prototype/src/lang/array.js

function $A(iterable) {
  if (!iterable) return [];
  if (iterable.toArray) return iterable.toArray();
  var length = iterable.length || 0, results = new Array(length);
  while (length--) results[length] = iterable[length];
  return results;
}

if (Prototype.Browser.WebKit) {
  $A = function(iterable) {
    if (!iterable) return [];    
    // In Safari, only use the `toArray` method if it's not a NodeList.
    // A NodeList is a function, has an function `item` property, and a numeric
    // `length` property. Adapted from Google Doctype.
    if (!(typeof iterable === 'function' && typeof iterable.length ===
        'number' && typeof iterable.item === 'function') && iterable.toArray)
      return iterable.toArray();
    var length = iterable.length || 0, results = new Array(length);
    while (length--) results[length] = iterable[length];
    return results;
  };
}

function $w(string) {
  if (!Object.isString(string)) return [];
  string = string.strip();
  return string ? string.split(/\s+/) : [];
}

Array.from = $A;

(function() {
  var arrayProto = Array.prototype,
      slice = arrayProto.slice,
      _each = arrayProto.forEach; // use native browser JS 1.6 implementation if available
  
  function each(iterator) {
    for (var i = 0, length = this.length; i < length; i++)
      iterator(this[i]);
  }
  if (!_each) _each = each;
  
  function clear() {
    this.length = 0;
    return this;
  }

  function first() {
    return this[0];
  }

  function last() {
    return this[this.length - 1];
  }

  function compact() {
    return this.select(function(value) {
      return value != null;
    });
  }

  function flatten() {
    return this.inject([], function(array, value) {
      if (Object.isArray(value))
        return array.concat(value.flatten());
      array.push(value);
      return array;
    });
  }

  function without() {
    var values = slice.call(arguments, 0);
    return this.select(function(value) {
      return !values.include(value);
    });
  }

  function reverse(inline) {
    return (inline !== false ? this : this.toArray())._reverse();
  }

  function reduce() {
    return this.length > 1 ? this : this[0];
  }

  function uniq(sorted) {
    return this.inject([], function(array, value, index) {
      if (0 == index || (sorted ? array.last() != value : !array.include(value)))
        array.push(value);
      return array;
    });
  }

  function intersect(array) { 
    return this.uniq().findAll(function(item) { 
      return array.detect(function(value) { return item === value });
    }); 
  }

  function clone() {
    return slice.call(this, 0);
  }

  function size() {
    return this.length;
  }

  function inspect() {
    return '[' + this.map(Object.inspect).join(', ') + ']';
  }

  function toJSON() {
    var results = [];
    this.each(function(object) {
      var value = Object.toJSON(object);
      if (!Object.isUndefined(value)) results.push(value);
    });
    return '[' + results.join(', ') + ']';
  }
  
  function indexOf(item, i) {
    i || (i = 0);
    var length = this.length;
    if (i < 0) i = length + i;
    for (; i < length; i++)
      if (this[i] === item) return i;
    return -1;
  }
  
  function lastIndexOf(item, i) {
    i = isNaN(i) ? this.length : (i < 0 ? this.length + i : i) + 1;
    var n = this.slice(0, i).reverse().indexOf(item);
    return (n < 0) ? n : i - n - 1;
  }
  
  function concat() {
    var array = [];
    for (var i = 0, length = this.length; i < length; i++) array.push(this[i]);
    for (var i = 0, length = arguments.length; i < length; i++) {
      if (Object.isArray(arguments[i])) {
        for (var j = 0, arrayLength = arguments[i].length; j < arrayLength; j++) 
          array.push(arguments[i][j]);
      } else { 
        array.push(arguments[i]);
      }
    }
    return array;
  }
  
  Object.extend(arrayProto, Enumerable);
  
  if (!arrayProto._reverse)
    arrayProto._reverse = arrayProto.reverse;
  
  Object.extend(arrayProto, {
    _each:     _each,
    clear:     clear,
    first:     first,
    last:      last,
    compact:   compact,
    flatten:   flatten,
    without:   without,
    reverse:   reverse,
    reduce:    reduce,
    uniq:      uniq,
    intersect: intersect,
    clone:     clone,
    toArray:   clone,
    size:      size,
    inspect:   inspect,
    toJSON:    toJSON
  });
  
  // use native browser JS 1.6 implementation if available
  if (!'indexOf'     in arrayProto) arrayProto.indexOf     = indexOf;
  if (!'lastIndexOf' in arrayProto) arrayProto.lastIndexOf = lastIndexOf;
  if (!'concat'      in arrayProto) arrayProto.concat      = concat;
})();