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/*
* Copyright (c) 1999, 2013, 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
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*/
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.
*
* 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.
*/
public class ListBuffer extends AbstractQueue {
public static ListBuffer of(T x) {
ListBuffer lb = new ListBuffer<>();
lb.add(x);
return lb;
}
/** The list of elements of this buffer.
*/
private List elems;
/** A pointer pointing to the last element of 'elems' containing data,
* or null if the list is empty.
*/
private List 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 orig = elems;
elems = last = List.of(orig.head);
while ((orig = orig.tail).nonEmpty()) {
last.tail = List.of(orig.head);
last = last.tail;
}
}
}
/** Prepend an element to buffer.
*/
public ListBuffer prepend(A x) {
elems = elems.prepend(x);
if (last == null) last = elems;
count++;
return this;
}
/** Append an element to buffer.
*/
public ListBuffer append(A x) {
Assert.checkNonNull(x);
if (shared) copy();
List newLast = List.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 appendList(List xs) {
while (xs.nonEmpty()) {
append(xs.head);
xs = xs.tail;
}
return this;
}
/** Append all elements in a list to buffer.
*/
public ListBuffer appendList(ListBuffer xs) {
return appendList(xs.toList());
}
/** Append all elements in an array to buffer.
*/
public ListBuffer appendArray(A[] xs) {
for (A x : xs) {
append(x);
}
return this;
}
/** Convert buffer to a list of all its elements.
*/
public List 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[] 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 iterator() {
return new Iterator() {
List 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 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;
}
}