/*
* @(#)$Id: ZeroOrOne.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.List;
import xbird.xquery.DynamicError;
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.expr.XQExpression;
import xbird.xquery.func.BuiltInFunction;
import xbird.xquery.func.FunctionSignature;
import xbird.xquery.meta.DynamicContext;
import xbird.xquery.meta.StaticContext;
import xbird.xquery.type.*;
/**
* fn:zero-or-one($arg as item()*) as item()?.
* <DIV lang="en"></DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
*/
public final class ZeroOrOne extends BuiltInFunction {
private static final long serialVersionUID = 7998331512034933930L;
public static final String SYMBOL = "fn:zero-or-one";
public ZeroOrOne() {
super(SYMBOL, TypeRegistry.safeGet("item()?"));
}
protected FunctionSignature[] signatures() {
final FunctionSignature[] s = new FunctionSignature[1];
s[0] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS });
return s;
}
@Override
public ZeroOrOne staticAnalysis(StaticContext context, List<? extends XQExpression> params)
throws XQueryException {
assert (params != null);
// infer return type from parameter types
final XQExpression p = params.get(0);
this._returnType = p.getType().prime();
assert (Type.Occurrence.OCC_ZERO_OR_ONE.accepts(_returnType.quantifier().getAlignment()));
return this;
}
public Sequence eval(final Sequence<? extends Item> contextSeq, final ValueSequence argv, final DynamicContext dynEnv)
throws XQueryException {
assert (argv != null && argv.size() == 1);
final Item arg = argv.getItem(0);
final Type argType = arg.getType();
final Type.Occurrence quantifier = argType.quantifier();
if(!Type.Occurrence.OCC_ZERO_OR_ONE.accepts(quantifier.getAlignment())) {
final Iterator<? extends Item> argItor = arg.iterator();
if(argItor.hasNext()) {
final Item first = argItor.next();
assert (first != null);
if(argItor.hasNext()) {
// Returns $arg if it contains one or more items. Otherwise, raises an error [err:FORG0004].
throw new DynamicError("err:FORG0004", "Invalid result sequence type was detected, $arg contains one or more items: "
+ arg.getType());
}
}
}
return arg;
}
}