//
// 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;

import java.util.*;

/**
 * This class implements the (?@<>) syntax that matches a balanced parenthesis.
 * Not in perl 5.
 */
class Group extends Pattern
{
  char op, cl;

  Group(char opi, char cli)
  {
    op = opi;
    cl = cli;
  }

  public int matchInternal(int pos, Pthings pt)
  {
    int i, count = 1;
    if (pos < pt.src.length())
    {
      if (!Masked(pos, pt) && pt.src.charAt(pos) != op)
      {
        return -1;
      }
    }
    for (i = pos + 1; i < pt.src.length(); i++)
    {
      char c = pt.src.charAt(i);
      boolean b = !Masked(i, pt);
      if (b && c == ESC)
      {
        i++;
      }
      else
      {
        if (b && c == cl)
        {
          count--;
        }
        if (count == 0)
        {
          return nextMatch(i + 1, pt);
        }
        if (b && c == op)
        {
          count++;
        }
      }
    }
    return -1;
  }

  public String toString()
  {
    return "(?@" + op + cl + ")" + nextString();
  }

  public patInt minChars()
  {
    return new patInt(2);
  }

  Pattern clone1(Hashtable h)
  {
    return new Group(op, cl);
  }
};