/*
 * Copyright (C) 1998-2018  Gerwin Klein <lsf@jflex.de>
 * SPDX-License-Identifier: BSD-3-Clause
 */

package jflex.dfa;

import jflex.logging.Out;

/**
 * A list of pairs of states. Used in old DFA minimization.
 *
 * @author Gerwin Klein
 * @version JFlex 1.9.1
 */
public final class StatePairList {

  // implemented as two arrays of integers.
  // java.util classes proved too inefficient.

  private int[] p;
  private int[] q;

  private int num;

  /** Constructor for StatePairList. */
  public StatePairList() {
    p = new int[8];
    q = new int[8];
    num = 0;
  }

  /**
   * addPair.
   *
   * @param i a int.
   * @param j a int.
   */
  public void addPair(int i, int j) {
    for (int x = 0; x < num; x++) {
      if (p[x] == i && q[x] == j) {
        return;
      }
    }

    if (num >= p.length) {
      increaseSize(num);
    }

    p[num] = i;
    q[num] = j;

    num++;
  }

  /**
   * markAll.
   *
   * @param list an array of {@link StatePairList} objects.
   * @param equiv an array of boolean.
   */
  public void markAll(StatePairList[][] list, boolean[][] equiv) {
    for (int x = 0; x < num; x++) {
      int i = p[x];
      int j = q[x];

      if (equiv[i][j]) {
        equiv[i][j] = false;
        if (list[i][j] != null) list[i][j].markAll(list, equiv);
      }
    }
  }

  private void increaseSize(int length) {
    length = Math.max(length + 1, 4 * p.length);
    Out.debug("increasing length to " + length); // $NON-NLS-1$

    int[] pn = new int[length];
    int[] qn = new int[length];

    System.arraycopy(p, 0, pn, 0, p.length);
    System.arraycopy(q, 0, qn, 0, q.length);

    p = pn;
    q = qn;
  }
}
