/**
* Copyright (C) 2008 Google Inc.
*
* 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 com.google.inject.internal;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.common.collect.Multimap;
import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.Provider;
import com.google.inject.Provides;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.Message;
import com.google.inject.util.Modules;
import java.lang.annotation.Annotation;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.List;
import java.util.logging.Logger;
/**
* Creates bindings to methods annotated with {@literal @}{@link Provides}. Use the scope and
* binding annotations on the provider method to configure the binding.
*
* @author crazybob@google.com (Bob Lee)
* @author jessewilson@google.com (Jesse Wilson)
*/
public final class ProviderMethodsModule implements Module {
private static final Key<Logger> LOGGER_KEY = Key.get(Logger.class);
private final Object delegate;
private final TypeLiteral<?> typeLiteral;
private final boolean skipFastClassGeneration;
private ProviderMethodsModule(Object delegate, boolean skipFastClassGeneration) {
this.delegate = checkNotNull(delegate, "delegate");
this.typeLiteral = TypeLiteral.get(this.delegate.getClass());
this.skipFastClassGeneration = skipFastClassGeneration;
}
/**
* Returns a module which creates bindings for provider methods from the given module.
*/
public static Module forModule(Module module) {
return forObject(module, false);
}
/**
* Returns a module which creates bindings for provider methods from the given object.
* This is useful notably for <a href="http://code.google.com/p/google-gin/">GIN</a>
*
* <p>This will skip bytecode generation for provider methods, since it is assumed that callers
* are only interested in Module metadata.
*/
public static Module forObject(Object object) {
return forObject(object, true);
}
private static Module forObject(Object object, boolean skipFastClassGeneration) {
// avoid infinite recursion, since installing a module always installs itself
if (object instanceof ProviderMethodsModule) {
return Modules.EMPTY_MODULE;
}
return new ProviderMethodsModule(object, skipFastClassGeneration);
}
public synchronized void configure(Binder binder) {
for (ProviderMethod<?> providerMethod : getProviderMethods(binder)) {
providerMethod.configure(binder);
}
}
public List<ProviderMethod<?>> getProviderMethods(Binder binder) {
List<ProviderMethod<?>> result = Lists.newArrayList();
Multimap<Signature, Method> methodsBySignature = HashMultimap.create();
for (Class<?> c = delegate.getClass(); c != Object.class; c = c.getSuperclass()) {
for (Method method : c.getDeclaredMethods()) {
// private/static methods cannot override or be overridden by other methods, so there is no
// point in indexing them.
// Skip synthetic methods and bridge methods since java will automatically generate
// synthetic overrides in some cases where we don't want to generate an error (e.g.
// increasing visibility of a subclass).
if (((method.getModifiers() & (Modifier.PRIVATE | Modifier.STATIC)) == 0)
&& !method.isBridge() && !method.isSynthetic()) {
methodsBySignature.put(new Signature(method), method);
}
if (isProvider(method)) {
result.add(createProviderMethod(binder, method));
}
}
}
// we have found all the providers and now need to identify if any were overridden
// In the worst case this will have O(n^2) in the number of @Provides methods, but that is only
// assuming that every method is an override, in general it should be very quick.
for (ProviderMethod<?> provider : result) {
Method method = provider.getMethod();
for (Method matchingSignature : methodsBySignature.get(new Signature(method))) {
// matching signature is in the same class or a super class, therefore method cannot be
// overridding it.
if (matchingSignature.getDeclaringClass().isAssignableFrom(method.getDeclaringClass())) {
continue;
}
// now we know matching signature is in a subtype of method.getDeclaringClass()
if (overrides(matchingSignature, method)) {
binder.addError(
"Overriding @Provides methods is not allowed."
+ "\n\t@Provides method: %s\n\toverridden by: %s",
method,
matchingSignature);
break;
}
}
}
return result;
}
/**
* Returns true if the method is a provider.
*
* Synthetic bridge methods are excluded. Starting with JDK 8, javac copies annotations onto
* bridge methods (which always have erased signatures).
*/
private static boolean isProvider(Method method) {
return !method.isBridge()
&& !method.isSynthetic()
&& method.isAnnotationPresent(Provides.class);
}
private final class Signature {
final Class<?>[] parameters;
final String name;
final int hashCode;
Signature(Method method) {
this.name = method.getName();
// We need to 'resolve' the parameters against the actual class type in case this method uses
// type parameters. This is so we can detect overrides of generic superclass methods where
// the subclass specifies the type parameter. javac implements these kinds of overrides via
// bridge methods, but we don't want to give errors on bridge methods (but rather the target
// of the bridge).
List<TypeLiteral<?>> resolvedParameterTypes = typeLiteral.getParameterTypes(method);
this.parameters = new Class<?>[resolvedParameterTypes.size()];
int i = 0;
for (TypeLiteral<?> type : resolvedParameterTypes) {
parameters[i] = type.getRawType();
}
this.hashCode = name.hashCode() + 31 * Arrays.hashCode(parameters);
}
@Override public boolean equals(Object obj) {
if (obj instanceof Signature) {
Signature other = (Signature) obj;
return other.name.equals(name) && Arrays.equals(parameters, other.parameters);
}
return false;
}
@Override public int hashCode() {
return hashCode;
}
}
/** Returns true if a overrides b, assumes that the signatures match */
private static boolean overrides(Method a, Method b) {
// See JLS section 8.4.8.1
int modifiers = b.getModifiers();
if (Modifier.isPublic(modifiers) || Modifier.isProtected(modifiers)) {
return true;
}
if (Modifier.isPrivate(modifiers)) {
return false;
}
// b must be package-private
return a.getDeclaringClass().getPackage().equals(b.getDeclaringClass().getPackage());
}
private <T> ProviderMethod<T> createProviderMethod(Binder binder, Method method) {
binder = binder.withSource(method);
Errors errors = new Errors(method);
// prepare the parameter providers
List<Dependency<?>> dependencies = Lists.newArrayList();
List<Provider<?>> parameterProviders = Lists.newArrayList();
List<TypeLiteral<?>> parameterTypes = typeLiteral.getParameterTypes(method);
Annotation[][] parameterAnnotations = method.getParameterAnnotations();
for (int i = 0; i < parameterTypes.size(); i++) {
Key<?> key = getKey(errors, parameterTypes.get(i), method, parameterAnnotations[i]);
if (key.equals(LOGGER_KEY)) {
// If it was a Logger, change the key to be unique & bind it to a
// provider that provides a logger with a proper name.
// This solves issue 482 (returning a new anonymous logger on every call exhausts memory)
Key<Logger> loggerKey = Key.get(Logger.class, UniqueAnnotations.create());
binder.bind(loggerKey).toProvider(new LogProvider(method));
key = loggerKey;
}
dependencies.add(Dependency.get(key));
parameterProviders.add(binder.getProvider(key));
}
@SuppressWarnings("unchecked") // Define T as the method's return type.
TypeLiteral<T> returnType = (TypeLiteral<T>) typeLiteral.getReturnType(method);
Key<T> key = getKey(errors, returnType, method, method.getAnnotations());
Class<? extends Annotation> scopeAnnotation
= Annotations.findScopeAnnotation(errors, method.getAnnotations());
for (Message message : errors.getMessages()) {
binder.addError(message);
}
return ProviderMethod.create(key, method, delegate, ImmutableSet.copyOf(dependencies),
parameterProviders, scopeAnnotation, skipFastClassGeneration);
}
<T> Key<T> getKey(Errors errors, TypeLiteral<T> type, Member member, Annotation[] annotations) {
Annotation bindingAnnotation = Annotations.findBindingAnnotation(errors, member, annotations);
return bindingAnnotation == null ? Key.get(type) : Key.get(type, bindingAnnotation);
}
@Override public boolean equals(Object o) {
return o instanceof ProviderMethodsModule
&& ((ProviderMethodsModule) o).delegate == delegate;
}
@Override public int hashCode() {
return delegate.hashCode();
}
/** A provider that returns a logger based on the method name. */
private static final class LogProvider implements Provider<Logger> {
private final String name;
public LogProvider(Method method) {
this.name = method.getDeclaringClass().getName() + "." + method.getName();
}
public Logger get() {
return Logger.getLogger(name);
}
}
}