/*
* 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.ImmutableList;
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.Provides;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.Message;
import com.google.inject.spi.ModuleAnnotatedMethodScanner;
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;
/**
* 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 final Object delegate;
private final TypeLiteral<?> typeLiteral;
private final boolean skipFastClassGeneration;
private final ModuleAnnotatedMethodScanner scanner;
private ProviderMethodsModule(
Object delegate, boolean skipFastClassGeneration, ModuleAnnotatedMethodScanner scanner) {
this.delegate = checkNotNull(delegate, "delegate");
this.typeLiteral = TypeLiteral.get(this.delegate.getClass());
this.skipFastClassGeneration = skipFastClassGeneration;
this.scanner = scanner;
}
/** Returns a module which creates bindings for provider methods from the given module. */
public static Module forModule(Module module) {
return forObject(module, false, ProvidesMethodScanner.INSTANCE);
}
/** Returns a module which creates bindings methods in the module that match the scanner. */
public static Module forModule(Object module, ModuleAnnotatedMethodScanner scanner) {
return forObject(module, false, scanner);
}
/**
* 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, ProvidesMethodScanner.INSTANCE);
}
private static Module forObject(
Object object, boolean skipFastClassGeneration, ModuleAnnotatedMethodScanner scanner) {
// avoid infinite recursion, since installing a module always installs itself
if (object instanceof ProviderMethodsModule) {
return Modules.EMPTY_MODULE;
}
return new ProviderMethodsModule(object, skipFastClassGeneration, scanner);
}
public Object getDelegateModule() {
return delegate;
}
@Override
public void configure(Binder binder) {
for (ProviderMethod<?> providerMethod : getProviderMethods(binder)) {
providerMethod.configure(binder);
}
}
public List<ProviderMethod<?>> getProviderMethods(Binder binder) {
List<ProviderMethod<?>> result = null;
// The highest class in the type hierarchy that contained a provider method definition.
Class<?> superMostClass = delegate.getClass();
for (Class<?> c = delegate.getClass(); c != Object.class; c = c.getSuperclass()) {
for (Method method : c.getDeclaredMethods()) {
Annotation annotation = getAnnotation(binder, method);
if (annotation != null) {
if (result == null) {
result = Lists.newArrayList();
}
result.add(createProviderMethod(binder, method, annotation));
superMostClass = c;
}
}
}
if (result == null) {
// We didn't find anything
return ImmutableList.of();
}
// We have found some provider methods, now we need to check if any were overridden.
// We do this as a separate pass to avoid calculating all the signatures when there are no
// provides methods, or when all provides methods are defined in a single class.
Multimap<Signature, Method> methodsBySignature = null;
// We can stop scanning when we see superMostClass, since no superclass method can override
// a method in a subclass. Corrollary, if superMostClass == delegate.getClass(), there can be
// no overrides of a provides method.
for (Class<?> c = delegate.getClass(); c != superMostClass; c = c.getSuperclass()) {
for (Method method : c.getDeclaredMethods()) {
if (((method.getModifiers() & (Modifier.PRIVATE | Modifier.STATIC)) == 0)
&& !method.isBridge()
&& !method.isSynthetic()) {
if (methodsBySignature == null) {
methodsBySignature = HashMultimap.create();
}
methodsBySignature.put(new Signature(typeLiteral, method), method);
}
}
}
if (methodsBySignature != null) {
// we have found all the signatures 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(typeLiteral, 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)) {
String annotationString =
provider.getAnnotation().annotationType() == Provides.class
? "@Provides"
: "@" + provider.getAnnotation().annotationType().getCanonicalName();
binder.addError(
"Overriding "
+ annotationString
+ " methods is not allowed."
+ "\n\t"
+ annotationString
+ " method: %s\n\toverridden by: %s",
method,
matchingSignature);
break;
}
}
}
}
return result;
}
/** Returns the annotation that is claimed by the scanner, or null if there is none. */
private Annotation getAnnotation(Binder binder, Method method) {
if (method.isBridge() || method.isSynthetic()) {
return null;
}
Annotation annotation = null;
for (Class<? extends Annotation> annotationClass : scanner.annotationClasses()) {
Annotation foundAnnotation = method.getAnnotation(annotationClass);
if (foundAnnotation != null) {
if (annotation != null) {
binder.addError(
"More than one annotation claimed by %s on method %s."
+ " Methods can only have one annotation claimed per scanner.",
scanner, method);
return null;
}
annotation = foundAnnotation;
}
}
return annotation;
}
private static final class Signature {
final Class<?>[] parameters;
final String name;
final int hashCode;
Signature(TypeLiteral<?> typeLiteral, 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, Annotation annotation) {
binder = binder.withSource(method);
Errors errors = new Errors(method);
// prepare the parameter providers
InjectionPoint point = InjectionPoint.forMethod(method, typeLiteral);
@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());
try {
key = scanner.prepareMethod(binder, annotation, key, point);
} catch (Throwable t) {
binder.addError(t);
}
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(point.getDependencies()),
scopeAnnotation,
skipFastClassGeneration,
annotation);
}
<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
&& ((ProviderMethodsModule) o).scanner == scanner;
}
@Override
public int hashCode() {
return delegate.hashCode();
}
}