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ensure - Ensure JavaScripts/HTML/CSS are loaded on-demand when needed

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4.97/5 (22 votes)
9 Jun 2008CPOL8 min read 151.5K   610   91  
A tiny JavaScript library that provides a handy function "ensure" which allows you to load JavaScript, HTML, CSS on-demand and then execute your code. ensure ensures that relevant JavaScript and HTML snippets are already in the browser DOM before executing your code that uses them.
/*  Prototype JavaScript framework, version 1.6.0
 *  (c) 2005-2007 Sam Stephenson
 *
 *  Prototype is freely distributable under the terms of an MIT-style license.
 *  For details, see the Prototype web site: http://www.prototypejs.org/
 *
 *--------------------------------------------------------------------------*/

var Prototype = {
  Version: '1.6.0',

  Browser: {
    IE:     !!(window.attachEvent && !window.opera),
    Opera:  !!window.opera,
    WebKit: navigator.userAgent.indexOf('AppleWebKit/') > -1,
    Gecko:  navigator.userAgent.indexOf('Gecko') > -1 && navigator.userAgent.indexOf('KHTML') == -1,
    MobileSafari: !!navigator.userAgent.match(/Apple.*Mobile.*Safari/)
  },

  BrowserFeatures: {
    XPath: !!document.evaluate,
    ElementExtensions: !!window.HTMLElement,
    SpecificElementExtensions:
      document.createElement('div').__proto__ &&
      document.createElement('div').__proto__ !==
        document.createElement('form').__proto__
  },

  ScriptFragment: '<script[^>]*>([\\S\\s]*?)<\/script>',
  JSONFilter: /^\/\*-secure-([\s\S]*)\*\/\s*$/,

  emptyFunction: function() { },
  K: function(x) { return x }
};

if (Prototype.Browser.MobileSafari)
  Prototype.BrowserFeatures.SpecificElementExtensions = false;

if (Prototype.Browser.WebKit)
  Prototype.BrowserFeatures.XPath = false;

/* Based on Alex Arnell's inheritance implementation. */
var Class = {
  create: function() {
    var parent = null, properties = $A(arguments);
    if (Object.isFunction(properties[0]))
      parent = properties.shift();

    function klass() {
      this.initialize.apply(this, arguments);
    }

    Object.extend(klass, Class.Methods);
    klass.superclass = parent;
    klass.subclasses = [];

    if (parent) {
      var subclass = function() { };
      subclass.prototype = parent.prototype;
      klass.prototype = new subclass;
      parent.subclasses.push(klass);
    }

    for (var i = 0; i < properties.length; i++)
      klass.addMethods(properties[i]);

    if (!klass.prototype.initialize)
      klass.prototype.initialize = Prototype.emptyFunction;

    klass.prototype.constructor = klass;

    return klass;
  }
};

Class.Methods = {
  addMethods: function(source) {
    var ancestor   = this.superclass && this.superclass.prototype;
    var properties = Object.keys(source);

    if (!Object.keys({ toString: true }).length)
      properties.push("toString", "valueOf");

    for (var i = 0, length = properties.length; i < length; i++) {
      var property = properties[i], value = source[property];
      if (ancestor && Object.isFunction(value) &&
          value.argumentNames().first() == "$super") {
        var method = value, value = Object.extend((function(m) {
          return function() { return ancestor[m].apply(this, arguments) };
        })(property).wrap(method), {
          valueOf:  function() { return method },
          toString: function() { return method.toString() }
        });
      }
      this.prototype[property] = value;
    }

    return this;
  }
};

var Abstract = { };

Object.extend = function(destination, source) {
  for (var property in source)
    destination[property] = source[property];
  return destination;
};

Object.extend(Object, {
  inspect: function(object) {
    try {
      if (object === undefined) return 'undefined';
      if (object === null) return 'null';
      return object.inspect ? object.inspect() : object.toString();
    } catch (e) {
      if (e instanceof RangeError) return '...';
      throw e;
    }
  },

  toJSON: function(object) {
    var type = typeof object;
    switch (type) {
      case 'undefined':
      case 'function':
      case 'unknown': return;
      case 'boolean': return object.toString();
    }

    if (object === null) return 'null';
    if (object.toJSON) return object.toJSON();
    if (Object.isElement(object)) return;

    var results = [];
    for (var property in object) {
      var value = Object.toJSON(object[property]);
      if (value !== undefined)
        results.push(property.toJSON() + ': ' + value);
    }

    return '{' + results.join(', ') + '}';
  },

  toQueryString: function(object) {
    return $H(object).toQueryString();
  },

  toHTML: function(object) {
    return object && object.toHTML ? object.toHTML() : String.interpret(object);
  },

  keys: function(object) {
    var keys = [];
    for (var property in object)
      keys.push(property);
    return keys;
  },

  values: function(object) {
    var values = [];
    for (var property in object)
      values.push(object[property]);
    return values;
  },

  clone: function(object) {
    return Object.extend({ }, object);
  },

  isElement: function(object) {
    return object && object.nodeType == 1;
  },

  isArray: function(object) {
    return object && object.constructor === Array;
  },

  isHash: function(object) {
    return object instanceof Hash;
  },

  isFunction: function(object) {
    return typeof object == "function";
  },

  isString: function(object) {
    return typeof object == "string";
  },

  isNumber: function(object) {
    return typeof object == "number";
  },

  isUndefined: function(object) {
    return typeof object == "undefined";
  }
});

Object.extend(Function.prototype, {
  argumentNames: function() {
    var names = this.toString().match(/^[\s\(]*function[^(]*\((.*?)\)/)[1].split(",").invoke("strip");
    return names.length == 1 && !names[0] ? [] : names;
  },

  bind: function() {
    if (arguments.length < 2 && arguments[0] === undefined) return this;
    var __method = this, args = $A(arguments), object = args.shift();
    return function() {
      return __method.apply(object, args.concat($A(arguments)));
    }
  },

  bindAsEventListener: function() {
    var __method = this, args = $A(arguments), object = args.shift();
    return function(event) {
      return __method.apply(object, [event || window.event].concat(args));
    }
  },

  curry: function() {
    if (!arguments.length) return this;
    var __method = this, args = $A(arguments);
    return function() {
      return __method.apply(this, args.concat($A(arguments)));
    }
  },

  delay: function() {
    var __method = this, args = $A(arguments), timeout = args.shift() * 1000;
    return window.setTimeout(function() {
      return __method.apply(__method, args);
    }, timeout);
  },

  wrap: function(wrapper) {
    var __method = this;
    return function() {
      return wrapper.apply(this, [__method.bind(this)].concat($A(arguments)));
    }
  },

  methodize: function() {
    if (this._methodized) return this._methodized;
    var __method = this;
    return this._methodized = function() {
      return __method.apply(null, [this].concat($A(arguments)));
    };
  }
});

Function.prototype.defer = Function.prototype.delay.curry(0.01);

Date.prototype.toJSON = function() {
  return '"' + this.getUTCFullYear() + '-' +
    (this.getUTCMonth() + 1).toPaddedString(2) + '-' +
    this.getUTCDate().toPaddedString(2) + 'T' +
    this.getUTCHours().toPaddedString(2) + ':' +
    this.getUTCMinutes().toPaddedString(2) + ':' +
    this.getUTCSeconds().toPaddedString(2) + 'Z"';
};

var Try = {
  these: function() {
    var returnValue;

    for (var i = 0, length = arguments.length; i < length; i++) {
      var lambda = arguments[i];
      try {
        returnValue = lambda();
        break;
      } catch (e) { }
    }

    return returnValue;
  }
};

RegExp.prototype.match = RegExp.prototype.test;

RegExp.escape = function(str) {
  return String(str).replace(/([.*+?^=!:${}()|[\]\/\\])/g, '\\$1');
};

/*--------------------------------------------------------------------------*/

var PeriodicalExecuter = Class.create({
  initialize: function(callback, frequency) {
    this.callback = callback;
    this.frequency = frequency;
    this.currentlyExecuting = false;

    this.registerCallback();
  },

  registerCallback: function() {
    this.timer = setInterval(this.onTimerEvent.bind(this), this.frequency * 1000);
  },

  execute: function() {
    this.callback(this);
  },

  stop: function() {
    if (!this.timer) return;
    clearInterval(this.timer);
    this.timer = null;
  },

  onTimerEvent: function() {
    if (!this.currentlyExecuting) {
      try {
        this.currentlyExecuting = true;
        this.execute();
      } finally {
        this.currentlyExecuting = false;
      }
    }
  }
});
Object.extend(String, {
  interpret: function(value) {
    return value == null ? '' : String(value);
  },
  specialChar: {
    '\b': '\\b',
    '\t': '\\t',
    '\n': '\\n',
    '\f': '\\f',
    '\r': '\\r',
    '\\': '\\\\'
  }
});

Object.extend(String.prototype, {
  gsub: function(pattern, replacement) {
    var result = '', source = this, match;
    replacement = arguments.callee.prepareReplacement(replacement);

    while (source.length > 0) {
      if (match = source.match(pattern)) {
        result += source.slice(0, match.index);
        result += String.interpret(replacement(match));
        source  = source.slice(match.index + match[0].length);
      } else {
        result += source, source = '';
      }
    }
    return result;
  },

  sub: function(pattern, replacement, count) {
    replacement = this.gsub.prepareReplacement(replacement);
    count = count === undefined ? 1 : count;

    return this.gsub(pattern, function(match) {
      if (--count < 0) return match[0];
      return replacement(match);
    });
  },

  scan: function(pattern, iterator) {
    this.gsub(pattern, iterator);
    return String(this);
  },

  truncate: function(length, truncation) {
    length = length || 30;
    truncation = truncation === undefined ? '...' : truncation;
    return this.length > length ?
      this.slice(0, length - truncation.length) + truncation : String(this);
  },

  strip: function() {
    return this.replace(/^\s+/, '').replace(/\s+$/, '');
  },

  stripTags: function() {
    return this.replace(/<\/?[^>]+>/gi, '');
  },

  stripScripts: function() {
    return this.replace(new RegExp(Prototype.ScriptFragment, 'img'), '');
  },

  extractScripts: function() {
    var matchAll = new RegExp(Prototype.ScriptFragment, 'img');
    var matchOne = new RegExp(Prototype.ScriptFragment, 'im');
    return (this.match(matchAll) || []).map(function(scriptTag) {
      return (scriptTag.match(matchOne) || ['', ''])[1];
    });
  },

  evalScripts: function() {
    return this.extractScripts().map(function(script) { return eval(script) });
  },

  escapeHTML: function() {
    var self = arguments.callee;
    self.text.data = this;
    return self.div.innerHTML;
  },

  unescapeHTML: function() {
    var div = new Element('div');
    div.innerHTML = this.stripTags();
    return div.childNodes[0] ? (div.childNodes.length > 1 ?
      $A(div.childNodes).inject('', function(memo, node) { return memo+node.nodeValue }) :
      div.childNodes[0].nodeValue) : '';
  },

  toQueryParams: function(separator) {
    var match = this.strip().match(/([^?#]*)(#.*)?$/);
    if (!match) return { };

    return match[1].split(separator || '&').inject({ }, function(hash, pair) {
      if ((pair = pair.split('='))[0]) {
        var key = decodeURIComponent(pair.shift());
        var value = pair.length > 1 ? pair.join('=') : pair[0];
        if (value != undefined) value = decodeURIComponent(value);

        if (key in hash) {
          if (!Object.isArray(hash[key])) hash[key] = [hash[key]];
          hash[key].push(value);
        }
        else hash[key] = value;
      }
      return hash;
    });
  },

  toArray: function() {
    return this.split('');
  },

  succ: function() {
    return this.slice(0, this.length - 1) +
      String.fromCharCode(this.charCodeAt(this.length - 1) + 1);
  },

  times: function(count) {
    return count < 1 ? '' : new Array(count + 1).join(this);
  },

  camelize: function() {
    var parts = this.split('-'), len = parts.length;
    if (len == 1) return parts[0];

    var camelized = this.charAt(0) == '-'
      ? parts[0].charAt(0).toUpperCase() + parts[0].substring(1)
      : parts[0];

    for (var i = 1; i < len; i++)
      camelized += parts[i].charAt(0).toUpperCase() + parts[i].substring(1);

    return camelized;
  },

  capitalize: function() {
    return this.charAt(0).toUpperCase() + this.substring(1).toLowerCase();
  },

  underscore: function() {
    return this.gsub(/::/, '/').gsub(/([A-Z]+)([A-Z][a-z])/,'#{1}_#{2}').gsub(/([a-z\d])([A-Z])/,'#{1}_#{2}').gsub(/-/,'_').toLowerCase();
  },

  dasherize: function() {
    return this.gsub(/_/,'-');
  },

  inspect: function(useDoubleQuotes) {
    var escapedString = this.gsub(/[\x00-\x1f\\]/, function(match) {
      var character = String.specialChar[match[0]];
      return character ? character : '\\u00' + match[0].charCodeAt().toPaddedString(2, 16);
    });
    if (useDoubleQuotes) return '"' + escapedString.replace(/"/g, '\\"') + '"';
    return "'" + escapedString.replace(/'/g, '\\\'') + "'";
  },

  toJSON: function() {
    return this.inspect(true);
  },

  unfilterJSON: function(filter) {
    return this.sub(filter || Prototype.JSONFilter, '#{1}');
  },

  isJSON: function() {
    var str = this.replace(/\\./g, '@').replace(/"[^"\\\n\r]*"/g, '');
    return (/^[,:{}\[\]0-9.\-+Eaeflnr-u \n\r\t]*$/).test(str);
  },

  evalJSON: function(sanitize) {
    var json = this.unfilterJSON();
    try {
      if (!sanitize || json.isJSON()) return eval('(' + json + ')');
    } catch (e) { }
    throw new SyntaxError('Badly formed JSON string: ' + this.inspect());
  },

  include: function(pattern) {
    return this.indexOf(pattern) > -1;
  },

  startsWith: function(pattern) {
    return this.indexOf(pattern) === 0;
  },

  endsWith: function(pattern) {
    var d = this.length - pattern.length;
    return d >= 0 && this.lastIndexOf(pattern) === d;
  },

  empty: function() {
    return this == '';
  },

  blank: function() {
    return /^\s*$/.test(this);
  },

  interpolate: function(object, pattern) {
    return new Template(this, pattern).evaluate(object);
  }
});

if (Prototype.Browser.WebKit || Prototype.Browser.IE) Object.extend(String.prototype, {
  escapeHTML: function() {
    return this.replace(/&/g,'&amp;').replace(/</g,'&lt;').replace(/>/g,'&gt;');
  },
  unescapeHTML: function() {
    return this.replace(/&amp;/g,'&').replace(/&lt;/g,'<').replace(/&gt;/g,'>');
  }
});

String.prototype.gsub.prepareReplacement = function(replacement) {
  if (Object.isFunction(replacement)) return replacement;
  var template = new Template(replacement);
  return function(match) { return template.evaluate(match) };
};

String.prototype.parseQuery = String.prototype.toQueryParams;

Object.extend(String.prototype.escapeHTML, {
  div:  document.createElement('div'),
  text: document.createTextNode('')
});

with (String.prototype.escapeHTML) div.appendChild(text);

var Template = Class.create({
  initialize: function(template, pattern) {
    this.template = template.toString();
    this.pattern = pattern || Template.Pattern;
  },

  evaluate: function(object) {
    if (Object.isFunction(object.toTemplateReplacements))
      object = object.toTemplateReplacements();

    return this.template.gsub(this.pattern, function(match) {
      if (object == null) return '';

      var before = match[1] || '';
      if (before == '\\') return match[2];

      var ctx = object, expr = match[3];
      var pattern = /^([^.[]+|\[((?:.*?[^\\])?)\])(\.|\[|$)/, match = pattern.exec(expr);
      if (match == null) return before;

      while (match != null) {
        var comp = match[1].startsWith('[') ? match[2].gsub('\\\\]', ']') : match[1];
        ctx = ctx[comp];
        if (null == ctx || '' == match[3]) break;
        expr = expr.substring('[' == match[3] ? match[1].length : match[0].length);
        match = pattern.exec(expr);
      }

      return before + String.interpret(ctx);
    }.bind(this));
  }
});
Template.Pattern = /(^|.|\r|\n)(#\{(.*?)\})/;

var $break = { };

var Enumerable = {
  each: function(iterator, context) {
    var index = 0;
    iterator = iterator.bind(context);
    try {
      this._each(function(value) {
        iterator(value, index++);
      });
    } catch (e) {
      if (e != $break) throw e;
    }
    return this;
  },

  eachSlice: function(number, iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var index = -number, slices = [], array = this.toArray();
    while ((index += number) < array.length)
      slices.push(array.slice(index, index+number));
    return slices.collect(iterator, context);
  },

  all: function(iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var result = true;
    this.each(function(value, index) {
      result = result && !!iterator(value, index);
      if (!result) throw $break;
    });
    return result;
  },

  any: function(iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var result = false;
    this.each(function(value, index) {
      if (result = !!iterator(value, index))
        throw $break;
    });
    return result;
  },

  collect: function(iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var results = [];
    this.each(function(value, index) {
      results.push(iterator(value, index));
    });
    return results;
  },

  detect: function(iterator, context) {
    iterator = iterator.bind(context);
    var result;
    this.each(function(value, index) {
      if (iterator(value, index)) {
        result = value;
        throw $break;
      }
    });
    return result;
  },

  findAll: function(iterator, context) {
    iterator = iterator.bind(context);
    var results = [];
    this.each(function(value, index) {
      if (iterator(value, index))
        results.push(value);
    });
    return results;
  },

  grep: function(filter, iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var results = [];

    if (Object.isString(filter))
      filter = new RegExp(filter);

    this.each(function(value, index) {
      if (filter.match(value))
        results.push(iterator(value, index));
    });
    return results;
  },

  include: function(object) {
    if (Object.isFunction(this.indexOf))
      if (this.indexOf(object) != -1) return true;

    var found = false;
    this.each(function(value) {
      if (value == object) {
        found = true;
        throw $break;
      }
    });
    return found;
  },

  inGroupsOf: function(number, fillWith) {
    fillWith = fillWith === undefined ? null : fillWith;
    return this.eachSlice(number, function(slice) {
      while(slice.length < number) slice.push(fillWith);
      return slice;
    });
  },

  inject: function(memo, iterator, context) {
    iterator = iterator.bind(context);
    this.each(function(value, index) {
      memo = iterator(memo, value, index);
    });
    return memo;
  },

  invoke: function(method) {
    var args = $A(arguments).slice(1);
    return this.map(function(value) {
      return value[method].apply(value, args);
    });
  },

  max: function(iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var result;
    this.each(function(value, index) {
      value = iterator(value, index);
      if (result == undefined || value >= result)
        result = value;
    });
    return result;
  },

  min: function(iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var result;
    this.each(function(value, index) {
      value = iterator(value, index);
      if (result == undefined || value < result)
        result = value;
    });
    return result;
  },

  partition: function(iterator, context) {
    iterator = iterator ? iterator.bind(context) : Prototype.K;
    var trues = [], falses = [];
    this.each(function(value, index) {
      (iterator(value, index) ?
        trues : falses).push(value);
    });
    return [trues, falses];
  },

  pluck: function(property) {
    var results = [];
    this.each(function(value) {
      results.push(value[property]);
    });
    return results;
  },

  reject: function(iterator, context) {
    iterator = iterator.bind(context);
    var results = [];
    this.each(function(value, index) {
      if (!iterator(value, index))
        results.push(value);
    });
    return results;
  },

  sortBy: function(iterator, context) {
    iterator = iterator.bind(context);
    return this.map(function(value, index) {
      return {value: value, criteria: iterator(value, index)};
    }).sort(function(left, right) {
      var a = left.criteria, b = right.criteria;
      return a < b ? -1 : a > b ? 1 : 0;
    }).pluck('value');
  },

  toArray: function() {
    return this.map();
  },

  zip: function() {
    var iterator = Prototype.K, args = $A(arguments);
    if (Object.isFunction(args.last()))
      iterator = args.pop();

    var collections = [this].concat(args).map($A);
    return this.map(function(value, index) {
      return iterator(collections.pluck(index));
    });
  },

  size: function() {
    return this.toArray().length;
  },

  inspect: function() {
    return '#<Enumerable:' + this.toArray().inspect() + '>';
  }
};

Object.extend(Enumerable, {
  map:     Enumerable.collect,
  find:    Enumerable.detect,
  select:  Enumerable.findAll,
  filter:  Enumerable.findAll,
  member:  Enumerable.include,
  entries: Enumerable.toArray,
  every:   Enumerable.all,
  some:    Enumerable.any
});
function $A(iterable) {
  if (!iterable) return [];
  if (iterable.toArray) return iterable.toArray();
  var length = iterable.length, results = new Array(length);
  while (length--) results[length] = iterable[length];
  return results;
}

if (Prototype.Browser.WebKit) {
  function $A(iterable) {
    if (!iterable) return [];
    if (!(Object.isFunction(iterable) && iterable == '[object NodeList]') &&
        iterable.toArray) return iterable.toArray();
    var length = iterable.length, results = new Array(length);
    while (length--) results[length] = iterable[length];
    return results;
  }
}

Array.from = $A;

Object.extend(Array.prototype, Enumerable);

if (!Array.prototype._reverse) Array.prototype._reverse = Array.prototype.reverse;

Object.extend(Array.prototype, {
  _each: function(iterator) {
    for (var i = 0, length = this.length; i < length; i++)
      iterator(this[i]);
  },

  clear: function() {
    this.length = 0;
    return this;
  },

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

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

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

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

  without: function() {
    var values = $A(arguments);
    return this.select(function(value) {
      return !values.include(value);
    });
  },

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

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

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

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

  clone: function() {
    return [].concat(this);
  },

  size: function() {
    return this.length;
  },

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

  toJSON: function() {
    var results = [];
    this.each(function(object) {
      var value = Object.toJSON(object);
      if (value !== undefined) results.push(value);
    });
    return '[' + results.join(', ') + ']';
  }
});

// use native browser JS 1.6 implementation if available
if (Object.isFunction(Array.prototype.forEach))
  Array.prototype._each = Array.prototype.forEach;

if (!Array.prototype.indexOf) Array.prototype.indexOf = function(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;
};

if (!Array.prototype.lastIndexOf) Array.prototype.lastIndexOf = function(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;
};

Array.prototype.toArray = Array.prototype.clone;

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

if (Prototype.Browser.Opera){
  Array.prototype.concat = function() {
    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(Number.prototype, {
  toColorPart: function() {
    return this.toPaddedString(2, 16);
  },

  succ: function() {
    return this + 1;
  },

  times: function(iterator) {
    $R(0, this, true).each(iterator);
    return this;
  },

  toPaddedString: function(length, radix) {
    var string = this.toString(radix || 10);
    return '0'.times(length - string.length) + string;
  },

  toJSON: function() {
    return isFinite(this) ? this.toString() : 'null';
  }
});

$w('abs round ceil floor').each(function(method){
  Number.prototype[method] = Math[method].methodize();
});
function $H(object) {
  return new Hash(object);
};

var Hash = Class.create(Enumerable, (function() {
  if (function() {
    var i = 0, Test = function(value) { this.key = value };
    Test.prototype.key = 'foo';
    for (var property in new Test('bar')) i++;
    return i > 1;
  }()) {
    function each(iterator) {
      var cache = [];
      for (var key in this._object) {
        var value = this._object[key];
        if (cache.include(key)) continue;
        cache.push(key);
        var pair = [key, value];
        pair.key = key;
        pair.value = value;
        iterator(pair);
      }
    }
  } else {
    function each(iterator) {
      for (var key in this._object) {
        var value = this._object[key], pair = [key, value];
        pair.key = key;
        pair.value = value;
        iterator(pair);
      }
    }
  }

  function toQueryPair(key, value) {
    if (Object.isUndefined(value)) return key;
    return key + '=' + encodeURIComponent(String.interpret(value));
  }

  return {
    initialize: function(object) {
      this._object = Object.isHash(object) ? object.toObject() : Object.clone(object);
    },

    _each: each,

    set: function(key, value) {
      return this._object[key] = value;
    },

    get: function(key) {
      return this._object[key];
    },

    unset: function(key) {
      var value = this._object[key];
      delete this._object[key];
      return value;
    },

    toObject: function() {
      return Object.clone(this._object);
    },

    keys: function() {
      return this.pluck('key');
    },

    values: function() {
      return this.pluck('value');
    },

    index: function(value) {
      var match = this.detect(function(pair) {
        return pair.value === value;
      });
      return match && match.key;
    },

    merge: function(object) {
      return this.clone().update(object);
    },

    update: function(object) {
      return new Hash(object).inject(this, function(result, pair) {
        result.set(pair.key, pair.value);
        return result;
      });
    },

    toQueryString: function() {
      return this.map(function(pair) {
        var key = encodeURIComponent(pair.key), values = pair.value;

        if (values && typeof values == 'object') {
          if (Object.isArray(values))
            return values.map(toQueryPair.curry(key)).join('&');
        }
        return toQueryPair(key, values);
      }).join('&');
    },

    inspect: function() {
      return '#<Hash:{' + this.map(function(pair) {
        return pair.map(Object.inspect).join(': ');
      }).join(', ') + '}>';
    },

    toJSON: function() {
      return Object.toJSON(this.toObject());
    },

    clone: function() {
      return new Hash(this);
    }
  }
})());

Hash.prototype.toTemplateReplacements = Hash.prototype.toObject;
Hash.from = $H;
var ObjectRange = Class.create(Enumerable, {
  initialize: function(start, end, exclusive) {
    this.start = start;
    this.end = end;
    this.exclusive = exclusive;
  },

  _each: function(iterator) {
    var value = this.start;
    while (this.include(value)) {
      iterator(value);
      value = value.succ();
    }
  },

  include: function(value) {
    if (value < this.start)
      return false;
    if (this.exclusive)
      return value < this.end;
    return value <= this.end;
  }
});

var $R = function(start, end, exclusive) {
  return new ObjectRange(start, end, exclusive);
};

var Ajax = {
  getTransport: function() {
    return Try.these(
      function() {return new XMLHttpRequest()},
      function() {return new ActiveXObject('Msxml2.XMLHTTP')},
      function() {return new ActiveXObject('Microsoft.XMLHTTP')}
    ) || false;
  },

  activeRequestCount: 0
};

Ajax.Responders = {
  responders: [],

  _each: function(iterator) {
    this.responders._each(iterator);
  },

  register: function(responder) {
    if (!this.include(responder))
      this.responders.push(responder);
  },

  unregister: function(responder) {
    this.responders = this.responders.without(responder);
  },

  dispatch: function(callback, request, transport, json) {
    this.each(function(responder) {
      if (Object.isFunction(responder[callback])) {
        try {
          responder[callback].apply(responder, [request, transport, json]);
        } catch (e) { }
      }
    });
  }
};

Object.extend(Ajax.Responders, Enumerable);

Ajax.Responders.register({
  onCreate:   function() { Ajax.activeRequestCount++ },
  onComplete: function() { Ajax.activeRequestCount-- }
});

Ajax.Base = Class.create({
  initialize: function(options) {
    this.options = {
      method:       'post',
      asynchronous: true,
      contentType:  'application/x-www-form-urlencoded',
      encoding:     'UTF-8',
      parameters:   '',
      evalJSON:     true,
      evalJS:       true
    };
    Object.extend(this.options, options || { });

    this.options.method = this.options.method.toLowerCase();
    if (Object.isString(this.options.parameters))
      this.options.parameters = this.options.parameters.toQueryParams();
  }
});

Ajax.Request = Class.create(Ajax.Base, {
  _complete: false,

  initialize: function($super, url, options) {
    $super(options);
    this.transport = Ajax.getTransport();
    this.request(url);
  },

  request: function(url) {
    this.url = url;
    this.method = this.options.method;
    var params = Object.clone(this.options.parameters);

    if (!['get', 'post'].include(this.method)) {
      // simulate other verbs over post
      params['_method'] = this.method;
      this.method = 'post';
    }

    this.parameters = params;

    if (params = Object.toQueryString(params)) {
      // when GET, append parameters to URL
      if (this.method == 'get')
        this.url += (this.url.include('?') ? '&' : '?') + params;
      else if (/Konqueror|Safari|KHTML/.test(navigator.userAgent))
        params += '&_=';
    }

    try {
      var response = new Ajax.Response(this);
      if (this.options.onCreate) this.options.onCreate(response);
      Ajax.Responders.dispatch('onCreate', this, response);

      this.transport.open(this.method.toUpperCase(), this.url,
        this.options.asynchronous);

      if (this.options.asynchronous) this.respondToReadyState.bind(this).defer(1);

      this.transport.onreadystatechange = this.onStateChange.bind(this);
      this.setRequestHeaders();

      this.body = this.method == 'post' ? (this.options.postBody || params) : null;
      this.transport.send(this.body);

      /* Force Firefox to handle ready state 4 for synchronous requests */
      if (!this.options.asynchronous && this.transport.overrideMimeType)
        this.onStateChange();

    }
    catch (e) {
      this.dispatchException(e);
    }
  },

  onStateChange: function() {
    var readyState = this.transport.readyState;
    if (readyState > 1 && !((readyState == 4) && this._complete))
      this.respondToReadyState(this.transport.readyState);
  },

  setRequestHeaders: function() {
    var headers = {
      'X-Requested-With': 'XMLHttpRequest',
      'X-Prototype-Version': Prototype.Version,
      'Accept': 'text/javascript, text/html, application/xml, text/xml, */*'
    };

    if (this.method == 'post') {
      headers['Content-type'] = this.options.contentType +
        (this.options.encoding ? '; charset=' + this.options.encoding : '');

      /* Force "Connection: close" for older Mozilla browsers to work
       * around a bug where XMLHttpRequest sends an incorrect
       * Content-length header. See Mozilla Bugzilla #246651.
       */
      if (this.transport.overrideMimeType &&
          (navigator.userAgent.match(/Gecko\/(\d{4})/) || [0,2005])[1] < 2005)
            headers['Connection'] = 'close';
    }

    // user-defined headers
    if (typeof this.options.requestHeaders == 'object') {
      var extras = this.options.requestHeaders;

      if (Object.isFunction(extras.push))
        for (var i = 0, length = extras.length; i < length; i += 2)
          headers[extras[i]] = extras[i+1];
      else
        $H(extras).each(function(pair) { headers[pair.key] = pair.value });
    }

    for (var name in headers)
      this.transport.setRequestHeader(name, headers[name]);
  },

  success: function() {
    var status = this.getStatus();
    return !status || (status >= 200 && status < 300);
  },

  getStatus: function() {
    try {
      return this.transport.status || 0;
    } catch (e) { return 0 }
  },

  respondToReadyState: function(readyState) {
    var state = Ajax.Request.Events[readyState], response = new Ajax.Response(this);

    if (state == 'Complete') {
      try {
        this._complete = true;
        (this.options['on' + response.status]
         || this.options['on' + (this.success() ? 'Success' : 'Failure')]
         || Prototype.emptyFunction)(response, response.headerJSON);
      } catch (e) {
        this.dispatchException(e);
      }

      var contentType = response.getHeader('Content-type');
      if (this.options.evalJS == 'force'
          || (this.options.evalJS && contentType
          && contentType.match(/^\s*(text|application)\/(x-)?(java|ecma)script(;.*)?\s*$/i)))
        this.evalResponse();
    }

    try {
      (this.options['on' + state] || Prototype.emptyFunction)(response, response.headerJSON);
      Ajax.Responders.dispatch('on' + state, this, response, response.headerJSON);
    } catch (e) {
      this.dispatchException(e);
    }

    if (state == 'Complete') {
      // avoid memory leak in MSIE: clean up
      this.transport.onreadystatechange = Prototype.emptyFunction;
    }
  },

  getHeader: function(name) {
    try {
      return this.transport.getResponseHeader(name);
    } catch (e) { return null }
  },

  evalResponse: function() {
    try {
      return eval((this.transport.responseText || '').unfilterJSON());
    } catch (e) {
      this.dispatchException(e);
    }
  },

  dispatchException: function(exception) {
    (this.options.onException || Prototype.emptyFunction)(this, exception);
    Ajax.Responders.dispatch('onException', this, exception);
  }
});

Ajax.Request.Events =
  ['Uninitialized', 'Loading', 'Loaded', 'Interactive', 'Complete'];

Ajax.Response = Class.create({
  initialize: function(request){
    this.request = request;
    var transport  = this.transport  = request.transport,
        readyState = this.readyState = transport.readyState;

    if((readyState > 2 && !Prototype.Browser.IE) || readyState == 4) {
      this.status       = this.getStatus();
      this.statusText   = this.getStatusText();
      this.responseText = String.interpret(transport.responseText);
      this.headerJSON   = this._getHeaderJSON();
    }

    if(readyState == 4) {
      var xml = transport.responseXML;
      this.responseXML  = xml === undefined ? null : xml;
      this.responseJSON = this._getResponseJSON();
    }
  },

  status:      0,
  statusText: '',

  getStatus: Ajax.Request.prototype.getStatus,

  getStatusText: function() {
    try {
      return this.transport.statusText || '';
    } catch (e) { return '' }
  },

  getHeader: Ajax.Request.prototype.getHeader,

  getAllHeaders: function() {
    try {
      return this.getAllResponseHeaders();
    } catch (e) { return null }
  },

  getResponseHeader: function(name) {
    return this.transport.getResponseHeader(name);
  },

  getAllResponseHeaders: function() {
    return this.transport.getAllResponseHeaders();
  },

  _getHeaderJSON: function() {
    var json = this.getHeader('X-JSON');
    if (!json) return null;
    json = decodeURIComponent(escape(json));
    try {
      return json.evalJSON(this.request.options.sanitizeJSON);
    } catch (e) {
      this.request.dispatchException(e);
    }
  },

  _getResponseJSON: function() {
    var options = this.request.options;
    if (!options.evalJSON || (options.evalJSON != 'force' &&
      !(this.getHeader('Content-type') || '').include('application/json')))
        return null;
    try {
      return this.transport.responseText.evalJSON(options.sanitizeJSON);
    } catch (e) {
      this.request.dispatchException(e);
    }
  }
});

Ajax.Updater = Class.create(Ajax.Request, {
  initialize: function($super, container, url, options) {
    this.container = {
      success: (container.success || container),
      failure: (container.failure || (container.success ? null : container))
    };

    options = options || { };
    var onComplete = options.onComplete;
    options.onComplete = (function(response, param) {
      this.updateContent(response.responseText);
      if (Object.isFunction(onComplete)) onComplete(response, param);
    }).bind(this);

    $super(url, options);
  },

  updateContent: function(responseText) {
    var receiver = this.container[this.success() ? 'success' : 'failure'],
        options = this.options;

    if (!options.evalScripts) responseText = responseText.stripScripts();

    if (receiver = $(receiver)) {
      if (options.insertion) {
        if (Object.isString(options.insertion)) {
          var insertion = { }; insertion[options.insertion] = responseText;
          receiver.insert(insertion);
        }
        else options.insertion(receiver, responseText);
      }
      else receiver.update(responseText);
    }

    if (this.success()) {
      if (this.onComplete) this.onComplete.bind(this).defer();
    }
  }
});

Ajax.PeriodicalUpdater = Class.create(Ajax.Base, {
  initialize: function($super, container, url, options) {
    $super(options);
    this.onComplete = this.options.onComplete;

    this.frequency = (this.options.frequency || 2);
    this.decay = (this.options.decay || 1);

    this.updater = { };
    this.container = container;
    this.url = url;

    this.start();
  },

  start: function() {
    this.options.onComplete = this.updateComplete.bind(this);
    this.onTimerEvent();
  },

  stop: function() {
    this.updater.options.onComplete = undefined;
    clearTimeout(this.timer);
    (this.onComplete || Prototype.emptyFunction).apply(this, arguments);
  },

  updateComplete: function(response) {
    if (this.options.decay) {
      this.decay = (response.responseText == this.lastText ?
        this.decay * this.options.decay : 1);

      this.lastText = response.responseText;
    }
    this.timer = this.onTimerEvent.bind(this).delay(this.decay * this.frequency);
  },

  onTimerEvent: function() {
    this.updater = new Ajax.Updater(this.container, this.url, this.options);
  }
});
function $(element) {
  if (arguments.length > 1) {
    for (var i = 0, elements = [], length = arguments.length; i < length; i++)
      elements.push($(arguments[i]));
    return elements;
  }
  if (Object.isString(element))
    element = document.getElementById(element);
  return Element.extend(element);
}

if (Prototype.BrowserFeatures.XPath) {
  document._getElementsByXPath = function(expression, parentElement) {
    var results = [];
    var query = document.evaluate(expression, $(parentElement) || document,
      null, XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);
    for (var i = 0, length = query.snapshotLength; i < length; i++)
      results.push(Element.extend(query.snapshotItem(i)));
    return results;
  };
}

/*--------------------------------------------------------------------------*/

if (!window.Node) var Node = { };

if (!Node.ELEMENT_NODE) {
  // DOM level 2 ECMAScript Language Binding
  Object.extend(Node, {
    ELEMENT_NODE: 1,
    ATTRIBUTE_NODE: 2,
    TEXT_NODE: 3,
    CDATA_SECTION_NODE: 4,
    ENTITY_REFERENCE_NODE: 5,
    ENTITY_NODE: 6,
    PROCESSING_INSTRUCTION_NODE: 7,
    COMMENT_NODE: 8,
    DOCUMENT_NODE: 9,
    DOCUMENT_TYPE_NODE: 10,
    DOCUMENT_FRAGMENT_NODE: 11,
    NOTATION_NODE: 12
  });
}

(function() {
  var element = this.Element;
  this.Element = function(tagName, attributes) {
    attributes = attributes || { };
    tagName = tagName.toLowerCase();
    var cache = Element.cache;
    if (Prototype.Browser.IE && attributes.name) {
      tagName = '<' + tagName + ' name="' + attributes.name + '">';
      delete attributes.name;
      return Element.writeAttribute(document.createElement(tagName), attributes);
    }
    if (!cache[tagName]) cache[tagName] = Element.extend(document.createElement(tagName));
    return Element.writeAttribute(cache[tagName].cloneNode(false), attributes);
  };
  Object.extend(this.Element, element || { });
}).call(window);

Element.cache = { };

Element.Methods = {
  visible: function(element) {
    return $(element).style.display != 'none';
  },

  toggle: function(element) {
    element = $(element);
    Element[Element.visible(element) ? 'hide' : 'show'](element);
    return element;
  },

  hide: function(element) {
    $(element).style.display = 'none';
    return element;
  },

  show: function(element) {
    $(element).style.display = '';
    return element;
  },

  remove: function(element) {
    element = $(element);
    element.parentNode.removeChild(element);
    return element;
  },

  update: function(element, content) {
    element = $(element);
    if (content && content.toElement) content = content.toElement();
    if (Object.isElement(content)) return element.update().insert(content);
    content = Object.toHTML(content);
    element.innerHTML = content.stripScripts();
    content.evalScripts.bind(content).defer();
    return element;
  },

  replace: function(element, content) {
    element = $(element);
    if (content && content.toElement) content = content.toElement();
    else if (!Object.isElement(content)) {
      content = Object.toHTML(content);
      var range = element.ownerDocument.createRange();
      range.selectNode(element);
      content.evalScripts.bind(content).defer();
      content = range.createContextualFragment(content.stripScripts());
    }
    element.parentNode.replaceChild(content, element);
    return element;
  },

  insert: function(element, insertions) {
    element = $(element);

    if (Object.isString(insertions) || Object.isNumber(insertions) ||
        Object.isElement(insertions) || (insertions && (insertions.toElement || insertions.toHTML)))
          insertions = {bottom:insertions};

    var content, t, range;

    for (position in insertions) {
      content  = insertions[position];
      position = position.toLowerCase();
      t = Element._insertionTranslations[position];

      if (content && content.toElement) content = content.toElement();
      if (Object.isElement(content)) {
        t.insert(element, content);
        continue;
      }

      content = Object.toHTML(content);

      range = element.ownerDocument.createRange();
      t.initializeRange(element, range);
      t.insert(element, range.createContextualFragment(content.stripScripts()));

      content.evalScripts.bind(content).defer();
    }

    return element;
  },

  wrap: function(element, wrapper, attributes) {
    element = $(element);
    if (Object.isElement(wrapper))
      $(wrapper).writeAttribute(attributes || { });
    else if (Object.isString(wrapper)) wrapper = new Element(wrapper, attributes);
    else wrapper = new Element('div', wrapper);
    if (element.parentNode)
      element.parentNode.replaceChild(wrapper, element);
    wrapper.appendChild(element);
    return wrapper;
  },

  inspect: function(element) {
    element = $(element);
    var result = '<' + element.tagName.toLowerCase();
    $H({'id': 'id', 'className': 'class'}).each(function(pair) {
      var property = pair.first(), attribute = pair.last();
      var value = (element[property] || '').toString();
      if (value) result += ' ' + attribute + '=' + value.inspect(true);
    });
    return result + '>';
  },

  recursivelyCollect: function(element, property) {
    element = $(element);
    var elements = [];
    while (element = element[property])
      if (element.nodeType == 1)
        elements.push(Element.extend(element));
    return elements;
  },

  ancestors: function(element) {
    return $(element).recursivelyCollect('parentNode');
  },

  descendants: function(element) {
    return $A($(element).getElementsByTagName('*')).each(Element.extend);
  },

  firstDescendant: function(element) {
    element = $(element).firstChild;
    while (element && element.nodeType != 1) element = element.nextSibling;
    return $(element);
  },

  immediateDescendants: function(element) {
    if (!(element = $(element).firstChild)) return [];
    while (element && element.nodeType != 1) element = element.nextSibling;
    if (element) return [element].concat($(element).nextSiblings());
    return [];
  },

  previousSiblings: function(element) {
    return $(element).recursivelyCollect('previousSibling');
  },

  nextSiblings: function(element) {
    return $(element).recursivelyCollect('nextSibling');
  },

  siblings: function(element) {
    element = $(element);
    return element.previousSiblings().reverse().concat(element.nextSiblings());
  },

  match: function(element, selector) {
    if (Object.isString(selector))
      selector = new Selector(selector);
    return selector.match($(element));
  },

  up: function(element, expression, index) {
    element = $(element);
    if (arguments.length == 1) return $(element.parentNode);
    var ancestors = element.ancestors();
    return expression ? Selector.findElement(ancestors, expression, index) :
      ancestors[index || 0];
  },

  down: function(element, expression, index) {
    element = $(element);
    if (arguments.length == 1) return element.firstDescendant();
    var descendants = element.descendants();
    return expression ? Selector.findElement(descendants, expression, index) :
      descendants[index || 0];
  },

  previous: function(element, expression, index) {
    element = $(element);
    if (arguments.length == 1) return $(Selector.handlers.previousElementSibling(element));
    var previousSiblings = element.previousSiblings();
    return expression ? Selector.findElement(previousSiblings, expression, index) :
      previousSiblings[index || 0];
  },

  next: function(element, expression, index) {
    element = $(element);
    if (arguments.length == 1) return $(Selector.handlers.nextElementSibling(element));
    var nextSiblings = element.nextSiblings();
    return expression ? Selector.findElement(nextSiblings, expression, index) :
      nextSiblings[index || 0];
  },

  select: function() {
    var args = $A(arguments), element = $(args.shift());
    return Selector.findChildElements(element, args);
  },

  adjacent: function() {
    var args = $A(arguments), element = $(args.shift());
    return Selector.findChildElements(element.parentNode, args).without(element);
  },

  identify: function(element) {
    element = $(element);
    var id = element.readAttribute('id'), self = arguments.callee;
    if (id) return id;
    do { id = 'anonymous_element_' + self.counter++ } while ($(id));
    element.writeAttribute('id', id);
    return id;
  },

  readAttribute: function(element, name) {
    element = $(element);
    if (Prototype.Browser.IE) {
      var t = Element._attributeTranslations.read;
      if (t.values[name]) return t.values[name](element, name);
      if (t.names[name]) name = t.names[name];
      if (name.include(':')) {
        return (!element.attributes || !element.attributes[name]) ? null :
         element.attributes[name].value;
      }
    }
    return element.getAttribute(name);
  },

  writeAttribute: function(element, name, value) {
    element = $(element);
    var attributes = { }, t = Element._attributeTranslations.write;

    if (typeof name == 'object') attributes = name;
    else attributes[name] = value === undefined ? true : value;

    for (var attr in attributes) {
      var name = t.names[attr] || attr, value = attributes[attr];
      if (t.values[attr]) name = t.values[attr](element, value);
      if (value === false || value === null)
        element.removeAttribute(name);
      else if (value === true)
        element.setAttribute(name, name);
      else element.setAttribute(name, value);
    }
    return element;
  },

  getHeight: function(element) {
    return $(element).getDimensions().height;
  },

  getWidth: function(element) {
    return $(element).getDimensions().width;
  },

  classNames: function(element) {
    return new Element.ClassNames(element);
  },

  hasClassName: function(element, className) {
    if (!(element = $(element))) return;
    var elementClassName = element.className;
    return (elementClassName.length > 0 && (elementClassName == className ||
      new RegExp("(^|\\s)" + className + "(\\s|$)").test(elementClassName)));
  },

  addClassName: function(element, className) {
    if (!(element = $(element))) return;
    if (!element.hasClassName(className))
      element.className += (element.className ? ' ' : '') + className;
    return element;
  },

  removeClassName: function(element, className) {
    if (!(element = $(element))) return;
    element.className = element.className.replace(
      new RegExp("(^|\\s+)" + className + "(\\s+|$)"), ' ').strip();
    return element;
  },

  toggleClassName: function(element, className) {
    if (!(element = $(element))) return;
    return element[element.hasClassName(className) ?
      'removeClassName' : 'addClassName'](className);
  },

  // removes whitespace-only text node children
  cleanWhitespace: function(element) {
    element = $(element);
    var node = element.firstChild;
    while (node) {
      var nextNode = node.nextSibling;
      if (node.nodeType == 3 && !/\S/.test(node.nodeValue))
        element.removeChild(node);
      node = nextNode;
    }
    return element;
  },

  empty: function(element) {
    return $(element).innerHTML.blank();
  },

  descendantOf: function(element, ancestor) {
    element = $(element), ancestor = $(ancestor);

    if (element.compareDocumentPosition)
      return (element.compareDocumentPosition(ancestor) & 8) === 8;

    if (element.sourceIndex && !Prototype.Browser.Opera) {
      var e = element.sourceIndex, a = ancestor.sourceIndex,
       nextAncestor = ancestor.nextSibling;
      if (!nextAncestor) {
        do { ancestor = ancestor.parentNode; }
        while (!(nextAncestor = ancestor.nextSibling) && ancestor.parentNode);
      }
      if (nextAncestor) return (e > a && e < nextAncestor.sourceIndex);
    }

    while (element = element.parentNode)
      if (element == ancestor) return true;
    return false;
  },

  scrollTo: function(element) {
    element = $(element);
    var pos = element.cumulativeOffset();
    window.scrollTo(pos[0], pos[1]);
    return element;
  },

  getStyle: function(element, style) {
    element = $(element);
    style = style == 'float' ? 'cssFloat' : style.camelize();
    var value = element.style[style];
    if (!value) {
      var css = document.defaultView.getComputedStyle(element, null);
      value = css ? css[style] : null;
    }
    if (style == 'opacity') return value ? parseFloat(value) : 1.0;
    return value == 'auto' ? null : value;
  },

  getOpacity: function(element) {
    return $(element).getStyle('opacity');
  },

  setStyle: function(element, styles) {
    element = $(element);
    var elementStyle = element.style, match;
    if (Object.isString(styles)) {
      element.style.cssText += ';' + styles;
      return styles.include('opacity') ?
        element.setOpacity(styles.match(/opacity:\s*(\d?\.?\d*)/)[1]) : element;
    }
    for (var property in styles)
      if (property == 'opacity') element.setOpacity(styles[property]);
      else
        elementStyle[(property == 'float' || property == 'cssFloat') ?
          (elementStyle.styleFloat === undefined ? 'cssFloat' : 'styleFloat') :
            property] = styles[property];

    return element;
  },

  setOpacity: function(element, value) {
    element = $(element);
    element.style.opacity = (value == 1 || value === '') ? '' :
      (value < 0.00001) ? 0 : value;
    return element;
  },

  getDimensions: function(element) {
    element = $(element);
    var display = $(element).getStyle('display');
    if (display != 'none' && display != null) // Safari bug
      return {width: element.offsetWidth, height: element.offsetHeight};

    // All *Width and *Height properties give 0 on elements with display none,
    // so enable the element temporarily
    var els = element.style;
    var originalVisibility = els.visibility;
    var originalPosition = els.position;
    var originalDisplay = els.display;
    els.visibility = 'hidden';
    els.position = 'absolute';
    els.display = 'block';
    var originalWidth = element.clientWidth;
    var originalHeight = element.clientHeight;
    els.display = originalDisplay;
    els.position = originalPosition;
    els.visibility = originalVisibility;
    return {width: originalWidth, height: originalHeight};
  },

  makePositioned: function(element) {
    element = $(element);
    var pos = Element.getStyle(element, 'position');
    if (pos == 'static' || !pos) {
      element._madePositioned = true;
      element.style.position = 'relative';
      // Opera returns the offset relative to the positioning context, when an
      // element is position relative but top and left have not been defined
      if (window.opera) {
        element.style.top = 0;
        element.style.left = 0;
      }
    }
    return element;
  },

  undoPositioned: function(element) {
    element = $(element);
    if (element._madePositioned) {
      element._madePositioned = undefined;
      element.style.position =
        element.style.top =
        element.style.left =
        element.style.bottom =
        element.style.right = '';
    }
    return element;
  },

  makeClipping: function(element) {
    element = $(element);
    if (element._overflow) return element;
    element._overflow = Element.getStyle(element, 'overflow') || 'auto';
    if (element._overflow !== 'hidden')
      element.style.overflow = 'hidden';
    return element;
  },

  undoClipping: function(element) {
    element = $(element);
    if (!element._overflow) return element;
    element.style.overflow = element._overflow == 'auto' ? '' : element._overflow;
    element._overflow = null;
    return element;
  },

  cumulativeOffset: function(element) {
    var valueT = 0, valueL = 0;
    do {
      valueT += element.offsetTop  || 0;
      valueL += element.offsetLeft || 0;
      element = element.offsetParent;
    } while (element);
    return Element._returnOffset(valueL, valueT);
  },

  positionedOffset: function(element) {
    var valueT = 0, valueL = 0;
    do {
      valueT += element.offsetTop  || 0;
      valueL += element.offsetLeft || 0;
      element = element.offsetParent;
      if (element) {
        if (element.tagName == 'BODY') break;
        var p = Element.getStyle(element, 'position');
        if (p == 'relative' || p == 'absolute') break;
      }
    } while (element);
    return Element._returnOffset(valueL, valueT);
  },

  absolutize: function(element) {
    element = $(element);
    if (element.getStyle('position') == 'absolute') return;
    // Position.prepare(); // To be done manually by Scripty when it needs it.

    var offsets = element.positionedOffset();
    var top     = offsets[1];
    var left    = offsets[0];
    var width   = element.clientWidth;
    var height  = element.clientHeight;

    element._originalLeft   = left - parseFloat(element.style.left  || 0);
    element._originalTop    = top  - parseFloat(element.style.top || 0);
    element._originalWidth  = element.style.width;
    element._originalHeight = element.style.height;

    element.style.position = 'absolute';
    element.style.top    = top + 'px';
    element.style.left   = left + 'px';
    element.style.width  = width + 'px';
    element.style.height = height + 'px';
    return element;
  },

  relativize: function(element) {
    element = $(element);
    if (element.getStyle('position') == 'relative') return;
    // Position.prepare(); // To be done manually by Scripty when it needs it.

    element.style.position = 'relative';
    var top  = parseFloat(element.style.top  || 0) - (element._originalTop || 0);
    var left = parseFloat(element.style.left || 0) - (element._originalLeft || 0);

    element.style.top    = top + 'px';
    element.style.left   = left + 'px';
    element.style.height = element._originalHeight;
    element.style.width  = element._originalWidth;
    return element;
  },

  cumulativeScrollOffset: function(element) {
    var valueT = 0, valueL = 0;
    do {
      valueT += element.scrollTop  || 0;
      valueL += element.scrollLeft || 0;
      element = element.parentNode;
    } while (element);
    return Element._returnOffset(valueL, valueT);
  },

  getOffsetParent: function(element) {
    if (element.offsetParent) return $(element.offsetParent);
    if (element == document.body) return $(element);

    while ((element = element.parentNode) && element != document.body)
      if (Element.getStyle(element, 'position') != 'static')
        return $(element);

    return $(document.body);
  },

  viewportOffset: function(forElement) {
    var valueT = 0, valueL = 0;

    var element = forElement;
    do {
      valueT += element.offsetTop  || 0;
      valueL += element.offsetLeft || 0;

      // Safari fix
      if (element.offsetParent == document.body &&
        Element.getStyle(element, 'position') == 'absolute') break;

    } while (element = element.offsetParent);

    element = forElement;
    do {
      if (!Prototype.Browser.Opera || element.tagName == 'BODY') {
        valueT -= element.scrollTop  || 0;
        valueL -= element.scrollLeft || 0;
      }
    } while (element = element.parentNode);

    return Element._returnOffset(valueL, valueT);
  },

  clonePosition: function(element, source) {
    var options = Object.extend({
      setLeft:    true,
      setTop:     true,
      setWidth:   true,
      setHeight:  true,
      offsetTop:  0,
      offsetLeft: 0
    }, arguments[2] || { });

    // find page position of source
    source = $(source);
    var p = source.viewportOffset();

    // find coordinate system to use
    element = $(element);
    var delta = [0, 0];
    var parent = null;
    // delta [0,0] will do fine with position: fixed elements,
    // position:absolute needs offsetParent deltas
    if (Element.getStyle(element, 'position') == 'absolute') {
      parent = element.getOffsetParent();
      delta = parent.viewportOffset();
    }

    // correct by body offsets (fixes Safari)
    if (parent == document.body) {
      delta[0] -= document.body.offsetLeft;
      delta[1] -= document.body.offsetTop;
    }

    // set position
    if (options.setLeft)   element.style.left  = (p[0] - delta[0] + options.offsetLeft) + 'px';
    if (options.setTop)    element.style.top   = (p[1] - delta[1] + options.offsetTop) + 'px';
    if (options.setWidth)  element.style.width = source.offsetWidth + 'px';
    if (options.setHeight) element.style.height = source.offsetHeight + 'px';
    return element;
  }
};

Element.Methods.identify.counter = 1;

Object.extend(Element.Methods, {
  getElementsBySelector: Element.Methods.select,
  childElements: Element.Methods.immediateDescendants
});

Element._attributeTranslations = {
  write: {
    names: {
      className: 'class',
      htmlFor:   'for'
    },
    values: { }
  }
};


if (!document.createRange || Prototype.Browser.Opera) {
  Element.Methods.insert = function(element, insertions) {
    element = $(element);

    if (Object.isString(insertions) || Object.isNumber(insertions) ||
        Object.isElement(insertions) || (insertions && (insertions.toElement || insertions.toHTML)))
          insertions = { bottom: insertions };

    var t = Element._insertionTranslations, content, position, pos, tagName;

    for (position in insertions) {
      content  = insertions[position];
      position = position.toLowerCase();
      pos      = t[position];

      if (content && content.toElement) content = content.toElement();
      if (Object.isElement(content)) {
        pos.insert(element, content);
        continue;
      }

      content = Object.toHTML(content);
      tagName = ((position == 'before' || position == 'after')
        ? element.parentNode : element).tagName.toUpperCase();

      if (t.tags[tagName]) {
        var fragments = Element._getContentFromAnonymousElement(tagName, content.stripScripts());
        if (position == 'top' || position == 'after') fragments.reverse();
        fragments.each(pos.insert.curry(element));
      }
      else element.insertAdjacentHTML(pos.adjacency, content.stripScripts());

      content.evalScripts.bind(content).defer();
    }

    return element;
  };
}

if (Prototype.Browser.Opera) {
  Element.Methods._getStyle = Element.Methods.getStyle;
  Element.Methods.getStyle = function(element, style) {
    switch(style) {
      case 'left':
      case 'top':
      case 'right':
      case 'bottom':
        if (Element._getStyle(element, 'position') == 'static') return null;
      default: return Element._getStyle(element, style);
    }
  };
  Element.Methods._readAttribute = Element.Methods.readAttribute;
  Element.Methods.readAttribute = function(element, attribute) {
    if (attribute == 'title') return element.title;
    return Element._readAttribute(element, attribute);
  };
}

else if (Prototype.Browser.IE) {
  $w('positionedOffset getOffsetParent viewportOffset').each(function(method) {
    Element.Methods[method] = Element.Methods[method].wrap(
      function(proceed, element) {
        element = $(element);
        var position = element.getStyle('position');
        if (position != 'static') return proceed(element);
        element.setStyle({ position: 'relative' });
        var value = proceed(element);
        element.setStyle({ position: position });
        return value;
      }
    );
  });

  Element.Methods.getStyle = function(element, style) {
    element = $(element);
    style = (style == 'float' || style == 'cssFloat') ? 'styleFloat' : style.camelize();
    var value = element.style[style];
    if (!value && element.currentStyle) value = element.currentStyle[style];

    if (style == 'opacity') {
      if (value = (element.getStyle('filter') || '').match(/alpha\(opacity=(.*)\)/))
        if (value[1]) return parseFloat(value[1]) / 100;
      return 1.0;
    }

    if (value == 'auto') {
      if ((style == 'width' || style == 'height') && (element.getStyle('display') != 'none'))
        return element['offset' + style.capitalize()] + 'px';
      return null;
    }
    return value;
  };

  Element.Methods.setOpacity = function(element, value) {
    function stripAlpha(filter){
      return filter.replace(/alpha\([^\)]*\)/gi,'');
    }
    element = $(element);
    var currentStyle = element.currentStyle;
    if ((currentStyle && !currentStyle.hasLayout) ||
      (!currentStyle && element.style.zoom == 'normal'))
        element.style.zoom = 1;

    var filter = element.getStyle('filter'), style = element.style;
    if (value == 1 || value === '') {
      (filter = stripAlpha(filter)) ?
        style.filter = filter : style.removeAttribute('filter');
      return element;
    } else if (value < 0.00001) value = 0;
    style.filter = stripAlpha(filter) +
      'alpha(opacity=' + (value * 100) + ')';
    return element;
  };

  Element._attributeTranslations = {
    read: {
      names: {
        'class': 'className',
        'for':   'htmlFor'
      },
      values: {
        _getAttr: function(element, attribute) {
          return element.getAttribute(attribute, 2);
        },
        _getAttrNode: function(element, attribute) {
          var node = element.getAttributeNode(attribute);
          return node ? node.value : "";
        },
        _getEv: function(element, attribute) {
          var attribute = element.getAttribute(attribute);
          return attribute ? attribute.toString().slice(23, -2) : null;
        },
        _flag: function(element, attribute) {
          return $(element).hasAttribute(attribute) ? attribute : null;
        },
        style: function(element) {
          return element.style.cssText.toLowerCase();
        },
        title: function(element) {
          return element.title;
        }
      }
    }
  };

  Element._attributeTranslations.write = {
    names: Object.clone(Element._attributeTranslations.read.names),
    values: {
      checked: function(element, value) {
        element.checked = !!value;
      },

      style: function(element, value) {
        element.style.cssText = value ? value : '';
      }
    }
  };

  Element._attributeTranslations.has = {};

  $w('colSpan rowSpan vAlign dateTime accessKey tabIndex ' +
      'encType maxLength readOnly longDesc').each(function(attr) {
    Element._attributeTranslations.write.names[attr.toLowerCase()] = attr;
    Element._attributeTranslations.has[attr.toLowerCase()] = attr;
  });

  (function(v) {
    Object.extend(v, {
      href:        v._getAttr,
      src:         v._getAttr,
      type:        v._getAttr,
      action:      v._getAttrNode,
      disabled:    v._flag,
      checked:     v._flag,
      readonly:    v._flag,
      multiple:    v._flag,
      onload:      v._getEv,
      onunload:    v._getEv,
      onclick:     v._getEv,
      ondblclick:  v._getEv,
      onmousedown: v._getEv,
      onmouseup:   v._getEv,
      onmouseover: v._getEv,
      onmousemove: v._getEv,
      onmouseout:  v._getEv,
      onfocus:     v._getEv,
      onblur:      v._getEv,
      onkeypress:  v._getEv,
      onkeydown:   v._getEv,
      onkeyup:     v._getEv,
      onsubmit:    v._getEv,
      onreset:     v._getEv,
      onselect:    v._getEv,
      onchange:    v._getEv
    });
  })(Element._attributeTranslations.read.values);
}

else if (Prototype.Browser.Gecko && /rv:1\.8\.0/.test(navigator.userAgent)) {
  Element.Methods.setOpacity = function(element, value) {
    element = $(element);
    element.style.opacity = (value == 1) ? 0.999999 :
      (value === '') ? '' : (value < 0.00001) ? 0 : value;
    return element;
  };
}

else if (Prototype.Browser.WebKit) {
  Element.Methods.setOpacity = function(element, value) {
    element = $(element);
    element.style.opacity = (value == 1 || value === '') ? '' :
      (value < 0.00001) ? 0 : value;

    if (value == 1)
      if(element.tagName == 'IMG' && element.width) {
        element.width++; element.width--;
      } else try {
        var n = document.createTextNode(' ');
        element.appendChild(n);
        element.removeChild(n);
      } catch (e) { }

    return element;
  };

  // Safari returns margins on body which is incorrect if the child is absolutely
  // positioned.  For performance reasons, redefine Position.cumulativeOffset for
  // KHTML/WebKit only.
  Element.Methods.cumulativeOffset = function(element) {
    var valueT = 0, valueL = 0;
    do {
      valueT += element.offsetTop  || 0;
      valueL += element.offsetLeft || 0;
      if (element.offsetParent == document.body)
        if (Element.getStyle(element, 'position') == 'absolute') break;

      element = element.offsetParent;
    } while (element);

    return Element._returnOffset(valueL, valueT);
  };
}

if (Prototype.Browser.IE || Prototype.Browser.Opera) {
  // IE and Opera are missing .innerHTML support for TABLE-related and SELECT elements
  Element.Methods.update = function(element, content) {
    element = $(element);

    if (content && content.toElement) content = content.toElement();
    if (Object.isElement(content)) return element.update().insert(content);

    content = Object.toHTML(content);
    var tagName = element.tagName.toUpperCase();

    if (tagName in Element._insertionTranslations.tags) {
      $A(element.childNodes).each(function(node) { element.removeChild(node) });
      Element._getContentFromAnonymousElement(tagName, content.stripScripts())
        .each(function(node) { element.appendChild(node) });
    }
    else element.innerHTML = content.stripScripts();

    content.evalScripts.bind(content).defer();
    return element;
  };
}

if (document.createElement('div').outerHTML) {
  Element.Methods.replace = function(element, content) {
    element = $(element);

    if (content && content.toElement) content = content.toElement();
    if (Object.isElement(content)) {
      element.parentNode.replaceChild(content, element);
      return element;
    }

    content = Object.toHTML(content);
    var parent = element.parentNode, tagName = parent.tagName.toUpperCase();

    if (Element._insertionTranslations.tags[tagName]) {
      var nextSibling = element.next();
      var fragments = Element._getContentFromAnonymousElement(tagName, content.stripScripts());
      parent.removeChild(element);
      if (nextSibling)
        fragments.each(function(node) { parent.insertBefore(node, nextSibling) });
      else
        fragments.each(function(node) { parent.appendChild(node) });
    }
    else element.outerHTML = content.stripScripts();

    content.evalScripts.bind(content).defer();
    return element;
  };
}

Element._returnOffset = function(l, t) {
  var result = [l, t];
  result.left = l;
  result.top = t;
  return result;
};

Element._getContentFromAnonymousElement = function(tagName, html) {
  var div = new Element('div'), t = Element._insertionTranslations.tags[tagName];
  div.innerHTML = t[0] + html + t[1];
  t[2].times(function() { div = div.firstChild });
  return $A(div.childNodes);
};

Element._insertionTranslations = {
  before: {
    adjacency: 'beforeBegin',
    insert: function(element, node) {
      element.parentNode.insertBefore(node, element);
    },
    initializeRange: function(element, range) {
      range.setStartBefore(element);
    }
  },
  top: {
    adjacency: 'afterBegin',
    insert: function(element, node) {
      element.insertBefore(node, element.firstChild);
    },
    initializeRange: function(element, range) {
      range.selectNodeContents(element);
      range.collapse(true);
    }
  },
  bottom: {
    adjacency: 'beforeEnd',
    insert: function(element, node) {
      element.appendChild(node);
    }
  },
  after: {
    adjacency: 'afterEnd',
    insert: function(element, node) {
      element.parentNode.insertBefore(node, element.nextSibling);
    },
    initializeRange: function(element, range) {
      range.setStartAfter(element);
    }
  },
  tags: {
    TABLE:  ['<table>',                '</table>',                   1],
    TBODY:  ['<table><tbody>',         '</tbody></table>',           2],
    TR:     ['<table><tbody><tr>',     '</tr></tbody></table>',      3],
    TD:     ['<table><tbody><tr><td>', '</td></tr></tbody></table>', 4],
    SELECT: ['<select>',               '</select>',                  1]
  }
};

(function() {
  this.bottom.initializeRange = this.top.initializeRange;
  Object.extend(this.tags, {
    THEAD: this.tags.TBODY,
    TFOOT: this.tags.TBODY,
    TH:    this.tags.TD
  });
}).call(Element._insertionTranslations);

Element.Methods.Simulated = {
  hasAttribute: function(element, attribute) {
    attribute = Element._attributeTranslations.has[attribute] || attribute;
    var node = $(element).getAttributeNode(attribute);
    return node && node.specified;
  }
};

Element.Methods.ByTag = { };

Object.extend(Element, Element.Methods);

if (!Prototype.BrowserFeatures.ElementExtensions &&
    document.createElement('div').__proto__) {
  window.HTMLElement = { };
  window.HTMLElement.prototype = document.createElement('div').__proto__;
  Prototype.BrowserFeatures.ElementExtensions = true;
}

Element.extend = (function() {
  if (Prototype.BrowserFeatures.SpecificElementExtensions)
    return Prototype.K;

  var Methods = { }, ByTag = Element.Methods.ByTag;

  var extend = Object.extend(function(element) {
    if (!element || element._extendedByPrototype ||
        element.nodeType != 1 || element == window) return element;

    var methods = Object.clone(Methods),
      tagName = element.tagName, property, value;

    // extend methods for specific tags
    if (ByTag[tagName]) Object.extend(methods, ByTag[tagName]);

    for (property in methods) {
      value = methods[property];
      if (Object.isFunction(value) && !(property in element))
        element[property] = value.methodize();
    }

    element._extendedByPrototype = Prototype.emptyFunction;
    return element;

  }, {
    refresh: function() {
      // extend methods for all tags (Safari doesn't need this)
      if (!Prototype.BrowserFeatures.ElementExtensions) {
        Object.extend(Methods, Element.Methods);
        Object.extend(Methods, Element.Methods.Simulated);
      }
    }
  });

  extend.refresh();
  return extend;
})();

Element.hasAttribute = function(element, attribute) {
  if (element.hasAttribute) return element.hasAttribute(attribute);
  return Element.Methods.Simulated.hasAttribute(element, attribute);
};

Element.addMethods = function(methods) {
  var F = Prototype.BrowserFeatures, T = Element.Methods.ByTag;

  if (!methods) {
    Object.extend(Form, Form.Methods);
    Object.extend(Form.Element, Form.Element.Methods);
    Object.extend(Element.Methods.ByTag, {
      "FORM":     Object.clone(Form.Methods),
      "INPUT":    Object.clone(Form.Element.Methods),
      "SELECT":   Object.clone(Form.Element.Methods),
      "TEXTAREA": Object.clone(Form.Element.Methods)
    });
  }

  if (arguments.length == 2) {
    var tagName = methods;
    methods = arguments[1];
  }

  if (!tagName) Object.extend(Element.Methods, methods || { });
  else {
    if (Object.isArray(tagName)) tagName.each(extend);
    else extend(tagName);
  }

  function extend(tagName) {
    tagName = tagName.toUpperCase();
    if (!Element.Methods.ByTag[tagName])
      Element.Methods.ByTag[tagName] = { };
    Object.extend(Element.Methods.ByTag[tagName], methods);
  }

  function copy(methods, destination, onlyIfAbsent) {
    onlyIfAbsent = onlyIfAbsent || false;
    for (var property in methods) {
      var value = methods[property];
      if (!Object.isFunction(value)) continue;
      if (!onlyIfAbsent || !(property in destination))
        destination[property] = value.methodize();
    }
  }

  function findDOMClass(tagName) {
    var klass;
    var trans = {
      "OPTGROUP": "OptGroup", "TEXTAREA": "TextArea", "P": "Paragraph",
      "FIELDSET": "FieldSet", "UL": "UList", "OL": "OList", "DL": "DList",
      "DIR": "Directory", "H1": "Heading", "H2": "Heading", "H3": "Heading",
      "H4": "Heading", "H5": "Heading", "H6": "Heading", "Q": "Quote",
      "INS": "Mod", "DEL": "Mod", "A": "Anchor", "IMG": "Image", "CAPTION":
      "TableCaption", "COL": "TableCol", "COLGROUP": "TableCol", "THEAD":
      "TableSection", "TFOOT": "TableSection", "TBODY": "TableSection", "TR":
      "TableRow", "TH": "TableCell", "TD": "TableCell", "FRAMESET":
      "FrameSet", "IFRAME": "IFrame"
    };
    if (trans[tagName]) klass = 'HTML' + trans[tagName] + 'Element';
    if (window[klass]) return window[klass];
    klass = 'HTML' + tagName + 'Element';
    if (window[klass]) return window[klass];
    klass = 'HTML' + tagName.capitalize() + 'Element';
    if (window[klass]) return window[klass];

    window[klass] = { };
    window[klass].prototype = document.createElement(tagName).__proto__;
    return window[klass];
  }

  if (F.ElementExtensions) {
    copy(Element.Methods, HTMLElement.prototype);
    copy(Element.Methods.Simulated, HTMLElement.prototype, true);
  }

  if (F.SpecificElementExtensions) {
    for (var tag in Element.Methods.ByTag) {
      var klass = findDOMClass(tag);
      if (Object.isUndefined(klass)) continue;
      copy(T[tag], klass.prototype);
    }
  }

  Object.extend(Element, Element.Methods);
  delete Element.ByTag;

  if (Element.extend.refresh) Element.extend.refresh();
  Element.cache = { };
};

document.viewport = {
  getDimensions: function() {
    var dimensions = { };
    $w('width height').each(function(d) {
      var D = d.capitalize();
      dimensions[d] = self['inner' + D] ||
       (document.documentElement['client' + D] || document.body['client' + D]);
    });
    return dimensions;
  },

  getWidth: function() {
    return this.getDimensions().width;
  },

  getHeight: function() {
    return this.getDimensions().height;
  },

  getScrollOffsets: function() {
    return Element._returnOffset(
      window.pageXOffset || document.documentElement.scrollLeft || document.body.scrollLeft,
      window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop);
  }
};
/* Portions of the Selector class are derived from Jack Slocum’s DomQuery,
 * part of YUI-Ext version 0.40, distributed under the terms of an MIT-style
 * license.  Please see http://www.yui-ext.com/ for more information. */

var Selector = Class.create({
  initialize: function(expression) {
    this.expression = expression.strip();
    this.compileMatcher();
  },

  compileMatcher: function() {
    // Selectors with namespaced attributes can't use the XPath version
    if (Prototype.BrowserFeatures.XPath && !(/(\[[\w-]*?:|:checked)/).test(this.expression))
      return this.compileXPathMatcher();

    var e = this.expression, ps = Selector.patterns, h = Selector.handlers,
        c = Selector.criteria, le, p, m;

    if (Selector._cache[e]) {
      this.matcher = Selector._cache[e];
      return;
    }

    this.matcher = ["this.matcher = function(root) {",
                    "var r = root, h = Selector.handlers, c = false, n;"];

    while (e && le != e && (/\S/).test(e)) {
      le = e;
      for (var i in ps) {
        p = ps[i];
        if (m = e.match(p)) {
          this.matcher.push(Object.isFunction(c[i]) ? c[i](m) :
    	      new Template(c[i]).evaluate(m));
          e = e.replace(m[0], '');
          break;
        }
      }
    }

    this.matcher.push("return h.unique(n);\n}");
    eval(this.matcher.join('\n'));
    Selector._cache[this.expression] = this.matcher;
  },

  compileXPathMatcher: function() {
    var e = this.expression, ps = Selector.patterns,
        x = Selector.xpath, le, m;

    if (Selector._cache[e]) {
      this.xpath = Selector._cache[e]; return;
    }

    this.matcher = ['.//*'];
    while (e && le != e && (/\S/).test(e)) {
      le = e;
      for (var i in ps) {
        if (m = e.match(ps[i])) {
          this.matcher.push(Object.isFunction(x[i]) ? x[i](m) :
            new Template(x[i]).evaluate(m));
          e = e.replace(m[0], '');
          break;
        }
      }
    }

    this.xpath = this.matcher.join('');
    Selector._cache[this.expression] = this.xpath;
  },

  findElements: function(root) {
    root = root || document;
    if (this.xpath) return document._getElementsByXPath(this.xpath, root);
    return this.matcher(root);
  },

  match: function(element) {
    this.tokens = [];

    var e = this.expression, ps = Selector.patterns, as = Selector.assertions;
    var le, p, m;

    while (e && le !== e && (/\S/).test(e)) {
      le = e;
      for (var i in ps) {
        p = ps[i];
        if (m = e.match(p)) {
          // use the Selector.assertions methods unless the selector
          // is too complex.
          if (as[i]) {
            this.tokens.push([i, Object.clone(m)]);
            e = e.replace(m[0], '');
          } else {
            // reluctantly do a document-wide search
            // and look for a match in the array
            return this.findElements(document).include(element);
          }
        }
      }
    }

    var match = true, name, matches;
    for (var i = 0, token; token = this.tokens[i]; i++) {
      name = token[0], matches = token[1];
      if (!Selector.assertions[name](element, matches)) {
        match = false; break;
      }
    }

    return match;
  },

  toString: function() {
    return this.expression;
  },

  inspect: function() {
    return "#<Selector:" + this.expression.inspect() + ">";
  }
});

Object.extend(Selector, {
  _cache: { },

  xpath: {
    descendant:   "//*",
    child:        "/*",
    adjacent:     "/following-sibling::*[1]",
    laterSibling: '/following-sibling::*',
    tagName:      function(m) {
      if (m[1] == '*') return '';
      return "[local-name()='" + m[1].toLowerCase() +
             "' or local-name()='" + m[1].toUpperCase() + "']";
    },
    className:    "[contains(concat(' ', @class, ' '), ' #{1} ')]",
    id:           "[@id='#{1}']",
    attrPresence: "[@#{1}]",
    attr: function(m) {
      m[3] = m[5] || m[6];
      return new Template(Selector.xpath.operators[m[2]]).evaluate(m);
    },
    pseudo: function(m) {
      var h = Selector.xpath.pseudos[m[1]];
      if (!h) return '';
      if (Object.isFunction(h)) return h(m);
      return new Template(Selector.xpath.pseudos[m[1]]).evaluate(m);
    },
    operators: {
      '=':  "[@#{1}='#{3}']",
      '!=': "[@#{1}!='#{3}']",
      '^=': "[starts-with(@#{1}, '#{3}')]",
      '$=': "[substring(@#{1}, (string-length(@#{1}) - string-length('#{3}') + 1))='#{3}']",
      '*=': "[contains(@#{1}, '#{3}')]",
      '~=': "[contains(concat(' ', @#{1}, ' '), ' #{3} ')]",
      '|=': "[contains(concat('-', @#{1}, '-'), '-#{3}-')]"
    },
    pseudos: {
      'first-child': '[not(preceding-sibling::*)]',
      'last-child':  '[not(following-sibling::*)]',
      'only-child':  '[not(preceding-sibling::* or following-sibling::*)]',
      'empty':       "[count(*) = 0 and (count(text()) = 0 or translate(text(), ' \t\r\n', '') = '')]",
      'checked':     "[@checked]",
      'disabled':    "[@disabled]",
      'enabled':     "[not(@disabled)]",
      'not': function(m) {
        var e = m[6], p = Selector.patterns,
            x = Selector.xpath, le, m, v;

        var exclusion = [];
        while (e && le != e && (/\S/).test(e)) {
          le = e;
          for (var i in p) {
            if (m = e.match(p[i])) {
              v = Object.isFunction(x[i]) ? x[i](m) : new Template(x[i]).evaluate(m);
              exclusion.push("(" + v.substring(1, v.length - 1) + ")");
              e = e.replace(m[0], '');
              break;
            }
          }
        }
        return "[not(" + exclusion.join(" and ") + ")]";
      },
      'nth-child':      function(m) {
        return Selector.xpath.pseudos.nth("(count(./preceding-sibling::*) + 1) ", m);
      },
      'nth-last-child': function(m) {
        return Selector.xpath.pseudos.nth("(count(./following-sibling::*) + 1) ", m);
      },
      'nth-of-type':    function(m) {
        return Selector.xpath.pseudos.nth("position() ", m);
      },
      'nth-last-of-type': function(m) {
        return Selector.xpath.pseudos.nth("(last() + 1 - position()) ", m);
      },
      'first-of-type':  function(m) {
        m[6] = "1"; return Selector.xpath.pseudos['nth-of-type'](m);
      },
      'last-of-type':   function(m) {
        m[6] = "1"; return Selector.xpath.pseudos['nth-last-of-type'](m);
      },
      'only-of-type':   function(m) {
        var p = Selector.xpath.pseudos; return p['first-of-type'](m) + p['last-of-type'](m);
      },
      nth: function(fragment, m) {
        var mm, formula = m[6], predicate;
        if (formula == 'even') formula = '2n+0';
        if (formula == 'odd')  formula = '2n+1';
        if (mm = formula.match(/^(\d+)$/)) // digit only
          return '[' + fragment + "= " + mm[1] + ']';
        if (mm = formula.match(/^(-?\d*)?n(([+-])(\d+))?/)) { // an+b
          if (mm[1] == "-") mm[1] = -1;
          var a = mm[1] ? Number(mm[1]) : 1;
          var b = mm[2] ? Number(mm[2]) : 0;
          predicate = "[((#{fragment} - #{b}) mod #{a} = 0) and " +
          "((#{fragment} - #{b}) div #{a} >= 0)]";
          return new Template(predicate).evaluate({
            fragment: fragment, a: a, b: b });
        }
      }
    }
  },

  criteria: {
    tagName:      'n = h.tagName(n, r, "#{1}", c);   c = false;',
    className:    'n = h.className(n, r, "#{1}", c); c = false;',
    id:           'n = h.id(n, r, "#{1}", c);        c = false;',
    attrPresence: 'n = h.attrPresence(n, r, "#{1}"); c = false;',
    attr: function(m) {
      m[3] = (m[5] || m[6]);
      return new Template('n = h.attr(n, r, "#{1}", "#{3}", "#{2}"); c = false;').evaluate(m);
    },
    pseudo: function(m) {
      if (m[6]) m[6] = m[6].replace(/"/g, '\\"');
      return new Template('n = h.pseudo(n, "#{1}", "#{6}", r, c); c = false;').evaluate(m);
    },
    descendant:   'c = "descendant";',
    child:        'c = "child";',
    adjacent:     'c = "adjacent";',
    laterSibling: 'c = "laterSibling";'
  },

  patterns: {
    // combinators must be listed first
    // (and descendant needs to be last combinator)
    laterSibling: /^\s*~\s*/,
    child:        /^\s*>\s*/,
    adjacent:     /^\s*\+\s*/,
    descendant:   /^\s/,

    // selectors follow
    tagName:      /^\s*(\*|[\w\-]+)(\b|$)?/,
    id:           /^#([\w\-\*]+)(\b|$)/,
    className:    /^\.([\w\-\*]+)(\b|$)/,
    pseudo:       /^:((first|last|nth|nth-last|only)(-child|-of-type)|empty|checked|(en|dis)abled|not)(\((.*?)\))?(\b|$|(?=\s)|(?=:))/,
    attrPresence: /^\[([\w]+)\]/,
    attr:         /\[((?:[\w-]*:)?[\w-]+)\s*(?:([!^$*~|]?=)\s*((['"])([^\4]*?)\4|([^'"][^\]]*?)))?\]/
  },

  // for Selector.match and Element#match
  assertions: {
    tagName: function(element, matches) {
      return matches[1].toUpperCase() == element.tagName.toUpperCase();
    },

    className: function(element, matches) {
      return Element.hasClassName(element, matches[1]);
    },

    id: function(element, matches) {
      return element.id === matches[1];
    },

    attrPresence: function(element, matches) {
      return Element.hasAttribute(element, matches[1]);
    },

    attr: function(element, matches) {
      var nodeValue = Element.readAttribute(element, matches[1]);
      return Selector.operators[matches[2]](nodeValue, matches[3]);
    }
  },

  handlers: {
    // UTILITY FUNCTIONS
    // joins two collections
    concat: function(a, b) {
      for (var i = 0, node; node = b[i]; i++)
        a.push(node);
      return a;
    },

    // marks an array of nodes for counting
    mark: function(nodes) {
      for (var i = 0, node; node = nodes[i]; i++)
        node._counted = true;
      return nodes;
    },

    unmark: function(nodes) {
      for (var i = 0, node; node = nodes[i]; i++)
        node._counted = undefined;
      return nodes;
    },

    // mark each child node with its position (for nth calls)
    // "ofType" flag indicates whether we're indexing for nth-of-type
    // rather than nth-child
    index: function(parentNode, reverse, ofType) {
      parentNode._counted = true;
      if (reverse) {
        for (var nodes = parentNode.childNodes, i = nodes.length - 1, j = 1; i >= 0; i--) {
          var node = nodes[i];
          if (node.nodeType == 1 && (!ofType || node._counted)) node.nodeIndex = j++;
        }
      } else {
        for (var i = 0, j = 1, nodes = parentNode.childNodes; node = nodes[i]; i++)
          if (node.nodeType == 1 && (!ofType || node._counted)) node.nodeIndex = j++;
      }
    },

    // filters out duplicates and extends all nodes
    unique: function(nodes) {
      if (nodes.length == 0) return nodes;
      var results = [], n;
      for (var i = 0, l = nodes.length; i < l; i++)
        if (!(n = nodes[i])._counted) {
          n._counted = true;
          results.push(Element.extend(n));
        }
      return Selector.handlers.unmark(results);
    },

    // COMBINATOR FUNCTIONS
    descendant: function(nodes) {
      var h = Selector.handlers;
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        h.concat(results, node.getElementsByTagName('*'));
      return results;
    },

    child: function(nodes) {
      var h = Selector.handlers;
      for (var i = 0, results = [], node; node = nodes[i]; i++) {
        for (var j = 0, children = [], child; child = node.childNodes[j]; j++)
          if (child.nodeType == 1 && child.tagName != '!') results.push(child);
      }
      return results;
    },

    adjacent: function(nodes) {
      for (var i = 0, results = [], node; node = nodes[i]; i++) {
        var next = this.nextElementSibling(node);
        if (next) results.push(next);
      }
      return results;
    },

    laterSibling: function(nodes) {
      var h = Selector.handlers;
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        h.concat(results, Element.nextSiblings(node));
      return results;
    },

    nextElementSibling: function(node) {
      while (node = node.nextSibling)
	      if (node.nodeType == 1) return node;
      return null;
    },

    previousElementSibling: function(node) {
      while (node = node.previousSibling)
        if (node.nodeType == 1) return node;
      return null;
    },

    // TOKEN FUNCTIONS
    tagName: function(nodes, root, tagName, combinator) {
      tagName = tagName.toUpperCase();
      var results = [], h = Selector.handlers;
      if (nodes) {
        if (combinator) {
          // fastlane for ordinary descendant combinators
          if (combinator == "descendant") {
            for (var i = 0, node; node = nodes[i]; i++)
              h.concat(results, node.getElementsByTagName(tagName));
            return results;
          } else nodes = this[combinator](nodes);
          if (tagName == "*") return nodes;
        }
        for (var i = 0, node; node = nodes[i]; i++)
          if (node.tagName.toUpperCase() == tagName) results.push(node);
        return results;
      } else return root.getElementsByTagName(tagName);
    },

    id: function(nodes, root, id, combinator) {
      var targetNode = $(id), h = Selector.handlers;
      if (!targetNode) return [];
      if (!nodes && root == document) return [targetNode];
      if (nodes) {
        if (combinator) {
          if (combinator == 'child') {
            for (var i = 0, node; node = nodes[i]; i++)
              if (targetNode.parentNode == node) return [targetNode];
          } else if (combinator == 'descendant') {
            for (var i = 0, node; node = nodes[i]; i++)
              if (Element.descendantOf(targetNode, node)) return [targetNode];
          } else if (combinator == 'adjacent') {
            for (var i = 0, node; node = nodes[i]; i++)
              if (Selector.handlers.previousElementSibling(targetNode) == node)
                return [targetNode];
          } else nodes = h[combinator](nodes);
        }
        for (var i = 0, node; node = nodes[i]; i++)
          if (node == targetNode) return [targetNode];
        return [];
      }
      return (targetNode && Element.descendantOf(targetNode, root)) ? [targetNode] : [];
    },

    className: function(nodes, root, className, combinator) {
      if (nodes && combinator) nodes = this[combinator](nodes);
      return Selector.handlers.byClassName(nodes, root, className);
    },

    byClassName: function(nodes, root, className) {
      if (!nodes) nodes = Selector.handlers.descendant([root]);
      var needle = ' ' + className + ' ';
      for (var i = 0, results = [], node, nodeClassName; node = nodes[i]; i++) {
        nodeClassName = node.className;
        if (nodeClassName.length == 0) continue;
        if (nodeClassName == className || (' ' + nodeClassName + ' ').include(needle))
          results.push(node);
      }
      return results;
    },

    attrPresence: function(nodes, root, attr) {
      if (!nodes) nodes = root.getElementsByTagName("*");
      var results = [];
      for (var i = 0, node; node = nodes[i]; i++)
        if (Element.hasAttribute(node, attr)) results.push(node);
      return results;
    },

    attr: function(nodes, root, attr, value, operator) {
      if (!nodes) nodes = root.getElementsByTagName("*");
      var handler = Selector.operators[operator], results = [];
      for (var i = 0, node; node = nodes[i]; i++) {
        var nodeValue = Element.readAttribute(node, attr);
        if (nodeValue === null) continue;
        if (handler(nodeValue, value)) results.push(node);
      }
      return results;
    },

    pseudo: function(nodes, name, value, root, combinator) {
      if (nodes && combinator) nodes = this[combinator](nodes);
      if (!nodes) nodes = root.getElementsByTagName("*");
      return Selector.pseudos[name](nodes, value, root);
    }
  },

  pseudos: {
    'first-child': function(nodes, value, root) {
      for (var i = 0, results = [], node; node = nodes[i]; i++) {
        if (Selector.handlers.previousElementSibling(node)) continue;
          results.push(node);
      }
      return results;
    },
    'last-child': function(nodes, value, root) {
      for (var i = 0, results = [], node; node = nodes[i]; i++) {
        if (Selector.handlers.nextElementSibling(node)) continue;
          results.push(node);
      }
      return results;
    },
    'only-child': function(nodes, value, root) {
      var h = Selector.handlers;
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        if (!h.previousElementSibling(node) && !h.nextElementSibling(node))
          results.push(node);
      return results;
    },
    'nth-child':        function(nodes, formula, root) {
      return Selector.pseudos.nth(nodes, formula, root);
    },
    'nth-last-child':   function(nodes, formula, root) {
      return Selector.pseudos.nth(nodes, formula, root, true);
    },
    'nth-of-type':      function(nodes, formula, root) {
      return Selector.pseudos.nth(nodes, formula, root, false, true);
    },
    'nth-last-of-type': function(nodes, formula, root) {
      return Selector.pseudos.nth(nodes, formula, root, true, true);
    },
    'first-of-type':    function(nodes, formula, root) {
      return Selector.pseudos.nth(nodes, "1", root, false, true);
    },
    'last-of-type':     function(nodes, formula, root) {
      return Selector.pseudos.nth(nodes, "1", root, true, true);
    },
    'only-of-type':     function(nodes, formula, root) {
      var p = Selector.pseudos;
      return p['last-of-type'](p['first-of-type'](nodes, formula, root), formula, root);
    },

    // handles the an+b logic
    getIndices: function(a, b, total) {
      if (a == 0) return b > 0 ? [b] : [];
      return $R(1, total).inject([], function(memo, i) {
        if (0 == (i - b) % a && (i - b) / a >= 0) memo.push(i);
        return memo;
      });
    },

    // handles nth(-last)-child, nth(-last)-of-type, and (first|last)-of-type
    nth: function(nodes, formula, root, reverse, ofType) {
      if (nodes.length == 0) return [];
      if (formula == 'even') formula = '2n+0';
      if (formula == 'odd')  formula = '2n+1';
      var h = Selector.handlers, results = [], indexed = [], m;
      h.mark(nodes);
      for (var i = 0, node; node = nodes[i]; i++) {
        if (!node.parentNode._counted) {
          h.index(node.parentNode, reverse, ofType);
          indexed.push(node.parentNode);
        }
      }
      if (formula.match(/^\d+$/)) { // just a number
        formula = Number(formula);
        for (var i = 0, node; node = nodes[i]; i++)
          if (node.nodeIndex == formula) results.push(node);
      } else if (m = formula.match(/^(-?\d*)?n(([+-])(\d+))?/)) { // an+b
        if (m[1] == "-") m[1] = -1;
        var a = m[1] ? Number(m[1]) : 1;
        var b = m[2] ? Number(m[2]) : 0;
        var indices = Selector.pseudos.getIndices(a, b, nodes.length);
        for (var i = 0, node, l = indices.length; node = nodes[i]; i++) {
          for (var j = 0; j < l; j++)
            if (node.nodeIndex == indices[j]) results.push(node);
        }
      }
      h.unmark(nodes);
      h.unmark(indexed);
      return results;
    },

    'empty': function(nodes, value, root) {
      for (var i = 0, results = [], node; node = nodes[i]; i++) {
        // IE treats comments as element nodes
        if (node.tagName == '!' || (node.firstChild && !node.innerHTML.match(/^\s*$/))) continue;
        results.push(node);
      }
      return results;
    },

    'not': function(nodes, selector, root) {
      var h = Selector.handlers, selectorType, m;
      var exclusions = new Selector(selector).findElements(root);
      h.mark(exclusions);
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        if (!node._counted) results.push(node);
      h.unmark(exclusions);
      return results;
    },

    'enabled': function(nodes, value, root) {
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        if (!node.disabled) results.push(node);
      return results;
    },

    'disabled': function(nodes, value, root) {
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        if (node.disabled) results.push(node);
      return results;
    },

    'checked': function(nodes, value, root) {
      for (var i = 0, results = [], node; node = nodes[i]; i++)
        if (node.checked) results.push(node);
      return results;
    }
  },

  operators: {
    '=':  function(nv, v) { return nv == v; },
    '!=': function(nv, v) { return nv != v; },
    '^=': function(nv, v) { return nv.startsWith(v); },
    '$=': function(nv, v) { return nv.endsWith(v); },
    '*=': function(nv, v) { return nv.include(v); },
    '~=': function(nv, v) { return (' ' + nv + ' ').include(' ' + v + ' '); },
    '|=': function(nv, v) { return ('-' + nv.toUpperCase() + '-').include('-' + v.toUpperCase() + '-'); }
  },

  matchElements: function(elements, expression) {
    var matches = new Selector(expression).findElements(), h = Selector.handlers;
    h.mark(matches);
    for (var i = 0, results = [], element; element = elements[i]; i++)
      if (element._counted) results.push(element);
    h.unmark(matches);
    return results;
  },

  findElement: function(elements, expression, index) {
    if (Object.isNumber(expression)) {
      index = expression; expression = false;
    }
    return Selector.matchElements(elements, expression || '*')[index || 0];
  },

  findChildElements: function(element, expressions) {
    var exprs = expressions.join(','), expressions = [];
    exprs.scan(/(([\w#:.~>+()\s-]+|\*|\[.*?\])+)\s*(,|$)/, function(m) {
      expressions.push(m[1].strip());
    });
    var results = [], h = Selector.handlers;
    for (var i = 0, l = expressions.length, selector; i < l; i++) {
      selector = new Selector(expressions[i].strip());
      h.concat(results, selector.findElements(element));
    }
    return (l > 1) ? h.unique(results) : results;
  }
});

function $$() {
  return Selector.findChildElements(document, $A(arguments));
}
var Form = {
  reset: function(form) {
    $(form).reset();
    return form;
  },

  serializeElements: function(elements, options) {
    if (typeof options != 'object') options = { hash: !!options };
    else if (options.hash === undefined) options.hash = true;
    var key, value, submitted = false, submit = options.submit;

    var data = elements.inject({ }, function(result, element) {
      if (!element.disabled && element.name) {
        key = element.name; value = $(element).getValue();
        if (value != null && (element.type != 'submit' || (!submitted &&
            submit !== false && (!submit || key == submit) && (submitted = true)))) {
          if (key in result) {
            // a key is already present; construct an array of values
            if (!Object.isArray(result[key])) result[key] = [result[key]];
            result[key].push(value);
          }
          else result[key] = value;
        }
      }
      return result;
    });

    return options.hash ? data : Object.toQueryString(data);
  }
};

Form.Methods = {
  serialize: function(form, options) {
    return Form.serializeElements(Form.getElements(form), options);
  },

  getElements: function(form) {
    return $A($(form).getElementsByTagName('*')).inject([],
      function(elements, child) {
        if (Form.Element.Serializers[child.tagName.toLowerCase()])
          elements.push(Element.extend(child));
        return elements;
      }
    );
  },

  getInputs: function(form, typeName, name) {
    form = $(form);
    var inputs = form.getElementsByTagName('input');

    if (!typeName && !name) return $A(inputs).map(Element.extend);

    for (var i = 0, matchingInputs = [], length = inputs.length; i < length; i++) {
      var input = inputs[i];
      if ((typeName && input.type != typeName) || (name && input.name != name))
        continue;
      matchingInputs.push(Element.extend(input));
    }

    return matchingInputs;
  },

  disable: function(form) {
    form = $(form);
    Form.getElements(form).invoke('disable');
    return form;
  },

  enable: function(form) {
    form = $(form);
    Form.getElements(form).invoke('enable');
    return form;
  },

  findFirstElement: function(form) {
    var elements = $(form).getElements().findAll(function(element) {
      return 'hidden' != element.type && !element.disabled;
    });
    var firstByIndex = elements.findAll(function(element) {
      return element.hasAttribute('tabIndex') && element.tabIndex >= 0;
    }).sortBy(function(element) { return element.tabIndex }).first();

    return firstByIndex ? firstByIndex : elements.find(function(element) {
      return ['input', 'select', 'textarea'].include(element.tagName.toLowerCase());
    });
  },

  focusFirstElement: function(form) {
    form = $(form);
    form.findFirstElement().activate();
    return form;
  },

  request: function(form, options) {
    form = $(form), options = Object.clone(options || { });

    var params = options.parameters, action = form.readAttribute('action') || '';
    if (action.blank()) action = window.location.href;
    options.parameters = form.serialize(true);

    if (params) {
      if (Object.isString(params)) params = params.toQueryParams();
      Object.extend(options.parameters, params);
    }

    if (form.hasAttribute('method') && !options.method)
      options.method = form.method;

    return new Ajax.Request(action, options);
  }
};

/*--------------------------------------------------------------------------*/

Form.Element = {
  focus: function(element) {
    $(element).focus();
    return element;
  },

  select: function(element) {
    $(element).select();
    return element;
  }
};

Form.Element.Methods = {
  serialize: function(element) {
    element = $(element);
    if (!element.disabled && element.name) {
      var value = element.getValue();
      if (value != undefined) {
        var pair = { };
        pair[element.name] = value;
        return Object.toQueryString(pair);
      }
    }
    return '';
  },

  getValue: function(element) {
    element = $(element);
    var method = element.tagName.toLowerCase();
    return Form.Element.Serializers[method](element);
  },

  setValue: function(element, value) {
    element = $(element);
    var method = element.tagName.toLowerCase();
    Form.Element.Serializers[method](element, value);
    return element;
  },

  clear: function(element) {
    $(element).value = '';
    return element;
  },

  present: function(element) {
    return $(element).value != '';
  },

  activate: function(element) {
    element = $(element);
    try {
      element.focus();
      if (element.select && (element.tagName.toLowerCase() != 'input' ||
          !['button', 'reset', 'submit'].include(element.type)))
        element.select();
    } catch (e) { }
    return element;
  },

  disable: function(element) {
    element = $(element);
    element.blur();
    element.disabled = true;
    return element;
  },

  enable: function(element) {
    element = $(element);
    element.disabled = false;
    return element;
  }
};

/*--------------------------------------------------------------------------*/

var Field = Form.Element;
var $F = Form.Element.Methods.getValue;

/*--------------------------------------------------------------------------*/

Form.Element.Serializers = {
  input: function(element, value) {
    switch (element.type.toLowerCase()) {
      case 'checkbox':
      case 'radio':
        return Form.Element.Serializers.inputSelector(element, value);
      default:
        return Form.Element.Serializers.textarea(element, value);
    }
  },

  inputSelector: function(element, value) {
    if (value === undefined) return element.checked ? element.value : null;
    else element.checked = !!value;
  },

  textarea: function(element, value) {
    if (value === undefined) return element.value;
    else element.value = value;
  },

  select: function(element, index) {
    if (index === undefined)
      return this[element.type == 'select-one' ?
        'selectOne' : 'selectMany'](element);
    else {
      var opt, value, single = !Object.isArray(index);
      for (var i = 0, length = element.length; i < length; i++) {
        opt = element.options[i];
        value = this.optionValue(opt);
        if (single) {
          if (value == index) {
            opt.selected = true;
            return;
          }
        }
        else opt.selected = index.include(value);
      }
    }
  },

  selectOne: function(element) {
    var index = element.selectedIndex;
    return index >= 0 ? this.optionValue(element.options[index]) : null;
  },

  selectMany: function(element) {
    var values, length = element.length;
    if (!length) return null;

    for (var i = 0, values = []; i < length; i++) {
      var opt = element.options[i];
      if (opt.selected) values.push(this.optionValue(opt));
    }
    return values;
  },

  optionValue: function(opt) {
    // extend element because hasAttribute may not be native
    return Element.extend(opt).hasAttribute('value') ? opt.value : opt.text;
  }
};

/*--------------------------------------------------------------------------*/

Abstract.TimedObserver = Class.create(PeriodicalExecuter, {
  initialize: function($super, element, frequency, callback) {
    $super(callback, frequency);
    this.element   = $(element);
    this.lastValue = this.getValue();
  },

  execute: function() {
    var value = this.getValue();
    if (Object.isString(this.lastValue) && Object.isString(value) ?
        this.lastValue != value : String(this.lastValue) != String(value)) {
      this.callback(this.element, value);
      this.lastValue = value;
    }
  }
});

Form.Element.Observer = Class.create(Abstract.TimedObserver, {
  getValue: function() {
    return Form.Element.getValue(this.element);
  }
});

Form.Observer = Class.create(Abstract.TimedObserver, {
  getValue: function() {
    return Form.serialize(this.element);
  }
});

/*--------------------------------------------------------------------------*/

Abstract.EventObserver = Class.create({
  initialize: function(element, callback) {
    this.element  = $(element);
    this.callback = callback;

    this.lastValue = this.getValue();
    if (this.element.tagName.toLowerCase() == 'form')
      this.registerFormCallbacks();
    else
      this.registerCallback(this.element);
  },

  onElementEvent: function() {
    var value = this.getValue();
    if (this.lastValue != value) {
      this.callback(this.element, value);
      this.lastValue = value;
    }
  },

  registerFormCallbacks: function() {
    Form.getElements(this.element).each(this.registerCallback, this);
  },

  registerCallback: function(element) {
    if (element.type) {
      switch (element.type.toLowerCase()) {
        case 'checkbox':
        case 'radio':
          Event.observe(element, 'click', this.onElementEvent.bind(this));
          break;
        default:
          Event.observe(element, 'change', this.onElementEvent.bind(this));
          break;
      }
    }
  }
});

Form.Element.EventObserver = Class.create(Abstract.EventObserver, {
  getValue: function() {
    return Form.Element.getValue(this.element);
  }
});

Form.EventObserver = Class.create(Abstract.EventObserver, {
  getValue: function() {
    return Form.serialize(this.element);
  }
});
if (!window.Event) var Event = { };

Object.extend(Event, {
  KEY_BACKSPACE: 8,
  KEY_TAB:       9,
  KEY_RETURN:   13,
  KEY_ESC:      27,
  KEY_LEFT:     37,
  KEY_UP:       38,
  KEY_RIGHT:    39,
  KEY_DOWN:     40,
  KEY_DELETE:   46,
  KEY_HOME:     36,
  KEY_END:      35,
  KEY_PAGEUP:   33,
  KEY_PAGEDOWN: 34,
  KEY_INSERT:   45,

  cache: { },

  relatedTarget: function(event) {
    var element;
    switch(event.type) {
      case 'mouseover': element = event.fromElement; break;
      case 'mouseout':  element = event.toElement;   break;
      default: return null;
    }
    return Element.extend(element);
  }
});

Event.Methods = (function() {
  var isButton;

  if (Prototype.Browser.IE) {
    var buttonMap = { 0: 1, 1: 4, 2: 2 };
    isButton = function(event, code) {
      return event.button == buttonMap[code];
    };

  } else if (Prototype.Browser.WebKit) {
    isButton = function(event, code) {
      switch (code) {
        case 0: return event.which == 1 && !event.metaKey;
        case 1: return event.which == 1 && event.metaKey;
        default: return false;
      }
    };

  } else {
    isButton = function(event, code) {
      return event.which ? (event.which === code + 1) : (event.button === code);
    };
  }

  return {
    isLeftClick:   function(event) { return isButton(event, 0) },
    isMiddleClick: function(event) { return isButton(event, 1) },
    isRightClick:  function(event) { return isButton(event, 2) },

    element: function(event) {
      var node = Event.extend(event).target;
      return Element.extend(node.nodeType == Node.TEXT_NODE ? node.parentNode : node);
    },

    findElement: function(event, expression) {
      var element = Event.element(event);
      return element.match(expression) ? element : element.up(expression);
    },

    pointer: function(event) {
      return {
        x: event.pageX || (event.clientX +
          (document.documentElement.scrollLeft || document.body.scrollLeft)),
        y: event.pageY || (event.clientY +
          (document.documentElement.scrollTop || document.body.scrollTop))
      };
    },

    pointerX: function(event) { return Event.pointer(event).x },
    pointerY: function(event) { return Event.pointer(event).y },

    stop: function(event) {
      Event.extend(event);
      event.preventDefault();
      event.stopPropagation();
      event.stopped = true;
    }
  };
})();

Event.extend = (function() {
  var methods = Object.keys(Event.Methods).inject({ }, function(m, name) {
    m[name] = Event.Methods[name].methodize();
    return m;
  });

  if (Prototype.Browser.IE) {
    Object.extend(methods, {
      stopPropagation: function() { this.cancelBubble = true },
      preventDefault:  function() { this.returnValue = false },
      inspect: function() { return "[object Event]" }
    });

    return function(event) {
      if (!event) return false;
      if (event._extendedByPrototype) return event;

      event._extendedByPrototype = Prototype.emptyFunction;
      var pointer = Event.pointer(event);
      Object.extend(event, {
        target: event.srcElement,
        relatedTarget: Event.relatedTarget(event),
        pageX:  pointer.x,
        pageY:  pointer.y
      });
      return Object.extend(event, methods);
    };

  } else {
    Event.prototype = Event.prototype || document.createEvent("HTMLEvents").__proto__;
    Object.extend(Event.prototype, methods);
    return Prototype.K;
  }
})();

Object.extend(Event, (function() {
  var cache = Event.cache;

  function getEventID(element) {
    if (element._eventID) return element._eventID;
    arguments.callee.id = arguments.callee.id || 1;
    return element._eventID = ++arguments.callee.id;
  }

  function getDOMEventName(eventName) {
    if (eventName && eventName.include(':')) return "dataavailable";
    return eventName;
  }

  function getCacheForID(id) {
    return cache[id] = cache[id] || { };
  }

  function getWrappersForEventName(id, eventName) {
    var c = getCacheForID(id);
    return c[eventName] = c[eventName] || [];
  }

  function createWrapper(element, eventName, handler) {
    var id = getEventID(element);
    var c = getWrappersForEventName(id, eventName);
    if (c.pluck("handler").include(handler)) return false;

    var wrapper = function(event) {
      if (!Event || !Event.extend ||
        (event.eventName && event.eventName != eventName))
          return false;

      Event.extend(event);
      handler.call(element, event)
    };

    wrapper.handler = handler;
    c.push(wrapper);
    return wrapper;
  }

  function findWrapper(id, eventName, handler) {
    var c = getWrappersForEventName(id, eventName);
    return c.find(function(wrapper) { return wrapper.handler == handler });
  }

  function destroyWrapper(id, eventName, handler) {
    var c = getCacheForID(id);
    if (!c[eventName]) return false;
    c[eventName] = c[eventName].without(findWrapper(id, eventName, handler));
  }

  function destroyCache() {
    for (var id in cache)
      for (var eventName in cache[id])
        cache[id][eventName] = null;
  }

  if (window.attachEvent) {
    window.attachEvent("onunload", destroyCache);
  }

  return {
    observe: function(element, eventName, handler) {
      element = $(element);
      var name = getDOMEventName(eventName);

      var wrapper = createWrapper(element, eventName, handler);
      if (!wrapper) return element;

      if (element.addEventListener) {
        element.addEventListener(name, wrapper, false);
      } else {
        element.attachEvent("on" + name, wrapper);
      }

      return element;
    },

    stopObserving: function(element, eventName, handler) {
      element = $(element);
      var id = getEventID(element), name = getDOMEventName(eventName);

      if (!handler && eventName) {
        getWrappersForEventName(id, eventName).each(function(wrapper) {
          element.stopObserving(eventName, wrapper.handler);
        });
        return element;

      } else if (!eventName) {
        Object.keys(getCacheForID(id)).each(function(eventName) {
          element.stopObserving(eventName);
        });
        return element;
      }

      var wrapper = findWrapper(id, eventName, handler);
      if (!wrapper) return element;

      if (element.removeEventListener) {
        element.removeEventListener(name, wrapper, false);
      } else {
        element.detachEvent("on" + name, wrapper);
      }

      destroyWrapper(id, eventName, handler);

      return element;
    },

    fire: function(element, eventName, memo) {
      element = $(element);
      if (element == document && document.createEvent && !element.dispatchEvent)
        element = document.documentElement;

      if (document.createEvent) {
        var event = document.createEvent("HTMLEvents");
        event.initEvent("dataavailable", true, true);
      } else {
        var event = document.createEventObject();
        event.eventType = "ondataavailable";
      }

      event.eventName = eventName;
      event.memo = memo || { };

      if (document.createEvent) {
        element.dispatchEvent(event);
      } else {
        element.fireEvent(event.eventType, event);
      }

      return event;
    }
  };
})());

Object.extend(Event, Event.Methods);

Element.addMethods({
  fire:          Event.fire,
  observe:       Event.observe,
  stopObserving: Event.stopObserving
});

Object.extend(document, {
  fire:          Element.Methods.fire.methodize(),
  observe:       Element.Methods.observe.methodize(),
  stopObserving: Element.Methods.stopObserving.methodize()
});

(function() {
  /* Support for the DOMContentLoaded event is based on work by Dan Webb,
     Matthias Miller, Dean Edwards and John Resig. */

  var timer, fired = false;

  function fireContentLoadedEvent() {
    if (fired) return;
    if (timer) window.clearInterval(timer);
    document.fire("dom:loaded");
    fired = true;
  }

  if (document.addEventListener) {
    if (Prototype.Browser.WebKit) {
      timer = window.setInterval(function() {
        if (/loaded|complete/.test(document.readyState))
          fireContentLoadedEvent();
      }, 0);

      Event.observe(window, "load", fireContentLoadedEvent);

    } else {
      document.addEventListener("DOMContentLoaded",
        fireContentLoadedEvent, false);
    }

  } else {
    document.write("<script id=__onDOMContentLoaded defer src=//:><\/script>");
    $("__onDOMContentLoaded").onreadystatechange = function() {
      if (this.readyState == "complete") {
        this.onreadystatechange = null;
        fireContentLoadedEvent();
      }
    };
  }
})();
/*------------------------------- DEPRECATED -------------------------------*/

Hash.toQueryString = Object.toQueryString;

var Toggle = { display: Element.toggle };

Element.Methods.childOf = Element.Methods.descendantOf;

var Insertion = {
  Before: function(element, content) {
    return Element.insert(element, {before:content});
  },

  Top: function(element, content) {
    return Element.insert(element, {top:content});
  },

  Bottom: function(element, content) {
    return Element.insert(element, {bottom:content});
  },

  After: function(element, content) {
    return Element.insert(element, {after:content});
  }
};

var $continue = new Error('"throw $continue" is deprecated, use "return" instead');

// This should be moved to script.aculo.us; notice the deprecated methods
// further below, that map to the newer Element methods.
var Position = {
  // set to true if needed, warning: firefox performance problems
  // NOT neeeded for page scrolling, only if draggable contained in
  // scrollable elements
  includeScrollOffsets: false,

  // must be called before calling withinIncludingScrolloffset, every time the
  // page is scrolled
  prepare: function() {
    this.deltaX =  window.pageXOffset
                || document.documentElement.scrollLeft
                || document.body.scrollLeft
                || 0;
    this.deltaY =  window.pageYOffset
                || document.documentElement.scrollTop
                || document.body.scrollTop
                || 0;
  },

  // caches x/y coordinate pair to use with overlap
  within: function(element, x, y) {
    if (this.includeScrollOffsets)
      return this.withinIncludingScrolloffsets(element, x, y);
    this.xcomp = x;
    this.ycomp = y;
    this.offset = Element.cumulativeOffset(element);

    return (y >= this.offset[1] &&
            y <  this.offset[1] + element.offsetHeight &&
            x >= this.offset[0] &&
            x <  this.offset[0] + element.offsetWidth);
  },

  withinIncludingScrolloffsets: function(element, x, y) {
    var offsetcache = Element.cumulativeScrollOffset(element);

    this.xcomp = x + offsetcache[0] - this.deltaX;
    this.ycomp = y + offsetcache[1] - this.deltaY;
    this.offset = Element.cumulativeOffset(element);

    return (this.ycomp >= this.offset[1] &&
            this.ycomp <  this.offset[1] + element.offsetHeight &&
            this.xcomp >= this.offset[0] &&
            this.xcomp <  this.offset[0] + element.offsetWidth);
  },

  // within must be called directly before
  overlap: function(mode, element) {
    if (!mode) return 0;
    if (mode == 'vertical')
      return ((this.offset[1] + element.offsetHeight) - this.ycomp) /
        element.offsetHeight;
    if (mode == 'horizontal')
      return ((this.offset[0] + element.offsetWidth) - this.xcomp) /
        element.offsetWidth;
  },

  // Deprecation layer -- use newer Element methods now (1.5.2).

  cumulativeOffset: Element.Methods.cumulativeOffset,

  positionedOffset: Element.Methods.positionedOffset,

  absolutize: function(element) {
    Position.prepare();
    return Element.absolutize(element);
  },

  relativize: function(element) {
    Position.prepare();
    return Element.relativize(element);
  },

  realOffset: Element.Methods.cumulativeScrollOffset,

  offsetParent: Element.Methods.getOffsetParent,

  page: Element.Methods.viewportOffset,

  clone: function(source, target, options) {
    options = options || { };
    return Element.clonePosition(target, source, options);
  }
};

/*--------------------------------------------------------------------------*/

if (!document.getElementsByClassName) document.getElementsByClassName = function(instanceMethods){
  function iter(name) {
    return name.blank() ? null : "[contains(concat(' ', @class, ' '), ' " + name + " ')]";
  }

  instanceMethods.getElementsByClassName = Prototype.BrowserFeatures.XPath ?
  function(element, className) {
    className = className.toString().strip();
    var cond = /\s/.test(className) ? $w(className).map(iter).join('') : iter(className);
    return cond ? document._getElementsByXPath('.//*' + cond, element) : [];
  } : function(element, className) {
    className = className.toString().strip();
    var elements = [], classNames = (/\s/.test(className) ? $w(className) : null);
    if (!classNames && !className) return elements;

    var nodes = $(element).getElementsByTagName('*');
    className = ' ' + className + ' ';

    for (var i = 0, child, cn; child = nodes[i]; i++) {
      if (child.className && (cn = ' ' + child.className + ' ') && (cn.include(className) ||
          (classNames && classNames.all(function(name) {
            return !name.toString().blank() && cn.include(' ' + name + ' ');
          }))))
        elements.push(Element.extend(child));
    }
    return elements;
  };

  return function(className, parentElement) {
    return $(parentElement || document.body).getElementsByClassName(className);
  };
}(Element.Methods);

/*--------------------------------------------------------------------------*/

Element.ClassNames = Class.create();
Element.ClassNames.prototype = {
  initialize: function(element) {
    this.element = $(element);
  },

  _each: function(iterator) {
    this.element.className.split(/\s+/).select(function(name) {
      return name.length > 0;
    })._each(iterator);
  },

  set: function(className) {
    this.element.className = className;
  },

  add: function(classNameToAdd) {
    if (this.include(classNameToAdd)) return;
    this.set($A(this).concat(classNameToAdd).join(' '));
  },

  remove: function(classNameToRemove) {
    if (!this.include(classNameToRemove)) return;
    this.set($A(this).without(classNameToRemove).join(' '));
  },

  toString: function() {
    return $A(this).join(' ');
  }
};

Object.extend(Element.ClassNames.prototype, Enumerable);

/*--------------------------------------------------------------------------*/

Element.addMethods();

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License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


Written By
Architect BT, UK (ex British Telecom)
United Kingdom United Kingdom

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