java/dagger/internal/codegen/BindsInstanceProcessingStep.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 com.google.common.collect.Iterables.getOnlyElement;
import static dagger.internal.codegen.ConfigurationAnnotations.getComponentOrSubcomponentAnnotation;
import static dagger.internal.codegen.ConfigurationAnnotations.getModuleAnnotation;
import static dagger.internal.codegen.DaggerElements.isAnyAnnotationPresent;
import static dagger.internal.codegen.DaggerStreams.toImmutableSet;
import static dagger.internal.codegen.ErrorMessages.BINDS_INSTANCE_IN_INVALID_COMPONENT;
import static dagger.internal.codegen.ErrorMessages.BINDS_INSTANCE_IN_MODULE;
import static dagger.internal.codegen.ErrorMessages.BINDS_INSTANCE_ONE_PARAMETER;
import static dagger.internal.codegen.MoreAnnotationMirrors.simpleName;
import static javax.lang.model.element.Modifier.ABSTRACT;

import com.google.auto.common.BasicAnnotationProcessor.ProcessingStep;
import com.google.auto.common.MoreElements;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.SetMultimap;
import dagger.BindsInstance;
import java.lang.annotation.Annotation;
import java.util.Set;
import java.util.stream.Stream;
import javax.annotation.processing.Messager;
import javax.inject.Inject;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.VariableElement;

/**
 * Processing step that validates that the {@code BindsInstance} annotation is applied to the
 * correct elements.
 */
final class BindsInstanceProcessingStep implements ProcessingStep {

  private static final ImmutableSet<Class<? extends Annotation>> COMPONENT_ANNOTATIONS =
      Stream.of(ComponentDescriptor.Kind.values())
          .map(ComponentDescriptor.Kind::annotationType)
          .collect(toImmutableSet());
  private static final ImmutableSet<Class<? extends Annotation>> MODULE_ANNOTATIONS =
      Stream.of(ModuleDescriptor.Kind.values())
          .map(ModuleDescriptor.Kind::moduleAnnotation)
          .collect(toImmutableSet());

  private final Messager messager;

  @Inject
  BindsInstanceProcessingStep(Messager messager) {
    this.messager = messager;
  }

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

  @Override
  public Set<Element> process(
      SetMultimap<Class<? extends Annotation>, Element> elementsByAnnotation) {
    for (Element element : elementsByAnnotation.get(BindsInstance.class)) {
      ExecutableElement method = MoreElements.asExecutable(element);
      ValidationReport.Builder<ExecutableElement> report = ValidationReport.about(method);
      if (!method.getModifiers().contains(ABSTRACT)) {
        report.addError("@BindsInstance methods must be abstract");
      }
      if (method.getParameters().size() != 1) {
        report.addError(BINDS_INSTANCE_ONE_PARAMETER);
      } else {
        VariableElement parameter = getOnlyElement(method.getParameters());
        if (FrameworkTypes.isFrameworkType(parameter.asType())) {
          report.addError("@BindsInstance parameters may not be framework types", parameter);
        }
      }
      TypeElement enclosingType = MoreElements.asType(method.getEnclosingElement());
      if (isAnyAnnotationPresent(enclosingType, MODULE_ANNOTATIONS)) {
        report.addError(
            String.format(
                BINDS_INSTANCE_IN_MODULE, simpleName(getModuleAnnotation(enclosingType).get())));
      }
      if (isAnyAnnotationPresent(enclosingType, COMPONENT_ANNOTATIONS)) {
        AnnotationMirror componentAnnotation =
            getComponentOrSubcomponentAnnotation(enclosingType).get();
        report.addError(
            String.format(BINDS_INSTANCE_IN_INVALID_COMPONENT, simpleName(componentAnnotation)));
      }
      report.build().printMessagesTo(messager);
    }
    return ImmutableSet.of();
  }
}