(() -> function.invoke(implementationArguments, scope));
         if(twoD) {
             return sampler.noise(arguments.getWorld().getSeed(), x, z);
         } else {
-            double y = this.y.apply(implementationArguments, scope).doubleValue();
+            double y = this.y.invoke(implementationArguments, scope).doubleValue();
             return sampler.noise(arguments.getWorld().getSeed(), x, y, z);
         }
     }
     
     @Override
-    public Position getPosition() {
+    public SourcePosition getPosition() {
         return position;
     }
     

common/addons/terrascript-function-sampler/src/main/java/com/dfsek/terra/addons/terrascript/sampler/SamplerFunctionBuilder.java

@@ -6,12 +6,12 @@ import java.util.Map;
 import java.util.Objects;
 
 import com.dfsek.terra.addons.noise.config.DimensionApplicableNoiseSampler;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression;
-import com.dfsek.terra.addons.terrascript.parser.lang.Returnable.ReturnType;
+import com.dfsek.terra.addons.terrascript.parser.lang.Expression.ReturnType;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.NumericConstant;
 import com.dfsek.terra.addons.terrascript.parser.lang.constants.StringConstant;
 import com.dfsek.terra.addons.terrascript.parser.lang.functions.FunctionBuilder;
-import com.dfsek.terra.addons.terrascript.tokenizer.Position;
+import com.dfsek.terra.addons.terrascript.tokenizer.SourcePosition;
 
 
 public class SamplerFunctionBuilder implements FunctionBuilder<com.dfsek.terra.addons.terrascript.parser.lang.functions.Function<Number>> {
@@ -33,25 +33,25 @@ public class SamplerFunctionBuilder implements FunctionBuilder<com.dfsek.terra.a
     
     @SuppressWarnings("unchecked")
     @Override
-    public com.dfsek.terra.addons.terrascript.parser.lang.functions.Function<Number> build(List<Returnable<?>> argumentList,
+    public com.dfsek.terra.addons.terrascript.parser.lang.functions.Function<Number> build(List<Expression<?>> argumentList,
-                                                                                           Position position) {
+                                                                                           SourcePosition position) {
-        Returnable<String> arg = (Returnable<String>) argumentList.get(0);
+        Expression<String> arg = (Expression<String>) argumentList.get(0);
         
         if(argumentList.size() == 3) { // 2D
             if(arg instanceof StringConstant constant) {
                 return new ConstantSamplerFunction(Objects.requireNonNull(samplers2d.get(constant.getConstant()),
                                                                           "No such 2D noise function " + constant.getConstant())
                                                           .getSampler(),
-                                                   (Returnable<Number>) argumentList.get(1),
+                                                   (Expression<Number>) argumentList.get(1),
                                                    new NumericConstant(0, position),
-                                                   (Returnable<Number>) argumentList.get(2),
+                                                   (Expression<Number>) argumentList.get(2),
                                                    true,
                                                    position);
             } else {
-                return new SamplerFunction((Returnable<String>) argumentList.get(0),
+                return new SamplerFunction((Expression<String>) argumentList.get(0),
-                                           (Returnable<Number>) argumentList.get(1),
+                                           (Expression<Number>) argumentList.get(1),
                                            new NumericConstant(0, position),
-                                           (Returnable<Number>) argumentList.get(2),
+                                           (Expression<Number>) argumentList.get(2),
                                            s -> Objects.requireNonNull(samplers2d.get(s.get()), "No such 2D noise function " + s.get())
                                                        .getSampler(),
                                            true,
@@ -63,16 +63,16 @@ public class SamplerFunctionBuilder implements FunctionBuilder<com.dfsek.terra.a
                 return new ConstantSamplerFunction(Objects.requireNonNull(samplers3d.get(constant.getConstant()),
                                                                           "No such 3D noise function " + constant.getConstant())
                                                           .getSampler(),
-                                                   (Returnable<Number>) argumentList.get(1),
+                                                   (Expression<Number>) argumentList.get(1),
-                                                   (Returnable<Number>) argumentList.get(2),
+                                                   (Expression<Number>) argumentList.get(2),
-                                                   (Returnable<Number>) argumentList.get(3),
+                                                   (Expression<Number>) argumentList.get(3),
                                                    true,
                                                    position);
             } else {
-                return new SamplerFunction((Returnable<String>) argumentList.get(0),
+                return new SamplerFunction((Expression<String>) argumentList.get(0),
-                                           (Returnable<Number>) argumentList.get(1),
+                                           (Expression<Number>) argumentList.get(1),
-                                           (Returnable<Number>) argumentList.get(2),
+                                           (Expression<Number>) argumentList.get(2),
-                                           (Returnable<Number>) argumentList.get(3),
+                                           (Expression<Number>) argumentList.get(3),
                                            s -> Objects.requireNonNull(samplers3d.get(s.get()), "No such 3D noise function " + s.get())
                                                        .getSampler(),
                                            true,