core/src/com/google/inject/internal/FactoryProxy.java

/**
 * 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.internal;

import com.google.inject.Key;
import com.google.inject.internal.InjectorImpl.JitLimitation;
import com.google.inject.internal.util.ToStringBuilder;
import com.google.inject.spi.Dependency;

/**
 * A placeholder which enables us to swap in the real factory once the injector is created.
 * Used for a linked binding, so that getting the linked binding returns the link's factory.
 */
final class FactoryProxy<T> implements InternalFactory<T>, CreationListener {

  private final InjectorImpl injector;
  private final Key<T> key;
  private final Key<? extends T> targetKey;
  private final Object source;

  private InternalFactory<? extends T> targetFactory;

  FactoryProxy(InjectorImpl injector, Key<T> key, Key<? extends T> targetKey, Object source) {
    this.injector = injector;
    this.key = key;
    this.targetKey = targetKey;
    this.source = source;
  }

  public void notify(final Errors errors) {
    try {
      targetFactory = injector.getInternalFactory(targetKey, errors.withSource(source), JitLimitation.NEW_OR_EXISTING_JIT);
    } catch (ErrorsException e) {
      errors.merge(e.getErrors());
    }
  }

  public T get(Errors errors, InternalContext context, Dependency<?> dependency, boolean linked)
      throws ErrorsException {
    context.pushState(targetKey, source);
    try {
      return targetFactory.get(errors.withSource(targetKey), context, dependency, true);
    } finally {
      context.popState();
    }
  }

  @Override public String toString() {
    return new ToStringBuilder(FactoryProxy.class)
        .add("key", key)
        .add("provider", targetFactory)
        .toString();
  }
}