/** section: Language, related to: Array
 *    $A(iterable) -> Array
 *
 *  Accepts an array-like collection (anything with numeric indices) and returns
 *  its equivalent as an actual Array object.
 *  This method is a convenience alias of [[Array.from]], but is the preferred way
 *  of casting to an Array.
 **/
function $A(iterable) {
  if (!iterable) return [];
  // Safari <2.0.4 crashes when accessing property of a node list with property accessor.
  // It nevertheless works fine with `in` operator, which is why we use it here
  if ('toArray' in Object(iterable)) return iterable.toArray();
  var length = iterable.length || 0, results = new Array(length);
  while (length--) results[length] = iterable[length];
  return results;
}

/** section: Language, related to: Array
 *  $w(string) -> Array
 *  - string (String): A string with zero or more spaces.
 *
 *  Splits a string into an array, treating all whitespace as delimiters.
 *
 *  Equivalent to Ruby's `%w{foo bar}` or Perl's `qw(foo bar)`.
**/
function $w(string) {
  if (!Object.isString(string)) return [];
  string = string.strip();
  return string ? string.split(/\s+/) : [];
}

/** alias of: $A
 *  Array.from(iterable) -> Array
**/
Array.from = $A;

/** section: Language
 * class Array
 *  includes Enumerable
 *
 *  Prototype extends all native JavaScript arrays with quite a few powerful
 *  methods.
 *
 *  This is done in two ways:
 *
 *  * It mixes in the [[Enumerable]] module, which brings in a ton of methods.
 *  * It adds quite a few extra methods, which are documented in this section.
 *
 *  With Prototype, arrays become much, much more than the trivial objects we
 *  used to manipulate, limiting ourselves to using their `length` property and
 *  their `[]` indexing operator. They become very powerful objects that
 *  greatly simplify the code for 99% of the common use cases involving them.
 *
 *  <h5>Why you should stop using for...in to iterate</h5>
 *
 *  Many JavaScript authors have been misled into using the `for...in` JavaScript
 *  construct to loop over array elements. This kind of code just won't work
 *  with Prototype.
 *
 *  The ECMA 262 standard, which defines ECMAScript 3rd edition, supposedly
 *  implemented by all major browsers including MSIE, defines ten methods
 *  on Array (&sect;15.4.4), including nice methods like `concat`, `join`, `pop`, and
 *  `push`.
 *
 *  This same standard explicitly defines that the `for...in` construct (&sect;12.6.4)
 *  exists to enumerate the properties of the object appearing on the right side
 *  of the `in` keyword. Only properties specifically marked as _non-enumerable_
 *  are ignored by such a loop. By default, the `prototype` and `length`
 *  properties are so marked, which prevents you from enumerating over array
 *  methods when using for...in. This comfort led developers to use `for...in` as a
 *  shortcut for indexing loops, when it is not its actual purpose.
 *
 *  However, Prototype has no way to mark the methods it adds to
 *  `Array.prototype` as non-enumerable. Therefore, using `for...in` on arrays
 *  when using Prototype will enumerate all extended methods as well, such as
 *  those coming from the [[Enumerable]] module, and those Prototype puts in the
 *  Array namespace (listed further below).
 *
 *  <h5>What you should use instead</h5>
 *
 *  You can revert to vanilla loops:
 *
 *      for (var index = 0; index < myArray.length; ++index) {
 *        var item = myArray[index];
 *        // Your code working on item here...
 *      }
 *
 *  Or you can use iterators, such as [[Array#each]]:
 *
 *      myArray.each(function(item) {
 *        // Your code working on item here...
 *      });
 *
 *
 *  The inability to use `for...in` on arrays is not much of a burden: as you'll
 *  see, most of what you used to loop over arrays for can be concisely done
 *  using the new methods provided by Array or the mixed-in [[Enumerable]]
 *  module. So manual loops should be fairly rare.
 *
 *
 *  <h5>A note on performance</h5>
 *
 *  Should you have a very large array, using iterators with lexical closures
 *  (anonymous functions that you pass to the iterators and that get invoked at
 *  every loop iteration) in methods like [[Array#each]] &mdash; _or_ relying on
 *  repetitive array construction (such as uniq), may yield unsatisfactory
 *  performance. In such cases, you're better off writing manual indexing loops,
 *  but take care then to cache the length property and use the prefix `++`
 *  operator:
 *
 *      // Custom loop with cached length property: maximum full-loop
 *      // performance on very large arrays!
 *      for (var index = 0, len = myArray.length; index < len; ++index) {
 *        var item = myArray[index];
 *        // Your code working on item here...
 *      }
 *
**/

(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;

  /**
   *  Array#clear() -> Array
   *
   *  Clears the array (makes it empty) and returns the array reference.
   *
   *  <h5>Example</h5>
   *
   *      var guys = ['Sam', 'Justin', 'Andrew', 'Dan'];
   *      guys.clear();
   *      // -> []
   *      guys
   *      // -> []
  **/
  function clear() {
    this.length = 0;
    return this;
  }

  /**
   *  Array#first() -> ?
   *
   *  Returns the array's first item (e.g., `array[0]`).
  **/
  function first() {
    return this[0];
  }

  /**
   *  Array#last() -> ?
   *
   *  Returns the array's last item (e.g., `array[array.length - 1]`).
  **/
  function last() {
    return this[this.length - 1];
  }

  /**
   *  Array#compact() -> Array
   *
   *  Returns a **copy** of the array without any `null` or `undefined` values.
   *
   *  <h5>Example</h5>
   *
   *      var orig = [undefined, 'A', undefined, 'B', null, 'C'];
   *      var copy = orig.compact();
   *      // orig -> [undefined, 'A', undefined, 'B', null, 'C'];
   *      // copy -> ['A', 'B', 'C'];
  **/
  function compact() {
    return this.select(function(value) {
      return value != null;
    });
  }

  /**
   *  Array#flatten() -> Array
   *
   *  Returns a flattened (one-dimensional) copy of the array, leaving
   *  the original array unchanged.
   *
   *  Nested arrays are recursively injected inline. This can prove very
   *  useful when handling the results of a recursive collection algorithm,
   *  for instance.
   *
   *  <h5>Example</h5>
   *
   *      var a = ['frank', ['bob', 'lisa'], ['jill', ['tom', 'sally']]];
   *      var b = a.flatten();
   *      // a -> ['frank', ['bob', 'lisa'], ['jill', ['tom', 'sally']]]
   *      // b -> ['frank', 'bob', 'lisa', 'jill', 'tom', 'sally']
  **/
  function flatten() {
    return this.inject([], function(array, value) {
      if (Object.isArray(value))
        return array.concat(value.flatten());
      array.push(value);
      return array;
    });
  }

  /**
   *  Array#without(value[, value...]) -> Array
   *  - value (?): A value to exclude.
   *
   *  Produces a new version of the array that does not contain any of the
   *  specified values, leaving the original array unchanged.
   *
   *  <h5>Examples</h5>
   *
   *      [3, 5, 6].without(3)
   *      // -> [5, 6]
   *
   *      [3, 5, 6, 20].without(20, 6)
   *      // -> [3, 5]
  **/
  function without() {
    var values = slice.call(arguments, 0);
    return this.select(function(value) {
      return !values.include(value);
    });
  }

  /**
   *  Array#reverse([inline = true]) -> Array
   *  - inline (Boolean): Whether to modify the array in place. Defaults to `true`.
   *      Clones the original array when `false`.
   *
   *  Reverses the array's contents, optionally cloning it first.
   *
   *  <h5>Examples</h5>
   *
   *      // Making a copy
   *      var nums = [3, 5, 6, 1, 20];
   *      var rev = nums.reverse(false);
   *      // nums -> [3, 5, 6, 1, 20]
   *      // rev -> [20, 1, 6, 5, 3]
   *
   *      // Working inline
   *      var nums = [3, 5, 6, 1, 20];
   *      nums.reverse();
   *      // nums -> [20, 1, 6, 5, 3]
  **/
  function reverse(inline) {
    return (inline === false ? this.toArray() : this)._reverse();
  }

  /**
   *  Array#uniq([sorted = false]) -> Array
   *  - sorted (Boolean): Whether the array has already been sorted. If `true`,
   *      a less-costly algorithm will be used.
   *
   *  Produces a duplicate-free version of an array. If no duplicates are
   *  found, the original array is returned.
   *
   *  On large arrays when `sorted` is `false`, this method has a potentially
   *  large performance cost.
   *
   *  <h5>Examples</h5>
   *
   *      [1, 3, 2, 1].uniq();
   *      // -> [1, 2, 3]
   *
   *      ['A', 'a'].uniq();
   *      // -> ['A', 'a'] (because String comparison is case-sensitive)
  **/
  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;
    });
  }

  /**
   *  Array#intersect(array) -> Array
   *  - array (Array): A collection of values.
   *
   *  Returns an array containing every item that is shared between the two
   *  given arrays.
  **/
  function intersect(array) {
    return this.uniq().findAll(function(item) {
      return array.detect(function(value) { return item === value });
    });
  }

  /** alias of: Array#clone
   *  Array#toArray() -> Array
  **/

  /**
   *  Array#clone() -> Array
   *
   *  Returns a duplicate of the array, leaving the original array intact.
  **/
  function clone() {
    return slice.call(this, 0);
  }

  /** related to: Enumerable#size
   *  Array#size() -> Number
   *
   *  Returns the size of the array (e.g., `array.length`).
   *
   *  This is just a local optimization of the mixed-in [[Enumerable#size]]
   *  which avoids array cloning and uses the array's native length property.
  **/
  function size() {
    return this.length;
  }

  /** related to: Object.inspect
   *  Array#inspect() -> String
   *
   *  Returns the debug-oriented string representation of an array.
   *
   *  <h5>Example</h5>
   *
   *      ['Apples', {good: 'yes', bad: 'no'}, 3, 34].inspect()
   *      // -> "['Apples', [object Object], 3, 34]"
  **/
  function inspect() {
    return '[' + this.map(Object.inspect).join(', ') + ']';
  }

  /** related to: Object.toJSON
   *  Array#toJSON() -> String
   *
   *  Returns a JSON string representation of the array.
   *
   *  <h5>Example</h5>
   *
   *      ['a', {b: null}].toJSON();
   *      //-> '["a", {"b": null}]'
  **/
  function toJSON() {
    var results = [];
    this.each(function(object) {
      var value = Object.toJSON(object);
      if (!Object.isUndefined(value)) results.push(value);
    });
    return '[' + results.join(', ') + ']';
  }

  /**
   *  Array#indexOf(item[, offset = 0]) -> Number
   *  - item (?): A value that may or may not be in the array.
   *  - offset (Number): The number of initial items to skip before beginning
   *      the search.
   *
   *  Returns the index of the first occurrence of `item` within the array,
   *  or `-1` if `item` doesn't exist in the array. `Array#indexOf` compares
   *  items using *strict equality* (`===`).
   *
   *  <h5>Examples</h5>
   *
   *      [3, 5, 6, 1, 20].indexOf(1)
   *      // -> 3
   *
   *      [3, 5, 6, 1, 20].indexOf(90)
   *      // -> -1 (not found)
   *
   *      ['1', '2', '3'].indexOf(1);
   *      // -> -1 (not found, 1 !== '1')
  **/
  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;
  }

  /** related to: Array#indexOf
   *  Array#lastIndexOf(item[, offset]) -> Number
   *  - item (?): A value that may or may not be in the array.
   *  - offset (Number): The number of items at the end to skip before beginning
   *      the search.
   *
   *  Returns the position of the last occurrence of `item` within the array &mdash; or
   *  `-1` if `item` doesn't exist in the array.
  **/
  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;
  }

  // Replaces a built-in function. No PDoc needed.
  function concat() {
    var array = slice.call(this, 0), item;
    for (var i = 0, length = arguments.length; i < length; i++) {
      item = arguments[i];
      if (Object.isArray(item) && !('callee' in item)) {
        for (var j = 0, arrayLength = item.length; j < arrayLength; j++)
          array.push(item[j]);
      } else {
        array.push(item);
      }
    }
    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,
    uniq:      uniq,
    intersect: intersect,
    clone:     clone,
    toArray:   clone,
    size:      size,
    inspect:   inspect,
    toJSON:    toJSON
  });

  // fix for opera
  var CONCAT_ARGUMENTS_BUGGY = (function() {
    return [].concat(arguments)[0][0] !== 1;
  })(1,2)

  if (CONCAT_ARGUMENTS_BUGGY) arrayProto.concat = concat;

  // use native browser JS 1.6 implementation if available
  if (!arrayProto.indexOf) arrayProto.indexOf = indexOf;
  if (!arrayProto.lastIndexOf) arrayProto.lastIndexOf = lastIndexOf;
})();