org.mapstruct.ap.MappingProcessor Maven / Gradle / Ivy
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/**
* Copyright 2012-2014 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;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.ServiceLoader;
import java.util.Set;
import javax.annotation.processing.AbstractProcessor;
import javax.annotation.processing.ProcessingEnvironment;
import javax.annotation.processing.Processor;
import javax.annotation.processing.RoundEnvironment;
import javax.annotation.processing.SupportedAnnotationTypes;
import javax.annotation.processing.SupportedOptions;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.TypeElement;
import javax.lang.model.util.ElementKindVisitor6;
import javax.tools.Diagnostic.Kind;
import org.mapstruct.ap.option.Options;
import org.mapstruct.ap.option.ReportingPolicy;
import org.mapstruct.ap.processor.DefaultModelElementProcessorContext;
import org.mapstruct.ap.processor.ModelElementProcessor;
import org.mapstruct.ap.processor.ModelElementProcessor.ProcessorContext;
import org.mapstruct.ap.util.AnnotationProcessingException;
/**
* A JSR 269 annotation {@link Processor} which generates the implementations for mapper interfaces (interfaces
* annotated with {@code @Mapper}).
*
* Implementation notes:
*
* The generation happens by incrementally building up a model representation of each mapper to be generated (a
* {@link Mapper} object), which is then written into the resulting Java source file.
*
* The model instantiation and processing happens in several phases/passes by applying a sequence of
* {@link ModelElementProcessor}s. The processors to apply are retrieved using the Java service loader mechanism and are
* processed in order of their {@link ModelElementProcessor#getPriority() priority}. The general processing flow is
* this:
*
* - retrieve mapping methods
* - create the {@code Mapper} model
* - perform enrichments and modifications (e.g. add annotations for dependency injection)
* - if no error occurred, write out the model into Java source files
*
*
* For reading annotation attributes, prisms as generated with help of the Hickory tool are used. These prisms allow a comfortable access to
* annotations and their attributes without depending on their class objects.
*
* The creation of Java source files is done using the FreeMarker template engine.
* Each node of the mapper model has a corresponding FreeMarker template file which provides the Java representation of
* that element and can include sub-elements via a custom FreeMarker directive. That way writing out a root node of the
* model ({@code Mapper}) will recursively include all contained sub-elements (such as its methods, their property
* mappings etc.).
*
* @author Gunnar Morling
*/
@SupportedAnnotationTypes("org.mapstruct.Mapper")
@SupportedOptions({
MappingProcessor.SUPPRESS_GENERATOR_TIMESTAMP,
MappingProcessor.UNMAPPED_TARGET_POLICY,
MappingProcessor.DEFAULT_COMPONENT_MODEL
})
public class MappingProcessor extends AbstractProcessor {
/**
* Whether this processor claims all processed annotations exclusively or not.
*/
private static final boolean ANNOTATIONS_CLAIMED_EXCLUSIVELY = false;
protected static final String SUPPRESS_GENERATOR_TIMESTAMP = "suppressGeneratorTimestamp";
protected static final String UNMAPPED_TARGET_POLICY = "unmappedTargetPolicy";
protected static final String DEFAULT_COMPONENT_MODEL = "defaultComponentModel";
private Options options;
@Override
public synchronized void init(ProcessingEnvironment processingEnv) {
super.init( processingEnv );
options = createOptions();
}
private Options createOptions() {
String unmappedTargetPolicy = processingEnv.getOptions().get( UNMAPPED_TARGET_POLICY );
return new Options(
Boolean.valueOf( processingEnv.getOptions().get( SUPPRESS_GENERATOR_TIMESTAMP ) ),
unmappedTargetPolicy != null ? ReportingPolicy.valueOf( unmappedTargetPolicy ) : null,
processingEnv.getOptions().get( DEFAULT_COMPONENT_MODEL )
);
}
@Override
public SourceVersion getSupportedSourceVersion() {
return SourceVersion.latestSupported();
}
@Override
public boolean process(final Set annotations, final RoundEnvironment roundEnvironment) {
for ( TypeElement annotation : annotations ) {
//Indicates that the annotation's type isn't on the class path of the compiled
//project. Let the compiler deal with that and print an appropriate error.
if ( annotation.getKind() != ElementKind.ANNOTATION_TYPE ) {
continue;
}
for ( Element mapperElement : roundEnvironment.getElementsAnnotatedWith( annotation ) ) {
TypeElement mapperTypeElement = asTypeElement( mapperElement );
// create a new context for each generated mapper in order to have imports of referenced types
// correctly managed;
// note that this assumes that a new source file is created for each mapper which must not
// necessarily be the case, e.g. in case of several mapper interfaces declared as inner types
// of one outer interface
ProcessorContext context = new DefaultModelElementProcessorContext( processingEnv, options );
processMapperTypeElement( context, mapperTypeElement );
}
}
return ANNOTATIONS_CLAIMED_EXCLUSIVELY;
}
/**
* Applies all registered {@link ModelElementProcessor}s to the given mapper
* type.
*
* @param context The processor context.
* @param mapperTypeElement The mapper type element.
*/
private void processMapperTypeElement(ProcessorContext context, TypeElement mapperTypeElement) {
Object model = null;
for ( ModelElementProcessor processor : getProcessors() ) {
try {
model = process( context, processor, mapperTypeElement, model );
}
catch ( AnnotationProcessingException e ) {
processingEnv.getMessager()
.printMessage(
Kind.ERROR,
e.getMessage(),
e.getElement(),
e.getAnnotationMirror(),
e.getAnnotationValue()
);
break;
}
}
}
private R process(ProcessorContext context, ModelElementProcessor processor,
TypeElement mapperTypeElement, Object modelElement) {
@SuppressWarnings("unchecked")
P sourceElement = (P) modelElement;
return processor.process( context, mapperTypeElement, sourceElement );
}
/**
* Retrieves all model element processors, ordered by their priority value
* (with the method retrieval processor having the lowest priority value (1)
* and the code generation processor the highest priority value.
*
* @return A list with all model element processors.
*/
private Iterable> getProcessors() {
// TODO Re-consider which class loader to use in case processors are
// loaded from other modules, too
@SuppressWarnings("rawtypes")
Iterator processorIterator = ServiceLoader.load(
ModelElementProcessor.class,
MappingProcessor.class.getClassLoader()
)
.iterator();
List> processors = new ArrayList>();
while ( processorIterator.hasNext() ) {
processors.add( processorIterator.next() );
}
Collections.sort( processors, new ProcessorComparator() );
return processors;
}
private TypeElement asTypeElement(Element element) {
return element.accept(
new ElementKindVisitor6() {
@Override
public TypeElement visitTypeAsInterface(TypeElement e, Void p) {
return e;
}
@Override
public TypeElement visitTypeAsClass(TypeElement e, Void p) {
return e;
}
}, null
);
}
private static class ProcessorComparator implements Comparator> {
@Override
public int compare(ModelElementProcessor o1, ModelElementProcessor o2) {
return
o1.getPriority() < o2.getPriority() ? -1 :
o1.getPriority() == o2.getPriority() ? 0 :
1;
}
}
}