[MNG-8232] Introduce ModelTransformer (#1702)

api/maven-api-core/src/main/java/org/apache/maven/api/services/ModelTransformerException.java

@@ -18,10 +18,14 @@
  */
 package org.apache.maven.api.services;
 
+import org.apache.maven.api.annotations.Experimental;
+
 /**
+ * Exception thrown when a {@link ModelTransformer} fails.
  *
  * @since 4.0.0
  */
+@Experimental
 public class ModelTransformerException extends MavenException {
 
     public ModelTransformerException(Exception e) {

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/ModelTransformer.java

@@ -0,0 +1,82 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.maven.api.spi;
+
+import org.apache.maven.api.annotations.Consumer;
+import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.annotations.Nonnull;
+import org.apache.maven.api.di.Named;
+import org.apache.maven.api.model.Model;
+import org.apache.maven.api.services.ModelTransformerException;
+
+/**
+ * Marker interface for model transformers.
+ *
+ * @since 4.0.0
+ */
+@Experimental
+@Consumer
+@Named
+public interface ModelTransformer extends SpiService {
+
+    /**
+     * Apply a transformation on the file model.
+     *
+     * This method will be called on each file model being loaded,
+     * just before validation.
+     *
+     * @param model the input model
+     * @return the transformed model, or the input model if no transformation is needed
+     * @throws ModelTransformerException
+     */
+    @Nonnull
+    default Model transformFileModel(@Nonnull Model model) throws ModelTransformerException {
+        return model;
+    }
+
+    /**
+     * Apply a transformation on the raw models.
+     *
+     * This method will be called on each raw model being loaded,
+     * just before validation.
+     *
+     * @param model the input model
+     * @return the transformed model, or the input model if no transformation is needed
+     * @throws ModelTransformerException
+     */
+    @Nonnull
+    default Model transformRawModel(@Nonnull Model model) throws ModelTransformerException {
+        return model;
+    }
+
+    /**
+     * Apply a transformation on the effective models.
+     *
+     * This method will be called on each effective model being loaded,
+     * just before validation.
+     *
+     * @param model the input model
+     * @return the transformed model, or the input model if no transformation is needed
+     * @throws ModelTransformerException
+     */
+    @Nonnull
+    default Model transformEffectiveModel(@Nonnull Model model) throws ModelTransformerException {
+        return model;
+    }
+}

api/maven-api-spi/src/main/java/org/apache/maven/api/spi/ModelTransformerException.java

@@ -0,0 +1,42 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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.apache.maven.api.spi;
+
+import org.apache.maven.api.annotations.Experimental;
+import org.apache.maven.api.services.MavenException;
+
+@Experimental
+public class ModelTransformerException extends MavenException {
+
+    public ModelTransformerException() {
+        this(null, null);
+    }
+
+    public ModelTransformerException(String message) {
+        this(message, null);
+    }
+
+    public ModelTransformerException(Throwable cause) {
+        this(null, cause);
+    }
+
+    public ModelTransformerException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

maven-api-impl/src/main/java/org/apache/maven/internal/impl/model/DefaultModelBuilder.java

@@ -145,6 +145,7 @@ public class DefaultModelBuilder implements ModelBuilder {
     private final ProfileActivationFilePathInterpolator profileActivationFilePathInterpolator;
     private final ModelTransformer transformer;
     private final ModelVersionParser versionParser;
+    private final List<org.apache.maven.api.spi.ModelTransformer> transformers;
 
     @SuppressWarnings("checkstyle:ParameterNumber")
     @Inject
@@ -166,7 +167,8 @@ public class DefaultModelBuilder implements ModelBuilder {
             PluginConfigurationExpander pluginConfigurationExpander,
             ProfileActivationFilePathInterpolator profileActivationFilePathInterpolator,
             ModelTransformer transformer,
-            ModelVersionParser versionParser) {
+            ModelVersionParser versionParser,
+            List<org.apache.maven.api.spi.ModelTransformer> transformers) {
         this.modelProcessor = modelProcessor;
         this.modelValidator = modelValidator;
         this.modelNormalizer = modelNormalizer;
@@ -185,6 +187,7 @@ public class DefaultModelBuilder implements ModelBuilder {
         this.profileActivationFilePathInterpolator = profileActivationFilePathInterpolator;
         this.transformer = transformer;
         this.versionParser = versionParser;
+        this.transformers = transformers;
     }
 
     @Override
@@ -590,6 +593,10 @@ public class DefaultModelBuilder implements ModelBuilder {
             resultModel = pluginConfigurationExpander.expandPluginConfiguration(resultModel, request, problems);
         }
 
+        for (var transformer : transformers) {
+            resultModel = transformer.transformEffectiveModel(resultModel);
+        }
+
         result.setEffectiveModel(resultModel);
 
         // effective model validation
@@ -803,6 +810,10 @@ public class DefaultModelBuilder implements ModelBuilder {
             }
         }
 
+        for (var transformer : transformers) {
+            model = transformer.transformFileModel(model);
+        }
+
         problems.setSource(model);
         modelValidator.validateFileModel(model, request, problems);
         if (hasFatalErrors(problems)) {
@@ -845,6 +856,10 @@ public class DefaultModelBuilder implements ModelBuilder {
             rawModel = rawModel.withModelVersion(namespace.substring(NAMESPACE_PREFIX.length()));
         }
 
+        for (var transformer : transformers) {
+            rawModel = transformer.transformRawModel(rawModel);
+        }
+
         modelValidator.validateRawModel(rawModel, request, problems);
 
         if (hasFatalErrors(problems)) {

maven-api-impl/src/test/java/org/apache/maven/internal/impl/standalone/RepositorySystemSupplier.java

@@ -1059,7 +1059,8 @@ public class RepositorySystemSupplier implements Supplier<RepositorySystem> {
                 new DefaultPluginConfigurationExpander(),
                 new ProfileActivationFilePathInterpolator(new DefaultPathTranslator(), new DefaultRootLocator()),
                 new BuildModelTransformer(),
-                new DefaultModelVersionParser(getVersionScheme()));
+                new DefaultModelVersionParser(getVersionScheme()),
+                List.of());
     }
 
     private RepositorySystem repositorySystem;

maven-core/src/main/java/org/apache/maven/internal/transformation/impl/DefaultConsumerPomBuilder.java

@@ -138,6 +138,9 @@ class DefaultConsumerPomBuilder implements ConsumerPomBuilder {
     @Inject
     private ProfileActivationFilePathInterpolator profileActivationFilePathInterpolator;
 
+    @Inject
+    private List<org.apache.maven.api.spi.ModelTransformer> transformers;
+
     Logger logger = LoggerFactory.getLogger(getClass());
 
     @Override
@@ -193,7 +196,8 @@ class DefaultConsumerPomBuilder implements ConsumerPomBuilder {
                 pluginConfigurationExpander,
                 profileActivationFilePathInterpolator,
                 modelTransformer,
-                versionParser);
+                versionParser,
+                transformers);
         InternalSession iSession = InternalSession.from(session);
         ModelBuilderRequest.ModelBuilderRequestBuilder request = ModelBuilderRequest.builder();
         request.projectBuild(true);

maven-resolver-provider/src/main/java/org/apache/maven/repository/internal/MavenRepositorySystemSupplier.java

@@ -1061,7 +1061,8 @@ public class MavenRepositorySystemSupplier implements Supplier<RepositorySystem>
                 new DefaultPluginConfigurationExpander(),
                 new ProfileActivationFilePathInterpolator(new DefaultPathTranslator(), new DefaultRootLocator()),
                 new BuildModelTransformer(),
-                new DefaultModelVersionParser(getVersionScheme()));
+                new DefaultModelVersionParser(getVersionScheme()),
+                List.of());
     }
 
     private RepositorySystem repositorySystem;