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/*
 * Copyright (C) 2006 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.Binding;
import com.google.inject.Key;
import com.google.inject.Provider;
import com.google.inject.spi.BindingScopingVisitor;
import com.google.inject.spi.ElementVisitor;
import com.google.inject.spi.InstanceBinding;

/** @author [email protected] (Bob Lee) */
public abstract class BindingImpl implements Binding {

  private final InjectorImpl injector;
  private final Key key;
  private final Object source;
  private final Scoping scoping;
  private final InternalFactory internalFactory;

  BindingImpl(
      InjectorImpl injector,
      Key key,
      Object source,
      InternalFactory internalFactory,
      Scoping scoping) {
    this.injector = injector;
    this.key = key;
    this.source = source;
    this.internalFactory = internalFactory;
    this.scoping = scoping;
  }

  BindingImpl(Object source, Key key, Scoping scoping) {
    this.internalFactory = null;
    this.injector = null;
    this.source = source;
    this.key = key;
    this.scoping = scoping;
  }

  @Override
  public Key getKey() {
    return key;
  }

  @Override
  public Object getSource() {
    return source;
  }

  private volatile Provider provider;

  @Override
  public Provider getProvider() {
    if (provider == null) {
      if (injector == null) {
        throw new UnsupportedOperationException("getProvider() not supported for module bindings");
      }

      provider = injector.getProvider(key);
    }
    return provider;
  }

  public InternalFactory getInternalFactory() {
    return internalFactory;
  }

  public Scoping getScoping() {
    return scoping;
  }

  /**
   * Is this a constant binding? This returns true for constant bindings as well as toInstance()
   * bindings.
   */
  public boolean isConstant() {
    return this instanceof InstanceBinding;
  }

  @Override
  public  V acceptVisitor(ElementVisitor visitor) {
    return visitor.visit(this);
  }

  @Override
  public  V acceptScopingVisitor(BindingScopingVisitor visitor) {
    return scoping.acceptVisitor(visitor);
  }

  protected BindingImpl withScoping(Scoping scoping) {
    throw new AssertionError();
  }

  protected BindingImpl withKey(Key key) {
    throw new AssertionError();
  }

  @Override
  public String toString() {
    return MoreObjects.toStringHelper(Binding.class)
        .add("key", key)
        .add("scope", scoping)
        .add("source", source)
        .toString();
  }

  public InjectorImpl getInjector() {
    return injector;
  }
}