com.google.inject.util.Node Maven / Gradle / Ivy
/**
* Copyright (C) 2009 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.util;
import com.google.inject.Key;
import com.google.inject.internal.Errors;
import com.google.inject.internal.util.ImmutableSet;
import com.google.inject.internal.util.Sets;
import java.lang.annotation.Annotation;
import java.util.Set;
/**
* A node in the scoped dependency graph. Each node has two scopes. The applied scope is the
* scope directly assigned to the binding by the user, such as in an {@code in()} clause. The
* effective scope is the narrowest scope in which this object is used. It is derived from
* the narrowest scope of the node's transitive dependencies. Each scope is modelled as a rank;
* higher numbers represent narrower scopes.
*/
class Node {
private final Key key;
private int appliedScope = Integer.MAX_VALUE;
private Node effectiveScopeDependency;
private int effectiveScope = Integer.MIN_VALUE;
private Class appliedScopeAnnotation;
/** Places that this node is injected. */
private Set users = ImmutableSet.of();
Node(Key key) {
this.key = key;
}
/**
* Initialize the scope ranks for this node. Called at most once per node.
*/
void setScopeRank(int rank, Class annotation) {
this.appliedScope = rank;
this.effectiveScope = rank;
this.appliedScopeAnnotation = annotation;
}
/**
* Sets this node's effective scope unless it's already better.
*/
private void setEffectiveScope(int effectiveScope, Node effectiveScopeDependency) {
if (this.effectiveScope >= effectiveScope) {
return;
}
this.effectiveScope = effectiveScope;
this.effectiveScopeDependency = effectiveScopeDependency;
pushScopeToUsers();
}
/**
* Pushes the narrowness of this node's effective scope to everyone that depends on this node.
*/
void pushScopeToUsers() {
for (Node user : users) {
user.setEffectiveScope(effectiveScope, this);
}
}
/**
* Returns true if this node has no dependency whose scope is narrower than itself.
*/
boolean isScopedCorrectly() {
return appliedScope >= effectiveScope;
}
boolean isEffectiveScopeAppliedScope() {
return appliedScope == effectiveScope;
}
/**
* Returns the most narrowly scoped dependency. If multiple such dependencies exist, the selection
* of which is returned is arbitrary.
*/
Node effectiveScopeDependency() {
return effectiveScopeDependency;
}
/**
* Mark this as a dependency of {@code node}.
*/
public void addUser(Node node) {
if (users.isEmpty()) {
users = Sets.newHashSet();
}
users.add(node);
}
@Override public String toString() {
return appliedScopeAnnotation != null
? Errors.convert(key) + " in @" + appliedScopeAnnotation.getSimpleName()
: Errors.convert(key).toString();
}
}