////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
// Copyright (c) 2018 Saxonica Limited.
// This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
// If a copy of the MPL was not distributed with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
// This Source Code Form is "Incompatible With Secondary Licenses", as defined by the Mozilla Public License, v. 2.0.
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

package net.sf.saxon.functions;

import net.sf.saxon.expr.XPathContext;
import net.sf.saxon.om.Sequence;
import net.sf.saxon.regex.RegexIterator;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.NumericValue;
import net.sf.saxon.value.StringValue;


public class RegexGroup extends SystemFunction {

    /**
     * Evaluate the expression
     *
     * @param context   the dynamic evaluation context
     * @param arguments the values of the arguments, supplied as Sequences
     * @return the result of the evaluation, in the form of a Sequence
     * @throws net.sf.saxon.trans.XPathException
     *          if a dynamic error occurs during the evaluation of the expression
     */
    public StringValue call(XPathContext context, Sequence[] arguments) throws XPathException {
        RegexIterator iter = context.getCurrentRegexIterator();
        if (iter == null) {
            return StringValue.EMPTY_STRING;
        }
        NumericValue gp0 = (NumericValue) arguments[0].head();
        String s = iter.getRegexGroup((int) gp0.longValue());
        return StringValue.makeStringValue(s);
    }
}

