/*
* ====================================================================
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*
*/
package org.apache.http.protocol;
import java.util.
Collection;
import java.util.
HashMap;
import java.util.
LinkedList;
import java.util.
Map;
/**
* Builder class to build a linked list (chain) of unique class instances. Each class can have
* only one instance in the list. Useful for building lists of protocol interceptors.
*
* @see ImmutableHttpProcessor
*
* @since 4.3
*/
final class
ChainBuilder<E> {
private final
LinkedList<E>
list;
private final
Map<
Class<?>, E>
uniqueClasses;
public
ChainBuilder() {
this.
list = new
LinkedList<E>();
this.
uniqueClasses = new
HashMap<
Class<?>, E>();
}
private void
ensureUnique(final E
e) {
final E
previous = this.
uniqueClasses.
remove(
e.
getClass());
if (
previous != null) {
this.
list.
remove(
previous);
}
this.
uniqueClasses.
put(
e.
getClass(),
e);
}
public
ChainBuilder<E>
addFirst(final E
e) {
if (
e == null) {
return this;
}
ensureUnique(
e);
this.
list.
addFirst(
e);
return this;
}
public
ChainBuilder<E>
addLast(final E
e) {
if (
e == null) {
return this;
}
ensureUnique(
e);
this.
list.
addLast(
e);
return this;
}
public
ChainBuilder<E>
addAllFirst(final
Collection<E>
c) {
if (
c == null) {
return this;
}
for (final E
e:
c) {
addFirst(
e);
}
return this;
}
public
ChainBuilder<E>
addAllFirst(final E...
c) {
if (
c == null) {
return this;
}
for (final E
e:
c) {
addFirst(
e);
}
return this;
}
public
ChainBuilder<E>
addAllLast(final
Collection<E>
c) {
if (
c == null) {
return this;
}
for (final E
e:
c) {
addLast(
e);
}
return this;
}
public
ChainBuilder<E>
addAllLast(final E...
c) {
if (
c == null) {
return this;
}
for (final E
e:
c) {
addLast(
e);
}
return this;
}
public
LinkedList<E>
build() {
return new
LinkedList<E>(this.
list);
}
}