java/dagger/internal/codegen/InnerSwitchingProviders.java

/*
 * Copyright (C) 2018 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.squareup.javapoet.MethodSpec.constructorBuilder;
import static dagger.model.RequestKind.INSTANCE;
import static javax.lang.model.element.Modifier.FINAL;
import static javax.lang.model.element.Modifier.PRIVATE;

import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.CodeBlock;
import com.squareup.javapoet.TypeName;
import com.squareup.javapoet.TypeSpec;
import dagger.model.Key;
import javax.inject.Provider;
import javax.lang.model.type.TypeMirror;

/**
 * Generates {@linkplain BindingExpression binding expressions} for a binding that is represented by
 * an inner {@code SwitchingProvider} class.
 */
final class InnerSwitchingProviders extends SwitchingProviders {
  private final ComponentBindingExpressions componentBindingExpressions;
  private final DaggerTypes types;

  InnerSwitchingProviders(
      GeneratedComponentModel generatedComponentModel,
      ComponentBindingExpressions componentBindingExpressions,
      DaggerTypes types) {
    super(generatedComponentModel, types);
    this.componentBindingExpressions = componentBindingExpressions;
    this.types = types;
  }

  /**
   * Returns the binding expression for a binding that satisfies a {@link Provider} requests with a
   * inner {@code SwitchingProvider} class.
   */
  BindingExpression newBindingExpression(ContributionBinding binding) {
    return new BindingExpression() {
      @Override
      Expression getDependencyExpression(ClassName requestingClass) {
        return getProviderExpression(new SwitchCase(binding, requestingClass));
      }
    };
  }

  @Override
  protected TypeSpec createSwitchingProviderType(TypeSpec.Builder builder) {
    return builder
        .addModifiers(PRIVATE, FINAL)
        .addField(TypeName.INT, "id", PRIVATE, FINAL)
        .addMethod(
            constructorBuilder()
                .addParameter(TypeName.INT, "id")
                .addStatement("this.id = id")
                .build())
        .build();
  }

  private final class SwitchCase implements SwitchingProviders.SwitchCase {
    private final ContributionBinding binding;
    private final ClassName requestingClass;

    SwitchCase(ContributionBinding binding, ClassName requestingClass) {
      this.binding = binding;
      this.requestingClass = requestingClass;
    }

    @Override
    public Key key() {
      return binding.key();
    }

    @Override
    public Expression getProviderExpression(ClassName switchType, int switchId) {
      TypeMirror instanceType = types.accessibleType(binding.contributedType(), requestingClass);
      return Expression.create(
          types.wrapType(instanceType, Provider.class),
          CodeBlock.of("new $T<>($L)", switchType, switchId));
    }

    @Override
    public Expression getReturnExpression() {
      return componentBindingExpressions.getDependencyExpression(
          binding.key(), INSTANCE, requestingClass);
    }
  }
}