aoqi@0: /*
aoqi@0:  * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.  Oracle designates this
aoqi@0:  * particular file as subject to the "Classpath" exception as provided
aoqi@0:  * by Oracle in the LICENSE file that accompanied this code.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  */
aoqi@0: 
aoqi@0: package com.sun.tools.javac.util;
aoqi@0: 
aoqi@0: import java.util.AbstractQueue;
aoqi@0: import java.util.Collection;
aoqi@0: import java.util.Iterator;
aoqi@0: import java.util.NoSuchElementException;
aoqi@0: 
aoqi@0: /** A class for constructing lists by appending elements. Modelled after
aoqi@0:  *  java.lang.StringBuffer.
aoqi@0:  *
aoqi@0:  *  <p><b>This is NOT part of any supported API.
aoqi@0:  *  If you write code that depends on this, you do so at your own risk.
aoqi@0:  *  This code and its internal interfaces are subject to change or
aoqi@0:  *  deletion without notice.</b>
aoqi@0:  */
aoqi@0: public class ListBuffer<A> extends AbstractQueue<A> {
aoqi@0: 
aoqi@0:     public static <T> ListBuffer<T> of(T x) {
aoqi@0:         ListBuffer<T> lb = new ListBuffer<T>();
aoqi@0:         lb.add(x);
aoqi@0:         return lb;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** The list of elements of this buffer.
aoqi@0:      */
aoqi@0:     private List<A> elems;
aoqi@0: 
aoqi@0:     /** A pointer pointing to the last element of 'elems' containing data,
aoqi@0:      *  or null if the list is empty.
aoqi@0:      */
aoqi@0:     private List<A> last;
aoqi@0: 
aoqi@0:     /** The number of element in this buffer.
aoqi@0:      */
aoqi@0:     private int count;
aoqi@0: 
aoqi@0:     /** Has a list been created from this buffer yet?
aoqi@0:      */
aoqi@0:     private boolean shared;
aoqi@0: 
aoqi@0:     /** Create a new initially empty list buffer.
aoqi@0:      */
aoqi@0:     public ListBuffer() {
aoqi@0:         clear();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public final void clear() {
aoqi@0:         this.elems = List.nil();
aoqi@0:         this.last = null;
aoqi@0:         count = 0;
aoqi@0:         shared = false;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Return the number of elements in this buffer.
aoqi@0:      */
aoqi@0:     public int length() {
aoqi@0:         return count;
aoqi@0:     }
aoqi@0:     public int size() {
aoqi@0:         return count;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Is buffer empty?
aoqi@0:      */
aoqi@0:     public boolean isEmpty() {
aoqi@0:         return count == 0;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Is buffer not empty?
aoqi@0:      */
aoqi@0:     public boolean nonEmpty() {
aoqi@0:         return count != 0;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Copy list and sets last.
aoqi@0:      */
aoqi@0:     private void copy() {
aoqi@0:         if (elems.nonEmpty()) {
aoqi@0:             List<A> orig = elems;
aoqi@0: 
aoqi@0:             elems = last = List.<A>of(orig.head);
aoqi@0: 
aoqi@0:             while ((orig = orig.tail).nonEmpty()) {
aoqi@0:                 last.tail = List.<A>of(orig.head);
aoqi@0:                 last = last.tail;
aoqi@0:             }
aoqi@0:         }
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Prepend an element to buffer.
aoqi@0:      */
aoqi@0:     public ListBuffer<A> prepend(A x) {
aoqi@0:         elems = elems.prepend(x);
aoqi@0:         if (last == null) last = elems;
aoqi@0:         count++;
aoqi@0:         return this;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Append an element to buffer.
aoqi@0:      */
aoqi@0:     public ListBuffer<A> append(A x) {
aoqi@0:         x.getClass(); // null check
aoqi@0:         if (shared) copy();
aoqi@0:         List<A> newLast = List.<A>of(x);
aoqi@0:         if (last != null) {
aoqi@0:             last.tail = newLast;
aoqi@0:             last = newLast;
aoqi@0:         } else {
aoqi@0:             elems = last = newLast;
aoqi@0:         }
aoqi@0:         count++;
aoqi@0:         return this;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Append all elements in a list to buffer.
aoqi@0:      */
aoqi@0:     public ListBuffer<A> appendList(List<A> xs) {
aoqi@0:         while (xs.nonEmpty()) {
aoqi@0:             append(xs.head);
aoqi@0:             xs = xs.tail;
aoqi@0:         }
aoqi@0:         return this;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Append all elements in a list to buffer.
aoqi@0:      */
aoqi@0:     public ListBuffer<A> appendList(ListBuffer<A> xs) {
aoqi@0:         return appendList(xs.toList());
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Append all elements in an array to buffer.
aoqi@0:      */
aoqi@0:     public ListBuffer<A> appendArray(A[] xs) {
aoqi@0:         for (int i = 0; i < xs.length; i++) {
aoqi@0:             append(xs[i]);
aoqi@0:         }
aoqi@0:         return this;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Convert buffer to a list of all its elements.
aoqi@0:      */
aoqi@0:     public List<A> toList() {
aoqi@0:         shared = true;
aoqi@0:         return elems;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Does the list contain the specified element?
aoqi@0:      */
aoqi@0:     public boolean contains(Object x) {
aoqi@0:         return elems.contains(x);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Convert buffer to an array
aoqi@0:      */
aoqi@0:     public <T> T[] toArray(T[] vec) {
aoqi@0:         return elems.toArray(vec);
aoqi@0:     }
aoqi@0:     public Object[] toArray() {
aoqi@0:         return toArray(new Object[size()]);
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** The first element in this buffer.
aoqi@0:      */
aoqi@0:     public A first() {
aoqi@0:         return elems.head;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** Return first element in this buffer and remove
aoqi@0:      */
aoqi@0:     public A next() {
aoqi@0:         A x = elems.head;
aoqi@0:         if (!elems.isEmpty()) {
aoqi@0:             elems = elems.tail;
aoqi@0:             if (elems.isEmpty()) last = null;
aoqi@0:             count--;
aoqi@0:         }
aoqi@0:         return x;
aoqi@0:     }
aoqi@0: 
aoqi@0:     /** An enumeration of all elements in this buffer.
aoqi@0:      */
aoqi@0:     public Iterator<A> iterator() {
aoqi@0:         return new Iterator<A>() {
aoqi@0:             List<A> elems = ListBuffer.this.elems;
aoqi@0:             public boolean hasNext() {
aoqi@0:                 return !elems.isEmpty();
aoqi@0:             }
aoqi@0:             public A next() {
aoqi@0:                 if (elems.isEmpty())
aoqi@0:                     throw new NoSuchElementException();
aoqi@0:                 A elem = elems.head;
aoqi@0:                 elems = elems.tail;
aoqi@0:                 return elem;
aoqi@0:             }
aoqi@0:             public void remove() {
aoqi@0:                 throw new UnsupportedOperationException();
aoqi@0:             }
aoqi@0:         };
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean add(A a) {
aoqi@0:         append(a);
aoqi@0:         return true;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean remove(Object o) {
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean containsAll(Collection<?> c) {
aoqi@0:         for (Object x: c) {
aoqi@0:             if (!contains(x))
aoqi@0:                 return false;
aoqi@0:         }
aoqi@0:         return true;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean addAll(Collection<? extends A> c) {
aoqi@0:         for (A a: c)
aoqi@0:             append(a);
aoqi@0:         return true;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean removeAll(Collection<?> c) {
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean retainAll(Collection<?> c) {
aoqi@0:         throw new UnsupportedOperationException();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public boolean offer(A a) {
aoqi@0:         append(a);
aoqi@0:         return true;
aoqi@0:     }
aoqi@0: 
aoqi@0:     public A poll() {
aoqi@0:         return next();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public A peek() {
aoqi@0:         return first();
aoqi@0:     }
aoqi@0: 
aoqi@0:     public A last() {
aoqi@0:         return last != null ? last.head : null;
aoqi@0:     }
aoqi@0: }