/*
* Copyright 1999-2006 Sun Microsystems, Inc. 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. Sun designates this
* particular file as subject to the "Classpath" exception as provided
* by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
* CA 95054 USA or visit www.sun.com if you need additional information or
* have any questions.
*/
package com.sun.tools.javac.util;
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 API supported by Sun Microsystems. 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> implements Collection<A> {
public static <T> ListBuffer<T> lb() {
return new ListBuffer<T>();
}
/** The list of elements of this buffer.
*/
public List<A> elems;
/** A pointer pointing to the last, sentinel element of `elems'.
*/
public List<A> last;
/** The number of element in this buffer.
*/
public int count;
/** Has a list been created from this buffer yet?
*/
public boolean shared;
/** Create a new initially empty list buffer.
*/
public ListBuffer() {
clear();
}
public final void clear() {
this.elems = new List<A>(null,null);
this.last = this.elems;
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() {
List<A> p = elems = new List<A>(elems.head, elems.tail);
while (true) {
List<A> tail = p.tail;
if (tail == null) break;
tail = new List<A>(tail.head, tail.tail);
p.setTail(tail);
p = tail;
}
last = p;
shared = false;
}
/** Prepend an element to buffer.
*/
public ListBuffer<A> prepend(A x) {
elems = elems.prepend(x);
count++;
return this;
}
/** Append an element to buffer.
*/
public ListBuffer<A> append(A x) {
if (shared) copy();
last.head = x;
last.setTail(new List<A>(null,null));
last = last.tail;
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;
}
/** Remove the first element in this buffer.
*/
public void remove() {
if (elems != last) {
elems = elems.tail;
count--;
}
}
/** Return first element in this buffer and remove
*/
public A next() {
A x = elems.head;
remove();
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 != last;
}
public A next() {
if (elems == last)
throw new NoSuchElementException();
A elem = elems.head;
elems = elems.tail;
return elem;
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
public boolean add(A a) {
throw new UnsupportedOperationException();
}
public boolean remove(Object o) {
throw new UnsupportedOperationException();
}
public boolean containsAll(Collection<?> c) {
throw new UnsupportedOperationException();
}
public boolean addAll(Collection<? extends A> c) {
throw new UnsupportedOperationException();
}
public boolean removeAll(Collection<?> c) {
throw new UnsupportedOperationException();
}
public boolean retainAll(Collection<?> c) {
throw new UnsupportedOperationException();
}
}