Switch Fix command resolution from enums to registry.

Allowing additional commands to be registered by other Metafacture modules as well as by third-party libraries/applications.

Also opens up the possibility to eventually enable Flux command registration in the same vein.

The command registry is scoped by Metafix instance in order to avoid global state.

Author: blackwinter

metafix/src/main/java/org/metafacture/metafix/FixCommand.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2025 hbz NRW
+ *
+ * Licensed under the Apache License, Version 2.0 the "License";
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.metafacture.metafix;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Documented
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+public @interface FixCommand {
+
+    /**
+     * Returns the Fix command name.
+     *
+     * @return Fix command name
+     */
+    String value();
+
+}

metafix/src/main/java/org/metafacture/metafix/Metafix.java

@@ -28,6 +28,7 @@
 import org.metafacture.framework.annotations.Out;
 import org.metafacture.framework.helpers.DefaultStreamReceiver;
 import org.metafacture.mangling.StreamFlattener;
+import org.metafacture.metafix.api.FixRegistry;
 import org.metafacture.metafix.fix.Expression;
 import org.metafacture.metamorph.api.Maps;
 
@@ -83,6 +84,7 @@ public class Metafix implements StreamPipe<StreamReceiver>, Maps {
     private static final String ENTITIES_NOT_BALANCED = "Entity starts and ends are not balanced";
 
     private final Deque<Integer> entityCountStack = new LinkedList<>();
+    private final FixRegistry registry = new FixRegistry();
     private final List<Closeable> resources = new ArrayList<>();
     private final List<Expression> expressions = new ArrayList<>();
     private final Map<String, Map<String, String>> maps = new HashMap<>();
@@ -308,6 +310,15 @@ public List<Expression> getExpressions() {
         return expressions;
     }
 
+    /**
+     * Returns the Fix registry.
+     *
+     * @return the Fix registry
+     */
+    public FixRegistry getRegistry() {
+        return registry;
+    }
+
     @Override
     public void startRecord(final String identifier) {
         currentRecord = new Record();

metafix/src/main/java/org/metafacture/metafix/RecordTransformer.java

@@ -22,6 +22,7 @@
 import org.metafacture.metafix.api.FixContext;
 import org.metafacture.metafix.api.FixFunction;
 import org.metafacture.metafix.api.FixPredicate;
+import org.metafacture.metafix.api.FixRegistry;
 import org.metafacture.metafix.fix.Do;
 import org.metafacture.metafix.fix.ElsIf;
 import org.metafacture.metafix.fix.Else;
@@ -62,6 +63,7 @@ public class RecordTransformer { // checkstyle-disable-line ClassFanOutComplexit
 
     private static final Logger LOG = LoggerFactory.getLogger(RecordTransformer.class);
 
+    private final FixRegistry registry;
     private final List<Consumer<Record>> consumers = new LinkedList<>();
     private final List<Map<String, String>> vars = new ArrayList<>(Collections.nCopies(Vars.values().length, null));
     private final Metafix metafix;
@@ -82,6 +84,7 @@ private enum Vars {
     private RecordTransformer(final Metafix metafix, final List<Expression> expressions, final RecordTransformer parent) {
         this.metafix = metafix;
         this.parent = parent;
+        this.registry = metafix.getRegistry();
 
         expressions.forEach(e -> {
             final Params params = new Params(e.getParams(), this);
@@ -143,7 +146,7 @@ public void transform(final Record record) {
 
     private void processDo(final Do expression, final Params params, final Options options) {
         processFix(() -> executionExceptionMessage(expression), () -> {
-            final FixContext context = getInstance(expression.getName(), FixContext.class, FixBind::valueOf);
+            final FixContext context = getInstance(expression.getName(), FixContext.class, registry::getBind);
             final RecordTransformer recordTransformer = childTransformer(expression.getElements());
 
             return record -> context.execute(metafix, record, params.resolve(), options.resolve(), recordTransformer);
@@ -158,10 +161,10 @@ private void processIf(final If ifExpression, final Params ifParams, final Optio
         final Supplier<String> elseMessageSupplier = () -> executionExceptionMessage(elseExpression, elseExpression.eResource());
 
         processFix(() -> executionExceptionMessage(ifExpression, ifExpression.eResource()), () -> {
-            final FixPredicate ifPredicate = getInstance(ifExpression.getName(), FixPredicate.class, FixConditional::valueOf);
+            final FixPredicate ifPredicate = getInstance(ifExpression.getName(), FixPredicate.class, registry::getConditional);
             final RecordTransformer ifTransformer = childTransformer(ifExpression.getElements());
 
-            final List<FixPredicate> elseIfPredicates = mapList(elseIfExpressions, e -> getInstance(e.getName(), FixPredicate.class, FixConditional::valueOf));
+            final List<FixPredicate> elseIfPredicates = mapList(elseIfExpressions, e -> getInstance(e.getName(), FixPredicate.class, registry::getConditional));
             final List<Params> elseIfParamsList = mapList(elseIfExpressions, e -> new Params(e.getParams(), this));
             final List<Options> elseIfOptionsList = mapList(elseIfExpressions, e -> new Options(e.getOptions(), this));
             final List<RecordTransformer> elseIfTransformers = mapList(elseIfExpressions, e -> childTransformer(e.getElements()));
@@ -200,7 +203,7 @@ private void processIf(final If ifExpression, final Params ifParams, final Optio
 
     private void processUnless(final Unless expression, final Params params, final Options options) {
         processFix(() -> executionExceptionMessage(expression, expression.eResource()), () -> {
-            final FixPredicate predicate = getInstance(expression.getName(), FixPredicate.class, FixConditional::valueOf);
+            final FixPredicate predicate = getInstance(expression.getName(), FixPredicate.class, registry::getConditional);
             final RecordTransformer recordTransformer = childTransformer(expression.getElements());
 
             return record -> {
@@ -213,7 +216,7 @@ private void processUnless(final Unless expression, final Params params, final O
 
     private void processFunction(final MethodCall expression, final Params params, final Options options) {
         processFix(() -> executionExceptionMessage(expression), () -> {
-            final FixFunction function = getInstance(expression.getName(), FixFunction.class, FixMethod::valueOf);
+            final FixFunction function = getInstance(expression.getName(), FixFunction.class, registry::getMethod);
             return record -> function.apply(metafix, record, params.resolve(), options.resolve());
         });
     }