/*
* 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 com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.Exposed;
import com.google.inject.Key;
import com.google.inject.PrivateBinder;
import com.google.inject.Provides;
import com.google.inject.internal.InternalProviderInstanceBindingImpl.InitializationTiming;
import com.google.inject.internal.util.StackTraceElements;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.HasDependencies;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderWithExtensionVisitor;
import com.google.inject.spi.ProvidesMethodBinding;
import com.google.inject.spi.ProvidesMethodTargetVisitor;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Set;
/**
* A provider that invokes a method and returns its result.
*
* @author jessewilson@google.com (Jesse Wilson)
*/
public abstract class ProviderMethod<T> extends InternalProviderInstanceBindingImpl.CyclicFactory<T>
implements HasDependencies, ProvidesMethodBinding<T>, ProviderWithExtensionVisitor<T> {
/**
* Creates a {@link ProviderMethod}.
*
* <p>Unless {@code skipFastClassGeneration} is set, this will use {@link
* net.sf.cglib.reflect.FastClass} to invoke the actual method, since it is significantly faster.
* However, this will fail if the method is {@code private} or {@code protected}, since fastclass
* is subject to java access policies.
*/
static <T> ProviderMethod<T> create(
Key<T> key,
Method method,
Object instance,
ImmutableSet<Dependency<?>> dependencies,
Class<? extends Annotation> scopeAnnotation,
boolean skipFastClassGeneration,
Annotation annotation) {
int modifiers = method.getModifiers();
/*if[AOP]*/
if (!skipFastClassGeneration) {
try {
net.sf.cglib.reflect.FastClass fc = BytecodeGen.newFastClassForMember(method);
if (fc != null) {
return new FastClassProviderMethod<T>(
key, fc, method, instance, dependencies, scopeAnnotation, annotation);
}
} catch (net.sf.cglib.core.CodeGenerationException e) {
/* fall-through */
}
}
/*end[AOP]*/
if (!Modifier.isPublic(modifiers)
|| !Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
method.setAccessible(true);
}
return new ReflectionProviderMethod<T>(
key, method, instance, dependencies, scopeAnnotation, annotation);
}
protected final Object instance;
protected final Method method;
private final Key<T> key;
private final Class<? extends Annotation> scopeAnnotation;
private final ImmutableSet<Dependency<?>> dependencies;
private final boolean exposed;
private final Annotation annotation;
/**
* Set by {@link #initialize(InjectorImpl, Errors)} so it is always available prior to injection.
*/
private SingleParameterInjector<?>[] parameterInjectors;
/** @param method the method to invoke. It's return type must be the same type as {@code key}. */
private ProviderMethod(
Key<T> key,
Method method,
Object instance,
ImmutableSet<Dependency<?>> dependencies,
Class<? extends Annotation> scopeAnnotation,
Annotation annotation) {
// We can be safely initialized eagerly since our bindings must exist statically and it is an
// error for them not to.
super(InitializationTiming.EAGER);
this.key = key;
this.scopeAnnotation = scopeAnnotation;
this.instance = instance;
this.dependencies = dependencies;
this.method = method;
this.exposed = method.isAnnotationPresent(Exposed.class);
this.annotation = annotation;
}
@Override
public Key<T> getKey() {
return key;
}
@Override
public Method getMethod() {
return method;
}
// exposed for GIN
public Object getInstance() {
return instance;
}
@Override
public Object getEnclosingInstance() {
return instance;
}
@Override
public Annotation getAnnotation() {
return annotation;
}
public void configure(Binder binder) {
binder = binder.withSource(method);
if (scopeAnnotation != null) {
binder.bind(key).toProvider(this).in(scopeAnnotation);
} else {
binder.bind(key).toProvider(this);
}
if (exposed) {
// the cast is safe 'cause the only binder we have implements PrivateBinder. If there's a
// misplaced @Exposed, calling this will add an error to the binder's error queue
((PrivateBinder) binder).expose(key);
}
}
@Override
void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
parameterInjectors = injector.getParametersInjectors(dependencies.asList(), errors);
}
@Override
protected T doProvision(Errors errors, InternalContext context, Dependency<?> dependency)
throws ErrorsException {
try {
T t = doProvision(SingleParameterInjector.getAll(errors, context, parameterInjectors));
errors.checkForNull(t, getMethod(), dependency);
return t;
} catch (IllegalAccessException e) {
throw new AssertionError(e);
} catch (InvocationTargetException userException) {
Throwable cause = userException.getCause() != null ? userException.getCause() : userException;
throw errors.withSource(getSource()).errorInProvider(cause).toException();
}
}
/** Extension point for our subclasses to implement the provisioning strategy. */
abstract T doProvision(Object[] parameters)
throws IllegalAccessException, InvocationTargetException;
@Override
public Set<Dependency<?>> getDependencies() {
return dependencies;
}
@Override
@SuppressWarnings("unchecked")
public <B, V> V acceptExtensionVisitor(
BindingTargetVisitor<B, V> visitor, ProviderInstanceBinding<? extends B> binding) {
if (visitor instanceof ProvidesMethodTargetVisitor) {
return ((ProvidesMethodTargetVisitor<T, V>) visitor).visit(this);
}
return visitor.visit(binding);
}
@Override
public String toString() {
String annotationString = annotation.toString();
// Show @Provides w/o the com.google.inject prefix.
if (annotation.annotationType() == Provides.class) {
annotationString = "@Provides";
} else if (annotationString.endsWith("()")) {
// Remove the common "()" suffix if there are no values.
annotationString = annotationString.substring(0, annotationString.length() - 2);
}
return annotationString + " " + StackTraceElements.forMember(method);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof ProviderMethod) {
ProviderMethod<?> o = (ProviderMethod<?>) obj;
return method.equals(o.method)
&& instance.equals(o.instance)
&& annotation.equals(o.annotation);
} else {
return false;
}
}
@Override
public int hashCode() {
// Avoid calling hashCode on 'instance', which is a user-object
// that might not be expecting it.
// (We need to call equals, so we do. But we can avoid hashCode.)
return Objects.hashCode(method, annotation);
}
/*if[AOP]*/
/**
* A {@link ProviderMethod} implementation that uses {@link net.sf.cglib.reflect.FastClass#invoke}
* to invoke the provider method.
*/
private static final class FastClassProviderMethod<T> extends ProviderMethod<T> {
final net.sf.cglib.reflect.FastClass fastClass;
final int methodIndex;
FastClassProviderMethod(
Key<T> key,
net.sf.cglib.reflect.FastClass fc,
Method method,
Object instance,
ImmutableSet<Dependency<?>> dependencies,
Class<? extends Annotation> scopeAnnotation,
Annotation annotation) {
super(key, method, instance, dependencies, scopeAnnotation, annotation);
this.fastClass = fc;
this.methodIndex = fc.getMethod(method).getIndex();
}
@SuppressWarnings("unchecked")
@Override
public T doProvision(Object[] parameters)
throws IllegalAccessException, InvocationTargetException {
return (T) fastClass.invoke(methodIndex, instance, parameters);
}
}
/*end[AOP]*/
/**
* A {@link ProviderMethod} implementation that invokes the method using normal java reflection.
*/
private static final class ReflectionProviderMethod<T> extends ProviderMethod<T> {
ReflectionProviderMethod(
Key<T> key,
Method method,
Object instance,
ImmutableSet<Dependency<?>> dependencies,
Class<? extends Annotation> scopeAnnotation,
Annotation annotation) {
super(key, method, instance, dependencies, scopeAnnotation, annotation);
}
@SuppressWarnings("unchecked")
@Override
T doProvision(Object[] parameters) throws IllegalAccessException, InvocationTargetException {
return (T) method.invoke(instance, parameters);
}
}
}