/*
* @(#)$Id: Subsequence.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.List;
import xbird.xquery.XQueryException;
import xbird.xquery.dm.value.Item;
import xbird.xquery.dm.value.Sequence;
import xbird.xquery.dm.value.literal.XNumber;
import xbird.xquery.dm.value.sequence.ValueSequence;
import xbird.xquery.expr.XQExpression;
import xbird.xquery.expr.path.FilterExpr;
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.DoubleType;
import xbird.xquery.type.xs.NumericType;
/**
* fn:subsequence.
* <DIV lang="en">
* <ul>
* <li>fn:subsequence($sourceSeq as item()*, $startingLoc as xs:double) as item()*</li>
* <li>fn:subsequence($sourceSeq as item()*, $startingLoc as xs:double, $length as xs:double) as item()*</li>
* </ul>
* </DIV>
* <DIV lang="ja"></DIV>
*
* @author Makoto YUI (yuin405+xbird@gmail.com)
*/
public final class Subsequence extends BuiltInFunction {
private static final long serialVersionUID = -1941283897300455851L;
public static final String SYMBOL = "fn:subsequence";
public Subsequence() {
super(SYMBOL, SequenceType.ANY_ITEMS);
}
protected FunctionSignature[] signatures() {
final FunctionSignature[] s = new FunctionSignature[4];
s[0] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS,
DoubleType.DOUBLE });
s[1] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS,
DoubleType.DOUBLE, DoubleType.DOUBLE });
// workaround
s[2] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS,
NumericType.getInstance() });
s[3] = new FunctionSignature(getName(), new Type[] { SequenceType.ANY_ITEMS,
NumericType.getInstance(), NumericType.getInstance() });
return s;
}
@Override
public Type getReturnType(List<XQExpression> params) {
if(params == null) {
throw new IllegalArgumentException();
}
this._returnType = params.get(0).getType();
return _returnType;
}
public Sequence eval(Sequence<? extends Item> contextSeq, ValueSequence argv, DynamicContext dynEnv)
throws XQueryException {
Item src = argv.getItem(0);
Item fromIt = argv.getItem(1);
final int from = ((XNumber) fromIt).getNumber().intValue();
final int arglen = argv.size();
if(arglen == 2) {
return new FilterExpr.Sliced(src, from, Integer.MAX_VALUE, dynEnv, getReturnType());
}
Item lengthIt = argv.getItem(2);
final int length = ((XNumber) lengthIt).getNumber().intValue(); //TODO exceeds Integer.MAX
if(length < 1) {
return ValueSequence.EMPTY_SEQUENCE;
}
return new FilterExpr.Sliced(src, from, from + length - 1, dynEnv, getReturnType());
}
}