java/dagger/internal/codegen/writing/SimpleMethodBindingExpression.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.writing;

import static com.google.auto.common.MoreElements.asExecutable;
import static com.google.auto.common.MoreElements.asType;
import static com.google.common.base.Preconditions.checkArgument;
import static dagger.internal.codegen.javapoet.CodeBlocks.makeParametersCodeBlock;
import static dagger.internal.codegen.javapoet.TypeNames.rawTypeName;
import static dagger.internal.codegen.langmodel.Accessibility.isTypeAccessibleFrom;
import static dagger.internal.codegen.writing.InjectionMethods.ProvisionMethod.requiresInjectionMethod;

import com.google.auto.common.MoreTypes;
import com.squareup.javapoet.ClassName;
import com.squareup.javapoet.CodeBlock;
import com.squareup.javapoet.MethodSpec;
import com.squareup.javapoet.TypeName;
import dagger.internal.codegen.binding.ComponentRequirement;
import dagger.internal.codegen.binding.ProvisionBinding;
import dagger.internal.codegen.compileroption.CompilerOptions;
import dagger.internal.codegen.javapoet.Expression;
import dagger.internal.codegen.kotlin.KotlinMetadataUtil;
import dagger.internal.codegen.langmodel.DaggerElements;
import dagger.internal.codegen.writing.InjectionMethods.ProvisionMethod;
import dagger.model.DependencyRequest;
import java.util.Optional;
import javax.lang.model.SourceVersion;
import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.type.DeclaredType;
import javax.lang.model.type.TypeMirror;

/**
 * A binding expression that invokes methods or constructors directly (without attempting to scope)
 * {@link dagger.model.RequestKind#INSTANCE} requests.
 */
final class SimpleMethodBindingExpression extends SimpleInvocationBindingExpression {
  private final CompilerOptions compilerOptions;
  private final ProvisionBinding provisionBinding;
  private final ComponentBindingExpressions componentBindingExpressions;
  private final MembersInjectionMethods membersInjectionMethods;
  private final ComponentRequirementExpressions componentRequirementExpressions;
  private final DaggerElements elements;
  private final SourceVersion sourceVersion;
  private final KotlinMetadataUtil metadataUtil;

  SimpleMethodBindingExpression(
      ProvisionBinding binding,
      CompilerOptions compilerOptions,
      ComponentBindingExpressions componentBindingExpressions,
      MembersInjectionMethods membersInjectionMethods,
      ComponentRequirementExpressions componentRequirementExpressions,
      DaggerElements elements,
      SourceVersion sourceVersion,
      KotlinMetadataUtil metadataUtil) {
    super(binding);
    this.compilerOptions = compilerOptions;
    this.provisionBinding = binding;
    this.metadataUtil = metadataUtil;
    checkArgument(
        provisionBinding.implicitDependencies().isEmpty(),
        "framework deps are not currently supported");
    checkArgument(provisionBinding.bindingElement().isPresent());
    this.componentBindingExpressions = componentBindingExpressions;
    this.membersInjectionMethods = membersInjectionMethods;
    this.componentRequirementExpressions = componentRequirementExpressions;
    this.elements = elements;
    this.sourceVersion = sourceVersion;
  }

  @Override
  Expression getDependencyExpression(ClassName requestingClass) {
    return requiresInjectionMethod(provisionBinding, compilerOptions, requestingClass)
        ? invokeInjectionMethod(requestingClass)
        : invokeMethod(requestingClass);
  }

  private Expression invokeMethod(ClassName requestingClass) {
    // TODO(dpb): align this with the contents of InlineMethods.create
    CodeBlock arguments =
        makeParametersCodeBlock(
            ProvisionMethod.invokeArguments(
                provisionBinding,
                request -> dependencyArgument(request, requestingClass).codeBlock(),
                requestingClass));
    ExecutableElement method = asExecutable(provisionBinding.bindingElement().get());
    CodeBlock invocation;
    switch (method.getKind()) {
      case CONSTRUCTOR:
        invocation = CodeBlock.of("new $T($L)", constructorTypeName(requestingClass), arguments);
        break;
      case METHOD:
        CodeBlock module;
        Optional<CodeBlock> requiredModuleInstance = moduleReference(requestingClass);
        if (requiredModuleInstance.isPresent()) {
          module = requiredModuleInstance.get();
        } else if (metadataUtil.isObjectClass(asType(method.getEnclosingElement()))) {
          // Call through the singleton instance.
          // See: https://kotlinlang.org/docs/reference/java-to-kotlin-interop.html#static-methods
          module = CodeBlock.of("$T.INSTANCE", provisionBinding.bindingTypeElement().get());
        } else {
          module = CodeBlock.of("$T", provisionBinding.bindingTypeElement().get());
        }
        invocation = CodeBlock.of("$L.$L($L)", module, method.getSimpleName(), arguments);
        break;
      default:
        throw new IllegalStateException();
    }

    return Expression.create(simpleMethodReturnType(), invocation);
  }

  private TypeName constructorTypeName(ClassName requestingClass) {
    DeclaredType type = MoreTypes.asDeclared(provisionBinding.key().type());
    TypeName typeName = TypeName.get(type);
    if (type.getTypeArguments().stream()
        .allMatch(t -> isTypeAccessibleFrom(t, requestingClass.packageName()))) {
      return typeName;
    }
    return rawTypeName(typeName);
  }

  private Expression invokeInjectionMethod(ClassName requestingClass) {
    return injectMembers(
        ProvisionMethod.invoke(
            provisionBinding,
            request -> dependencyArgument(request, requestingClass).codeBlock(),
            requestingClass,
            moduleReference(requestingClass),
            compilerOptions,
            metadataUtil));
  }

  private Expression dependencyArgument(DependencyRequest dependency, ClassName requestingClass) {
    return componentBindingExpressions.getDependencyArgumentExpression(dependency, requestingClass);
  }

  private Expression injectMembers(CodeBlock instance) {
    if (provisionBinding.injectionSites().isEmpty()) {
      return Expression.create(simpleMethodReturnType(), instance);
    }
    if (sourceVersion.compareTo(SourceVersion.RELEASE_7) <= 0) {
      // Java 7 type inference can't figure out that instance in
      // injectParameterized(Parameterized_Factory.newParameterized()) is Parameterized<T> and not
      // Parameterized<Object>
      if (!MoreTypes.asDeclared(provisionBinding.key().type()).getTypeArguments().isEmpty()) {
        TypeName keyType = TypeName.get(provisionBinding.key().type());
        instance = CodeBlock.of("($T) ($T) $L", keyType, rawTypeName(keyType), instance);
      }
    }
    MethodSpec membersInjectionMethod = membersInjectionMethods.getOrCreate(provisionBinding.key());
    TypeMirror returnType =
        membersInjectionMethod.returnType.equals(TypeName.OBJECT)
            ? elements.getTypeElement(Object.class).asType()
            : provisionBinding.key().type();
    return Expression.create(returnType, CodeBlock.of("$N($L)", membersInjectionMethod, instance));
  }

  private Optional<CodeBlock> moduleReference(ClassName requestingClass) {
    return provisionBinding.requiresModuleInstance()
        ? provisionBinding
            .contributingModule()
            .map(Element::asType)
            .map(ComponentRequirement::forModule)
            .map(module -> componentRequirementExpressions.getExpression(module, requestingClass))
        : Optional.empty();
  }

  private TypeMirror simpleMethodReturnType() {
    return provisionBinding.contributedPrimitiveType().orElse(provisionBinding.key().type());
  }
}