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.common.base.MoreObjects;
import com.google.inject.Key;
import com.google.inject.internal.InjectorImpl.JitLimitation;
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;
  }

  @Override
  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());
    }
  }

  @Override
  public T get(InternalContext context, Dependency<?> dependency, boolean linked)
      throws InternalProvisionException {
    Key<? extends T> localTargetKey = targetKey;
    context.pushState(localTargetKey, source);

    try {
      return targetFactory.get(context, dependency, true);
    } catch (InternalProvisionException ipe) {
      throw ipe.addSource(localTargetKey);
      } finally {
        context.popState();

    }
  }

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