/**
* 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.inject.Scope;
import com.google.inject.Scopes;
import com.google.inject.Singleton;
import com.google.inject.Stage;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.binder.ScopedBindingBuilder;
import com.google.inject.spi.BindingScopingVisitor;
import java.lang.annotation.Annotation;
/**
* References a scope, either directly (as a scope instance), or indirectly (as a scope annotation).
* The scope's eager or laziness is also exposed.
*
* @author jessewilson@google.com (Jesse Wilson)
*/
public abstract class Scoping {
/**
* No scoping annotation has been applied. Note that this is different from {@code
* in(Scopes.NO_SCOPE)}, where the 'NO_SCOPE' has been explicitly applied.
*/
public static final Scoping UNSCOPED = new Scoping() {
public <V> V acceptVisitor(BindingScopingVisitor<V> visitor) {
return visitor.visitNoScoping();
}
@Override public Scope getScopeInstance() {
return Scopes.NO_SCOPE;
}
@Override public String toString() {
return Scopes.NO_SCOPE.toString();
}
public void applyTo(ScopedBindingBuilder scopedBindingBuilder) {
// do nothing
}
};
public static final Scoping SINGLETON_ANNOTATION = new Scoping() {
public <V> V acceptVisitor(BindingScopingVisitor<V> visitor) {
return visitor.visitScopeAnnotation(Singleton.class);
}
@Override public Class<? extends Annotation> getScopeAnnotation() {
return Singleton.class;
}
@Override public String toString() {
return Singleton.class.getName();
}
public void applyTo(ScopedBindingBuilder scopedBindingBuilder) {
scopedBindingBuilder.in(Singleton.class);
}
};
public static final Scoping SINGLETON_INSTANCE = new Scoping() {
public <V> V acceptVisitor(BindingScopingVisitor<V> visitor) {
return visitor.visitScope(Scopes.SINGLETON);
}
@Override public Scope getScopeInstance() {
return Scopes.SINGLETON;
}
@Override public String toString() {
return Scopes.SINGLETON.toString();
}
public void applyTo(ScopedBindingBuilder scopedBindingBuilder) {
scopedBindingBuilder.in(Scopes.SINGLETON);
}
};
public static final Scoping EAGER_SINGLETON = new Scoping() {
public <V> V acceptVisitor(BindingScopingVisitor<V> visitor) {
return visitor.visitEagerSingleton();
}
@Override public Scope getScopeInstance() {
return Scopes.SINGLETON;
}
@Override public String toString() {
return "eager singleton";
}
public void applyTo(ScopedBindingBuilder scopedBindingBuilder) {
scopedBindingBuilder.asEagerSingleton();
}
};
public static Scoping forAnnotation(final Class<? extends Annotation> scopingAnnotation) {
if (scopingAnnotation == Singleton.class) {
return SINGLETON_ANNOTATION;
}
return new Scoping() {
public <V> V acceptVisitor(BindingScopingVisitor<V> visitor) {
return visitor.visitScopeAnnotation(scopingAnnotation);
}
@Override public Class<? extends Annotation> getScopeAnnotation() {
return scopingAnnotation;
}
@Override public String toString() {
return scopingAnnotation.getName();
}
public void applyTo(ScopedBindingBuilder scopedBindingBuilder) {
scopedBindingBuilder.in(scopingAnnotation);
}
};
}
public static Scoping forInstance(final Scope scope) {
if (scope == Scopes.SINGLETON) {
return SINGLETON_INSTANCE;
}
return new Scoping() {
public <V> V acceptVisitor(BindingScopingVisitor<V> visitor) {
return visitor.visitScope(scope);
}
@Override public Scope getScopeInstance() {
return scope;
}
@Override public String toString() {
return scope.toString();
}
public void applyTo(ScopedBindingBuilder scopedBindingBuilder) {
scopedBindingBuilder.in(scope);
}
};
}
/**
* Returns true if this scope was explicitly applied. If no scope was explicitly applied then the
* scoping annotation will be used.
*/
public boolean isExplicitlyScoped() {
return this != UNSCOPED;
}
/**
* Returns true if this is the default scope. In this case a new instance will be provided for
* each injection.
*/
public boolean isNoScope() {
return getScopeInstance() == Scopes.NO_SCOPE;
}
/**
* Returns true if this scope is a singleton that should be loaded eagerly in {@code stage}.
*/
public boolean isEagerSingleton(Stage stage) {
if (this == EAGER_SINGLETON) {
return true;
}
if (stage == Stage.PRODUCTION) {
return this == SINGLETON_ANNOTATION || this == SINGLETON_INSTANCE;
}
return false;
}
/**
* Returns the scope instance, or {@code null} if that isn't known for this instance.
*/
public Scope getScopeInstance() {
return null;
}
/**
* Returns the scope annotation, or {@code null} if that isn't known for this instance.
*/
public Class<? extends Annotation> getScopeAnnotation() {
return null;
}
public abstract <V> V acceptVisitor(BindingScopingVisitor<V> visitor);
public abstract void applyTo(ScopedBindingBuilder scopedBindingBuilder);
private Scoping() {}
/** Scopes an internal factory. */
static <T> InternalFactory<? extends T> scope(Key<T> key, InjectorImpl injector,
InternalFactory<? extends T> creator, Scoping scoping) {
if (scoping.isNoScope()) {
return creator;
}
Scope scope = scoping.getScopeInstance();
Provider<T> scoped
= scope.scope(key, new ProviderToInternalFactoryAdapter<T>(injector, creator));
return new InternalFactoryToProviderAdapter<T>(
Initializables.<Provider<? extends T>>of(scoped));
}
/**
* Replaces annotation scopes with instance scopes using the Injector's annotation-to-instance
* map. If the scope annotation has no corresponding instance, an error will be added and unscoped
* will be retuned.
*/
static Scoping makeInjectable(Scoping scoping, InjectorImpl injector, Errors errors) {
Class<? extends Annotation> scopeAnnotation = scoping.getScopeAnnotation();
if (scopeAnnotation == null) {
return scoping;
}
Scope scope = injector.state.getScope(scopeAnnotation);
if (scope != null) {
return forInstance(scope);
}
errors.scopeNotFound(scopeAnnotation);
return UNSCOPED;
}
}