java/dagger/internal/codegen/InjectionMethods.java - platform/external/dagger2 - Gitiles

 /*
  * 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.CaseFormat.LOWER_CAMEL;
 import static com.google.common.base.CaseFormat.UPPER_CAMEL;
 import static com.squareup.javapoet.MethodSpec.methodBuilder;
 import static dagger.internal.codegen.Accessibility.isElementAccessibleFrom;
 import static dagger.internal.codegen.Accessibility.isRawTypeAccessible;
 import static dagger.internal.codegen.Accessibility.isRawTypePubliclyAccessible;
 import static dagger.internal.codegen.Accessibility.isTypeAccessibleFrom;
 import static dagger.internal.codegen.CodeBlocks.makeParametersCodeBlock;
 import static dagger.internal.codegen.CodeBlocks.toConcatenatedCodeBlock;
 import static dagger.internal.codegen.ConfigurationAnnotations.getNullableType;
 import static dagger.internal.codegen.SourceFiles.generatedClassNameForBinding;
 import static dagger.internal.codegen.SourceFiles.membersInjectorNameForType;
 import static dagger.internal.codegen.TypeNames.rawTypeName;
 import static dagger.internal.codegen.Util.toImmutableList;
 import static java.util.stream.Collectors.toList;
 import static javax.lang.model.element.Modifier.PUBLIC;
 import static javax.lang.model.element.Modifier.STATIC;
 import static javax.lang.model.type.TypeKind.VOID;

 import com.google.auto.common.MoreElements;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.squareup.javapoet.ClassName;
 import com.squareup.javapoet.CodeBlock;
 import com.squareup.javapoet.MethodSpec;
 import com.squareup.javapoet.ParameterSpec;
 import com.squareup.javapoet.TypeName;
 import com.squareup.javapoet.TypeVariableName;
 import dagger.internal.codegen.DependencyRequest.Kind;
 import dagger.internal.codegen.MembersInjectionBinding.InjectionSite;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Optional;
 import java.util.function.Function;
 import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.Parameterizable;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.element.TypeParameterElement;
 import javax.lang.model.element.VariableElement;
 import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
 import javax.lang.model.util.Types;

 /**
  * Injection methods are static methods that implement provision and/or injection in one step:
  *
  * <ul>
  *   <li>methods that invoke {@code @Inject} constructors and do members injection if necessary
  *   <li>methods that call {@code @Provides} module methods
  *   <li>methods that perform members injection
  * </ul>
  */
 // TODO(ronshapiro): add examples for each class of injection method
 final class InjectionMethods {
   /**
    * A static method that returns an object from a {@code @Provides} method or an {@code @Inject}ed
    * constructor. Its parameters match the dependency requests for constructor and members
    * injection.
    *
    * <p>For {@code @Provides} methods named "foo", the method name is "proxyFoo". If the
    * {@code @Provides} method and its raw parameter types are publicly accessible, no method is
    * necessary and this method returns {@link Optional#empty()}.
    *
    * <p>TODO(ronshapiro): At the moment non-static {@code @Provides} methods are not supported.
    *
    * <p>Example:
    *
    * <pre><code>
    * abstract class FooModule {
    *   {@literal @Provides} static Foo provideFoo(Bar bar, Baz baz) { … }
    * }
    *
    * public static proxyProvideFoo(Bar bar, Baz baz) { … }
    * </code></pre>
    *
    * <p>For {@code @Inject}ed constructors, the method name is "newFoo". If the constructor and its
    * raw parameter types are publicly accessible, no method is necessary and this method returns
    * {@code Optional#empty()}.
    *
    * <p>Example:
    *
    * <pre><code>
    * class Foo {
    *   {@literal @Inject} Foo(Bar bar) {}
    * }
    *
    * public static Foo newFoo(Bar bar) { … }
    * </code></pre>
    */
   static final class ProvisionMethod {

     /**
      * Returns a method that invokes the binding's {@linkplain ProvisionBinding#bindingElement()
      * constructor} and injects the instance's members, if necessary. If {@link
      * #shouldCreateInjectionMethod(ProvisionBinding) no method is necessary}, then {@link
      * Optional#empty()} is returned.
      */
     static Optional<MethodSpec> create(ProvisionBinding binding) {
       if (!shouldCreateInjectionMethod(binding)) {
         return Optional.empty();
       }
       ExecutableElement element = MoreElements.asExecutable(binding.bindingElement().get());
       switch (element.getKind()) {
         case CONSTRUCTOR:
           return Optional.of(constructorProxy(element));
         case METHOD:
           return Optional.of(
               methodProxy(element, methodName(element), ReceiverAccessibility.IGNORE));
         default:
           throw new AssertionError(element);
       }
     }

     /**
      * Invokes the injection method for {@code binding}, with the dependencies transformed with the
      * {@code dependencyUsage} function.
      */
     static CodeBlock invoke(
         ProvisionBinding binding,
         Function<DependencyRequest, CodeBlock> dependencyUsage,
         ClassName requestingClass,
         Optional<CodeBlock> moduleReference) {
       ImmutableList.Builder<CodeBlock> arguments = ImmutableList.builder();
       moduleReference.ifPresent(arguments::add);
       arguments.addAll(
           injectionMethodArguments(
               binding.provisionDependencies(), dependencyUsage, requestingClass));
       return callInjectionMethod(
           create(binding).get().name,
           arguments.build(),
           generatedClassNameForBinding(binding),
           requestingClass);
     }

     private static MethodSpec constructorProxy(ExecutableElement constructor) {
       UniqueNameSet names = new UniqueNameSet();
       TypeElement enclosingType = MoreElements.asType(constructor.getEnclosingElement());
       MethodSpec.Builder method =
           methodBuilder(methodName(constructor))
               .returns(TypeName.get(enclosingType.asType()))
               .addModifiers(PUBLIC, STATIC);

       copyTypeParameters(enclosingType, method);
       copyThrows(constructor, method);

       return method
           .addStatement(
               "return new $T($L)", enclosingType, copyParameters(constructor, method, names))
           .build();
     }

     /**
      * Returns {@code true} if injecting an instance of {@code binding} from {@code callingPackage}
      * requires the use of an injection method.
      */
     static boolean requiresInjectionMethod(ProvisionBinding binding, String callingPackage) {
       ExecutableElement method = MoreElements.asExecutable(binding.bindingElement().get());
       return !binding.injectionSites().isEmpty()
           || !isElementAccessibleFrom(method, callingPackage)
           || method
               .getParameters()
               .stream()
               .map(VariableElement::asType)
               .anyMatch(type -> !isRawTypeAccessible(type, callingPackage));
     }

     private static boolean shouldCreateInjectionMethod(ProvisionBinding binding) {
       return requiresInjectionMethod(binding, "dagger.should.never.exist");
     }

     /**
      * Returns the name of the {@code static} method that wraps {@code method}. For methods that are
      * associated with {@code @Inject} constructors, the method will also inject all {@link
      * InjectionSite}s.
      */
     private static String methodName(ExecutableElement method) {
       switch (method.getKind()) {
         case CONSTRUCTOR:
           return "new" + method.getEnclosingElement().getSimpleName();
         case METHOD:
           return "proxy" + LOWER_CAMEL.to(UPPER_CAMEL, method.getSimpleName().toString());
         default:
           throw new AssertionError(method);
       }
     }
   }

   /**
    * A static method that injects one member of an instance of a type. Its first parameter is an
    * instance of the type to be injected. The remaining parameters match the dependency requests for
    * the injection site.
    *
    * <p>Example:
    *
    * <pre><code>
    * class Foo {
    *   {@literal @Inject} Bar bar;
    *   {@literal @Inject} void setThings(Baz baz, Qux qux) {}
    * }
    *
    * public static injectBar(Foo instance, Bar bar) { … }
    * public static injectSetThings(Foo instance, Baz baz, Qux qux) { … }
    * </code></pre>
    */
   static final class InjectionSiteMethod {
     /**
      * When a type has an inaccessible member from a supertype (e.g. an @Inject field in a parent
      * that's in a different package), a method in the supertype's package must be generated to give
      * the subclass's members injector a way to inject it. Each potentially inaccessible member
      * receives its own method, as the subclass may need to inject them in a different order from
      * the parent class.
      */
     static MethodSpec create(InjectionSite injectionSite) {
       String methodName = methodName(injectionSite);
       switch (injectionSite.kind()) {
         case METHOD:
           return methodProxy(
               MoreElements.asExecutable(injectionSite.element()),
               methodName,
               ReceiverAccessibility.CAST_IF_NOT_PUBLIC);
         case FIELD:
           return fieldProxy(MoreElements.asVariable(injectionSite.element()), methodName);
         default:
           throw new AssertionError(injectionSite);
       }
     }

     /**
      * Invokes each of the injection methods for {@code injectionSites}, with the dependencies
      * transformed using the {@code dependencyUsage} function.
      *
      * @param instanceType the type of the {@code instance} parameter
      */
     static CodeBlock invokeAll(
         ImmutableSet<InjectionSite> injectionSites,
         ClassName generatedTypeName,
         CodeBlock instanceCodeBlock,
         TypeMirror instanceType,
         Types types,
         Function<DependencyRequest, CodeBlock> dependencyUsage) {
       return injectionSites
           .stream()
           .map(
               injectionSite -> {
                 TypeMirror injectSiteType =
                     types.erasure(injectionSite.element().getEnclosingElement().asType());

                 // If instance has been declared as Object because it is not accessible from the
                 // component, but the injectionSite is in a supertype of instanceType that is
                 // publicly accessible, the InjectionSiteMethod will request the actual type and not
                 // Object as the first parameter. If so, cast to the supertype which is accessible
                 // from within generatedTypeName
                 CodeBlock maybeCastedInstance =
                     !types.isSubtype(instanceType, injectSiteType)
                             && isTypeAccessibleFrom(injectSiteType, generatedTypeName.packageName())
                         ? CodeBlock.of("($T) $L", injectSiteType, instanceCodeBlock)
                         : instanceCodeBlock;
                 return CodeBlock.of(
                     "$L;",
                     invoke(injectionSite, generatedTypeName, maybeCastedInstance, dependencyUsage));
               })
           .collect(toConcatenatedCodeBlock());
     }

     /**
      * Invokes the injection method for {@code injectionSite}, with the dependencies transformed
      * using the {@code dependencyUsage} function.
      */
     private static CodeBlock invoke(
         InjectionSite injectionSite,
         ClassName generatedTypeName,
         CodeBlock instanceCodeBlock,
         Function<DependencyRequest, CodeBlock> dependencyUsage) {
       List<CodeBlock> arguments = new ArrayList<>();
       arguments.add(instanceCodeBlock);
       if (!injectionSite.dependencies().isEmpty()) {
         arguments.addAll(
             injectionSite
                 .dependencies()
                 .stream()
                 .map(dependencyUsage)
                 .collect(toList()));
       }
       return callInjectionMethod(
           create(injectionSite).name,
           arguments,
           membersInjectorNameForType(
               MoreElements.asType(injectionSite.element().getEnclosingElement())),
           generatedTypeName);
     }

     /*
      * TODO(ronshapiro): this isn't perfect, as collisions could still exist. Some examples:
      *
      *  - @Inject void members() {} will generate a method that conflicts with the instance
      *    method `injectMembers(T)`
      *  - Adding the index could conflict with another member:
      *      @Inject void a(Object o) {}
      *      @Inject void a(String s) {}
      *      @Inject void a1(String s) {}
      *
      *    Here, Method a(String) will add the suffix "1", which will conflict with the method
      *    generated for a1(String)
      *  - Members named "members" or "methods" could also conflict with the {@code static} injection
      *    method.
      */
     private static String methodName(InjectionSite injectionSite) {
       int index = injectionSite.indexAmongAtInjectMembersWithSameSimpleName();
       String indexString = index == 0 ? "" : String.valueOf(index + 1);
       return "inject"
           + LOWER_CAMEL.to(UPPER_CAMEL, injectionSite.element().getSimpleName().toString())
           + indexString;
     }
   }

   /**
    * Returns an argument list suitable for calling an injection method. Down-casts any arguments
    * that are {@code Object} (or {@code Provider<Object>}) at the caller but not the method.
    *
    * @param dependencies the dependencies used by the method
    * @param dependencyUsage function to apply on each of {@code dependencies} before casting
    * @param requestingClass the class calling the injection method
    */
   private static ImmutableList<CodeBlock> injectionMethodArguments(
       ImmutableSet<DependencyRequest> dependencies,
       Function<DependencyRequest, CodeBlock> dependencyUsage,
       ClassName requestingClass) {
     return dependencies.stream()
         .map(dep -> injectionMethodArgument(dep, dependencyUsage.apply(dep), requestingClass))
         .collect(toImmutableList());
   }

   private static CodeBlock injectionMethodArgument(
       DependencyRequest dependency, CodeBlock argument, ClassName generatedTypeName) {
     TypeMirror keyType = dependency.key().type();
     CodeBlock.Builder codeBlock = CodeBlock.builder();
     if (!isRawTypeAccessible(keyType, generatedTypeName.packageName())
         && isTypeAccessibleFrom(keyType, generatedTypeName.packageName())) {
       if (!dependency.kind().equals(Kind.INSTANCE)) {
         TypeName usageTypeName = accessibleType(dependency);
         codeBlock.add("($T) ($T)", usageTypeName, rawTypeName(usageTypeName));
       } else if (dependency.requestElement().get().asType().getKind().equals(TypeKind.TYPEVAR)) {
         codeBlock.add("($T)", keyType);
       }
     }
     return codeBlock.add(argument).build();
   }

   /**
    * Returns the parameter type for {@code dependency}. If the raw type is not accessible, returns
    * {@link Object}.
    */
   private static TypeName accessibleType(DependencyRequest dependency) {
     TypeName typeName = dependency.kind().typeName(accessibleType(dependency.key().type()));
     return dependency.requestsPrimitiveType() ? typeName.unbox() : typeName;
   }

   /**
    * Returns the accessible type for {@code type}. If the raw type is not accessible, returns {@link
    * Object}.
    */
   private static TypeName accessibleType(TypeMirror type) {
     return isRawTypePubliclyAccessible(type) ? TypeName.get(type) : TypeName.OBJECT;
   }

   private static CodeBlock callInjectionMethod(
       String methodName,
       List<CodeBlock> arguments,
       ClassName enclosingClass,
       ClassName requestingClass) {
     CodeBlock.Builder invocation = CodeBlock.builder();
     if (!enclosingClass.equals(requestingClass)) {
       invocation.add("$T.", enclosingClass);
     }
     return invocation.add("$L($L)", methodName, makeParametersCodeBlock(arguments)).build();
   }

   private enum ReceiverAccessibility {
     CAST_IF_NOT_PUBLIC {
       @Override
       TypeName parameterType(TypeMirror type) {
         return accessibleType(type);
       }

       @Override
       CodeBlock potentiallyCast(CodeBlock instance, TypeMirror instanceType) {
         return instanceWithPotentialCast(instance, instanceType);
       }
     },
     IGNORE {
       @Override
       TypeName parameterType(TypeMirror type) {
         return TypeName.get(type);
       }

       @Override
       CodeBlock potentiallyCast(CodeBlock instance, TypeMirror instanceType) {
         return instance;
       }
     },
     ;

     abstract TypeName parameterType(TypeMirror type);
     abstract CodeBlock potentiallyCast(CodeBlock instance, TypeMirror instanceType);
   }

   private static CodeBlock instanceWithPotentialCast(CodeBlock instance, TypeMirror instanceType) {
     return isRawTypePubliclyAccessible(instanceType)
         ? instance
         : CodeBlock.of("(($T) $L)", instanceType, instance);
   }

   private static MethodSpec methodProxy(
       ExecutableElement method, String methodName, ReceiverAccessibility receiverAccessibility) {
     TypeElement enclosingType = MoreElements.asType(method.getEnclosingElement());
     MethodSpec.Builder methodBuilder = methodBuilder(methodName).addModifiers(PUBLIC, STATIC);

     UniqueNameSet nameSet = new UniqueNameSet();
     if (!method.getModifiers().contains(STATIC)) {
       methodBuilder.addParameter(
           receiverAccessibility.parameterType(enclosingType.asType()),
           nameSet.getUniqueName("instance"));
     }
     CodeBlock arguments = copyParameters(method, methodBuilder, nameSet);
     if (!method.getReturnType().getKind().equals(VOID)) {
       methodBuilder.returns(TypeName.get(method.getReturnType()));
       getNullableType(method)
           .ifPresent(nullableType -> CodeBlocks.addAnnotation(methodBuilder, nullableType));
       methodBuilder.addCode("return ");
     }
     if (method.getModifiers().contains(STATIC)) {
       methodBuilder.addCode("$T", rawTypeName(TypeName.get(enclosingType.asType())));
     } else {
       copyTypeParameters(enclosingType, methodBuilder);
       // "instance" is guaranteed b/c it was the first name into the UniqueNameSet
       methodBuilder.addCode(
           receiverAccessibility.potentiallyCast(CodeBlock.of("instance"), enclosingType.asType()));
     }
     copyTypeParameters(method, methodBuilder);
     copyThrows(method, methodBuilder);

     methodBuilder.addCode(".$N($L);", method.getSimpleName(), arguments);
     return methodBuilder.build();
   }

   private static MethodSpec fieldProxy(VariableElement field, String methodName) {
     TypeElement enclosingType = MoreElements.asType(field.getEnclosingElement());
     MethodSpec.Builder methodBuilder = methodBuilder(methodName).addModifiers(PUBLIC, STATIC);
     copyTypeParameters(enclosingType, methodBuilder);

     UniqueNameSet nameSet = new UniqueNameSet();
     String instanceName = nameSet.getUniqueName("instance");
     methodBuilder.addParameter(accessibleType(enclosingType.asType()), instanceName);
     return methodBuilder
         .addCode(
             "$L.$L = $L;",
             instanceWithPotentialCast(CodeBlock.of(instanceName), enclosingType.asType()),
             field.getSimpleName(),
             copyParameter(field, methodBuilder, nameSet))
         .build();
   }

   private static void copyThrows(ExecutableElement method, MethodSpec.Builder methodBuilder) {
     for (TypeMirror thrownType : method.getThrownTypes()) {
       methodBuilder.addException(TypeName.get(thrownType));
     }
   }

   private static CodeBlock copyParameters(
       ExecutableElement method, MethodSpec.Builder methodBuilder, UniqueNameSet nameSet) {
     ImmutableList.Builder<CodeBlock> argumentsBuilder = ImmutableList.builder();
     for (VariableElement parameter : method.getParameters()) {
       argumentsBuilder.add(copyParameter(parameter, methodBuilder, nameSet));
     }
     methodBuilder.varargs(method.isVarArgs());
     return makeParametersCodeBlock(argumentsBuilder.build());
   }

   private static CodeBlock copyParameter(
       VariableElement element, MethodSpec.Builder methodBuilder, UniqueNameSet nameSet) {
     TypeMirror elementType = element.asType();
     boolean useObject = !isRawTypePubliclyAccessible(elementType);
     TypeName typeName = useObject ? TypeName.OBJECT : TypeName.get(elementType);
     String name = nameSet.getUniqueName(element.getSimpleName().toString());
     ParameterSpec parameter =
         ParameterSpec.builder(typeName, name).build();
     methodBuilder.addParameter(parameter);
     return useObject
         ? CodeBlock.of("($T) $N", elementType, parameter)
         : CodeBlock.of("$N", parameter);
   }

   private static void copyTypeParameters(
       Parameterizable parameterizable, MethodSpec.Builder methodBuilder) {
     for (TypeParameterElement typeParameterElement : parameterizable.getTypeParameters()) {
       methodBuilder.addTypeVariable(TypeVariableName.get(typeParameterElement));
     }
   }
 }
	/*
	* 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.CaseFormat.LOWER_CAMEL;
	import static com.google.common.base.CaseFormat.UPPER_CAMEL;
	import static com.squareup.javapoet.MethodSpec.methodBuilder;
	import static dagger.internal.codegen.Accessibility.isElementAccessibleFrom;
	import static dagger.internal.codegen.Accessibility.isRawTypeAccessible;
	import static dagger.internal.codegen.Accessibility.isRawTypePubliclyAccessible;
	import static dagger.internal.codegen.Accessibility.isTypeAccessibleFrom;
	import static dagger.internal.codegen.CodeBlocks.makeParametersCodeBlock;
	import static dagger.internal.codegen.CodeBlocks.toConcatenatedCodeBlock;
	import static dagger.internal.codegen.ConfigurationAnnotations.getNullableType;
	import static dagger.internal.codegen.SourceFiles.generatedClassNameForBinding;
	import static dagger.internal.codegen.SourceFiles.membersInjectorNameForType;
	import static dagger.internal.codegen.TypeNames.rawTypeName;
	import static dagger.internal.codegen.Util.toImmutableList;
	import static java.util.stream.Collectors.toList;
	import static javax.lang.model.element.Modifier.PUBLIC;
	import static javax.lang.model.element.Modifier.STATIC;
	import static javax.lang.model.type.TypeKind.VOID;

	import com.google.auto.common.MoreElements;
	import com.google.common.collect.ImmutableList;
	import com.google.common.collect.ImmutableSet;
	import com.squareup.javapoet.ClassName;
	import com.squareup.javapoet.CodeBlock;
	import com.squareup.javapoet.MethodSpec;
	import com.squareup.javapoet.ParameterSpec;
	import com.squareup.javapoet.TypeName;
	import com.squareup.javapoet.TypeVariableName;
	import dagger.internal.codegen.DependencyRequest.Kind;
	import dagger.internal.codegen.MembersInjectionBinding.InjectionSite;
	import java.util.ArrayList;
	import java.util.List;
	import java.util.Optional;
	import java.util.function.Function;
	import javax.lang.model.element.ExecutableElement;
	import javax.lang.model.element.Parameterizable;
	import javax.lang.model.element.TypeElement;
	import javax.lang.model.element.TypeParameterElement;
	import javax.lang.model.element.VariableElement;
	import javax.lang.model.type.TypeKind;
	import javax.lang.model.type.TypeMirror;
	import javax.lang.model.util.Types;

	/**
	* Injection methods are static methods that implement provision and/or injection in one step:
	*
	* <ul>
	* <li>methods that invoke {@code @Inject} constructors and do members injection if necessary
	* <li>methods that call {@code @Provides} module methods
	* <li>methods that perform members injection
	* </ul>
	*/
	// TODO(ronshapiro): add examples for each class of injection method
	final class InjectionMethods {
	/**
	* A static method that returns an object from a {@code @Provides} method or an {@code @Inject}ed
	* constructor. Its parameters match the dependency requests for constructor and members
	* injection.
	*
	* <p>For {@code @Provides} methods named "foo", the method name is "proxyFoo". If the
	* {@code @Provides} method and its raw parameter types are publicly accessible, no method is
	* necessary and this method returns {@link Optional#empty()}.
	*
	* <p>TODO(ronshapiro): At the moment non-static {@code @Provides} methods are not supported.
	*
	* <p>Example:
	*
	* <pre><code>
	* abstract class FooModule {
	* {@literal @Provides} static Foo provideFoo(Bar bar, Baz baz) { … }
	* }
	*
	* public static proxyProvideFoo(Bar bar, Baz baz) { … }
	* </code></pre>
	*
	* <p>For {@code @Inject}ed constructors, the method name is "newFoo". If the constructor and its
	* raw parameter types are publicly accessible, no method is necessary and this method returns
	* {@code Optional#empty()}.
	*
	* <p>Example:
	*
	* <pre><code>
	* class Foo {
	* {@literal @Inject} Foo(Bar bar) {}
	* }
	*
	* public static Foo newFoo(Bar bar) { … }
	* </code></pre>
	*/
	static final class ProvisionMethod {

	/**
	* Returns a method that invokes the binding's {@linkplain ProvisionBinding#bindingElement()
	* constructor} and injects the instance's members, if necessary. If {@link
	* #shouldCreateInjectionMethod(ProvisionBinding) no method is necessary}, then {@link
	* Optional#empty()} is returned.
	*/
	static Optional<MethodSpec> create(ProvisionBinding binding) {
	if (!shouldCreateInjectionMethod(binding)) {
	return Optional.empty();
	}
	ExecutableElement element = MoreElements.asExecutable(binding.bindingElement().get());
	switch (element.getKind()) {
	case CONSTRUCTOR:
	return Optional.of(constructorProxy(element));
	case METHOD:
	return Optional.of(
	methodProxy(element, methodName(element), ReceiverAccessibility.IGNORE));
	default:
	throw new AssertionError(element);
	}
	}

	/**
	* Invokes the injection method for {@code binding}, with the dependencies transformed with the
	* {@code dependencyUsage} function.
	*/
	static CodeBlock invoke(
	ProvisionBinding binding,
	Function<DependencyRequest, CodeBlock> dependencyUsage,
	ClassName requestingClass,
	Optional<CodeBlock> moduleReference) {
	ImmutableList.Builder<CodeBlock> arguments = ImmutableList.builder();
	moduleReference.ifPresent(arguments::add);
	arguments.addAll(
	injectionMethodArguments(
	binding.provisionDependencies(), dependencyUsage, requestingClass));
	return callInjectionMethod(
	create(binding).get().name,
	arguments.build(),
	generatedClassNameForBinding(binding),
	requestingClass);
	}

	private static MethodSpec constructorProxy(ExecutableElement constructor) {
	UniqueNameSet names = new UniqueNameSet();
	TypeElement enclosingType = MoreElements.asType(constructor.getEnclosingElement());
	MethodSpec.Builder method =
	methodBuilder(methodName(constructor))
	.returns(TypeName.get(enclosingType.asType()))
	.addModifiers(PUBLIC, STATIC);

	copyTypeParameters(enclosingType, method);
	copyThrows(constructor, method);

	return method
	.addStatement(
	"return new $T($L)", enclosingType, copyParameters(constructor, method, names))
	.build();
	}

	/**
	* Returns {@code true} if injecting an instance of {@code binding} from {@code callingPackage}
	* requires the use of an injection method.
	*/
	static boolean requiresInjectionMethod(ProvisionBinding binding, String callingPackage) {
	ExecutableElement method = MoreElements.asExecutable(binding.bindingElement().get());
	return !binding.injectionSites().isEmpty()
	\|\| !isElementAccessibleFrom(method, callingPackage)
	\|\| method
	.getParameters()
	.stream()
	.map(VariableElement::asType)
	.anyMatch(type -> !isRawTypeAccessible(type, callingPackage));
	}

	private static boolean shouldCreateInjectionMethod(ProvisionBinding binding) {
	return requiresInjectionMethod(binding, "dagger.should.never.exist");
	}

	/**
	* Returns the name of the {@code static} method that wraps {@code method}. For methods that are
	* associated with {@code @Inject} constructors, the method will also inject all {@link
	* InjectionSite}s.
	*/
	private static String methodName(ExecutableElement method) {
	switch (method.getKind()) {
	case CONSTRUCTOR:
	return "new" + method.getEnclosingElement().getSimpleName();
	case METHOD:
	return "proxy" + LOWER_CAMEL.to(UPPER_CAMEL, method.getSimpleName().toString());
	default:
	throw new AssertionError(method);
	}
	}
	}

	/**
	* A static method that injects one member of an instance of a type. Its first parameter is an
	* instance of the type to be injected. The remaining parameters match the dependency requests for
	* the injection site.
	*
	* <p>Example:
	*
	* <pre><code>
	* class Foo {
	* {@literal @Inject} Bar bar;
	* {@literal @Inject} void setThings(Baz baz, Qux qux) {}
	* }
	*
	* public static injectBar(Foo instance, Bar bar) { … }
	* public static injectSetThings(Foo instance, Baz baz, Qux qux) { … }
	* </code></pre>
	*/
	static final class InjectionSiteMethod {
	/**
	* When a type has an inaccessible member from a supertype (e.g. an @Inject field in a parent
	* that's in a different package), a method in the supertype's package must be generated to give
	* the subclass's members injector a way to inject it. Each potentially inaccessible member
	* receives its own method, as the subclass may need to inject them in a different order from
	* the parent class.
	*/
	static MethodSpec create(InjectionSite injectionSite) {
	String methodName = methodName(injectionSite);
	switch (injectionSite.kind()) {
	case METHOD:
	return methodProxy(
	MoreElements.asExecutable(injectionSite.element()),
	methodName,
	ReceiverAccessibility.CAST_IF_NOT_PUBLIC);
	case FIELD:
	return fieldProxy(MoreElements.asVariable(injectionSite.element()), methodName);
	default:
	throw new AssertionError(injectionSite);
	}
	}

	/**
	* Invokes each of the injection methods for {@code injectionSites}, with the dependencies
	* transformed using the {@code dependencyUsage} function.
	*
	* @param instanceType the type of the {@code instance} parameter
	*/
	static CodeBlock invokeAll(
	ImmutableSet<InjectionSite> injectionSites,
	ClassName generatedTypeName,
	CodeBlock instanceCodeBlock,
	TypeMirror instanceType,
	Types types,
	Function<DependencyRequest, CodeBlock> dependencyUsage) {
	return injectionSites
	.stream()
	.map(
	injectionSite -> {
	TypeMirror injectSiteType =
	types.erasure(injectionSite.element().getEnclosingElement().asType());

	// If instance has been declared as Object because it is not accessible from the
	// component, but the injectionSite is in a supertype of instanceType that is
	// publicly accessible, the InjectionSiteMethod will request the actual type and not
	// Object as the first parameter. If so, cast to the supertype which is accessible
	// from within generatedTypeName
	CodeBlock maybeCastedInstance =
	!types.isSubtype(instanceType, injectSiteType)
	&& isTypeAccessibleFrom(injectSiteType, generatedTypeName.packageName())
	? CodeBlock.of("($T) $L", injectSiteType, instanceCodeBlock)
	: instanceCodeBlock;
	return CodeBlock.of(
	"$L;",
	invoke(injectionSite, generatedTypeName, maybeCastedInstance, dependencyUsage));
	})
	.collect(toConcatenatedCodeBlock());
	}

	/**
	* Invokes the injection method for {@code injectionSite}, with the dependencies transformed
	* using the {@code dependencyUsage} function.
	*/
	private static CodeBlock invoke(
	InjectionSite injectionSite,
	ClassName generatedTypeName,
	CodeBlock instanceCodeBlock,
	Function<DependencyRequest, CodeBlock> dependencyUsage) {
	List<CodeBlock> arguments = new ArrayList<>();
	arguments.add(instanceCodeBlock);
	if (!injectionSite.dependencies().isEmpty()) {
	arguments.addAll(
	injectionSite
	.dependencies()
	.stream()
	.map(dependencyUsage)
	.collect(toList()));
	}
	return callInjectionMethod(
	create(injectionSite).name,
	arguments,
	membersInjectorNameForType(
	MoreElements.asType(injectionSite.element().getEnclosingElement())),
	generatedTypeName);
	}

	/*
	* TODO(ronshapiro): this isn't perfect, as collisions could still exist. Some examples:
	*
	* - @Inject void members() {} will generate a method that conflicts with the instance
	* method `injectMembers(T)`
	* - Adding the index could conflict with another member:
	* @Inject void a(Object o) {}
	* @Inject void a(String s) {}
	* @Inject void a1(String s) {}
	*
	* Here, Method a(String) will add the suffix "1", which will conflict with the method
	* generated for a1(String)
	* - Members named "members" or "methods" could also conflict with the {@code static} injection
	* method.
	*/
	private static String methodName(InjectionSite injectionSite) {
	int index = injectionSite.indexAmongAtInjectMembersWithSameSimpleName();
	String indexString = index == 0 ? "" : String.valueOf(index + 1);
	return "inject"
	+ LOWER_CAMEL.to(UPPER_CAMEL, injectionSite.element().getSimpleName().toString())
	+ indexString;
	}
	}

	/**
	* Returns an argument list suitable for calling an injection method. Down-casts any arguments
	* that are {@code Object} (or {@code Provider<Object>}) at the caller but not the method.
	*
	* @param dependencies the dependencies used by the method
	* @param dependencyUsage function to apply on each of {@code dependencies} before casting
	* @param requestingClass the class calling the injection method
	*/
	private static ImmutableList<CodeBlock> injectionMethodArguments(
	ImmutableSet<DependencyRequest> dependencies,
	Function<DependencyRequest, CodeBlock> dependencyUsage,
	ClassName requestingClass) {
	return dependencies.stream()
	.map(dep -> injectionMethodArgument(dep, dependencyUsage.apply(dep), requestingClass))
	.collect(toImmutableList());
	}

	private static CodeBlock injectionMethodArgument(
	DependencyRequest dependency, CodeBlock argument, ClassName generatedTypeName) {
	TypeMirror keyType = dependency.key().type();
	CodeBlock.Builder codeBlock = CodeBlock.builder();
	if (!isRawTypeAccessible(keyType, generatedTypeName.packageName())
	&& isTypeAccessibleFrom(keyType, generatedTypeName.packageName())) {
	if (!dependency.kind().equals(Kind.INSTANCE)) {
	TypeName usageTypeName = accessibleType(dependency);
	codeBlock.add("($T) ($T)", usageTypeName, rawTypeName(usageTypeName));
	} else if (dependency.requestElement().get().asType().getKind().equals(TypeKind.TYPEVAR)) {
	codeBlock.add("($T)", keyType);
	}
	}
	return codeBlock.add(argument).build();
	}

	/**
	* Returns the parameter type for {@code dependency}. If the raw type is not accessible, returns
	* {@link Object}.
	*/
	private static TypeName accessibleType(DependencyRequest dependency) {
	TypeName typeName = dependency.kind().typeName(accessibleType(dependency.key().type()));
	return dependency.requestsPrimitiveType() ? typeName.unbox() : typeName;
	}

	/**
	* Returns the accessible type for {@code type}. If the raw type is not accessible, returns {@link
	* Object}.
	*/
	private static TypeName accessibleType(TypeMirror type) {
	return isRawTypePubliclyAccessible(type) ? TypeName.get(type) : TypeName.OBJECT;
	}

	private static CodeBlock callInjectionMethod(
	String methodName,
	List<CodeBlock> arguments,
	ClassName enclosingClass,
	ClassName requestingClass) {
	CodeBlock.Builder invocation = CodeBlock.builder();
	if (!enclosingClass.equals(requestingClass)) {
	invocation.add("$T.", enclosingClass);
	}
	return invocation.add("$L($L)", methodName, makeParametersCodeBlock(arguments)).build();
	}

	private enum ReceiverAccessibility {
	CAST_IF_NOT_PUBLIC {
	@Override
	TypeName parameterType(TypeMirror type) {
	return accessibleType(type);
	}

	@Override
	CodeBlock potentiallyCast(CodeBlock instance, TypeMirror instanceType) {
	return instanceWithPotentialCast(instance, instanceType);
	}
	},
	IGNORE {
	@Override
	TypeName parameterType(TypeMirror type) {
	return TypeName.get(type);
	}

	@Override
	CodeBlock potentiallyCast(CodeBlock instance, TypeMirror instanceType) {
	return instance;
	}
	},
	;

	abstract TypeName parameterType(TypeMirror type);
	abstract CodeBlock potentiallyCast(CodeBlock instance, TypeMirror instanceType);
	}

	private static CodeBlock instanceWithPotentialCast(CodeBlock instance, TypeMirror instanceType) {
	return isRawTypePubliclyAccessible(instanceType)
	? instance
	: CodeBlock.of("(($T) $L)", instanceType, instance);
	}

	private static MethodSpec methodProxy(
	ExecutableElement method, String methodName, ReceiverAccessibility receiverAccessibility) {
	TypeElement enclosingType = MoreElements.asType(method.getEnclosingElement());
	MethodSpec.Builder methodBuilder = methodBuilder(methodName).addModifiers(PUBLIC, STATIC);

	UniqueNameSet nameSet = new UniqueNameSet();
	if (!method.getModifiers().contains(STATIC)) {
	methodBuilder.addParameter(
	receiverAccessibility.parameterType(enclosingType.asType()),
	nameSet.getUniqueName("instance"));
	}
	CodeBlock arguments = copyParameters(method, methodBuilder, nameSet);
	if (!method.getReturnType().getKind().equals(VOID)) {
	methodBuilder.returns(TypeName.get(method.getReturnType()));
	getNullableType(method)
	.ifPresent(nullableType -> CodeBlocks.addAnnotation(methodBuilder, nullableType));
	methodBuilder.addCode("return ");
	}
	if (method.getModifiers().contains(STATIC)) {
	methodBuilder.addCode("$T", rawTypeName(TypeName.get(enclosingType.asType())));
	} else {
	copyTypeParameters(enclosingType, methodBuilder);
	// "instance" is guaranteed b/c it was the first name into the UniqueNameSet
	methodBuilder.addCode(
	receiverAccessibility.potentiallyCast(CodeBlock.of("instance"), enclosingType.asType()));
	}
	copyTypeParameters(method, methodBuilder);
	copyThrows(method, methodBuilder);

	methodBuilder.addCode(".$N($L);", method.getSimpleName(), arguments);
	return methodBuilder.build();
	}

	private static MethodSpec fieldProxy(VariableElement field, String methodName) {
	TypeElement enclosingType = MoreElements.asType(field.getEnclosingElement());
	MethodSpec.Builder methodBuilder = methodBuilder(methodName).addModifiers(PUBLIC, STATIC);
	copyTypeParameters(enclosingType, methodBuilder);

	UniqueNameSet nameSet = new UniqueNameSet();
	String instanceName = nameSet.getUniqueName("instance");
	methodBuilder.addParameter(accessibleType(enclosingType.asType()), instanceName);
	return methodBuilder
	.addCode(
	"$L.$L = $L;",
	instanceWithPotentialCast(CodeBlock.of(instanceName), enclosingType.asType()),
	field.getSimpleName(),
	copyParameter(field, methodBuilder, nameSet))
	.build();
	}

	private static void copyThrows(ExecutableElement method, MethodSpec.Builder methodBuilder) {
	for (TypeMirror thrownType : method.getThrownTypes()) {
	methodBuilder.addException(TypeName.get(thrownType));
	}
	}

	private static CodeBlock copyParameters(
	ExecutableElement method, MethodSpec.Builder methodBuilder, UniqueNameSet nameSet) {
	ImmutableList.Builder<CodeBlock> argumentsBuilder = ImmutableList.builder();
	for (VariableElement parameter : method.getParameters()) {
	argumentsBuilder.add(copyParameter(parameter, methodBuilder, nameSet));
	}
	methodBuilder.varargs(method.isVarArgs());
	return makeParametersCodeBlock(argumentsBuilder.build());
	}

	private static CodeBlock copyParameter(
	VariableElement element, MethodSpec.Builder methodBuilder, UniqueNameSet nameSet) {
	TypeMirror elementType = element.asType();
	boolean useObject = !isRawTypePubliclyAccessible(elementType);
	TypeName typeName = useObject ? TypeName.OBJECT : TypeName.get(elementType);
	String name = nameSet.getUniqueName(element.getSimpleName().toString());
	ParameterSpec parameter =
	ParameterSpec.builder(typeName, name).build();
	methodBuilder.addParameter(parameter);
	return useObject
	? CodeBlock.of("($T) $N", elementType, parameter)
	: CodeBlock.of("$N", parameter);
	}

	private static void copyTypeParameters(
	Parameterizable parameterizable, MethodSpec.Builder methodBuilder) {
	for (TypeParameterElement typeParameterElement : parameterizable.getTypeParameters()) {
	methodBuilder.addTypeVariable(TypeVariableName.get(typeParameterElement));
	}
	}
	}