Repeat function with named item

repeater.js

/*
 * Fair License (Fair)
 *
 * Copyright (c) 2012, IWAMURO Motonori
 *
 * Usage of the works is permitted provided that this instrument is
 * retained with the works, so that any entity that uses the works is
 * notified of this instrument.
 *
 * DISCLAIMER: THE WORKS ARE WITHOUT WARRANTY.
 */

/*
 * Repeat function with named item.
 *
 * CASE1:
 *   var rp0 = new Repeater();
 *   rp0.add(NAME1, ITEM1, ..., NAMEn, ITEMn);
 *   rp0.each(function(i, name, item) {...});
 *     or
 *   // bound this in function
 *   rp0.each(this, function(i, name, item) {...});
 *
 *   rp0.length is added data count.
 *
 * CASE2:
 *   var rp0 = new Repeater();
 *   var rp1 = new Repeater();
 *   rp0.add(NAME01, ITEM01, ..., NAME0n, ITEM0n);
 *   rp1.add(NAME11, ITEM11, ..., NAME1m, ITEM1m);
 *   rp0.each(rp1, function(i0, name0, item0, i1, name1, item1) {...});
 *     or
 *   // bound this in function
 *   rp0.each(rp1, this, function(i0, name0, item0, i1, name1, item1) {...});
 *
 *   rp0.each(rp1, ...) same as:
 *   for (var i0 = 0; i0 < rp0.length; i0++) {
 *     var name0 = rp0.data[i0].name; // * pseudo code
 *     var item0 = rp0.data[i0].item; // * pseudo code
 *     for (var i1 = 0; i1 < rp1.length; i1++) {
 *       var name1 = rp1.data[i1].name; // * pseudo code
 *       var item1 = rp1.data[i1].item; // * pseudo code
 *       ...
 *     }
 *   }
 *
 * CASEn:
 *   var rp0 = new Repeater();
 *   ...
 *   var rpN = new Repeater();
 *   ...
 *   rp0.each(rp1, ..., rpN, function(i0, name0, item0, ..., iN, nameN, itemN) {});
 *     or
 *   rp0.each(rp1, ..., rpN, this, function(...) {});
 */
var Repeater = (function() {

  // constructor
  function Repeater() {
    this.data = [];
    this.length = 0;
  }

  // public methods
  Repeater.prototype = {

    // add items.
    add: function(/* NAME1, ITEM1, ..., NAMEn, ITEMn */) {
      var len = arguments.length;
      if (len % 2 == 1 || len == 0)
        throw "arguments length is odd or 0. It is required even and 2 or more.";
      var offset = this.data.length;
      for (var i = 0; i < len; i += 2) {
        var name = arguments[i];
        var item = arguments[i + 1];
        this.data.push([offset + i, name, item]);
      }
      this.length = this.data.length;
      return this;
    },

    // call function with each item as parameters.
    each: function(/* [RP1, ..., RPn,] [SELF,] FUNC */) {
      var len = arguments.length;
      var func = arguments[--len];
      var self;
      if (arguments[len - 1] instanceof Repeater)
        self = null;
      else
        self = arguments[--len];
      if (len == 0) {
        for (var i = 0; i < this.length; i++)
          func.apply(self, this.data[i]);
      } else {
        _nestedEach.call(this, [],
                         Array.prototype.slice.call(arguments, 0, len),
                         self, func);
      }
    }
  };

  // private methods

  // call function with each items of each Repeater as parameters.
  function _nestedEach(args, rps, self, func) {
    var i;
    if (rps.length == 0) {
      for (i = 0; i < this.length; i++)
        func.apply(self, args.concat(this.data[i]));
    } else {
      var rp = rps.shift();
      for (i = 0; i < this.length; i++)
        _nestedEach.call(rp, args.concat(this.data[i]), rps, self, func);
    }
  }

  return Repeater;
})();