WeekdayNum.java

// Copyright (C) 2006 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package com.google.ical.values;

/**
 * represents a day of the week in a month or year such as the
 * third monday of the month.  A negative num indicates it counts from the
 * end of the month or year.
 *
 * <blockquote>
 * Each BYDAY value can also be preceded by a positive (+n) or negative
 * (-n) integer. If present, this indicates the nth occurrence of the
 * specific day within the MONTHLY or YEARLY RRULE. For example, within
 * a MONTHLY rule, +1MO (or simply 1MO) represents the first Monday
 * within the month, whereas -1MO represents the last Monday of the
 * month. If an integer modifier is not present, it means all days of
 * this type within the specified frequency. For example, within a
 * MONTHLY rule, MO represents all Mondays within the month.
 * </blockquote>
 *
 * @author mikesamuel+svn@gmail.com (Mike Samuel)
 */
public class WeekdayNum {
  public final int num;
  public final Weekday wday;

  /**
   * @param num in -53,53
   * @param wday non null.
   */
  public WeekdayNum(int num, Weekday wday) {
    if (!(-53 <= num && 53 >= num && null != wday)) {
      throw new IllegalArgumentException();
    }
    this.num = num;
    this.wday = wday;
  }
  public String toIcal() {
    return (0 != this.num)
        ? String.valueOf(this.num) + this.wday
        : this.wday.toString();
  }
  @Override
  public String toString() {
    return toIcal();
  }
  @Override
  public boolean equals(Object o) {
    if (!(o instanceof WeekdayNum)) { return false; }
    WeekdayNum wdn = (WeekdayNum) o;
    return this.num == wdn.num && this.wday == wdn.wday;
  }

  @Override
  public int hashCode() {
    return num ^ (53 * wday.hashCode());
  }
}