/*
* @(#)$Id: Exists.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 xbird.xquery.XQueryException;
import xbird.xquery.dm.value.Item;
import xbird.xquery.dm.value.Sequence;
import xbird.xquery.dm.value.sequence.ValueSequence;
import xbird.xquery.dm.value.xsi.BooleanValue;
import xbird.xquery.func.BuiltInFunction;
import xbird.xquery.func.FunctionSignature;
import xbird.xquery.meta.DynamicContext;
import xbird.xquery.type.SequenceType;
import xbird.xquery.type.Type;
import xbird.xquery.type.xs.BooleanType;
/**
* fn:exists($arg as item()*) as xs:boolean.
* <DIV lang="en">
* If the value of $arg is not the empty sequence,
* the function returns true; otherwise, the function returns false.
* </DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
* @link http://www.w3.org/TR/xquery-operators/#func-exists
*/
public final class Exists extends BuiltInFunction {
private static final long serialVersionUID = 7894256339020808566L;
public static final String SYMBOL = "fn:exists";
public Exists() {
super(SYMBOL, BooleanType.BOOLEAN);
}
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);
if(arg.isEmpty()) {
return BooleanValue.FALSE;
} else {
return BooleanValue.TRUE;
}
}
}