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A fast dependency injector for Android and Java.
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/*
* 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.writing;
import static androidx.room.compiler.processing.XElementKt.isConstructor;
import static androidx.room.compiler.processing.XElementKt.isMethod;
import static androidx.room.compiler.processing.XElementKt.isMethodParameter;
import static androidx.room.compiler.processing.XTypeKt.isVoid;
import static com.google.common.base.CaseFormat.LOWER_CAMEL;
import static com.google.common.base.CaseFormat.UPPER_CAMEL;
import static com.google.common.base.Preconditions.checkArgument;
import static com.squareup.javapoet.MethodSpec.methodBuilder;
import static dagger.internal.codegen.binding.AssistedInjectionAnnotations.isAssistedParameter;
import static dagger.internal.codegen.binding.SourceFiles.generatedClassNameForBinding;
import static dagger.internal.codegen.binding.SourceFiles.memberInjectedFieldSignatureForVariable;
import static dagger.internal.codegen.binding.SourceFiles.membersInjectorNameForType;
import static dagger.internal.codegen.extension.DaggerStreams.toImmutableList;
import static dagger.internal.codegen.extension.DaggerStreams.toImmutableMap;
import static dagger.internal.codegen.javapoet.CodeBlocks.makeParametersCodeBlock;
import static dagger.internal.codegen.javapoet.CodeBlocks.toConcatenatedCodeBlock;
import static dagger.internal.codegen.javapoet.CodeBlocks.toParametersCodeBlock;
import static dagger.internal.codegen.javapoet.TypeNames.rawTypeName;
import static dagger.internal.codegen.langmodel.Accessibility.isRawTypeAccessible;
import static dagger.internal.codegen.langmodel.Accessibility.isRawTypePubliclyAccessible;
import static dagger.internal.codegen.xprocessing.XElements.asConstructor;
import static dagger.internal.codegen.xprocessing.XElements.asExecutable;
import static dagger.internal.codegen.xprocessing.XElements.asField;
import static dagger.internal.codegen.xprocessing.XElements.asMethod;
import static dagger.internal.codegen.xprocessing.XElements.asMethodParameter;
import static dagger.internal.codegen.xprocessing.XElements.asTypeElement;
import static dagger.internal.codegen.xprocessing.XElements.getSimpleName;
import static dagger.internal.codegen.xprocessing.XTypeElements.typeVariableNames;
import static dagger.internal.codegen.xprocessing.XTypes.erasedTypeName;
import static javax.lang.model.element.Modifier.PUBLIC;
import static javax.lang.model.element.Modifier.STATIC;
import androidx.room.compiler.processing.XAnnotation;
import androidx.room.compiler.processing.XConstructorElement;
import androidx.room.compiler.processing.XExecutableElement;
import androidx.room.compiler.processing.XExecutableParameterElement;
import androidx.room.compiler.processing.XFieldElement;
import androidx.room.compiler.processing.XMethodElement;
import androidx.room.compiler.processing.XType;
import androidx.room.compiler.processing.XTypeElement;
import androidx.room.compiler.processing.XVariableElement;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableSet;
import com.squareup.javapoet.AnnotationSpec;
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 dagger.internal.Preconditions;
import dagger.internal.codegen.base.UniqueNameSet;
import dagger.internal.codegen.binding.AssistedInjectionBinding;
import dagger.internal.codegen.binding.ContributionBinding;
import dagger.internal.codegen.binding.InjectionBinding;
import dagger.internal.codegen.binding.MembersInjectionBinding.InjectionSite;
import dagger.internal.codegen.binding.Nullability;
import dagger.internal.codegen.binding.ProvisionBinding;
import dagger.internal.codegen.compileroption.CompilerOptions;
import dagger.internal.codegen.extension.DaggerCollectors;
import dagger.internal.codegen.javapoet.TypeNames;
import dagger.internal.codegen.model.DaggerAnnotation;
import dagger.internal.codegen.model.DependencyRequest;
import dagger.internal.codegen.xprocessing.XAnnotations;
import java.util.List;
import java.util.Optional;
import java.util.function.Function;
/** Convenience methods for creating and invoking {@link InjectionMethod}s. */
final class InjectionMethods {
/**
* A 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.
*
* For {@code @Provides} methods named "foo", the method name is "proxyFoo". For example:
*
*
* abstract class FooModule {
* {@literal @Provides} static Foo provideFoo(Bar bar, Baz baz) { … }
* }
*
* public static proxyProvideFoo(Bar bar, Baz baz) { … }
*
*
* For {@code @Inject}ed constructors, the method name is "newFoo". For example:
*
*
* class Foo {
* {@literal @Inject} Foo(Bar bar) {}
* }
*
* public static Foo newFoo(Bar bar) { … }
*
*/
static final class ProvisionMethod {
// These names are already defined in factories and shouldn't be used for the proxy method name.
private static final ImmutableSet BANNED_PROXY_NAMES = ImmutableSet.of("get", "create");
/**
* Returns a method that invokes the binding's constructor and injects the instance's members.
*/
static MethodSpec create(ContributionBinding binding, CompilerOptions compilerOptions) {
XExecutableElement executableElement = asExecutable(binding.bindingElement().get());
if (isConstructor(executableElement)) {
return constructorProxy(asConstructor(executableElement));
} else if (isMethod(executableElement)) {
XMethodElement method = asMethod(executableElement);
String methodName =
BANNED_PROXY_NAMES.contains(getSimpleName(method))
? "proxy" + LOWER_CAMEL.to(UPPER_CAMEL, getSimpleName(method))
: getSimpleName(method);
return methodProxy(
method,
methodName,
InstanceCastPolicy.IGNORE,
CheckNotNullPolicy.get(binding, compilerOptions));
}
throw new AssertionError(executableElement);
}
/**
* Invokes the injection method for {@code binding}, with the dependencies transformed with the
* {@code dependencyUsage} function.
*/
static CodeBlock invoke(
ContributionBinding binding,
Function dependencyUsage,
Function uniqueAssistedParameterName,
ClassName requestingClass,
Optional moduleReference,
CompilerOptions compilerOptions) {
ImmutableList.Builder arguments = ImmutableList.builder();
moduleReference.ifPresent(arguments::add);
invokeArguments(binding, dependencyUsage, uniqueAssistedParameterName)
.forEach(arguments::add);
ClassName enclosingClass = generatedClassNameForBinding(binding);
MethodSpec methodSpec = create(binding, compilerOptions);
return invokeMethod(methodSpec, arguments.build(), enclosingClass, requestingClass);
}
static ImmutableList invokeArguments(
ContributionBinding binding,
Function dependencyUsage,
Function uniqueAssistedParameterName) {
ImmutableMap dependencyRequestMap =
provisionDependencies(binding).stream()
.collect(
toImmutableMap(
request -> asMethodParameter(request.requestElement().get().xprocessing()),
request -> request));
ImmutableList.Builder arguments = ImmutableList.builder();
XExecutableElement method = asExecutable(binding.bindingElement().get());
for (XExecutableParameterElement parameter : method.getParameters()) {
if (isAssistedParameter(parameter)) {
arguments.add(CodeBlock.of("$L", uniqueAssistedParameterName.apply(parameter)));
} else if (dependencyRequestMap.containsKey(parameter)) {
DependencyRequest request = dependencyRequestMap.get(parameter);
arguments.add(dependencyUsage.apply(request));
} else {
throw new AssertionError("Unexpected parameter: " + parameter);
}
}
return arguments.build();
}
private static ImmutableSet provisionDependencies(
ContributionBinding binding) {
switch (binding.kind()) {
case INJECTION:
return ((InjectionBinding) binding).constructorDependencies();
case ASSISTED_INJECTION:
return ((AssistedInjectionBinding) binding).constructorDependencies();
case PROVISION:
return ((ProvisionBinding) binding).dependencies();
default:
throw new AssertionError("Unexpected binding kind: " + binding.kind());
}
}
private static MethodSpec constructorProxy(XConstructorElement constructor) {
XTypeElement enclosingType = constructor.getEnclosingElement();
MethodSpec.Builder builder =
methodBuilder("newInstance")
.addModifiers(PUBLIC, STATIC)
.varargs(constructor.isVarArgs())
.returns(enclosingType.getType().getTypeName())
.addTypeVariables(typeVariableNames(enclosingType));
copyThrows(builder, constructor);
CodeBlock arguments =
copyParameters(builder, new UniqueNameSet(), constructor.getParameters());
return builder
.addStatement("return new $T($L)", enclosingType.getType().getTypeName(), arguments)
.build();
}
}
/**
* 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.
*
* Example:
*
*
* 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) { … }
*
*/
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(
asMethod(injectionSite.element()),
methodName,
InstanceCastPolicy.CAST_IF_NOT_PUBLIC,
CheckNotNullPolicy.IGNORE);
case FIELD:
Optional qualifier =
injectionSite.dependencies().stream()
// methods for fields have a single dependency request
.collect(DaggerCollectors.onlyElement())
.key()
.qualifier()
.map(DaggerAnnotation::xprocessing);
return fieldProxy(asField(injectionSite.element()), methodName, qualifier);
}
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 injectionSites,
ClassName generatedTypeName,
CodeBlock instanceCodeBlock,
XType instanceType,
Function dependencyUsage) {
return injectionSites.stream()
.map(
injectionSite -> {
XType injectSiteType = injectionSite.enclosingTypeElement().getType();
// 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 =
instanceType.getTypeName().equals(TypeName.OBJECT)
&& isRawTypeAccessible(injectSiteType, generatedTypeName.packageName())
? CodeBlock.of("($T) $L", erasedTypeName(injectSiteType), instanceCodeBlock)
: instanceCodeBlock;
return CodeBlock.of(
"$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 dependencyUsage) {
ImmutableList arguments =
ImmutableList.builder()
.add(instanceCodeBlock)
.addAll(
injectionSite.dependencies().stream()
.map(dependencyUsage)
.collect(toImmutableList()))
.build();
ClassName enclosingClass = membersInjectorNameForType(injectionSite.enclosingTypeElement());
MethodSpec methodSpec = create(injectionSite);
return invokeMethod(methodSpec, arguments, enclosingClass, 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, getSimpleName(injectionSite.element()))
+ indexString;
}
}
private enum InstanceCastPolicy {
CAST_IF_NOT_PUBLIC, IGNORE;
boolean useObjectType(XType instanceType) {
return this == CAST_IF_NOT_PUBLIC && !isRawTypePubliclyAccessible(instanceType);
}
}
private enum CheckNotNullPolicy {
IGNORE, CHECK_FOR_NULL;
CodeBlock checkForNull(CodeBlock maybeNull) {
return this.equals(IGNORE)
? maybeNull
: CodeBlock.of("$T.checkNotNullFromProvides($L)", Preconditions.class, maybeNull);
}
static CheckNotNullPolicy get(ContributionBinding binding, CompilerOptions compilerOptions) {
return binding.shouldCheckForNull(compilerOptions) ? CHECK_FOR_NULL : IGNORE;
}
}
private static MethodSpec methodProxy(
XMethodElement method,
String methodName,
InstanceCastPolicy instanceCastPolicy,
CheckNotNullPolicy checkNotNullPolicy) {
XTypeElement enclosingType = asTypeElement(method.getEnclosingElement());
MethodSpec.Builder builder =
methodBuilder(methodName)
.addModifiers(PUBLIC, STATIC)
.varargs(method.isVarArgs())
.addTypeVariables(method.getExecutableType().getTypeVariableNames());
UniqueNameSet parameterNameSet = new UniqueNameSet();
CodeBlock instance;
if (method.isStatic() || enclosingType.isCompanionObject()) {
instance = CodeBlock.of("$T", rawTypeName(enclosingType.getType().getTypeName()));
} else if (enclosingType.isKotlinObject()) {
// Call through the singleton instance.
// See: https://kotlinlang.org/docs/reference/java-to-kotlin-interop.html#static-methods
instance = CodeBlock.of("$T.INSTANCE", rawTypeName(enclosingType.getType().getTypeName()));
} else {
builder.addTypeVariables(typeVariableNames(enclosingType));
boolean useObject = instanceCastPolicy.useObjectType(enclosingType.getType());
instance = copyInstance(builder, parameterNameSet, enclosingType.getType(), useObject);
}
CodeBlock arguments = copyParameters(builder, parameterNameSet, method.getParameters());
CodeBlock invocation =
checkNotNullPolicy.checkForNull(
CodeBlock.of("$L.$L($L)", instance, method.getJvmName(), arguments));
copyThrows(builder, method);
if (isVoid(method.getReturnType())) {
return builder.addStatement("$L", invocation).build();
} else {
Nullability nullability = Nullability.of(method);
nullability
.nullableAnnotations()
.forEach(builder::addAnnotation);
return builder
.returns(method.getReturnType().getTypeName())
.addStatement("return $L", invocation)
.build();
}
}
private static MethodSpec fieldProxy(
XFieldElement field, String methodName, Optional qualifier) {
XTypeElement enclosingType = asTypeElement(field.getEnclosingElement());
MethodSpec.Builder builder =
methodBuilder(methodName)
.addModifiers(PUBLIC, STATIC)
.addAnnotation(
AnnotationSpec.builder(TypeNames.INJECTED_FIELD_SIGNATURE)
.addMember("value", "$S", memberInjectedFieldSignatureForVariable(field))
.build())
.addTypeVariables(typeVariableNames(enclosingType));
qualifier.map(XAnnotations::getAnnotationSpec).ifPresent(builder::addAnnotation);
boolean useObject = !isRawTypePubliclyAccessible(enclosingType.getType());
UniqueNameSet parameterNameSet = new UniqueNameSet();
CodeBlock instance =
copyInstance(builder, parameterNameSet, enclosingType.getType(), useObject);
CodeBlock argument = copyParameters(builder, parameterNameSet, ImmutableList.of(field));
return builder.addStatement("$L.$L = $L", instance, getSimpleName(field), argument).build();
}
private static CodeBlock invokeMethod(
MethodSpec methodSpec,
ImmutableList parameters,
ClassName enclosingClass,
ClassName requestingClass) {
checkArgument(methodSpec.parameters.size() == parameters.size());
CodeBlock parameterBlock = makeParametersCodeBlock(parameters);
return enclosingClass.equals(requestingClass)
? CodeBlock.of("$L($L)", methodSpec.name, parameterBlock)
: CodeBlock.of("$T.$L($L)", enclosingClass, methodSpec.name, parameterBlock);
}
private static void copyThrows(MethodSpec.Builder methodBuilder, XExecutableElement method) {
method.getThrownTypes().stream().map(XType::getTypeName).forEach(methodBuilder::addException);
}
private static CodeBlock copyParameters(
MethodSpec.Builder methodBuilder,
UniqueNameSet parameterNameSet,
List parameters) {
return parameters.stream()
.map(
parameter -> {
String name =
parameterNameSet.getUniqueName(
isMethodParameter(parameter)
? asMethodParameter(parameter).getJvmName()
: getSimpleName(parameter));
boolean useObject = !isRawTypePubliclyAccessible(parameter.getType());
return copyParameter(methodBuilder, parameter.getType(), name, useObject);
})
.collect(toParametersCodeBlock());
}
private static CodeBlock copyParameter(
MethodSpec.Builder methodBuilder, XType type, String name, boolean useObject) {
TypeName typeName = useObject ? TypeName.OBJECT : type.getTypeName();
methodBuilder.addParameter(ParameterSpec.builder(typeName, name).build());
return useObject ? CodeBlock.of("($T) $L", type.getTypeName(), name) : CodeBlock.of("$L", name);
}
private static CodeBlock copyInstance(
MethodSpec.Builder methodBuilder,
UniqueNameSet parameterNameSet,
XType type,
boolean useObject) {
CodeBlock instance =
copyParameter(methodBuilder, type, parameterNameSet.getUniqueName("instance"), useObject);
// If we had to cast the instance add an extra parenthesis incase we're calling a method on it.
return useObject ? CodeBlock.of("($L)", instance) : instance;
}
}