com.google.inject.internal.WeakKeySet Maven / Gradle / Ivy
/**
* 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.Key;
import com.google.inject.internal.util.Sets;
import java.util.Set;
/**
* Minimal set that doesn't hold strong references to the contained keys.
*
* @author [email protected] (Jesse Wilson)
*/
final class WeakKeySet {
/**
* We store strings rather than keys so we don't hold strong references.
*
* One potential problem with this approach is that parent and child injectors cannot define
* keys whose class names are equal but class loaders are different. This shouldn't be an issue
* in practice.
*/
private Set backingSet;
public boolean add(Key key) {
if (backingSet == null) {
backingSet = Sets.newHashSet();
}
return backingSet.add(key.toString());
}
public boolean contains(Object o) {
// avoid calling key.toString() if the backing set is empty. toString is expensive in aggregate,
// and most WeakKeySets are empty in practice (because they're used by top-level injectors)
return backingSet != null && o instanceof Key && backingSet.contains(o.toString());
}
}