package com.jclark.xsl.tr;

final class Priority {
  private final double n;
  static private final Priority defaultCache[] = new Priority[]{
    new Priority(-0.5),
    new Priority(-0.25),
    new Priority(0.0),
    new Priority(0.5)
  };

  private Priority(double n) {
    this.n = n;
  }

  // -2 means -0.5; -1 means -0.25; 0 means 0; 1 means 0.5
  public static Priority createDefault(int p) {
    if (p < -2 || p > 1)
      throw new IllegalArgumentException("bad default");
    return defaultCache[p + 2];
  }

  public static Priority create(String s) throws NumberFormatException {
    if (s == null)
      return null;
    return new Priority(Double.valueOf(s).doubleValue());
  }
  
  public int compareTo(Priority p) {
    if (n == p.n)
      return 0;
    return n < p.n ? -1 : 1;
  }

}