package com.jclark.xsl.tr;

import com.jclark.xsl.om.*;
import com.jclark.xsl.util.Comparator;
import com.jclark.xsl.expr.ExprContext;
import com.jclark.xsl.expr.StringExpr;

class NodeComparatorTemplate implements ComparatorTemplate {
  private final Comparator cmp;
  private final StringExpr expr;

  NodeComparatorTemplate(Comparator cmp, StringExpr expr) {
    this.cmp = cmp;
    this.expr = expr;
  }

  public Comparator instantiate(Node node, final ExprContext context) {
    return new Comparator() {
      public int compare(Object o1, Object o2) {
	return cmp.compare(getKey(o1), getKey(o2));
      }
      private String getKey(Object obj) {
	try {
	  return expr.eval((Node)obj, context);
	}
	catch (XSLException e) {
	  throw new UncheckedXSLException(e);
	}
      }
    };
  }
}