package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

class SumFunction extends Function1 {
  ConvertibleExpr makeCallExpr(ConvertibleExpr e) throws ParseException {
    final NodeSetExpr nse = e.makeNodeSetExpr();
    return new ConvertibleNumberExpr() {
      public double eval(Node node, ExprContext context) throws XSLException {
	return sum(nse.eval(node, context));
      }
    };
  }

  static private final double sum(NodeIterator iter) throws XSLException {
    double n = 0.0;
    for (;;) {
      Node node = iter.next();
      if (node == null)
	break;
      n += Converter.toNumber(Converter.toString(node));
    }
    return n;
  }
}