tion(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 = typeof x[i] == 'function' ? 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|([^'"][^\]]*?)))?\]/
  },

  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--) {
          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 (!nodes && root == document) return targetNode ? [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) {
      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 (typeof expression == 'number') {
      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, getHash) {
    var data = elements.inject({}, function(result, element) {
      if (!element.disabled && element.name) {
        var key = element.name, value = $(element).getValue();
        if (value != null) {
         	if (key in result) {
            if (result[key].constructor != Array) result[key] = [result[key]];
            result[key].push(value);
          }
          else result[key] = value;
        }
      }
      return result;
    });

    return getHash ? data : Hash.toQueryString(data);
  }
};

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

  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) {
    return $(form).getElements().find(function(element) {
      return element.type != 'hidden' && !element.disabled &&
        ['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;
    options.parameters = form.serialize(true);

    if (params) {
      if (typeof params == 'string') params = params.toQueryParams();
      Object.extend(options.parameters, params);
    }

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

    return new Ajax.Request(form.readAttribute('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 Hash.toQueryString(pair);
      }
    }
    return '';
  },

  getValue: function(element) {
    element = $(element);
    var method = element.tagName.toLowerCase();
    return Form.Element.Serializers[method](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) {
    switch (element.type.toLowerCase()) {
      case 'checkbox':
      case 'radio':
        return Form.Element.Serializers.inputSelector(element);
      default:
        return Form.Element.Serializers.textarea(element);
    }
  },

  inputSelector: function(element) {
    return element.checked ? element.value : null;
  },

  textarea: function(element) {
    return element.value;
  },

  select: function(element) {
    return this[element.type == 'select-one' ?
      'selectOne' : 'selectMany'](element);
  },

  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 = function() {}
Abstract.TimedObserver.prototype = {
  initialize: function(element, frequency, callback) {
    this.frequency = frequency;
    this.element   = $(element);
    this.callback  = callback;

    this.lastValue = this.getValue();
    this.registerCallback();
  },

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

  onTimerEvent: function() {
    var value = this.getValue();
    var changed = ('string' == typeof this.lastValue && 'string' == typeof value
      ? this.lastValue != value : String(this.lastValue) != String(value));
    if (changed) {
      this.callback(this.element, value);
      this.lastValue = value;
    }
  }
}

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

Form.Observer = Class.create();
Form.Observer.prototype = Object.extend(new Abstract.TimedObserver(), {
  getValu