#32 Preparing aggregated model to allow nodes to write out themselves using specific templates

processor/src/main/java/org/mapstruct/ap/MapperGenerationVisitor.java

@@ -130,8 +130,7 @@ public class MapperGenerationVisitor extends ElementKindVisitor6<Void, Void> {
             throw new RuntimeException( e );
         }
 
-        ModelWriter modelWriter = new ModelWriter( "mapper-implementation.ftl" );
-        modelWriter.writeModel( sourceFile, model );
+        new ModelWriter().writeModel( sourceFile, model );
     }
 
     private Mapper retrieveModel(TypeElement element) {

processor/src/main/java/org/mapstruct/ap/model/AbstractModelElement.java

@@ -0,0 +1,39 @@
+/**
+ *  Copyright 2012-2013 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  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.mapstruct.ap.model;
+
+import java.io.Writer;
+
+import org.mapstruct.ap.writer.FreeMarkerModelElementWriter;
+
+/**
+ * Default implementation of {@link ModelElement} which writes model elements
+ * using FreeMarker templates. By default, the fully-qualified class name of the
+ * given model element type, appended with the extension {@code *.ftl} is used
+ * as template file name.
+ *
+ * @author Gunnar Morling
+ */
+public class AbstractModelElement implements ModelElement {
+
+    @Override
+    public void write(Context context, Writer writer) throws Exception {
+        new FreeMarkerModelElementWriter().write( this, context, writer );
+    }
+}

processor/src/main/java/org/mapstruct/ap/model/Mapper.java

@@ -24,7 +24,7 @@ import java.util.SortedSet;
 import java.util.TreeSet;
 import javax.annotation.Generated;
 
-public class Mapper {
+public class Mapper extends AbstractModelElement {
 
     private final String packageName;
     private final String interfaceName;

processor/src/main/java/org/mapstruct/ap/model/ModelElement.java

@@ -0,0 +1,57 @@
+/**
+ *  Copyright 2012-2013 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  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.mapstruct.ap.model;
+
+import java.io.Writer;
+
+/**
+ * A model element with the ability to write itself into a given {@link Writer}.
+ *
+ * @author Gunnar Morling
+ */
+public interface ModelElement {
+
+    /**
+     * Passed to {@link ModelElement}, providing access to additional data
+     * specific to a given implementation of the model serialization mechanism.
+     *
+     * @author Gunnar Morling
+     */
+    interface Context {
+
+        /**
+         * Retrieves the object with the given type from this context.
+         *
+         * @param type The type of the object to retrieve from this context.
+         *
+         * @return The object with the given type from this context.
+         */
+        <T> T get(Class<T> type);
+    }
+
+    /**
+     * Writes this model element to the given writer.
+     *
+     * @param context Provides additional data specific to the used implementation
+     * of the model serialization mechanism.
+     * @param writer The writer to write this model to. Must not be closed by
+     * implementations.
+     */
+    void write(Context context, Writer writer) throws Exception;
+}

processor/src/main/java/org/mapstruct/ap/writer/FreeMarkerModelElementWriter.java

@@ -0,0 +1,46 @@
+/**
+ *  Copyright 2012-2013 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  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.mapstruct.ap.writer;
+
+import java.io.Writer;
+
+import freemarker.template.Configuration;
+import freemarker.template.Template;
+import org.mapstruct.ap.model.ModelElement;
+import org.mapstruct.ap.model.ModelElement.Context;
+
+/**
+ * Delegate for writing given {@link ModelElements} into a {@link Writer} using
+ * FreeMarker templates.
+ *
+ * @author Gunnar Morling
+ */
+public class FreeMarkerModelElementWriter {
+
+    public void write(ModelElement modelElement, Context context, Writer writer) throws Exception {
+        write( modelElement, modelElement.getClass().getName() + ".ftl", context, writer );
+    }
+
+    public void write(ModelElement modelElement, String templateName, Context context, Writer writer) throws Exception {
+        Configuration configuration = context.get( Configuration.class );
+
+        Template template = configuration.getTemplate( templateName );
+        template.process( modelElement, writer );
+    }
+}

processor/src/main/java/org/mapstruct/ap/writer/ModelIncludeDirective.java

@@ -0,0 +1,78 @@
+/**
+ *  Copyright 2012-2013 Gunnar Morling (http://www.gunnarmorling.de/)
+ *  and/or other contributors as indicated by the @authors tag. See the
+ *  copyright.txt file in the distribution for a full listing of all
+ *  contributors.
+ *
+ *  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.mapstruct.ap.writer;
+
+import java.io.IOException;
+import java.util.Map;
+
+import freemarker.core.Environment;
+import freemarker.ext.beans.BeanModel;
+import freemarker.template.TemplateDirectiveBody;
+import freemarker.template.TemplateDirectiveModel;
+import freemarker.template.TemplateException;
+import freemarker.template.TemplateModel;
+import org.mapstruct.ap.model.ModelElement;
+import org.mapstruct.ap.writer.ModelWriter.DefaultModelElementWriterContext;
+
+/**
+ * A {@link TemplateDirectiveModel} which allows to recursively write a graph of
+ * {@link ModelElement}s, with each element using its own template. Elements are
+ * imported into the parent template by using this directive like so:
+ * {@code <@includeModel object=myProperty/>}.
+ *
+ * @author Gunnar Morling
+ */
+public class ModelIncludeDirective implements TemplateDirectiveModel {
+
+    private DefaultModelElementWriterContext context;
+
+    public ModelIncludeDirective(DefaultModelElementWriterContext context) {
+        this.context = context;
+    }
+
+    @Override
+    public void execute(Environment env, @SuppressWarnings("rawtypes") Map params, TemplateModel[] loopVars,
+                        TemplateDirectiveBody body)
+        throws TemplateException, IOException {
+
+        Object wrappedObject = ( (BeanModel) params.get( "object" ) ).getWrappedObject();
+
+        if ( !( wrappedObject instanceof ModelElement ) ) {
+            throw new IllegalArgumentException( "Given object isn't a ModelElement:" + wrappedObject );
+        }
+
+        ModelElement modelElement = (ModelElement) wrappedObject;
+
+        try {
+            modelElement.write( context, env.getOut() );
+        }
+        catch ( TemplateException te ) {
+            throw te;
+        }
+        catch ( IOException ioe ) {
+            throw ioe;
+        }
+        catch ( RuntimeException re ) {
+            throw re;
+        }
+        catch ( Exception e ) {
+            throw new RuntimeException( e );
+        }
+    }
+}

processor/src/main/java/org/mapstruct/ap/writer/ModelWriter.java

@@ -19,11 +19,14 @@
 package org.mapstruct.ap.writer;
 
 import java.io.BufferedWriter;
+import java.util.HashMap;
+import java.util.Map;
 import javax.tools.JavaFileObject;
 
 import freemarker.template.Configuration;
 import freemarker.template.DefaultObjectWrapper;
-import freemarker.template.Template;
+import org.mapstruct.ap.model.ModelElement;
+import org.mapstruct.ap.model.ModelElement.Context;
 
 /**
  * Writes Java source files based on given mapper models, using a FreeMarker
@@ -39,25 +42,22 @@ public class ModelWriter {
      */
     private static final Configuration CONFIGURATION;
 
-    private final String templateName;
-
     static {
         CONFIGURATION = new Configuration();
         CONFIGURATION.setClassForTemplateLoading( ModelWriter.class, "/" );
         CONFIGURATION.setObjectWrapper( new DefaultObjectWrapper() );
+        CONFIGURATION.setSharedVariable(
+            "includeModel",
+            new ModelIncludeDirective( new DefaultModelElementWriterContext( CONFIGURATION ) )
+        );
     }
 
-    public ModelWriter(String templateName) {
-        this.templateName = templateName;
-    }
-
-    public void writeModel(JavaFileObject sourceFile, Object model) {
-
+    public void writeModel(JavaFileObject sourceFile, ModelElement model) {
         try {
             BufferedWriter writer = new BufferedWriter( sourceFile.openWriter() );
 
-            Template template = CONFIGURATION.getTemplate( templateName );
-            template.process( model, writer );
+            model.write( new DefaultModelElementWriterContext( CONFIGURATION ), writer );
+
             writer.flush();
             writer.close();
         }
@@ -68,4 +68,25 @@ public class ModelWriter {
             throw new RuntimeException( e );
         }
     }
+
+    /**
+     * {@link Context} implementation which provides access to the current
+     * FreeMarker {@link Configuration}.
+     *
+     * @author Gunnar Morling
+     */
+    static class DefaultModelElementWriterContext implements Context {
+
+        private Map<Class<?>, Object> values = new HashMap<Class<?>, Object>();
+
+        private DefaultModelElementWriterContext(Configuration configuration) {
+            values.put( Configuration.class, configuration );
+        }
+
+        @Override
+        @SuppressWarnings("unchecked")
+        public <T> T get(Class<T> type) {
+            return (T) values.get( type );
+        }
+    }
 }