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/**
* 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.
*
* <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.
*/
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.
*/
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.
*/
public Key<T> getKey() {
return this.key;
}
/**
* 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.
*/
public InjectionPoint getInjectionPoint() {
return injectionPoint;
}
/**
* 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();
}
}
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