/*
 * 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.spi;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Lists;
import com.google.inject.Key;
import com.google.inject.internal.MoreTypes;
import java.util.List;
import java.util.Set;

A variable that can be resolved by an injector.

Use get to build a freestanding dependency, or InjectionPoint to build one that's attached to a constructor, method or field.

Author:crazybob@google.com (Bob Lee), jessewilson@google.com (Jesse Wilson)
Since:2.0
/** * A variable that can be resolved by an injector. * * <p>Use {@link #get} to build a freestanding dependency, or {@link InjectionPoint} to build one * that's attached to a constructor, method or field. * * @author crazybob@google.com (Bob Lee) * @author jessewilson@google.com (Jesse Wilson) * @since 2.0 */
public final class Dependency<T> { private final InjectionPoint injectionPoint; private final Key<T> key; private final boolean nullable; private final int parameterIndex; Dependency(InjectionPoint injectionPoint, Key<T> key, boolean nullable, int parameterIndex) { this.injectionPoint = injectionPoint; this.key = checkNotNull(key, "key"); this.nullable = nullable; this.parameterIndex = parameterIndex; }
Returns a new dependency that is not attached to an injection point. The returned dependency is nullable.
/** * Returns a new dependency that is not attached to an injection point. The returned dependency is * nullable. */
public static <T> Dependency<T> get(Key<T> key) { return new Dependency<T>(null, MoreTypes.canonicalizeKey(key), true, -1); }
Returns the dependencies from the given injection points.
/** Returns the dependencies from the given injection points. */
public static Set<Dependency<?>> forInjectionPoints(Set<InjectionPoint> injectionPoints) { List<Dependency<?>> dependencies = Lists.newArrayList(); for (InjectionPoint injectionPoint : injectionPoints) { dependencies.addAll(injectionPoint.getDependencies()); } return ImmutableSet.copyOf(dependencies); }
Returns the key to the binding that satisfies this dependency.
/** Returns the key to the binding that satisfies this dependency. */
public Key<T> getKey() { return this.key; }
Returns true if null is a legal value for this dependency.
/** Returns true if null is a legal value for this dependency. */
public boolean isNullable() { return nullable; }
Returns the injection point to which this dependency belongs, or null if this dependency isn't attached to a particular injection point.
/** * Returns the injection point to which this dependency belongs, or null if this dependency isn't * attached to a particular injection point. */
public InjectionPoint getInjectionPoint() { return injectionPoint; }
Returns the index of this dependency in the injection point's parameter list, or -1 if this dependency does not belong to a parameter list. Only method and constuctor dependencies are elements in a parameter list.
/** * Returns the index of this dependency in the injection point's parameter list, or {@code -1} if * this dependency does not belong to a parameter list. Only method and constuctor dependencies * are elements in a parameter list. */
public int getParameterIndex() { return parameterIndex; } @Override public int hashCode() { return Objects.hashCode(injectionPoint, parameterIndex, key); } @Override public boolean equals(Object o) { if (o instanceof Dependency) { Dependency dependency = (Dependency) o; return Objects.equal(injectionPoint, dependency.injectionPoint) && Objects.equal(parameterIndex, dependency.parameterIndex) && Objects.equal(key, dependency.key); } else { return false; } } @Override public String toString() { StringBuilder builder = new StringBuilder(); builder.append(key); if (injectionPoint != null) { builder.append("@").append(injectionPoint); if (parameterIndex != -1) { builder.append("[").append(parameterIndex).append("]"); } } return builder.toString(); } }