package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

class SubstringBeforeFunction extends Function2 {
  ConvertibleExpr makeCallExpr(ConvertibleExpr e1, ConvertibleExpr e2) {
    final StringExpr se1 = e1.makeStringExpr();
    final StringExpr se2 = e2.makeStringExpr();
    return new ConvertibleStringExpr() {
      public String eval(Node node, ExprContext context) throws XSLException {
	return stringBefore(se1.eval(node, context),
			    se2.eval(node, context));
      }
    };
  }

  static final String stringBefore(String s1, String s2) {
    int i = s1.indexOf(s2);
    return i < 0 ? "" : s1.substring(0, i);
  } 
}