Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.  Oracle designates this

  * particular file as subject to the "Classpath" exception as provided

  * by Oracle in the LICENSE file that accompanied this code.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

  * or visit www.oracle.com if you need additional information or have any

  * questions.

  */

 package com.sun.tools.javac.util;

 import java.util.AbstractQueue;

 import java.util.Collection;

 import java.util.Iterator;

 import java.util.NoSuchElementException;

 /** A class for constructing lists by appending elements. Modelled after

  *  java.lang.StringBuffer.

  *

  *  <p><b>This is NOT part of any supported API.

  *  If you write code that depends on this, you do so at your own risk.

  *  This code and its internal interfaces are subject to change or

  *  deletion without notice.</b>

  */

 public class ListBuffer<A> extends AbstractQueue<A> {

     public static <T> ListBuffer<T> lb() {

         return new ListBuffer<T>();

     }

     public static <T> ListBuffer<T> of(T x) {

         ListBuffer<T> lb = new ListBuffer<T>();

         lb.add(x);

         return lb;

     }

     /** The list of elements of this buffer.

      */

     private List<A> elems;

     /** A pointer pointing to the last element of 'elems' containing data,

      *  or null if the list is empty.

      */

     private List<A> last;

     /** The number of element in this buffer.

      */

     private int count;

     /** Has a list been created from this buffer yet?

      */

     private boolean shared;

     /** Create a new initially empty list buffer.

      */

     public ListBuffer() {

         clear();

     }

     public final void clear() {

         this.elems = List.nil();

         this.last = null;

         count = 0;

         shared = false;

     }

     /** Return the number of elements in this buffer.

      */

     public int length() {

         return count;

     }

     public int size() {

         return count;

     }

     /** Is buffer empty?

      */

     public boolean isEmpty() {

         return count == 0;

     }

     /** Is buffer not empty?

      */

     public boolean nonEmpty() {

         return count != 0;

     }

     /** Copy list and sets last.

      */

     private void copy() {

         if (elems.nonEmpty()) {

             List<A> orig = elems;

             elems = last = List.<A>of(orig.head);

             while ((orig = orig.tail).nonEmpty()) {

                 last.tail = List.<A>of(orig.head);

                 last = last.tail;

             }

         }

     }

     /** Prepend an element to buffer.

      */

     public ListBuffer<A> prepend(A x) {

         elems = elems.prepend(x);

         if (last == null) last = elems;

         count++;

         return this;

     }

     /** Append an element to buffer.

      */

     public ListBuffer<A> append(A x) {

         x.getClass(); // null check

         if (shared) copy();

         List<A> newLast = List.<A>of(x);

         if (last != null) {

             last.tail = newLast;

             last = newLast;

         } else {

             elems = last = newLast;

         }

         count++;

         return this;

     }

     /** Append all elements in a list to buffer.

      */

     public ListBuffer<A> appendList(List<A> xs) {

         while (xs.nonEmpty()) {

             append(xs.head);

             xs = xs.tail;

         }

         return this;

     }

     /** Append all elements in a list to buffer.

      */

     public ListBuffer<A> appendList(ListBuffer<A> xs) {

         return appendList(xs.toList());

     }

     /** Append all elements in an array to buffer.

      */

     public ListBuffer<A> appendArray(A[] xs) {

         for (int i = 0; i < xs.length; i++) {

             append(xs[i]);

         }

         return this;

     }

     /** Convert buffer to a list of all its elements.

      */

     public List<A> toList() {

         shared = true;

         return elems;

     }

     /** Does the list contain the specified element?

      */

     public boolean contains(Object x) {

         return elems.contains(x);

     }

     /** Convert buffer to an array

      */

     public <T> T[] toArray(T[] vec) {

         return elems.toArray(vec);

     }

     public Object[] toArray() {

         return toArray(new Object[size()]);

     }

     /** The first element in this buffer.

      */

     public A first() {

         return elems.head;

     }

     /** Return first element in this buffer and remove

      */

     public A next() {

         A x = elems.head;

         if (!elems.isEmpty()) {

             elems = elems.tail;

             if (elems.isEmpty()) last = null;

             count--;

         }

         return x;

     }

     /** An enumeration of all elements in this buffer.

      */

     public Iterator<A> iterator() {

         return new Iterator<A>() {

             List<A> elems = ListBuffer.this.elems;

             public boolean hasNext() {

                 return !elems.isEmpty();

             }

             public A next() {

                 if (elems.isEmpty())

                     throw new NoSuchElementException();

                 A elem = elems.head;

                 elems = elems.tail;

                 return elem;

             }

             public void remove() {

                 throw new UnsupportedOperationException();

             }

         };

     }

     public boolean add(A a) {

         append(a);

         return true;

     }

     public boolean remove(Object o) {

         throw new UnsupportedOperationException();

     }

     public boolean containsAll(Collection<?> c) {

         for (Object x: c) {

             if (!contains(x))

                 return false;

         }

         return true;

     }

     public boolean addAll(Collection<? extends A> c) {

         for (A a: c)

             append(a);

         return true;

     }

     public boolean removeAll(Collection<?> c) {

         throw new UnsupportedOperationException();

     }

     public boolean retainAll(Collection<?> c) {

         throw new UnsupportedOperationException();

     }

     public boolean offer(A a) {

         append(a);

         return true;

     }

     public A poll() {

         return next();

     }

     public A peek() {

         return first();

     }

     public A last() {

         return last != null ? last.head : null;

     }

 }