/* document.getElementsBySelector(selector)

   - returns an array of element objects from the current document

     matching the CSS selector. Selectors can contain element names, 

     class names and ids and can be nested. For example:

       elements = document.getElementsBySelect('div#main p a.external')

     Will return an array of all 'a' elements with 'external' in their 

     class attribute that are contained inside 'p' elements that are 

     contained inside the 'div' element which has id="main"

   New in version 0.4: Support for CSS2 and CSS3 attribute selectors:

   See http://www.w3.org/TR/css3-selectors/#attribute-selectors

   Version 0.4 - Simon Willison, March 25th 2003

   -- Works in Phoenix 0.5, Mozilla 1.3, Opera 7, Internet Explorer 6, Internet Explorer 5 on Windows

   -- Opera 7 fails 

*/

function getAllChildren(e) {

  // Returns all children of element. Workaround required for IE5/Windows. Ugh.

  return e.all ? e.all : e.getElementsByTagName('*');

}

document.getElementsBySelector = function(selector) {

  // Attempt to fail gracefully in lesser browsers

  if (!document.getElementsByTagName) {

    return new Array();

  }

  // Split selector in to tokens

  var tokens = selector.split(' ');

  var currentContext = new Array(document);

  for (var i = 0; i < tokens.length; i++) {

    token = tokens[i].replace(/^\s+/,'').replace(/\s+$/,'');;

    if (token.indexOf('#') > -1) {

      // Token is an ID selector

      var bits = token.split('#');

      var tagName = bits[0];

      var id = bits[1];

      var element = document.getElementById(id);

      if (tagName && element.nodeName.toLowerCase() != tagName) {

        // tag with that ID not found, return false

        return new Array();

      }

      // Set currentContext to contain just this element

      currentContext = new Array(element);

      continue; // Skip to next token

    }

    if (token.indexOf('.') > -1) {

      // Token contains a class selector

      var bits = token.split('.');

      var tagName = bits[0];

      var className = bits[1];

      if (!tagName) {

        tagName = '*';

      }

      // Get elements matching tag, filter them for class selector

      var found = new Array;

      var foundCount = 0;

      for (var h = 0; h < currentContext.length; h++) {

        var elements;

        if (tagName == '*') {

            elements = getAllChildren(currentContext[h]);

        } else {

            try {

                elements = currentContext[h].getElementsByTagName(tagName);

            }

            catch(e) {

                elements = [];

            }

        }

        for (var j = 0; j < elements.length; j++) {

          found[foundCount++] = elements[j];

        }

      }

      currentContext = new Array;

      var currentContextIndex = 0;

      for (var k = 0; k < found.length; k++) {

        if (found[k].className && found[k].className.match(new RegExp('\\b'+className+'\\b'))) {

          currentContext[currentContextIndex++] = found[k];

        }

      }

      continue; // Skip to next token

    }

    // Code to deal with attribute selectors

    if (token.match(/^(\w*)\[(\w+)([=~\|\^\$\*]?)=?"?([^\]"]*)"?\]$/)) {

      var tagName = RegExp.$1;

      var attrName = RegExp.$2;

      var attrOperator = RegExp.$3;

      var attrValue = RegExp.$4;

      if (!tagName) {

        tagName = '*';

      }

      // Grab all of the tagName elements within current context

      var found = new Array;

      var foundCount = 0;

      for (var h = 0; h < currentContext.length; h++) {

        var elements;

        if (tagName == '*') {

            elements = getAllChildren(currentContext[h]);

        } else {

            elements = currentContext[h].getElementsByTagName(tagName);

        }

        for (var j = 0; j < elements.length; j++) {

          found[foundCount++] = elements[j];

        }

      }

      currentContext = new Array;

      var currentContextIndex = 0;

      var checkFunction; // This function will be used to filter the elements

      switch (attrOperator) {

        case '=': // Equality

          checkFunction = function(e) { return (e.getAttribute(attrName) == attrValue); };

          break;

        case '~': // Match one of space seperated words 

          checkFunction = function(e) { return (e.getAttribute(attrName).match(new RegExp('\\b'+attrValue+'\\b'))); };

          break;

        case '|': // Match start with value followed by optional hyphen

          checkFunction = function(e) { return (e.getAttribute(attrName).match(new RegExp('^'+attrValue+'-?'))); };

          break;

        case '^': // Match starts with value

          checkFunction = function(e) { return (e.getAttribute(attrName).indexOf(attrValue) == 0); };

          break;

        case '$': // Match ends with value - fails with "Warning" in Opera 7

          checkFunction = function(e) { return (e.getAttribute(attrName).lastIndexOf(attrValue) == e.getAttribute(attrName).length - attrValue.length); };

          break;

        case '*': // Match ends with value

          checkFunction = function(e) { return (e.getAttribute(attrName).indexOf(attrValue) > -1); };

          break;

        default :

          // Just test for existence of attribute

          checkFunction = function(e) { return e.getAttribute(attrName); };

      }

      currentContext = new Array;

      var currentContextIndex = 0;

      for (var k = 0; k < found.length; k++) {

        if (checkFunction(found[k])) {

          currentContext[currentContextIndex++] = found[k];

        }

      }

      // alert('Attribute Selector: '+tagName+' '+attrName+' '+attrOperator+' '+attrValue);

      continue; // Skip to next token

    }

    // If we get here, token is JUST an element (not a class or ID selector)

    tagName = token;

    var found = new Array;

    var foundCount = 0;

    for (var h = 0; h < currentContext.length; h++) {

      var elements = currentContext[h].getElementsByTagName(tagName);

      for (var j = 0; j < elements.length; j++) {

        found[foundCount++] = elements[j];

      }

    }

    currentContext = found;

  }

  return currentContext;

}

/* That revolting regular expression explained 

/^(\w+)\[(\w+)([=~\|\^\$\*]?)=?"?([^\]"]*)"?\]$/

  \---/  \---/\-------------/    \-------/

    |      |         |               |

    |      |         |           The value

    |      |    ~,|,^,$,* or =

    |   Attribute 

   Tag

*/