package com.jclark.xsl.expr;

import com.jclark.xsl.om.*;

class TranslateFunction extends Function3 {
  ConvertibleExpr makeCallExpr(ConvertibleExpr e1, ConvertibleExpr e2, ConvertibleExpr e3) {
    final StringExpr se1 = e1.makeStringExpr();
    final StringExpr se2 = e2.makeStringExpr();
    final StringExpr se3 = e3.makeStringExpr();
    return new ConvertibleStringExpr() {
      public String eval(Node node, ExprContext context) throws XSLException {
	return translate(se1.eval(node, context),
			 se2.eval(node, context),
			 se3.eval(node, context));
      }
    };
  }

  private static String translate(String s1, String s2, String s3) {
    StringBuffer buf = new StringBuffer();
    for (int i = 0; i < s1.length(); i++) {
      char c = s1.charAt(i);
      // FIXME deal with surrogates properly
      int j = s2.indexOf(c);
      if (j < s3.length())
	buf.append(j < 0 ? c : s3.charAt(j));
    }
    return buf.toString();
  }
}