//
// This software is now distributed according to
// the Lesser Gnu Public License.  Please see
// http://www.gnu.org/copyleft/lesser.txt for
// the details.
//    -- Happy Computing!
//
package com.stevesoft.pat;

/**
 * This method implements the pattern elements $1, $2, etc in a substitution
 * rule. The apply(StringBufferLike sb,RegRes rr) method of this ReplaceRule
 * simply appends the contents of rr.stringMatched(n), where n is the integer
 * supplied to the constructor.
 */
public class BackRefRule extends ReplaceRule
{
  int n;

  public BackRefRule(int n)
  {
    this.n = n;
  }

  public void apply(StringBufferLike sb, RegRes res)
  {
    String x = res.stringMatched(n);
    sb.appendStr(x == null ? "" : x);
  }

  public String toString1()
  {
    return "$" + n;
  }

  public Object clone1()
  {
    return new BackRefRule(n);
  }
}