/*
* @(#)$Id: Reverse.java 3619 2008-03-26 07:23:03Z yui $
*
* Copyright 2006-2008 Makoto YUI
*
* Licensed 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.
*
* Contributors:
* Makoto YUI - initial implementation
*/
package xbird.xquery.func.seq;
import java.util.Iterator;
import java.util.Stack;
import xbird.util.iterator.ReverseIterator;
import xbird.xquery.XQueryException;
import xbird.xquery.dm.value.*;
import xbird.xquery.dm.value.sequence.ValueSequence;
import xbird.xquery.func.BuiltInFunction;
import xbird.xquery.func.FunctionSignature;
import xbird.xquery.meta.*;
import xbird.xquery.type.SequenceType;
import xbird.xquery.type.Type;
/**
* fn:reverse($arg as item()*) as item()*.
* <DIV lang="en">
* Reverses the order of items in a sequence. If $arg is the empty sequence,
* the empty sequence is returned.
* </DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
* @link http://www.w3.org/TR/xquery-operators/#func-reverse
*/
public final class Reverse extends BuiltInFunction {
private static final long serialVersionUID = 2154542136553587421L;
public static final String SYMBOL = "fn:reverse";
public Reverse() {
super(SYMBOL, SequenceType.ANY_ITEMS);
}
protected FunctionSignature[] signatures() {
final FunctionSignature[] s = new FunctionSignature[1];
s[0] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS });
return s;
}
public Sequence eval(Sequence<? extends Item> contextSeq, ValueSequence argv, DynamicContext dynEnv) throws XQueryException {
assert (argv != null && argv.size() == 1);
Item arg = argv.getItem(0);
return new Reverser(arg, dynEnv);
}
private static final class Reverser extends AbstractSequence<Item> {
private static final long serialVersionUID = -7288851327130322738L;
private Stack<Item> _itemStack = null;
private final Sequence<Item> _src;
Reverser(Sequence<Item> src, DynamicContext dynEnv) {
super(dynEnv);
assert (src != null);
this._src = src;
}
public boolean next(IFocus focus) throws XQueryException {
final Iterator<Item> baseItor = focus.getBaseFocus();
if(baseItor.hasNext()) {
final Item next = baseItor.next();
focus.setContextItem(next);
return true;
}
return false;
}
public Focus<Item> iterator() {
if(_itemStack == null) {
final Stack<Item> st = new Stack<Item>();
final IFocus<Item> srcItor = _src.iterator();
for(Item it : srcItor) {
st.push(it);
}
srcItor.closeQuietly();
this._itemStack = st;
}
final Iterator<Item> baseItor = new ReverseIterator<Item>(_itemStack);
return new Focus<Item>(this, baseItor, _dynEnv);
}
public Type getType() {
return _src.getType();
}
@Override
public boolean isEmpty() {
return _src.isEmpty();
}
}
}