package org.orbeon.saxon.functions;
import org.orbeon.saxon.expr.*;
import org.orbeon.saxon.om.Item;
import org.orbeon.saxon.regex.RegexIterator;
import org.orbeon.saxon.trans.XPathException;
import org.orbeon.saxon.value.AtomicValue;
import org.orbeon.saxon.value.NumericValue;
import org.orbeon.saxon.value.StringValue;


public class RegexGroup extends SystemFunction implements XSLTFunction {

    /**
    * preEvaluate: this method suppresses compile-time evaluation by doing nothing
     * @param visitor an expression visitor
     */

    public Expression preEvaluate(ExpressionVisitor visitor) {
        return this;
    }

    /**
    * Evaluate in a general context
    */

    public Item evaluateItem(XPathContext c) throws XPathException {
        AtomicValue gp0 = (AtomicValue)argument[0].evaluateItem(c);
        NumericValue gp = (NumericValue)gp0;
        RegexIterator iter = c.getCurrentRegexIterator();
        if (iter == null) {
            return StringValue.EMPTY_STRING;
        }
        String s = iter.getRegexGroup((int)gp.longValue());
        if (s == null) {
            return StringValue.EMPTY_STRING;
        }
        return StringValue.makeStringValue(s);
    }

    /**
    * Determine the dependencies
    */

    public int getIntrinsicDependencies() {
       return StaticProperty.DEPENDS_ON_REGEX_GROUP;
    }

}




//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//
