1 /** 2 * Copyright (C) 2008 Google Inc. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.inject.spi; 18 19 import static com.google.common.base.Preconditions.checkNotNull; 20 21 import com.google.common.base.Objects; 22 import com.google.common.collect.ImmutableSet; 23 import com.google.common.collect.Lists; 24 import com.google.inject.Key; 25 import com.google.inject.internal.MoreTypes; 26 27 import java.util.List; 28 import java.util.Set; 29 30 /** 31 * A variable that can be resolved by an injector. 32 * 33 * <p>Use {@link #get} to build a freestanding dependency, or {@link InjectionPoint} to build one 34 * that's attached to a constructor, method or field. 35 * 36 * @author crazybob@google.com (Bob Lee) 37 * @author jessewilson@google.com (Jesse Wilson) 38 * @since 2.0 39 */ 40 public final class Dependency<T> { 41 private final InjectionPoint injectionPoint; 42 private final Key<T> key; 43 private final boolean nullable; 44 private final int parameterIndex; 45 Dependency(InjectionPoint injectionPoint, Key<T> key, boolean nullable, int parameterIndex)46 Dependency(InjectionPoint injectionPoint, Key<T> key, boolean nullable, int parameterIndex) { 47 this.injectionPoint = injectionPoint; 48 this.key = checkNotNull(key, "key"); 49 this.nullable = nullable; 50 this.parameterIndex = parameterIndex; 51 } 52 53 /** 54 * Returns a new dependency that is not attached to an injection point. The returned dependency is 55 * nullable. 56 */ get(Key<T> key)57 public static <T> Dependency<T> get(Key<T> key) { 58 return new Dependency<T>(null, MoreTypes.canonicalizeKey(key), true, -1); 59 } 60 61 /** 62 * Returns the dependencies from the given injection points. 63 */ forInjectionPoints(Set<InjectionPoint> injectionPoints)64 public static Set<Dependency<?>> forInjectionPoints(Set<InjectionPoint> injectionPoints) { 65 List<Dependency<?>> dependencies = Lists.newArrayList(); 66 for (InjectionPoint injectionPoint : injectionPoints) { 67 dependencies.addAll(injectionPoint.getDependencies()); 68 } 69 return ImmutableSet.copyOf(dependencies); 70 } 71 72 /** 73 * Returns the key to the binding that satisfies this dependency. 74 */ getKey()75 public Key<T> getKey() { 76 return this.key; 77 } 78 79 /** 80 * Returns true if null is a legal value for this dependency. 81 */ isNullable()82 public boolean isNullable() { 83 return nullable; 84 } 85 86 /** 87 * Returns the injection point to which this dependency belongs, or null if this dependency isn't 88 * attached to a particular injection point. 89 */ getInjectionPoint()90 public InjectionPoint getInjectionPoint() { 91 return injectionPoint; 92 } 93 94 /** 95 * Returns the index of this dependency in the injection point's parameter list, or {@code -1} if 96 * this dependency does not belong to a parameter list. Only method and constuctor dependencies 97 * are elements in a parameter list. 98 */ getParameterIndex()99 public int getParameterIndex() { 100 return parameterIndex; 101 } 102 hashCode()103 @Override public int hashCode() { 104 return Objects.hashCode(injectionPoint, parameterIndex, key); 105 } 106 equals(Object o)107 @Override public boolean equals(Object o) { 108 if (o instanceof Dependency) { 109 Dependency dependency = (Dependency) o; 110 return Objects.equal(injectionPoint, dependency.injectionPoint) 111 && Objects.equal(parameterIndex, dependency.parameterIndex) 112 && Objects.equal(key, dependency.key); 113 } else { 114 return false; 115 } 116 } 117 toString()118 @Override public String toString() { 119 StringBuilder builder = new StringBuilder(); 120 builder.append(key); 121 if (injectionPoint != null) { 122 builder.append("@").append(injectionPoint); 123 if (parameterIndex != -1) { 124 builder.append("[").append(parameterIndex).append("]"); 125 } 126 } 127 return builder.toString(); 128 } 129 } 130