java/dagger/internal/codegen/MultibindingAnnotationsProcessingStep.java

/*
 * Copyright (C) 2016 The Dagger Authors.
 *
 * 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 dagger.internal.codegen;

import static dagger.internal.codegen.DaggerElements.getAnnotationMirror;
import static javax.lang.model.util.ElementFilter.methodsIn;

import com.google.auto.common.BasicAnnotationProcessor.ProcessingStep;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Multimaps;
import com.google.common.collect.SetMultimap;
import dagger.multibindings.ElementsIntoSet;
import dagger.multibindings.IntoMap;
import dagger.multibindings.IntoSet;
import java.lang.annotation.Annotation;
import java.util.Set;
import javax.annotation.processing.Messager;
import javax.inject.Inject;
import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.tools.Diagnostic.Kind;

/**
 * Processing step that verifies that {@link IntoSet}, {@link ElementsIntoSet} and {@link IntoMap}
 * are not present on non-binding methods.
 */
final class MultibindingAnnotationsProcessingStep implements ProcessingStep {
  private final AnyBindingMethodValidator anyBindingMethodValidator;
  private final Messager messager;

  @Inject
  MultibindingAnnotationsProcessingStep(
      AnyBindingMethodValidator anyBindingMethodValidator, Messager messager) {
    this.anyBindingMethodValidator = anyBindingMethodValidator;
    this.messager = messager;
  }

  @Override
  public Set<? extends Class<? extends Annotation>> annotations() {
    return ImmutableSet.of(IntoSet.class, ElementsIntoSet.class, IntoMap.class);
  }

  @Override
  public Set<Element> process(
      SetMultimap<Class<? extends Annotation>, Element> elementsByAnnotation) {
    Multimaps.asMap(elementsByAnnotation)
        .forEach(
            (annotation, elements) -> {
              for (ExecutableElement method : methodsIn(elements)) {
                if (!anyBindingMethodValidator.isBindingMethod(method)) {
                  messager.printMessage(
                      Kind.ERROR,
                      "Multibinding annotations may only be on "
                          + "@Provides, @Produces, or @Binds methods",
                      method,
                      getAnnotationMirror(method, annotation).get());
                }
              }
            });
    return ImmutableSet.of();
  }
}