selector.js

/* 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. */

/** section: DOM
 *  class Selector
 *
 *  A class that queries the document for elements that match a given CSS
 *  selector.
**/
var Selector = Class.create({
  /**
   *  new Selector(expression)
   *  - expression (String): A CSS selector.
   *
   *  Creates a `Selector` with the given CSS selector.
  **/
  initialize: function(expression) {
    this.expression = expression.strip();

    if (this.shouldUseSelectorsAPI()) {
      this.mode = 'selectorsAPI';
    } else if (this.shouldUseXPath()) {
      this.mode = 'xpath';
      this.compileXPathMatcher();
    } else {
      this.mode = "normal";
      this.compileMatcher();
    }

  },

  shouldUseXPath: (function() {

    // Some versions of Opera 9.x produce incorrect results when using XPath
    // with descendant combinators.
    // see: http://opera.remcol.ath.cx/bugs/index.php?action=bug&id=652
    var IS_DESCENDANT_SELECTOR_BUGGY = (function(){
      var isBuggy = false;
      if (document.evaluate && window.XPathResult) {
        var el = document.createElement('div');
        el.innerHTML = '<ul><li></li></ul><div><ul><li></li></ul></div>';

        var xpath = ".//*[local-name()='ul' or local-name()='UL']" +
          "//*[local-name()='li' or local-name()='LI']";

        var result = document.evaluate(xpath, el, null,
          XPathResult.ORDERED_NODE_SNAPSHOT_TYPE, null);

        isBuggy = (result.snapshotLength !== 2);
        el = null;
      }
      return isBuggy;
    })();

    return function() {
      if (!Prototype.BrowserFeatures.XPath) return false;

      var e = this.expression;

      // Safari 3 chokes on :*-of-type and :empty
      if (Prototype.Browser.WebKit &&
       (e.include("-of-type") || e.include(":empty")))
        return false;

      // XPath can't do namespaced attributes, nor can it read
      // the "checked" property from DOM nodes
      if ((/(\[[\w-]*?:|:checked)/).test(e))
        return false;

      if (IS_DESCENDANT_SELECTOR_BUGGY) return false;

      return true;
    }

  })(),

  shouldUseSelectorsAPI: function() {
    if (!Prototype.BrowserFeatures.SelectorsAPI) return false;

    if (Selector.CASE_INSENSITIVE_CLASS_NAMES) return false;

    if (!Selector._div) Selector._div = new Element('div');

    // Make sure the browser treats the selector as valid. Test on an
    // isolated element to minimize cost of this check.
    try {
      Selector._div.querySelector(this.expression);
    } catch(e) {
      return false;
    }

    return true;
  },

  compileMatcher: function() {
    var e = this.expression, ps = Selector.patterns, h = Selector.handlers,
        c = Selector.criteria, le, p, m, len = ps.length, name;

    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 = 0; i<len; i++) {
        p = ps[i].re;
        name = ps[i].name;
        if (m = e.match(p)) {
          this.matcher.push(Object.isFunction(c[name]) ? c[name](m) :
            new Template(c[name]).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, len = ps.length, name;

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

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

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

  /**
   *  Selector#findElements(root) -> [Element...]
   *  - root (Element || document): A "scope" to search within. All results will
   *    be descendants of this node.
   *
   *  Searches the document for elements that match the instance's CSS
   *  selector.
  **/
  findElements: function(root) {
    root = root || document;
    var e = this.expression, results;

    switch (this.mode) {
      case 'selectorsAPI':
        // querySelectorAll queries document-wide, then filters to descendants
        // of the context element. That's not what we want.
        // Add an explicit context to the selector if necessary.
        if (root !== document) {
          var oldId = root.id, id = $(root).identify();
          // Escape special characters in the ID.
          id = id.replace(/([\.:])/g, "\\$1");
          e = "#" + id + " " + e;
        }

        results = $A(root.querySelectorAll(e)).map(Element.extend);
        root.id = oldId;

        return results;
      case 'xpath':
        return document._getElementsByXPath(this.xpath, root);
      default:
       return this.matcher(root);
    }
  },

  /**
   *  Selector#match(element) -> Boolean
   *
   *  Tests whether a `element` matches the instance's CSS selector.
  **/
  match: function(element) {
    this.tokens = [];

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

    while (e && le !== e && (/\S/).test(e)) {
      le = e;
      for (var i = 0; i<len; i++) {
        p = ps[i].re;
        name = ps[i].name;
        if (m = e.match(p)) {
          // use the Selector.assertions methods unless the selector
          // is too complex.
          if (as[name]) {
            this.tokens.push([name, 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() + ">";
  }
});

if (Prototype.BrowserFeatures.SelectorsAPI &&
 document.compatMode === 'BackCompat') {
  // Versions of Safari 3 before 3.1.2 treat class names case-insensitively in
  // quirks mode. If we detect this behavior, we should use a different
  // approach.
  Selector.CASE_INSENSITIVE_CLASS_NAMES = (function(){
    var div = document.createElement('div'),
     span = document.createElement('span');

    div.id = "prototype_test_id";
    span.className = 'Test';
    div.appendChild(span);
    var isIgnored = (div.querySelector('#prototype_test_id .test') !== null);
    div = span = null;
    return isIgnored;
  })();
}

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: function(m) {
      m[1] = m[1].toLowerCase();
      return new Template("[@#{1}]").evaluate(m);
    },
    attr: function(m) {
      m[1] = m[1].toLowerCase();
      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)]",
      'checked':     "[@checked]",
      'disabled':    "[(@disabled) and (@type!='hidden')]",
      'enabled':     "[not(@disabled) and (@type!='hidden')]",
      'not': function(m) {
        var e = m[6], p = Selector.patterns,
            x = Selector.xpath, le, v, len = p.length, name;

        var exclusion = [];
        while (e && le != e && (/\S/).test(e)) {
          le = e;
          for (var i = 0; i<len; i++) {
            name = p[i].name
            if (m = e.match(p[i].re)) {
              v = Object.isFunction(x[name]) ? x[name](m) : new Template(x[name]).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); c = false;',
    attr: function(m) {
      m[3] = (m[5] || m[6]);
      return new Template('n = h.attr(n, r, "#{1}", "#{3}", "#{2}", c); 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)
    { name: 'laterSibling', re: /^\s*~\s*/ },
    { name: 'child',        re: /^\s*>\s*/ },
    { name: 'adjacent',     re: /^\s*\+\s*/ },
    { name: 'descendant',   re: /^\s/ },

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

  // 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 nodeValue && Selector.operators[matches[2]](nodeValue, matches[5] || matches[6]);
    }
  },

  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) {
      var _true = Prototype.emptyFunction;
      for (var i = 0, node; node = nodes[i]; i++)
        node._countedByPrototype = _true;
      return nodes;
    },

    unmark: (function(){

      // IE improperly serializes _countedByPrototype in (inner|outer)HTML
      // due to node properties being mapped directly to attributes
      var PROPERTIES_ATTRIBUTES_MAP = (function(){
        var el = document.createElement('div'),
            isBuggy = false,
            propName = '_countedByPrototype',
            value = 'x'
        el[propName] = value;
        isBuggy = (el.getAttribute(propName) === value);
        el = null;
        return isBuggy;
      })();

      return PROPERTIES_ATTRIBUTES_MAP ?
        function(nodes) {
          for (var i = 0, node; node = nodes[i]; i++)
            node.removeAttribute('_countedByPrototype');
          return nodes;
        } :
        function(nodes) {
          for (var i = 0, node; node = nodes[i]; i++)
            node._countedByPrototype = void 0;
          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._countedByPrototype = Prototype.emptyFunction;
      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._countedByPrototype)) node.nodeIndex = j++;
        }
      } else {
        for (var i = 0, j = 1, nodes = parentNode.childNodes; node = nodes[i]; i++)
          if (node.nodeType == 1 && (!ofType || node._countedByPrototype)) 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++)
        // use `typeof` operator to prevent errors
        if (typeof (n = nodes[i])._countedByPrototype == 'undefined') {
          n._countedByPrototype = Prototype.emptyFunction;
          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, 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) {
      var uTagName = 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() === uTagName) results.push(node);
        return results;
      } else return root.getElementsByTagName(tagName);
    },

    id: function(nodes, root, id, combinator) {
      var targetNode = $(id), h = Selector.handlers;

      if (root == document) {
        // We don't have to deal with orphan nodes. Easy.
        if (!targetNode) return [];
        if (!nodes) return [targetNode];
      } else {
        // In IE, we can check sourceIndex to see if root is attached
        // to the document. If not (or if sourceIndex is not present),
        // we do it the hard way.
        if (!root.sourceIndex || root.sourceIndex < 1) {
          var nodes = root.getElementsByTagName('*');
          for (var j = 0, node; node = nodes[j]; j++) {
            if (node.id === id) return [node];
          }
        }
      }

      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, combinator) {
      if (!nodes) nodes = root.getElementsByTagName("*");
      if (nodes && combinator) nodes = this[combinator](nodes);
      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, combinator) {
      if (!nodes) nodes = root.getElementsByTagName("*");
      if (nodes && combinator) nodes = this[combinator](nodes);
      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._countedByPrototype) {
          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) 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._countedByPrototype) 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 && (!node.type || node.type !== 'hidden'))
          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 == v || nv && nv.startsWith(v); },
    '$=': function(nv, v) { return nv == v || nv && nv.endsWith(v); },
    '*=': function(nv, v) { return nv == v || nv && nv.include(v); },
    '~=': function(nv, v) { return (' ' + nv + ' ').include(' ' + v + ' '); },
    '|=': function(nv, v) { return ('-' + (nv || "").toUpperCase() +
     '-').include('-' + (v || "").toUpperCase() + '-'); }
  },

  /**
   *  Selector.split(expression) -> [String...]
   *
   *  Takes a string of CSS selectors separated by commas; returns an array
   *  of individual selectors.
   *
   *  Safer than doing a naive `Array#split`, since selectors can have commas
   *  in other places.
  **/
  split: function(expression) {
    var expressions = [];
    expression.scan(/(([\w#:.~>+()\s-]+|\*|\[.*?\])+)\s*(,|$)/, function(m) {
      expressions.push(m[1].strip());
    });
    return expressions;
  },

  /**
   *  Selector.matchElements(elements, expression) -> [Element...]
   *
   *  Filters the given collection of elements with `expression`.
   *
   *  The only nodes returned will be those that match the given CSS selector.
  **/
  matchElements: function(elements, expression) {
    var matches = $$(expression), h = Selector.handlers;
    h.mark(matches);
    for (var i = 0, results = [], element; element = elements[i]; i++)
      if (element._countedByPrototype) results.push(element);
    h.unmark(matches);
    return results;
  },

  /**
   *  Selector.findElement(elements, expression[, index = 0]) -> Element
   *  Selector.findElement(elements[, index = 0]) -> Element
   *
   *  Returns the `index`th element in the collection that matches
   *  `expression`.
   *
   *  Returns the `index`th element overall if `expression` is not given.
  **/
  findElement: function(elements, expression, index) {
    if (Object.isNumber(expression)) {
      index = expression; expression = false;
    }
    return Selector.matchElements(elements, expression || '*')[index || 0];
  },

  /**
   *  Selector.findChildElements(element, expressions) -> [Element...]
   *
   *  Searches beneath `element` for any elements that match the selector
   *  (or selectors) specified in `expressions`.
  **/
  findChildElements: function(element, expressions) {
    expressions = Selector.split(expressions.join(','));
    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;
  }
});

if (Prototype.Browser.IE) {
  Object.extend(Selector.handlers, {
    // IE returns comment nodes on getElementsByTagName("*").
    // Filter them out.
    concat: function(a, b) {
      for (var i = 0, node; node = b[i]; i++)
        if (node.tagName !== "!") a.push(node);
      return a;
    }
  });
}

/** related to: Selector
 *  $$(expression...) -> [Element...]
 *
 *  Returns all elements in the document that match the provided CSS selectors.
**/
function $$() {
  return Selector.findChildElements(document, $A(arguments));
}