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/**
* Copyright (C) 2006 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.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.inject.Key;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.DependencyAndSource;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
/**
* Internal context. Used to coordinate injections and support circular
* dependencies.
*
* @author crazybob@google.com (Bob Lee)
*/
final class InternalContext {
private Map<Object, ConstructionContext<?>> constructionContexts = Maps.newHashMap();
/** Keeps track of the type that is currently being requested for injection. */
private Dependency<?> dependency;
/** Keeps track of the hierarchy of types needed during injection. */
private final DependencyStack state = new DependencyStack();
@SuppressWarnings("unchecked")
public <T> ConstructionContext<T> getConstructionContext(Object key) {
ConstructionContext<T> constructionContext
= (ConstructionContext<T>) constructionContexts.get(key);
if (constructionContext == null) {
constructionContext = new ConstructionContext<T>();
constructionContexts.put(key, constructionContext);
}
return constructionContext;
}
public Dependency<?> getDependency() {
return dependency;
}
/** Sets the new current dependency & adds it to the state. */
public Dependency<?> pushDependency(Dependency<?> dependency, Object source) {
Dependency<?> previous = this.dependency;
this.dependency = dependency;
state.add(dependency, source);
return previous;
}
/** Pops the current state & sets the new dependency. */
public void popStateAndSetDependency(Dependency<?> newDependency) {
state.pop();
this.dependency = newDependency;
}
/** Adds to the state without setting the dependency. */
public void pushState(Key<?> key, Object source) {
state.add(key, source);
}
/** Pops from the state without setting a dependency. */
public void popState() {
state.pop();
}
/** Returns the current dependency chain (all the state). */
public List<DependencyAndSource> getDependencyChain() {
ImmutableList.Builder<DependencyAndSource> builder = ImmutableList.builder();
for (int i = 0; i < state.size(); i += 2) {
Object evenEntry = state.get(i);
Dependency<?> dependency;
if (evenEntry instanceof Key) {
dependency = Dependency.get((Key<?>) evenEntry);
} else {
dependency = (Dependency<?>) evenEntry;
}
builder.add(new DependencyAndSource(dependency, state.get(i + 1)));
}
return builder.build();
}
/**
* Keeps track of the hierarchy of types needed during injection.
*
* <p>This is a pairwise combination of dependencies and sources, with dependencies or keys on
* even indices, and sources on odd indices. This structure is to avoid the memory overhead of
* DependencyAndSource objects, which can add to several tens of megabytes in large applications.
*/
private static final class DependencyStack {
private Object[] elements = new Object[16];
private int size = 0;
public void add(Object dependencyOrKey, Object source) {
if (elements.length < size + 2) {
elements = Arrays.copyOf(elements, (elements.length*3)/2 + 2);
}
elements[size++] = dependencyOrKey;
elements[size++] = source;
}
public void pop() {
elements[--size] = null;
elements[--size] = null;
}
public Object get(int i) {
return elements[i];
}
public int size() {
return size;
}
}
}
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