Add FailKeyword

common/src/main/java/com/dfsek/terra/api/structures/parser/Parser.java

@@ -16,6 +16,7 @@ import com.dfsek.terra.api.structures.parser.lang.functions.builtin.PowFunction;
 import com.dfsek.terra.api.structures.parser.lang.functions.builtin.SqrtFunction;
 import com.dfsek.terra.api.structures.parser.lang.keywords.BreakKeyword;
 import com.dfsek.terra.api.structures.parser.lang.keywords.ContinueKeyword;
+import com.dfsek.terra.api.structures.parser.lang.keywords.FailKeyword;
 import com.dfsek.terra.api.structures.parser.lang.keywords.IfKeyword;
 import com.dfsek.terra.api.structures.parser.lang.keywords.ReturnKeyword;
 import com.dfsek.terra.api.structures.parser.lang.keywords.WhileKeyword;
@@ -268,7 +269,7 @@ public class Parser {
             Token token = tokens.get(0);
             if(token.getType().equals(Token.Type.BLOCK_END)) break; // Stop parsing at block end.
 
-            ParserUtil.checkType(token, Token.Type.IDENTIFIER, Token.Type.IF_STATEMENT, Token.Type.WHILE_LOOP, Token.Type.NUMBER_VARIABLE, Token.Type.STRING_VARIABLE, Token.Type.BOOLEAN_VARIABLE, Token.Type.RETURN, Token.Type.BREAK, Token.Type.CONTINUE);
+            ParserUtil.checkType(token, Token.Type.IDENTIFIER, Token.Type.IF_STATEMENT, Token.Type.WHILE_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);
 
             if(token.isLoopLike()) { // Parse loop-like tokens (if, while, etc)
                 parsedItems.add(parseLoopLike(tokens, parsedVariables));
@@ -299,6 +300,7 @@ public class Parser {
             } else if(token.getType().equals(Token.Type.RETURN)) parsedItems.add(new ReturnKeyword(tokens.remove(0).getPosition()));
             else if(token.getType().equals(Token.Type.BREAK)) parsedItems.add(new BreakKeyword(tokens.remove(0).getPosition()));
             else if(token.getType().equals(Token.Type.CONTINUE)) parsedItems.add(new ContinueKeyword(tokens.remove(0).getPosition()));
+            else if(token.getType().equals(Token.Type.FAIL)) parsedItems.add(new FailKeyword(tokens.remove(0).getPosition()));
             else throw new UnsupportedOperationException("Unexpected token " + token.getType() + ": " + token.getPosition());
 
             if(!tokens.isEmpty()) ParserUtil.checkType(tokens.remove(0), Token.Type.STATEMENT_END, Token.Type.BLOCK_END);

common/src/main/java/com/dfsek/terra/api/structures/parser/lang/Block.java

@@ -37,6 +37,6 @@ public class Block implements Item<Block.ReturnLevel> {
     }
 
     public enum ReturnLevel {
-        NONE, BREAK, CONTINUE, RETURN
+        NONE, BREAK, CONTINUE, RETURN, FAIL
     }
 }

common/src/main/java/com/dfsek/terra/api/structures/parser/lang/keywords/FailKeyword.java

@@ -0,0 +1,30 @@
+package com.dfsek.terra.api.structures.parser.lang.keywords;
+
+import com.dfsek.terra.api.structures.parser.lang.Block;
+import com.dfsek.terra.api.structures.parser.lang.Keyword;
+import com.dfsek.terra.api.structures.structure.Rotation;
+import com.dfsek.terra.api.structures.structure.buffer.Buffer;
+import com.dfsek.terra.api.structures.tokenizer.Position;
+
+public class FailKeyword implements Keyword<Block.ReturnLevel> {
+    private final Position position;
+
+    public FailKeyword(Position position) {
+        this.position = position;
+    }
+
+    @Override
+    public Block.ReturnLevel apply(Buffer buffer, Rotation rotation, int recursions) {
+        return Block.ReturnLevel.FAIL;
+    }
+
+    @Override
+    public Position getPosition() {
+        return position;
+    }
+
+    @Override
+    public ReturnType returnType() {
+        return ReturnType.VOID;
+    }
+}

common/src/main/java/com/dfsek/terra/api/structures/script/StructureScript.java

@@ -44,10 +44,18 @@ public class StructureScript {
         this.id = parser.getID();
     }
 
-    public void execute(Location location, Rotation rotation) {
+    /**
+     * Paste the structure at a location
+     *
+     * @param location Location to paste structure
+     * @param rotation Rotation of structure
+     * @return Whether generation was successful
+     */
+    public boolean execute(Location location, Rotation rotation) {
         StructureBuffer buffer = new StructureBuffer(location);
-        block.apply(buffer, rotation, 0);
+        Block.ReturnLevel level = block.apply(buffer, rotation, 0);
         buffer.paste();
+        return !level.equals(Block.ReturnLevel.FAIL);
     }
 
     public void executeInBuffer(Buffer buffer, Rotation rotation, int recursions) {

common/src/main/java/com/dfsek/terra/api/structures/tokenizer/Token.java

@@ -207,6 +207,10 @@ public class Token {
          * Break statement
          */
         BREAK,
+        /**
+         * Fail statement. Like return keyword, but specifies that generation has failed.
+         */
+        FAIL,
         /**
          * ID declaration
          */

common/src/main/java/com/dfsek/terra/api/structures/tokenizer/Tokenizer.java

@@ -140,6 +140,8 @@ public class Tokenizer {
             return new Token(tokenString, Token.Type.CONTINUE, new Position(reader.getLine(), reader.getIndex()));
         if(tokenString.equals("break"))
             return new Token(tokenString, Token.Type.BREAK, new Position(reader.getLine(), reader.getIndex()));
+        if(tokenString.equals("fail"))
+            return new Token(tokenString, Token.Type.FAIL, new Position(reader.getLine(), reader.getIndex()));
 
         if(tokenString.equals("id"))
             return new Token(tokenString, Token.Type.ID, new Position(reader.getLine(), reader.getIndex()));