create MetaMapPreprocessor

common/implementation/src/main/java/com/dfsek/terra/config/preprocessor/MetaMapPreprocessor.java

@@ -0,0 +1,59 @@
+package com.dfsek.terra.config.preprocessor;
+
+import com.dfsek.tectonic.config.Configuration;
+import com.dfsek.tectonic.exception.LoadException;
+import com.dfsek.tectonic.loading.ConfigLoader;
+import com.dfsek.tectonic.preprocessor.Result;
+import com.dfsek.terra.api.config.meta.Meta;
+import com.dfsek.terra.api.util.reflection.TypeKey;
+import org.jetbrains.annotations.NotNull;
+
+import java.lang.reflect.AnnotatedType;
+import java.lang.reflect.ParameterizedType;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+public class MetaMapPreprocessor extends MetaPreprocessor<Meta> {
+    public MetaMapPreprocessor(Map<String, Configuration> configs) {
+        super(configs);
+    }
+
+    private static final TypeKey<List<String>> STRING_LIST = new TypeKey<>() {};
+    @SuppressWarnings("unchecked")
+    @Override
+    public @NotNull <T> Result<T> process(AnnotatedType t, T c, ConfigLoader loader, Meta annotation) {
+        if(t.getType() instanceof ParameterizedType) {
+            ParameterizedType parameterizedType = (ParameterizedType) t.getType();
+            if(parameterizedType.getRawType() instanceof Class) { // Should always be true but we check anyways
+                Class<?> baseClass = (Class<?>) parameterizedType.getRawType();
+
+                if(Map.class.isAssignableFrom(baseClass) && c instanceof Map) { // List metaconfig
+                    Map<Object, Object> map = (Map<Object, Object>) c;
+
+                    Map<Object, Object> newMap = new HashMap<>(map);
+
+                    if(map.containsKey("<<")) {
+                        newMap.putAll(map);
+                        newMap.remove("<<"); // Remove placeholder
+
+                        List<String> keys = (List<String>) loader.loadType(STRING_LIST.getAnnotatedType(), map.get("<<"));
+                        keys.forEach(key -> {
+                            Object meta = getMetaValue(key);
+                            if(!(meta instanceof Map)) {
+                                throw new LoadException("MetaMap injection candidate must be list, is type " + meta.getClass().getCanonicalName());
+                            }
+                            newMap.putAll((Map<?, ?>) meta);
+                        });
+                        return (Result<T>) Result.overwrite(newMap);
+                    }
+
+
+                }
+            }
+        }
+
+        return Result.noOp();
+    }
+}