| /** |
| * 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.ImmutableSet; |
| import com.google.inject.internal.Sets; |
| import java.lang.annotation.Annotation; |
| import java.util.Set; |
| |
| /** |
| * A node in the scoped dependency graph. Each node has two scopes. The <i>applied scope</i> is the |
| * scope directly assigned to the binding by the user, such as in an {@code in()} clause. The |
| * <i>effective scope</i> 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<? extends Annotation> appliedScopeAnnotation; |
| |
| /** Places that this node is injected. */ |
| private Set<Node> 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<? extends Annotation> 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(); |
| } |
| } |