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 import java.util.List; 27 import java.util.Set; 28 29 /** 30 * A variable that can be resolved by an injector. 31 * 32 * <p>Use {@link #get} to build a freestanding dependency, or {@link InjectionPoint} to build one 33 * that's attached to a constructor, method or field. 34 * 35 * @author crazybob@google.com (Bob Lee) 36 * @author jessewilson@google.com (Jesse Wilson) 37 * @since 2.0 38 */ 39 public final class Dependency<T> { 40 private final InjectionPoint injectionPoint; 41 private final Key<T> key; 42 private final boolean nullable; 43 private final int parameterIndex; 44 Dependency(InjectionPoint injectionPoint, Key<T> key, boolean nullable, int parameterIndex)45 Dependency(InjectionPoint injectionPoint, Key<T> key, boolean nullable, int parameterIndex) { 46 this.injectionPoint = injectionPoint; 47 this.key = checkNotNull(key, "key"); 48 this.nullable = nullable; 49 this.parameterIndex = parameterIndex; 50 } 51 52 /** 53 * Returns a new dependency that is not attached to an injection point. The returned dependency is 54 * nullable. 55 */ get(Key<T> key)56 public static <T> Dependency<T> get(Key<T> key) { 57 return new Dependency<T>(null, MoreTypes.canonicalizeKey(key), true, -1); 58 } 59 60 /** Returns the dependencies from the given injection points. */ forInjectionPoints(Set<InjectionPoint> injectionPoints)61 public static Set<Dependency<?>> forInjectionPoints(Set<InjectionPoint> injectionPoints) { 62 List<Dependency<?>> dependencies = Lists.newArrayList(); 63 for (InjectionPoint injectionPoint : injectionPoints) { 64 dependencies.addAll(injectionPoint.getDependencies()); 65 } 66 return ImmutableSet.copyOf(dependencies); 67 } 68 69 /** Returns the key to the binding that satisfies this dependency. */ getKey()70 public Key<T> getKey() { 71 return this.key; 72 } 73 74 /** Returns true if null is a legal value for this dependency. */ isNullable()75 public boolean isNullable() { 76 return nullable; 77 } 78 79 /** 80 * Returns the injection point to which this dependency belongs, or null if this dependency isn't 81 * attached to a particular injection point. 82 */ getInjectionPoint()83 public InjectionPoint getInjectionPoint() { 84 return injectionPoint; 85 } 86 87 /** 88 * Returns the index of this dependency in the injection point's parameter list, or {@code -1} if 89 * this dependency does not belong to a parameter list. Only method and constuctor dependencies 90 * are elements in a parameter list. 91 */ getParameterIndex()92 public int getParameterIndex() { 93 return parameterIndex; 94 } 95 96 @Override hashCode()97 public int hashCode() { 98 return Objects.hashCode(injectionPoint, parameterIndex, key); 99 } 100 101 @Override equals(Object o)102 public boolean equals(Object o) { 103 if (o instanceof Dependency) { 104 Dependency dependency = (Dependency) o; 105 return Objects.equal(injectionPoint, dependency.injectionPoint) 106 && Objects.equal(parameterIndex, dependency.parameterIndex) 107 && Objects.equal(key, dependency.key); 108 } else { 109 return false; 110 } 111 } 112 113 @Override toString()114 public String toString() { 115 StringBuilder builder = new StringBuilder(); 116 builder.append(key); 117 if (injectionPoint != null) { 118 builder.append("@").append(injectionPoint); 119 if (parameterIndex != -1) { 120 builder.append("[").append(parameterIndex).append("]"); 121 } 122 } 123 return builder.toString(); 124 } 125 } 126