/*
* eXist Open Source Native XML Database
* Copyright (C) 2001-2009 The eXist Project
* http://exist-db.org
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $Id$
*/
package org.exist.xquery.functions;
import org.exist.dom.ExtArrayNodeSet;
import org.exist.dom.NodeSet;
import org.exist.dom.QName;
import org.exist.xquery.*;
import org.exist.xquery.value.DoubleValue;
import org.exist.xquery.value.FunctionParameterSequenceType;
import org.exist.xquery.value.FunctionReturnSequenceType;
import org.exist.xquery.value.Item;
import org.exist.xquery.value.Sequence;
import org.exist.xquery.value.SequenceIterator;
import org.exist.xquery.value.SequenceType;
import org.exist.xquery.value.Type;
import org.exist.xquery.value.ValueSequence;
/**
* Implements the fn:subsequence function.
*
* @author Wolfgang Meier (wolfgang@exist-db.org)
*/
public class FunSubSequence extends Function {
public final static FunctionSignature signatures[] = {
new FunctionSignature(
new QName("subsequence", Function.BUILTIN_FUNCTION_NS),
"Returns a subsequence of the items in $source-sequence, "
+ "items starting at the position, $starting-at, "
+ "up to the end of the sequence are included.",
new SequenceType[] {
new FunctionParameterSequenceType("source", Type.ITEM, Cardinality.ZERO_OR_MORE, "The source sequence"),
new FunctionParameterSequenceType("starting-at", Type.DOUBLE, Cardinality.EXACTLY_ONE, "The starting position in the $source")
},
new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_MORE, "the subsequence")),
new FunctionSignature(
new QName("subsequence", Function.BUILTIN_FUNCTION_NS),
"Returns a subsequence of the items in $source, "
+ "starting at the position, $starting-at, "
+ "including the number of items indicated by $length.",
new SequenceType[] {
new FunctionParameterSequenceType("source", Type.ITEM, Cardinality.ZERO_OR_MORE, "The source sequence"),
new FunctionParameterSequenceType("starting-at", Type.DOUBLE, Cardinality.EXACTLY_ONE, "The starting position in the $source"),
new FunctionParameterSequenceType("length", Type.DOUBLE, Cardinality.EXACTLY_ONE, "The length of the subsequence")
},
new FunctionReturnSequenceType(Type.ITEM, Cardinality.ZERO_OR_MORE, "the subsequence")) };
/**
* @param context
*/
public FunSubSequence(XQueryContext context, FunctionSignature signature) {
super(context, signature);
}
public void analyze(AnalyzeContextInfo contextInfo) throws XPathException {
// statically check the argument list
checkArguments();
// call analyze for each argument
inPredicate = (contextInfo.getFlags() & IN_PREDICATE) > 0;
contextId = contextInfo.getContextId();
contextInfo.setParent(this);
for(int i = 0; i < getArgumentCount(); i++) {
AnalyzeContextInfo argContextInfo = new AnalyzeContextInfo(contextInfo);
getArgument(i).analyze(argContextInfo);
if (i == 0)
contextInfo.setStaticReturnType(argContextInfo.getStaticReturnType());
}
}
/*
* (non-Javadoc)
*
* @see org.exist.xquery.Expression#eval(org.exist.dom.DocumentSet,
* org.exist.xquery.value.Sequence, org.exist.xquery.value.Item)
*/
public Sequence eval(Sequence contextSequence, Item contextItem) throws XPathException {
if (context.getProfiler().isEnabled()) {
context.getProfiler().start(this);
context.getProfiler().message(this, Profiler.DEPENDENCIES,
"DEPENDENCIES",
Dependency.getDependenciesName(this.getDependencies()));
if (contextSequence != null)
context.getProfiler().message(this, Profiler.START_SEQUENCES,
"CONTEXT SEQUENCE", contextSequence);
if (contextItem != null)
context.getProfiler().message(this, Profiler.START_SEQUENCES,
"CONTEXT ITEM", contextItem.toSequence());
}
Sequence result;
Sequence seq = getArgument(0).eval(contextSequence, contextItem);
if (seq.isEmpty())
result = Sequence.EMPTY_SEQUENCE;
else {
int start = ((DoubleValue) getArgument(1).eval(contextSequence,
contextItem).convertTo(Type.DOUBLE)).getInt();
int length = Integer.MAX_VALUE;
if (getSignature().getArgumentCount() == 3) {
length = ((DoubleValue) getArgument(2).eval(
contextSequence, contextItem)
.convertTo(Type.DOUBLE)).getInt();
}
// TODO : exception? -pb
if (start < 0) {
length = length + start - 1;
start = 0;
} else if (start == 0) {
--length;
--start;
} else
--start;
Sequence tmp;
if (seq instanceof NodeSet)
tmp = new ExtArrayNodeSet();
else
tmp = new ValueSequence();
Item item;
SequenceIterator iterator = seq.iterate();
for(int i = 0; i < start; i++) {
item = iterator.nextItem();
}
int i=0;
while (iterator.hasNext() && i < length) {
item = iterator.nextItem();
tmp.add(item);
i++;
}
result = i>0?tmp:Sequence.EMPTY_SEQUENCE;
}
if (context.getProfiler().isEnabled())
context.getProfiler().end(this, "", result);
return result;
}
}