java/dagger/internal/codegen/ComponentMethodBindingExpression.java

/*
 * Copyright (C) 2017 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.base.Preconditions.checkNotNull;

import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.CodeBlock;
import com.squareup.javapoet.MethodSpec;
import dagger.internal.codegen.ComponentDescriptor.ComponentMethodDescriptor;
import dagger.model.RequestKind;

/**
 * A binding expression that implements and uses a component method.
 *
 * <p>Dependents of this binding expression will just call the component method.
 */
final class ComponentMethodBindingExpression extends BindingExpression {
  private final BindingMethodImplementation methodImplementation;
  private final GeneratedComponentModel generatedComponentModel;
  private final ComponentMethodDescriptor componentMethod;
  private final ComponentBindingExpressions componentBindingExpressions;

  ComponentMethodBindingExpression(
      ResolvedBindings resolvedBindings,
      RequestKind requestKind,
      BindingMethodImplementation methodImplementation,
      GeneratedComponentModel generatedComponentModel,
      ComponentMethodDescriptor componentMethod,
      ComponentBindingExpressions componentBindingExpressions) {
    super(resolvedBindings, requestKind);
    this.methodImplementation = checkNotNull(methodImplementation);
    this.generatedComponentModel = checkNotNull(generatedComponentModel);
    this.componentMethod = checkNotNull(componentMethod);
    this.componentBindingExpressions = checkNotNull(componentBindingExpressions);
  }

  @Override
  protected CodeBlock doGetComponentMethodImplementation(
      ComponentMethodDescriptor componentMethod, ClassName componentName) {
    // There could be several methods on the component for the same request key and kind.
    // Only one should use the BindingMethodImplementation; the others can delegate that one. So
    // use methodImplementation.body() only if componentMethod equals the method for this instance.
    
    // Separately, the method might be defined on a supertype that is also a supertype of some
    // parent component. In that case, the same ComponentMethodDescriptor will be used to add a CMBE
    // for the parent and the child. Only the parent's should use the BindingMethodImplementation;
    // the child's can delegate to the parent. So use methodImplementation.body() only if
    // componentName equals the component for this instance.
    return componentMethod.equals(this.componentMethod)
            && componentName.equals(generatedComponentModel.name())
        ? methodImplementation.body()
        : super.doGetComponentMethodImplementation(componentMethod, componentName);
  }

  @Override
  Expression getDependencyExpression(ClassName requestingClass) {
    MethodSpec implementedMethod = componentBindingExpressions.getComponentMethod(componentMethod);
    return Expression.create(
        methodImplementation.returnType(),
        requestingClass.equals(generatedComponentModel.name())
            ? CodeBlock.of("$N()", implementedMethod)
            : CodeBlock.of("$T.this.$N()", generatedComponentModel.name(), implementedMethod));
  }
}