深入学习jquery源码之jQuery的选择器引擎Sizzle(一)

深入学习jquery源码之jQuery的选择器引擎Sizzle

Sizzle是一个纯javascript CSS选择器引擎。jquery1.3开始使用sizzle,Sizzle一反传统采取了相反的Right To Left的查询匹配方式,效率提高.Sizzle是jQuery作者John Resig新写的DOM选择器引擎,速度号称业界第一.Sizzle完全独立于jQuery,若不想用jQuery,你可只用Sizzle实现,压缩3K多http://url.cn/J73IkN
一般选择器的匹配模式(包括jq1.2之前),都是一个顺序的思维方式,在需要递进式匹配时,比如$(‘div span’) 这样的匹配时,执行的操作都是先匹配页面中div然后再匹配它的节点下的span标签,之后返回结果。
Sizzle则采取了相反Right To Left的实现方式,先搜寻页面中所有的span标签,再其后的操作中才去判断它的父节点(包括父节点以上)是否为div,是则压入数组,否则pass,进入下一判断,最后返回该操作序列。
深入学习jquery源码之jQuery的选择器引擎Sizzle(一)_第1张图片

当我们给$符传递进一个参数(也可能是多个)时,此时它会根据参数的类型(domElement | string | fn | array)进入不同的流程,在此,重点看 string 类型的处理,因为只有它才可以触发Sizzle。首先调用正则匹配看是否为创建dom节点的操作,然后看是否为简单id匹配,这一步也由正则匹配完成,否则进入jQuery.fn.find()函数,由此进入Sizzle的天地。

当进入Sizzle时,一般情况下会配备三参:所要匹配的选择符,上下文,匹配的结果集。调用正则对传入的selector做一次”预匹配”.

var chunker = /((?:\((?:\([^()]+\)|[^()]+)+\)|\[(?:\[[^[\]]*\]|['"][^'"]*['"]|[^[\]'"]+)+\]|\\.|[^ >+~,(\[\\]+)+|[>+~])(\s*,\s*)?/g,
让我们看一下一个简单选择器的实现过程:比如 div > p。我们要先找出符合条件的div[div],再找出符合条件的p[p],最后在上下文里[div]过滤出符合条件”>”的p[p];抽象一点的说法就是:在已知的上下文里,根据关系找出相应的节点。他们靠关系联系起来。那么对于选择器的操作也就是根据关系来分组。一次次缩小上下文,直到找出符合条件的节点。

回到我们的话题,还是先看看这个令人费解的正则,相信你会有更好的分析方法,但是眼下,我还是一点点的拆分,让它表达的更清晰一点。先按照分组拆,即():

((?:\((?:\([^()]+\)|[^()]+)+\)|\[(?:\[[^\[\]]*\]|['"][^'"]*['"]|[^\[\]'"]+)+\]|\\.|[^ >+~,(\[\\]+)+|[>+~])

(\s*,\s*)?

((?:.|\r|\n)*)
第一行还是有点长,用’|'拆分它:

1. (?:\((?:\([^()]+\)
2.[^()]+)+\)
3. \[(?:\[[^[\]]*\]
4. [^[\]]+)+\]|\\.
5.[^ >+~,(\[]+)+
6.[>+~]
对于如div > p。会得到数组结果['div','>','p']。

对于更复杂的选择器,如div.classname > p.classname。会得到结果['div.classname','>','p.classname']。

对于具有合并的‘,’,只是递归调用下获取结果再合并而已。过程开始变得简单起来。

对于普通的解析过程,我们遵循着从左到右的顺序即可完成我们的目标。

让我们总结下步骤:

1.先查找页面上所有的div 

2.循环所有的div,查找每个div下的p  

3.合并结果
Sizzle用了截然相反的步骤:

1.先查找页面上所有的p 

2.循环所有的p,查找每个p的父元素
  1.如果不是div,遍历上一层。
  2.如果已经是顶层,排除此p。
  3.如果是div,则保存此p元素。
由子元素来查找父元素,能得到更好的效率。看,打破常规思维后不仅步骤更简单了,而且效率上也得到了些许提升。

所有的选择器都可以这样解析吗?不是,采用right -> left的顺序是有前提条件的:没有位置关系的约束。

比如如下这段html:

p1content

p2content

p3content

p4content

对于选择器:$(“div p:first”)只会返回["#p1"]

而$(“div p:first-child”)则返回["#p1", "#p3"]

两者的区别在于位置filter的结果依赖于它前面的selector解析的结果,而其它 filter,只依赖于当前元素本身,就可以判断它是否满足filter。

那Sizzle是通过什么来判定进入哪一个流程呢,答案是origPOS的正则匹配,origPos指向了Expr中match对象的POS属性,而POS中存储了五花八门的位置类约束,如下:

/:(nth|eq|gt|lt|first|last|even|odd)(?:\((\d*)\))?(?=[^-]|$)/     //POS的值
这样一来,第一步的流程判断就已明朗。

当处于1的情况时:
首先根据需要对当前处理的A数组元素进行一系列修正操作(Expr.relative主刀)。然后调用posProcess函数对修复后的元素进行匹配.

其中,还需一层判断,如果有层级约束,eg ‘>,’:input’ 会转化为 ‘> :input’,因为在最初调用chunker进行预匹配的时候,这些是会被分割为单个数组元素的,但在这里需要将它们做一次合并,这是由posProcess所处理的数据格式所决定的

源码片段a: — posProcess函数匹配核心

//如果存在伪类选择符,从selector中移除,并保存在later中 // 这样一来,匹配对象便分离出来:selector(简单选择符存储器)和later(伪类选择符存储器)。 while ( (match = Expr.match.PSEUDO.exec( selector )) ) {     later += match[0];     selector = selector.replace( Expr.match.PSEUDO, "" ); } //构造selector,并调用Sizzle进行匹配,将结果存储在tmpSet中 selector = Expr.relative[selector] ? selector + "*" : selector; for ( var i = 0, l = root.length; i < l; i++ ) {     Sizzle( selector, root[i], tmpSet ); } // 最后便是filter的过滤 return Sizzle.filter( later, tmpSet );
源码片段b: — 对预匹配后的数组A中元素的处理

//这个为特例,被正则分割的A数组长度为2,则合并数组元素,上下文则原封不动为Sizzle传递进来的context。 if ( parts.length === 2 && Expr.relative[ parts[0] ] ) {     // 完成一次匹配, 由posProcess 内部调用 filter进行匹配     // 但在匹配前,完成了一次连接选择符的操作     // 存入set,注 set 当前还不是最终的结果,其这里的set和上面的tmpSet一样,都是一个"暂时性"的结果集     set = posProcess( parts[0] + parts[1], context );
源码片段c: — 如果存在位置约束关系, 正向匹配。

set = Expr.relative[ parts[0] ] ?     [ context ] :     // 否则对队列首元素进行一次简单匹配操作     Sizzle( parts.shift(), context );
分析Expr.relative,可以看出,它包含了4种dom元素间关系的判断,分别是 “+”, “>”, “”, “~”

每一轮的匹配,都会先判断A数组的首元素是不是代表tag间关系符(+,>等) ,而做后续处理.同时对A数组进行循环,依次做类似的处理

源码片段d — 对A数组(parts)的循环处理及后续

while ( parts.length ) {     // 依次对 所匹配到的 数组中元素进行 递进匹配     selector = parts.shift();     //   '>'  -> '>input' 的形式     if ( Expr.relative[ selector ] )         selector += parts.shift();     set = posProcess( selector, set );
当处于2的情况时:
就有着不同之处,先看小片代码

源码片段e: — 根据当前流程设置ret(两种情况)

//为ret绑定正确的返回值 var ret = seed ?       //seed 为上一次调用sizzle返回值, 即前文中提到的set|tmpset     //将预匹配后的A数组(parts)中的最后元素设置为ret的expr属性,set属性设为上一次匹配的结果集。     { expr: parts.pop(), set: makeArray(seed) } :     //如果是第一次调用,则进行匹配操作,调用find函数     // 以parts数组最末元素为当前选择符,进行匹配操作,同时设置与之相关的context     Sizzle.find( parts.pop(), parts.length === 1 && context.parentNode ? context.parentNode : context, isXML(context) );
2的情况为一般逻辑处理,从这小段代码便可得到Sizzle的匹配机制,每一次的调用都以数组末元素为基准,以上一次(或预设context)为上下文约束关系以右到左的匹配,最后返回匹配结果。结合了DOM结构的特性,性能上也得到了大幅的提升。

我们知道选择器的类型是有效率差别的,id选择器效率最高,其次是class、name、tag、最后是最差的*表达式。在Sizzle.find函数中,会按照这个效率的顺序查找元素,如果没有id就找class,依次下去。当然,class的支持需要方法getElementsByClassName。如果没有,就只好从id跳到name。

if ( document.getElementsByClassName && document.documentElement.getElementsByClassName ) (function(){     // ...     // 如果支持直接获取,则将获取class的方法 直接添加进 Expr.order中   ['ID', 'NAME', 'TAG']     Expr.order.splice(1, 0, "CLASS");     //同时在find中追加对class的获取     Expr.find.CLASS = function(match, context, isXML) {         if ( typeof context.getElementsByClassName !== "undefined" && !isXML ) {             return context.getElementsByClassName(match[1]);         }     }; })();
在Sizzle.find函数中,做了一系列的逻辑判断,来保证返回结果的正确性,首先在进入find时,保证了expr不为空的,然后根据表达式类型(id|name|tag|class?)来选择与之对应的匹配分支进行实现,最后再做适当的收尾工作,将返回结果定义为对象,来移交给filter,完成整个流程。

源码片段f: — find 函数核心

//order: [ "ID", "NAME", "TAG" ] // 当然,如果浏览器支持对class的直接获取时,order中就会出现class的相关匹配规则 for ( var i = 0, l = Expr.order.length; i < l; i++ ) {     var type = Expr.order[i], match;     // 根据 type 对所传进来的expr 进行正则匹配     // match中通过正则限制了这三类匹配方式的条件。     // 1. ID: /#((?:[\w\u00c0-\uFFFF_-]|\\.)+)/,     // 2. NAME: /
name=[′"]∗((?:[\w\u00c0−\uFFFF−]|.)+)[′"]∗
name=[′"]∗((?:[\w\u00c0−\uFFFF−]|.)+)[′"]∗
/,     // 3. TAG: /^((?:[\w\u00c0-\uFFFF\*_-]|\\.)+)/,     if ( (match = Expr.match[ type ].exec( expr )) ) {         var left = RegExp.leftContext;         //保证返回结果的正确性,如果存在\,则删除         if ( left.substr( left.length - 1 ) !== "\\" ) {             match[1] = (match[1] || "").replace(/\\/g, "");             // 根据type调用 sizzle.selector.find方法获取结果集。             set = Expr.find[ type ]( match, context, isXML );             if ( set != null ) {                 //如果匹配成功,删除已经匹配的expr                 expr = expr.replace( Expr.match[ type ], "" );                 break;             }         }     } } return {set: set, expr: expr}; };
在所返回的对象中,expr的作用便是为了辅佐filter这把大器所需要完成任务的工具,到此就可以调用Sizzle.filter对ret.set再做一次精确匹配(匹配规则即ret.expr),以及tag间的位置约束关系的匹配(这部分同1中类似).

源码片段g: — 和源码片段d有类似之处。不作详述

    while ( parts.length ) {         var cur = parts.pop(), pop = cur;         // 是否存在 类似这样的匹配 eg:  '+',  '>'等         if ( !Expr.relative[ cur ] ) {             cur = "";         } else {             //如果存在层间关系的约束  则修复 cur 和pop的指向             // eg  ['div', '+', 'span'] =>   pop = div;  cur = '+'; 并进入 relative的匹配。             pop = parts.pop();         }         //  确保拥有上下文 代码略过         Expr.relative[ cur ]( checkSet, pop, isXML(context) );     }
之后便接近sizzle尾声:结果集的处理(将所匹配的结果set 追加进 result中)。当然,如果有多表达式,便会再一次调用。
 

源码解析

以’div > span p span:last’这个选择符为例,看看它的调用链是如何顺次完成的。

根据对源码的剖析,理解如下:

jquery.init -> jquery.prototype.find
进入Sizzle(对xml的判断) -> 设置parts数组等在匹配中所需要的元素 -> 根据数组长度以及调用origPos进行判断,来决定进入哪个分支,在这个实例下进入分支1
循环调用Sizzle进行匹配,将结果存入set中(因为在这一过程中是循环调用,所以对Sizzle的判断也是需要多次,进入哪一分支当然也会是不一样的,比如第二轮循环判断则进入分支2中进行处理) ,对于>号的处理,也会将它合并在其后的span中,构成新的选择符 ‘>span’,然后进入Expr.relative进行匹配,同时调用posProcess。
调用Sizzle.find 匹配除伪类以外的部分(即这里的选择器不包含:last),首先会调用Expr.find的find方法来判断是否为哪一类匹配,在这一实例中,为TAG匹配。
对从4步中生成的对象进行过滤,匹配’>'(这一步的匹配是由Sizzle.filter触发,由Expr.relative完成),而在匹配’span:last’时则由posProcess来触发,设置later值(:first)以及selector(span),对span的匹配和4步骤一样,重复匹配,而对:first的匹配则是第5步的重头戏,也就是调用Sizzle.filter来完成, 由此便生成了最后的匹配结果。
对于有‘,’这样需要合并的选择器,Sizzle在获取结果后会按照文档流进行排序。所以,你可能会遇到这样的问题:把一个结果集append到新的节点后,新的节点可能不会按照你书写的选择器的顺序出现。

以上,可以得出以下结论:大致通过如下步骤来完成:

1.对表达式分组。
2.选择合适的处理顺序。
3.在当前的上下文里过滤要找的节点。并更新上下文。重复这一过程,直到结尾。
4.对结果排序,如果需要的话。
5.返回结果数组。
前向兼容
querySelectorAll
其实不止这一处,在Sizzle的API手册中Internal部分的find 函数(与filter构成了Sizzle的两把宝剑),在传递进该方法的参数可以用querySelectorAll() (依赖于当前的浏览器执行环境) 直接获取时,它则直接调用该方法,既拥有了向前兼容的特性,又达到了速度的提升。

虽然有些环境实现了方法querySelectorAll,但是会有bug。

//如果当前document 支持 querySelectorAll方法,则将浏览器可以完成的匹配完全交给浏览器 if ( document.querySelectorAll ) (function(){     var oldSizzle = Sizzle;     // 解决Safari bug 略过 ...     Sizzle = function(query, context, extra, seed){         context = context || document;     // 因为querySelectorAll 在domElement 节点上操作时,存在bug 所以多了这样的判断     // bug info: http://ejohn.org/blog/thoughts-on-queryselectorall/         if ( !seed && context.nodeType === 9 && !isXML(context) ) {             return makeArray( context.querySelectorAll(query), extra );         }         // querySelectorAll 可用则直接返回结果,否则才调用 sizzle         return oldSizzle(query, context, extra, seed);     };     // oldSizzle 方法追加进 新的 Sizzle 中 })();
对于任何一个开发者,我想,若浏览器原生已提供了实现方法,他都不会去高效而求繁琐吧。这一点在Sizzle中得到了充分的体现,总是尽可能的使用相应环境下已实现的原生方法。所以在IE的低版本中(比如IE6)Sizzle的表现更加出众,在高级的浏览器中的对比却没有那么大的差别。

扩展
如何定义自己的选择器呢.如果项目中频繁使用某些过滤规则,是不是把它作为一个选择器更有效呢。
既然javascript的对象可以任意扩充,只要我们访问得到,那么我们就可以很轻松得创建出自己的选择器

在jQuery.expr.filter对象中,有很多内置的选择器,比如 ‘disabled’,'text’,那我们就扩充它,比如,想寻找包含span的div元素

// filter的简写  ':' jQuery.expr[":"] = jQuery.expr.filters; $.extend($.expr[':'], {     hasSpan: function(e) {        return $(e).find('span').length > 0;     } });
这样,我们就拥有了 ‘:hasSpan’ 的选择器,使用当然和默认的一样。

//直接用就可以了 $('div:hasSpan')....
比较
再拾YUI3,在经过大幅度变化,以全新姿态出现,从选择器上的执行上效率不逊色于Sizzle几毫,初看YUI时就一直对它的模块细粒度化赞不绝口,但是从如我这样的实用主义者的角度来看,选择器就应该是一个单独的模块,就如同jQuery分离而出的Sizzle。但在YUI term眼里,为了让代码的组织结构看上去更加的理想化,更加具有”YUI3“的特色,将之在代码结构上又细分出一二三,比起Sizzle的简洁,它显得太过学院派。

除此,在选择器的扩展上,sizzle表现胜于YUI3 selector,在实现css1~css3选择器的基础上,又对常用的功能进行了扩展。比如对表单元素快捷操作。据我所知,开发者对这类型选择器的使用频率并不是想象中那么低。既然有了模块的细分,为什么不将这部分作为一个可扩充性的功能点模块融入框架中呢。Sizzle于开发者就如同一块可口味佳的点心,满足我们各式各样的胃口,简洁,不失其功能的强劲,这点非常值得称道。

总得来看,Sizzle与YUI就好象一个面向实际与理想主义的比较。这里没有对错之分,从不同角度来看,都能略窥其各自的禅意。前者从如何为开发者带来便利的角度考虑,让开发者实时觉得它的简单可信赖。后者,也寄托了自己对web的构想,如果浏览器原生全部支持css3-selector,那岂不是完全不用引入该模块了,不过我想,真到那时候,各框架也都会有很大的变化了,只是我对这一天的到来抱有比较消极的态度,这是后话。

总结
本文从总体上讨论了jQuery之Sizzle选择器的实现原理,通过一个初步的流程分析,让各位读者对此有一个大致印象,毫无疑问,更深层次的匹配,也只是它的递归调用,再匹配而已。

这里,没有做与其他框架在效率上的比较,如果你还对它的效率还有所怀疑的话,你可以自行比较。

如果你感兴趣,更推荐你继续去探索在1.4中着重优化的api源码,或许,会给你更多的启示

思考
从jQuery的角度来讲,Sizzle的出现随之也带来了web上的一些新的局面,在追求效率的同时,即使是这类单种子模式的库也是需要将之分离开来,来设计成能够独立使用,独立维护的引擎。

从选择器的角度来讲,Sizzle这次算法的提升,我初步的结论是它结合了DOM这一特定的数据结构,使其每次的匹配能够更精准,以此获得引擎效率上的提升。

我们可否多想想,在思维的开拓上能给我们留下多少财富。很多问题的解决,在换一种新的思维方式后,是不是常常会有柳暗花明的感觉呢。

 

jquery源码

jQuery.find = Sizzle;
jQuery.expr = Sizzle.selectors;
jQuery.expr[":"] = jQuery.expr.pseudos;
jQuery.unique = Sizzle.uniqueSort;
jQuery.text = Sizzle.getText;
jQuery.isXMLDoc = Sizzle.isXML;
jQuery.contains = Sizzle.contains;

var Sizzle =
        /*!
         * Sizzle CSS Selector Engine v2.2.0-pre
         * http://sizzlejs.com/
         *
         * Copyright 2008, 2014 jQuery Foundation, Inc. and other contributors
         * Released under the MIT license
         * http://jquery.org/license
         *
         * Date: 2014-12-16
         */
        (function (window) {

            var i,
                support,
                Expr,
                getText,
                isXML,
                tokenize,
                compile,
                select,
                outermostContext,
                sortInput,
                hasDuplicate,

                // Local document vars
                setDocument,
                document,
                docElem,
                documentIsHTML,
                rbuggyQSA,
                rbuggyMatches,
                matches,
                contains,

                // Instance-specific data
                expando = "sizzle" + 1 * new Date(),
                preferredDoc = window.document,
                dirruns = 0,
                done = 0,
                classCache = createCache(),
                tokenCache = createCache(),
                compilerCache = createCache(),
                sortOrder = function (a, b) {
                    if (a === b) {
                        hasDuplicate = true;
                    }
                    return 0;
                },

                // General-purpose constants
                MAX_NEGATIVE = 1 << 31,

                // Instance methods
                hasOwn = ({}).hasOwnProperty,
                arr = [],
                pop = arr.pop,
                push_native = arr.push,
                push = arr.push,
                slice = arr.slice,
                // Use a stripped-down indexOf as it's faster than native
                // http://jsperf.com/thor-indexof-vs-for/5
                indexOf = function (list, elem) {
                    var i = 0,
                        len = list.length;
                    for (; i < len; i++) {
                        if (list[i] === elem) {
                            return i;
                        }
                    }
                    return -1;
                },

                booleans = "checked|selected|async|autofocus|autoplay|controls|defer|disabled|hidden|ismap|loop|multiple|open|readonly|required|scoped",

                // Regular expressions

                // Whitespace characters http://www.w3.org/TR/css3-selectors/#whitespace
                whitespace = "[\\x20\\t\\r\\n\\f]",
                // http://www.w3.org/TR/css3-syntax/#characters
                characterEncoding = "(?:\\\\.|[\\w-]|[^\\x00-\\xa0])+",

                // Loosely modeled on CSS identifier characters
                // An unquoted value should be a CSS identifier http://www.w3.org/TR/css3-selectors/#attribute-selectors
                // Proper syntax: http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier
                identifier = characterEncoding.replace("w", "w#"),

                // Attribute selectors: http://www.w3.org/TR/selectors/#attribute-selectors
                attributes = "\\[" + whitespace + "*(" + characterEncoding + ")(?:" + whitespace +
                    // Operator (capture 2)
                    "*([*^$|!~]?=)" + whitespace +
                    // "Attribute values must be CSS identifiers [capture 5] or strings [capture 3 or capture 4]"
                    "*(?:'((?:\\\\.|[^\\\\'])*)'|\"((?:\\\\.|[^\\\\\"])*)\"|(" + identifier + "))|)" + whitespace +
                    "*\\]",

                pseudos = ":(" + characterEncoding + ")(?:\\((" +
                    // To reduce the number of selectors needing tokenize in the preFilter, prefer arguments:
                    // 1. quoted (capture 3; capture 4 or capture 5)
                    "('((?:\\\\.|[^\\\\'])*)'|\"((?:\\\\.|[^\\\\\"])*)\")|" +
                    // 2. simple (capture 6)
                    "((?:\\\\.|[^\\\\()[\\]]|" + attributes + ")*)|" +
                    // 3. anything else (capture 2)
                    ".*" +
                    ")\\)|)",

                // Leading and non-escaped trailing whitespace, capturing some non-whitespace characters preceding the latter
                rwhitespace = new RegExp(whitespace + "+", "g"),
                rtrim = new RegExp("^" + whitespace + "+|((?:^|[^\\\\])(?:\\\\.)*)" + whitespace + "+$", "g"),

                rcomma = new RegExp("^" + whitespace + "*," + whitespace + "*"),
                rcombinators = new RegExp("^" + whitespace + "*([>+~]|" + whitespace + ")" + whitespace + "*"),

                rattributeQuotes = new RegExp("=" + whitespace + "*([^\\]'\"]*?)" + whitespace + "*\\]", "g"),

                rpseudo = new RegExp(pseudos),
                ridentifier = new RegExp("^" + identifier + "$"),

                matchExpr = {
                    "ID": new RegExp("^#(" + characterEncoding + ")"),
                    "CLASS": new RegExp("^\\.(" + characterEncoding + ")"),
                    "TAG": new RegExp("^(" + characterEncoding.replace("w", "w*") + ")"),
                    "ATTR": new RegExp("^" + attributes),
                    "PSEUDO": new RegExp("^" + pseudos),
                    "CHILD": new RegExp("^:(only|first|last|nth|nth-last)-(child|of-type)(?:\\(" + whitespace +
                        "*(even|odd|(([+-]|)(\\d*)n|)" + whitespace + "*(?:([+-]|)" + whitespace +
                        "*(\\d+)|))" + whitespace + "*\\)|)", "i"),
                    "bool": new RegExp("^(?:" + booleans + ")$", "i"),
                    // For use in libraries implementing .is()
                    // We use this for POS matching in `select`
                    "needsContext": new RegExp("^" + whitespace + "*[>+~]|:(even|odd|eq|gt|lt|nth|first|last)(?:\\(" +
                        whitespace + "*((?:-\\d)?\\d*)" + whitespace + "*\\)|)(?=[^-]|$)", "i")
                },

                rinputs = /^(?:input|select|textarea|button)$/i,
                rheader = /^h\d$/i,

                rnative = /^[^{]+\{\s*\[native \w/,

                // Easily-parseable/retrievable ID or TAG or CLASS selectors
                rquickExpr = /^(?:#([\w-]+)|(\w+)|\.([\w-]+))$/,

                rsibling = /[+~]/,
                rescape = /'|\\/g,

                // CSS escapes http://www.w3.org/TR/CSS21/syndata.html#escaped-characters
                runescape = new RegExp("\\\\([\\da-f]{1,6}" + whitespace + "?|(" + whitespace + ")|.)", "ig"),
                funescape = function (_, escaped, escapedWhitespace) {
                    var high = "0x" + escaped - 0x10000;
                    // NaN means non-codepoint
                    // Support: Firefox<24
                    // Workaround erroneous numeric interpretation of +"0x"
                    return high !== high || escapedWhitespace ?
                        escaped :
                        high < 0 ?
                        // BMP codepoint
                        String.fromCharCode(high + 0x10000) :
                        // Supplemental Plane codepoint (surrogate pair)
                        String.fromCharCode(high >> 10 | 0xD800, high & 0x3FF | 0xDC00);
                },

                // Used for iframes
                // See setDocument()
                // Removing the function wrapper causes a "Permission Denied"
                // error in IE
                unloadHandler = function () {
                    setDocument();
                };

            // Optimize for push.apply( _, NodeList )
            try {
                push.apply(
                    (arr = slice.call(preferredDoc.childNodes)),
                    preferredDoc.childNodes
                );
                // Support: Android<4.0
                // Detect silently failing push.apply
                arr[preferredDoc.childNodes.length].nodeType;
            } catch (e) {
                push = {
                    apply: arr.length ?

                        // Leverage slice if possible
                        function (target, els) {
                            push_native.apply(target, slice.call(els));
                        } :

                        // Support: IE<9
                        // Otherwise append directly
                        function (target, els) {
                            var j = target.length,
                                i = 0;
                            // Can't trust NodeList.length
                            while ((target[j++] = els[i++])) { }
                            target.length = j - 1;
                        }
                };
            }

            function Sizzle(selector, context, results, seed) {
                var match, elem, m, nodeType,
                    // QSA vars
                    i, groups, old, nid, newContext, newSelector;

                if ((context ? context.ownerDocument || context : preferredDoc) !== document) {
                    setDocument(context);
                }

                context = context || document;
                results = results || [];
                nodeType = context.nodeType;

                if (typeof selector !== "string" || !selector ||
                    nodeType !== 1 && nodeType !== 9 && nodeType !== 11) {

                    return results;
                }

                if (!seed && documentIsHTML) {

                    // Try to shortcut find operations when possible (e.g., not under DocumentFragment)
                    if (nodeType !== 11 && (match = rquickExpr.exec(selector))) {
                        // Speed-up: Sizzle("#ID")
                        if ((m = match[1])) {
                            if (nodeType === 9) {
                                elem = context.getElementById(m);
                                // Check parentNode to catch when Blackberry 4.6 returns
                                // nodes that are no longer in the document (jQuery #6963)
                                if (elem && elem.parentNode) {
                                    // Handle the case where IE, Opera, and Webkit return items
                                    // by name instead of ID
                                    if (elem.id === m) {
                                        results.push(elem);
                                        return results;
                                    }
                                } else {
                                    return results;
                                }
                            } else {
                                // Context is not a document
                                if (context.ownerDocument && (elem = context.ownerDocument.getElementById(m)) &&
                                    contains(context, elem) && elem.id === m) {
                                    results.push(elem);
                                    return results;
                                }
                            }

                            // Speed-up: Sizzle("TAG")
                        } else if (match[2]) {
                            push.apply(results, context.getElementsByTagName(selector));
                            return results;

                            // Speed-up: Sizzle(".CLASS")
                        } else if ((m = match[3]) && support.getElementsByClassName) {
                            push.apply(results, context.getElementsByClassName(m));
                            return results;
                        }
                    }

                    // QSA path
                    if (support.qsa && (!rbuggyQSA || !rbuggyQSA.test(selector))) {
                        nid = old = expando;
                        newContext = context;
                        newSelector = nodeType !== 1 && selector;

                        // qSA works strangely on Element-rooted queries
                        // We can work around this by specifying an extra ID on the root
                        // and working up from there (Thanks to Andrew Dupont for the technique)
                        // IE 8 doesn't work on object elements
                        if (nodeType === 1 && context.nodeName.toLowerCase() !== "object") {
                            groups = tokenize(selector);

                            if ((old = context.getAttribute("id"))) {
                                nid = old.replace(rescape, "\\$&");
                            } else {
                                context.setAttribute("id", nid);
                            }
                            nid = "[id='" + nid + "'] ";

                            i = groups.length;
                            while (i--) {
                                groups[i] = nid + toSelector(groups[i]);
                            }
                            newContext = rsibling.test(selector) && testContext(context.parentNode) || context;
                            newSelector = groups.join(",");
                        }

                        if (newSelector) {
                            try {
                                push.apply(results,
                                    newContext.querySelectorAll(newSelector)
                                );
                                return results;
                            } catch (qsaError) {
                            } finally {
                                if (!old) {
                                    context.removeAttribute("id");
                                }
                            }
                        }
                    }
                }

                // All others
                return select(selector.replace(rtrim, "$1"), context, results, seed);
            }

            /**
             * Create key-value caches of limited size
             * @returns {Function(string, Object)} Returns the Object data after storing it on itself with
             *	property name the (space-suffixed) string and (if the cache is larger than Expr.cacheLength)
             *	deleting the oldest entry
             */
            function createCache() {
                var keys = [];

                function cache(key, value) {
                    // Use (key + " ") to avoid collision with native prototype properties (see Issue #157)
                    if (keys.push(key + " ") > Expr.cacheLength) {
                        // Only keep the most recent entries
                        delete cache[keys.shift()];
                    }
                    return (cache[key + " "] = value);
                }
                return cache;
            }

            /**
             * Mark a function for special use by Sizzle
             * @param {Function} fn The function to mark
             */
            function markFunction(fn) {
                fn[expando] = true;
                return fn;
            }

            /**
             * Support testing using an element
             * @param {Function} fn Passed the created div and expects a boolean result
             */
            function assert(fn) {
                var div = document.createElement("div");

                try {
                    return !!fn(div);
                } catch (e) {
                    return false;
                } finally {
                    // Remove from its parent by default
                    if (div.parentNode) {
                        div.parentNode.removeChild(div);
                    }
                    // release memory in IE
                    div = null;
                }
            }

            /**
             * Adds the same handler for all of the specified attrs
             * @param {String} attrs Pipe-separated list of attributes
             * @param {Function} handler The method that will be applied
             */
            function addHandle(attrs, handler) {
                var arr = attrs.split("|"),
                    i = attrs.length;

                while (i--) {
                    Expr.attrHandle[arr[i]] = handler;
                }
            }

            /**
             * Checks document order of two siblings
             * @param {Element} a
             * @param {Element} b
             * @returns {Number} Returns less than 0 if a precedes b, greater than 0 if a follows b
             */
            function siblingCheck(a, b) {
                var cur = b && a,
                    diff = cur && a.nodeType === 1 && b.nodeType === 1 &&
                        (~b.sourceIndex || MAX_NEGATIVE) -
                        (~a.sourceIndex || MAX_NEGATIVE);

                // Use IE sourceIndex if available on both nodes
                if (diff) {
                    return diff;
                }

                // Check if b follows a
                if (cur) {
                    while ((cur = cur.nextSibling)) {
                        if (cur === b) {
                            return -1;
                        }
                    }
                }

                return a ? 1 : -1;
            }

            /**
             * Returns a function to use in pseudos for input types
             * @param {String} type
             */
            function createInputPseudo(type) {
                return function (elem) {
                    var name = elem.nodeName.toLowerCase();
                    return name === "input" && elem.type === type;
                };
            }

            /**
             * Returns a function to use in pseudos for buttons
             * @param {String} type
             */
            function createButtonPseudo(type) {
                return function (elem) {
                    var name = elem.nodeName.toLowerCase();
                    return (name === "input" || name === "button") && elem.type === type;
                };
            }

            /**
             * Returns a function to use in pseudos for positionals
             * @param {Function} fn
             */
            function createPositionalPseudo(fn) {
                return markFunction(function (argument) {
                    argument = +argument;
                    return markFunction(function (seed, matches) {
                        var j,
                            matchIndexes = fn([], seed.length, argument),
                            i = matchIndexes.length;

                        // Match elements found at the specified indexes
                        while (i--) {
                            if (seed[(j = matchIndexes[i])]) {
                                seed[j] = !(matches[j] = seed[j]);
                            }
                        }
                    });
                });
            }

            /**
             * Checks a node for validity as a Sizzle context
             * @param {Element|Object=} context
             * @returns {Element|Object|Boolean} The input node if acceptable, otherwise a falsy value
             */
            function testContext(context) {
                return context && typeof context.getElementsByTagName !== "undefined" && context;
            }

            // Expose support vars for convenience
            support = Sizzle.support = {};

            /**
             * Detects XML nodes
             * @param {Element|Object} elem An element or a document
             * @returns {Boolean} True iff elem is a non-HTML XML node
             */
            isXML = Sizzle.isXML = function (elem) {
                // documentElement is verified for cases where it doesn't yet exist
                // (such as loading iframes in IE - #4833)
                var documentElement = elem && (elem.ownerDocument || elem).documentElement;
                return documentElement ? documentElement.nodeName !== "HTML" : false;
            };

            /**
             * Sets document-related variables once based on the current document
             * @param {Element|Object} [doc] An element or document object to use to set the document
             * @returns {Object} Returns the current document
             */
            setDocument = Sizzle.setDocument = function (node) {
                var hasCompare, parent,
                    doc = node ? node.ownerDocument || node : preferredDoc;

                // If no document and documentElement is available, return
                if (doc === document || doc.nodeType !== 9 || !doc.documentElement) {
                    return document;
                }

                // Set our document
                document = doc;
                docElem = doc.documentElement;
                parent = doc.defaultView;

                // Support: IE>8
                // If iframe document is assigned to "document" variable and if iframe has been reloaded,
                // IE will throw "permission denied" error when accessing "document" variable, see jQuery #13936
                // IE6-8 do not support the defaultView property so parent will be undefined
                if (parent && parent !== parent.top) {
                    // IE11 does not have attachEvent, so all must suffer
                    if (parent.addEventListener) {
                        parent.addEventListener("unload", unloadHandler, false);
                    } else if (parent.attachEvent) {
                        parent.attachEvent("onunload", unloadHandler);
                    }
                }

                /* Support tests
                ---------------------------------------------------------------------- */
                documentIsHTML = !isXML(doc);

                /* Attributes
                ---------------------------------------------------------------------- */

                // Support: IE<8
                // Verify that getAttribute really returns attributes and not properties
                // (excepting IE8 booleans)
                support.attributes = assert(function (div) {
                    div.className = "i";
                    return !div.getAttribute("className");
                });

                /* getElement(s)By*
                ---------------------------------------------------------------------- */

                // Check if getElementsByTagName("*") returns only elements
                support.getElementsByTagName = assert(function (div) {
                    div.appendChild(doc.createComment(""));
                    return !div.getElementsByTagName("*").length;
                });

                // Support: IE<9
                support.getElementsByClassName = rnative.test(doc.getElementsByClassName);

                // Support: IE<10
                // Check if getElementById returns elements by name
                // The broken getElementById methods don't pick up programatically-set names,
                // so use a roundabout getElementsByName test
                support.getById = assert(function (div) {
                    docElem.appendChild(div).id = expando;
                    return !doc.getElementsByName || !doc.getElementsByName(expando).length;
                });

                // ID find and filter
                if (support.getById) {
                    Expr.find["ID"] = function (id, context) {
                        if (typeof context.getElementById !== "undefined" && documentIsHTML) {
                            var m = context.getElementById(id);
                            // Check parentNode to catch when Blackberry 4.6 returns
                            // nodes that are no longer in the document #6963
                            return m && m.parentNode ? [m] : [];
                        }
                    };
                    Expr.filter["ID"] = function (id) {
                        var attrId = id.replace(runescape, funescape);
                        return function (elem) {
                            return elem.getAttribute("id") === attrId;
                        };
                    };
                } else {
                    // Support: IE6/7
                    // getElementById is not reliable as a find shortcut
                    delete Expr.find["ID"];

                    Expr.filter["ID"] = function (id) {
                        var attrId = id.replace(runescape, funescape);
                        return function (elem) {
                            var node = typeof elem.getAttributeNode !== "undefined" && elem.getAttributeNode("id");
                            return node && node.value === attrId;
                        };
                    };
                }

                // Tag
                Expr.find["TAG"] = support.getElementsByTagName ?
                    function (tag, context) {
                        if (typeof context.getElementsByTagName !== "undefined") {
                            return context.getElementsByTagName(tag);

                            // DocumentFragment nodes don't have gEBTN
                        } else if (support.qsa) {
                            return context.querySelectorAll(tag);
                        }
                    } :

                    function (tag, context) {
                        var elem,
                            tmp = [],
                            i = 0,
                            // By happy coincidence, a (broken) gEBTN appears on DocumentFragment nodes too
                            results = context.getElementsByTagName(tag);

                        // Filter out possible comments
                        if (tag === "*") {
                            while ((elem = results[i++])) {
                                if (elem.nodeType === 1) {
                                    tmp.push(elem);
                                }
                            }

                            return tmp;
                        }
                        return results;
                    };

                // Class
                Expr.find["CLASS"] = support.getElementsByClassName && function (className, context) {
                    if (documentIsHTML) {
                        return context.getElementsByClassName(className);
                    }
                };

                /* QSA/matchesSelector
                ---------------------------------------------------------------------- */

                // QSA and matchesSelector support

                // matchesSelector(:active) reports false when true (IE9/Opera 11.5)
                rbuggyMatches = [];

                // qSa(:focus) reports false when true (Chrome 21)
                // We allow this because of a bug in IE8/9 that throws an error
                // whenever `document.activeElement` is accessed on an iframe
                // So, we allow :focus to pass through QSA all the time to avoid the IE error
                // See http://bugs.jquery.com/ticket/13378
                rbuggyQSA = [];

                if ((support.qsa = rnative.test(doc.querySelectorAll))) {
                    // Build QSA regex
                    // Regex strategy adopted from Diego Perini
                    assert(function (div) {
                        // Select is set to empty string on purpose
                        // This is to test IE's treatment of not explicitly
                        // setting a boolean content attribute,
                        // since its presence should be enough
                        // http://bugs.jquery.com/ticket/12359
                        docElem.appendChild(div).innerHTML = "" +
                            "";

                        // Support: IE8, Opera 11-12.16
                        // Nothing should be selected when empty strings follow ^= or $= or *=
                        // The test attribute must be unknown in Opera but "safe" for WinRT
                        // http://msdn.microsoft.com/en-us/library/ie/hh465388.aspx#attribute_section
                        if (div.querySelectorAll("[msallowcapture^='']").length) {
                            rbuggyQSA.push("[*^$]=" + whitespace + "*(?:''|\"\")");
                        }

                        // Support: IE8
                        // Boolean attributes and "value" are not treated correctly
                        if (!div.querySelectorAll("[selected]").length) {
                            rbuggyQSA.push("\\[" + whitespace + "*(?:value|" + booleans + ")");
                        }

                        // Support: Chrome<29, Android<4.2+, Safari<7.0+, iOS<7.0+, PhantomJS<1.9.7+
                        if (!div.querySelectorAll("[id~=" + expando + "-]").length) {
                            rbuggyQSA.push("~=");
                        }

                        // Webkit/Opera - :checked should return selected option elements
                        // http://www.w3.org/TR/2011/REC-css3-selectors-20110929/#checked
                        // IE8 throws error here and will not see later tests
                        if (!div.querySelectorAll(":checked").length) {
                            rbuggyQSA.push(":checked");
                        }

                        // Support: Safari 8+, iOS 8+
                        // https://bugs.webkit.org/show_bug.cgi?id=136851
                        // In-page `selector#id sibing-combinator selector` fails
                        if (!div.querySelectorAll("a#" + expando + "+*").length) {
                            rbuggyQSA.push(".#.+[+~]");
                        }
                    });

                    assert(function (div) {
                        // Support: Windows 8 Native Apps
                        // The type and name attributes are restricted during .innerHTML assignment
                        var input = doc.createElement("input");
                        input.setAttribute("type", "hidden");
                        div.appendChild(input).setAttribute("name", "D");

                        // Support: IE8
                        // Enforce case-sensitivity of name attribute
                        if (div.querySelectorAll("[name=d]").length) {
                            rbuggyQSA.push("name" + whitespace + "*[*^$|!~]?=");
                        }

                        // FF 3.5 - :enabled/:disabled and hidden elements (hidden elements are still enabled)
                        // IE8 throws error here and will not see later tests
                        if (!div.querySelectorAll(":enabled").length) {
                            rbuggyQSA.push(":enabled", ":disabled");
                        }

                        // Opera 10-11 does not throw on post-comma invalid pseudos
                        div.querySelectorAll("*,:x");
                        rbuggyQSA.push(",.*:");
                    });
                }

                if ((support.matchesSelector = rnative.test((matches = docElem.matches ||
                    docElem.webkitMatchesSelector ||
                    docElem.mozMatchesSelector ||
                    docElem.oMatchesSelector ||
                    docElem.msMatchesSelector)))) {

                    assert(function (div) {
                        // Check to see if it's possible to do matchesSelector
                        // on a disconnected node (IE 9)
                        support.disconnectedMatch = matches.call(div, "div");

                        // This should fail with an exception
                        // Gecko does not error, returns false instead
                        matches.call(div, "[s!='']:x");
                        rbuggyMatches.push("!=", pseudos);
                    });
                }

                rbuggyQSA = rbuggyQSA.length && new RegExp(rbuggyQSA.join("|"));
                rbuggyMatches = rbuggyMatches.length && new RegExp(rbuggyMatches.join("|"));

                /* Contains
                ---------------------------------------------------------------------- */
                hasCompare = rnative.test(docElem.compareDocumentPosition);

                // Element contains another
                // Purposefully does not implement inclusive descendent
                // As in, an element does not contain itself
                contains = hasCompare || rnative.test(docElem.contains) ?
                    function (a, b) {
                        var adown = a.nodeType === 9 ? a.documentElement : a,
                            bup = b && b.parentNode;
                        return a === bup || !!(bup && bup.nodeType === 1 && (
                            adown.contains ?
                                adown.contains(bup) :
                                a.compareDocumentPosition && a.compareDocumentPosition(bup) & 16
                        ));
                    } :
                    function (a, b) {
                        if (b) {
                            while ((b = b.parentNode)) {
                                if (b === a) {
                                    return true;
                                }
                            }
                        }
                        return false;
                    };

                /* Sorting
                ---------------------------------------------------------------------- */

                // Document order sorting
                sortOrder = hasCompare ?
                    function (a, b) {

                        // Flag for duplicate removal
                        if (a === b) {
                            hasDuplicate = true;
                            return 0;
                        }

                        // Sort on method existence if only one input has compareDocumentPosition
                        var compare = !a.compareDocumentPosition - !b.compareDocumentPosition;
                        if (compare) {
                            return compare;
                        }

                        // Calculate position if both inputs belong to the same document
                        compare = (a.ownerDocument || a) === (b.ownerDocument || b) ?
                            a.compareDocumentPosition(b) :

                            // Otherwise we know they are disconnected
                            1;

                        // Disconnected nodes
                        if (compare & 1 ||
                            (!support.sortDetached && b.compareDocumentPosition(a) === compare)) {

                            // Choose the first element that is related to our preferred document
                            if (a === doc || a.ownerDocument === preferredDoc && contains(preferredDoc, a)) {
                                return -1;
                            }
                            if (b === doc || b.ownerDocument === preferredDoc && contains(preferredDoc, b)) {
                                return 1;
                            }

                            // Maintain original order
                            return sortInput ?
                                (indexOf(sortInput, a) - indexOf(sortInput, b)) :
                                0;
                        }

                        return compare & 4 ? -1 : 1;
                    } :
                    function (a, b) {
                        // Exit early if the nodes are identical
                        if (a === b) {
                            hasDuplicate = true;
                            return 0;
                        }

                        var cur,
                            i = 0,
                            aup = a.parentNode,
                            bup = b.parentNode,
                            ap = [a],
                            bp = [b];

                        // Parentless nodes are either documents or disconnected
                        if (!aup || !bup) {
                            return a === doc ? -1 :
                                b === doc ? 1 :
                                aup ? -1 :
                                bup ? 1 :
                                sortInput ?
                                (indexOf(sortInput, a) - indexOf(sortInput, b)) :
                                0;

                            // If the nodes are siblings, we can do a quick check
                        } else if (aup === bup) {
                            return siblingCheck(a, b);
                        }

                        // Otherwise we need full lists of their ancestors for comparison
                        cur = a;
                        while ((cur = cur.parentNode)) {
                            ap.unshift(cur);
                        }
                        cur = b;
                        while ((cur = cur.parentNode)) {
                            bp.unshift(cur);
                        }

                        // Walk down the tree looking for a discrepancy
                        while (ap[i] === bp[i]) {
                            i++;
                        }

                        return i ?
                            // Do a sibling check if the nodes have a common ancestor
                            siblingCheck(ap[i], bp[i]) :

                            // Otherwise nodes in our document sort first
                            ap[i] === preferredDoc ? -1 :
                            bp[i] === preferredDoc ? 1 :
                            0;
                    };

                return doc;
            };

            Sizzle.matches = function (expr, elements) {
                return Sizzle(expr, null, null, elements);
            };

            Sizzle.matchesSelector = function (elem, expr) {
                // Set document vars if needed
                if ((elem.ownerDocument || elem) !== document) {
                    setDocument(elem);
                }

                // Make sure that attribute selectors are quoted
                expr = expr.replace(rattributeQuotes, "='$1']");

                if (support.matchesSelector && documentIsHTML &&
                    (!rbuggyMatches || !rbuggyMatches.test(expr)) &&
                    (!rbuggyQSA || !rbuggyQSA.test(expr))) {

                    try {
                        var ret = matches.call(elem, expr);

                        // IE 9's matchesSelector returns false on disconnected nodes
                        if (ret || support.disconnectedMatch ||
                            // As well, disconnected nodes are said to be in a document
                            // fragment in IE 9
                            elem.document && elem.document.nodeType !== 11) {
                            return ret;
                        }
                    } catch (e) { }
                }

                return Sizzle(expr, document, null, [elem]).length > 0;
            };

            Sizzle.contains = function (context, elem) {
                // Set document vars if needed
                if ((context.ownerDocument || context) !== document) {
                    setDocument(context);
                }
                return contains(context, elem);
            };

            Sizzle.attr = function (elem, name) {
                // Set document vars if needed
                if ((elem.ownerDocument || elem) !== document) {
                    setDocument(elem);
                }

                var fn = Expr.attrHandle[name.toLowerCase()],
                    // Don't get fooled by Object.prototype properties (jQuery #13807)
                    val = fn && hasOwn.call(Expr.attrHandle, name.toLowerCase()) ?
                        fn(elem, name, !documentIsHTML) :
                        undefined;

                return val !== undefined ?
                    val :
                    support.attributes || !documentIsHTML ?
                    elem.getAttribute(name) :
                    (val = elem.getAttributeNode(name)) && val.specified ?
                    val.value :
                    null;
            };

            Sizzle.error = function (msg) {
                throw new Error("Syntax error, unrecognized expression: " + msg);
            };

            /**
             * Document sorting and removing duplicates
             * @param {ArrayLike} results
             */
            Sizzle.uniqueSort = function (results) {
                var elem,
                    duplicates = [],
                    j = 0,
                    i = 0;

                // Unless we *know* we can detect duplicates, assume their presence
                hasDuplicate = !support.detectDuplicates;
                sortInput = !support.sortStable && results.slice(0);
                results.sort(sortOrder);

                if (hasDuplicate) {
                    while ((elem = results[i++])) {
                        if (elem === results[i]) {
                            j = duplicates.push(i);
                        }
                    }
                    while (j--) {
                        results.splice(duplicates[j], 1);
                    }
                }

                // Clear input after sorting to release objects
                // See https://github.com/jquery/sizzle/pull/225
                sortInput = null;

                return results;
            };

            /**
             * Utility function for retrieving the text value of an array of DOM nodes
             * @param {Array|Element} elem
             */
            getText = Sizzle.getText = function (elem) {
                var node,
                    ret = "",
                    i = 0,
                    nodeType = elem.nodeType;

                if (!nodeType) {
                    // If no nodeType, this is expected to be an array
                    while ((node = elem[i++])) {
                        // Do not traverse comment nodes
                        ret += getText(node);
                    }
                } else if (nodeType === 1 || nodeType === 9 || nodeType === 11) {
                    // Use textContent for elements
                    // innerText usage removed for consistency of new lines (jQuery #11153)
                    if (typeof elem.textContent === "string") {
                        return elem.textContent;
                    } else {
                        // Traverse its children
                        for (elem = elem.firstChild; elem; elem = elem.nextSibling) {
                            ret += getText(elem);
                        }
                    }
                } else if (nodeType === 3 || nodeType === 4) {
                    return elem.nodeValue;
                }
                // Do not include comment or processing instruction nodes

                return ret;
            };

            Expr = Sizzle.selectors = {

                // Can be adjusted by the user
                cacheLength: 50,

                createPseudo: markFunction,

                match: matchExpr,

                attrHandle: {},

                find: {},

                relative: {
                    ">": { dir: "parentNode", first: true },
                    " ": { dir: "parentNode" },
                    "+": { dir: "previousSibling", first: true },
                    "~": { dir: "previousSibling" }
                },

                preFilter: {
                    "ATTR": function (match) {
                        match[1] = match[1].replace(runescape, funescape);

                        // Move the given value to match[3] whether quoted or unquoted
                        match[3] = (match[3] || match[4] || match[5] || "").replace(runescape, funescape);

                        if (match[2] === "~=") {
                            match[3] = " " + match[3] + " ";
                        }

                        return match.slice(0, 4);
                    },

                    "CHILD": function (match) {
                        /* matches from matchExpr["CHILD"]
                            1 type (only|nth|...)
                            2 what (child|of-type)
                            3 argument (even|odd|\d*|\d*n([+-]\d+)?|...)
                            4 xn-component of xn+y argument ([+-]?\d*n|)
                            5 sign of xn-component
                            6 x of xn-component
                            7 sign of y-component
                            8 y of y-component
                        */
                        match[1] = match[1].toLowerCase();

                        if (match[1].slice(0, 3) === "nth") {
                            // nth-* requires argument
                            if (!match[3]) {
                                Sizzle.error(match[0]);
                            }

                            // numeric x and y parameters for Expr.filter.CHILD
                            // remember that false/true cast respectively to 0/1
                            match[4] = +(match[4] ? match[5] + (match[6] || 1) : 2 * (match[3] === "even" || match[3] === "odd"));
                            match[5] = +((match[7] + match[8]) || match[3] === "odd");

                            // other types prohibit arguments
                        } else if (match[3]) {
                            Sizzle.error(match[0]);
                        }

                        return match;
                    },

                    "PSEUDO": function (match) {
                        var excess,
                            unquoted = !match[6] && match[2];

                        if (matchExpr["CHILD"].test(match[0])) {
                            return null;
                        }

                        // Accept quoted arguments as-is
                        if (match[3]) {
                            match[2] = match[4] || match[5] || "";

                            // Strip excess characters from unquoted arguments
                        } else if (unquoted && rpseudo.test(unquoted) &&
                            // Get excess from tokenize (recursively)
                            (excess = tokenize(unquoted, true)) &&
                            // advance to the next closing parenthesis
                            (excess = unquoted.indexOf(")", unquoted.length - excess) - unquoted.length)) {

                            // excess is a negative index
                            match[0] = match[0].slice(0, excess);
                            match[2] = unquoted.slice(0, excess);
                        }

                        // Return only captures needed by the pseudo filter method (type and argument)
                        return match.slice(0, 3);
                    }
                },

                filter: {

                    "TAG": function (nodeNameSelector) {
                        var nodeName = nodeNameSelector.replace(runescape, funescape).toLowerCase();
                        return nodeNameSelector === "*" ?
                            function () { return true; } :
                            function (elem) {
                                return elem.nodeName && elem.nodeName.toLowerCase() === nodeName;
                            };
                    },

                    "CLASS": function (className) {
                        var pattern = classCache[className + " "];

                        return pattern ||
                            (pattern = new RegExp("(^|" + whitespace + ")" + className + "(" + whitespace + "|$)")) &&
                            classCache(className, function (elem) {
                                return pattern.test(typeof elem.className === "string" && elem.className || typeof elem.getAttribute !== "undefined" && elem.getAttribute("class") || "");
                            });
                    },

                    "ATTR": function (name, operator, check) {
                        return function (elem) {
                            var result = Sizzle.attr(elem, name);

                            if (result == null) {
                                return operator === "!=";
                            }
                            if (!operator) {
                                return true;
                            }

                            result += "";

                            return operator === "=" ? result === check :
                                operator === "!=" ? result !== check :
                                operator === "^=" ? check && result.indexOf(check) === 0 :
                                operator === "*=" ? check && result.indexOf(check) > -1 :
                                operator === "$=" ? check && result.slice(-check.length) === check :
                                operator === "~=" ? (" " + result.replace(rwhitespace, " ") + " ").indexOf(check) > -1 :
                                operator === "|=" ? result === check || result.slice(0, check.length + 1) === check + "-" :
                                false;
                        };
                    },

                    "CHILD": function (type, what, argument, first, last) {
                        var simple = type.slice(0, 3) !== "nth",
                            forward = type.slice(-4) !== "last",
                            ofType = what === "of-type";

                        return first === 1 && last === 0 ?

                            // Shortcut for :nth-*(n)
                            function (elem) {
                                return !!elem.parentNode;
                            } :

                            function (elem, context, xml) {
                                var cache, outerCache, node, diff, nodeIndex, start,
                                    dir = simple !== forward ? "nextSibling" : "previousSibling",
                                    parent = elem.parentNode,
                                    name = ofType && elem.nodeName.toLowerCase(),
                                    useCache = !xml && !ofType;

                                if (parent) {

                                    // :(first|last|only)-(child|of-type)
                                    if (simple) {
                                        while (dir) {
                                            node = elem;
                                            while ((node = node[dir])) {
                                                if (ofType ? node.nodeName.toLowerCase() === name : node.nodeType === 1) {
                                                    return false;
                                                }
                                            }
                                            // Reverse direction for :only-* (if we haven't yet done so)
                                            start = dir = type === "only" && !start && "nextSibling";
                                        }
                                        return true;
                                    }

                                    start = [forward ? parent.firstChild : parent.lastChild];

                                    // non-xml :nth-child(...) stores cache data on `parent`
                                    if (forward && useCache) {
                                        // Seek `elem` from a previously-cached index
                                        outerCache = parent[expando] || (parent[expando] = {});
                                        cache = outerCache[type] || [];
                                        nodeIndex = cache[0] === dirruns && cache[1];
                                        diff = cache[0] === dirruns && cache[2];
                                        node = nodeIndex && parent.childNodes[nodeIndex];

                                        while ((node = ++nodeIndex && node && node[dir] ||

                                            // Fallback to seeking `elem` from the start
                                            (diff = nodeIndex = 0) || start.pop())) {

                                            // When found, cache indexes on `parent` and break
                                            if (node.nodeType === 1 && ++diff && node === elem) {
                                                outerCache[type] = [dirruns, nodeIndex, diff];
                                                break;
                                            }
                                        }

                                        // Use previously-cached element index if available
                                    } else if (useCache && (cache = (elem[expando] || (elem[expando] = {}))[type]) && cache[0] === dirruns) {
                                        diff = cache[1];

                                        // xml :nth-child(...) or :nth-last-child(...) or :nth(-last)?-of-type(...)
                                    } else {
                                        // Use the same loop as above to seek `elem` from the start
                                        while ((node = ++nodeIndex && node && node[dir] ||
                                            (diff = nodeIndex = 0) || start.pop())) {

                                            if ((ofType ? node.nodeName.toLowerCase() === name : node.nodeType === 1) && ++diff) {
                                                // Cache the index of each encountered element
                                                if (useCache) {
                                                    (node[expando] || (node[expando] = {}))[type] = [dirruns, diff];
                                                }

                                                if (node === elem) {
                                                    break;
                                                }
                                            }
                                        }
                                    }

                                    // Incorporate the offset, then check against cycle size
                                    diff -= last;
                                    return diff === first || (diff % first === 0 && diff / first >= 0);
                                }
                            };
                    },

                    "PSEUDO": function (pseudo, argument) {
                        // pseudo-class names are case-insensitive
                        // http://www.w3.org/TR/selectors/#pseudo-classes
                        // Prioritize by case sensitivity in case custom pseudos are added with uppercase letters
                        // Remember that setFilters inherits from pseudos
                        var args,
                            fn = Expr.pseudos[pseudo] || Expr.setFilters[pseudo.toLowerCase()] ||
                                Sizzle.error("unsupported pseudo: " + pseudo);

                        // The user may use createPseudo to indicate that
                        // arguments are needed to create the filter function
                        // just as Sizzle does
                        if (fn[expando]) {
                            return fn(argument);
                        }

                        // But maintain support for old signatures
                        if (fn.length > 1) {
                            args = [pseudo, pseudo, "", argument];
                            return Expr.setFilters.hasOwnProperty(pseudo.toLowerCase()) ?
                                markFunction(function (seed, matches) {
                                    var idx,
                                        matched = fn(seed, argument),
                                        i = matched.length;
                                    while (i--) {
                                        idx = indexOf(seed, matched[i]);
                                        seed[idx] = !(matches[idx] = matched[i]);
                                    }
                                }) :
                                function (elem) {
                                    return fn(elem, 0, args);
                                };
                        }

                        return fn;
                    }
                },

                pseudos: {
                    // Potentially complex pseudos
                    "not": markFunction(function (selector) {
                        // Trim the selector passed to compile
                        // to avoid treating leading and trailing
                        // spaces as combinators
                        var input = [],
                            results = [],
                            matcher = compile(selector.replace(rtrim, "$1"));

                        return matcher[expando] ?
                            markFunction(function (seed, matches, context, xml) {
                                var elem,
                                    unmatched = matcher(seed, null, xml, []),
                                    i = seed.length;

                                // Match elements unmatched by `matcher`
                                while (i--) {
                                    if ((elem = unmatched[i])) {
                                        seed[i] = !(matches[i] = elem);
                                    }
                                }
                            }) :
                            function (elem, context, xml) {
                                input[0] = elem;
                                matcher(input, null, xml, results);
                                // Don't keep the element (issue #299)
                                input[0] = null;
                                return !results.pop();
                            };
                    }),

                    "has": markFunction(function (selector) {
                        return function (elem) {
                            return Sizzle(selector, elem).length > 0;
                        };
                    }),

                    "contains": markFunction(function (text) {
                        text = text.replace(runescape, funescape);
                        return function (elem) {
                            return (elem.textContent || elem.innerText || getText(elem)).indexOf(text) > -1;
                        };
                    }),

                    // "Whether an element is represented by a :lang() selector
                    // is based solely on the element's language value
                    // being equal to the identifier C,
                    // or beginning with the identifier C immediately followed by "-".
                    // The matching of C against the element's language value is performed case-insensitively.
                    // The identifier C does not have to be a valid language name."
                    // http://www.w3.org/TR/selectors/#lang-pseudo
                    "lang": markFunction(function (lang) {
                        // lang value must be a valid identifier
                        if (!ridentifier.test(lang || "")) {
                            Sizzle.error("unsupported lang: " + lang);
                        }
                        lang = lang.replace(runescape, funescape).toLowerCase();
                        return function (elem) {
                            var elemLang;
                            do {
                                if ((elemLang = documentIsHTML ?
                                    elem.lang :
                                    elem.getAttribute("xml:lang") || elem.getAttribute("lang"))) {

                                    elemLang = elemLang.toLowerCase();
                                    return elemLang === lang || elemLang.indexOf(lang + "-") === 0;
                                }
                            } while ((elem = elem.parentNode) && elem.nodeType === 1);
                            return false;
                        };
                    }),

                    // Miscellaneous
                    "target": function (elem) {
                        var hash = window.location && window.location.hash;
                        return hash && hash.slice(1) === elem.id;
                    },

                    "root": function (elem) {
                        return elem === docElem;
                    },

                    "focus": function (elem) {
                        return elem === document.activeElement && (!document.hasFocus || document.hasFocus()) && !!(elem.type || elem.href || ~elem.tabIndex);
                    },

                    // Boolean properties
                    "enabled": function (elem) {
                        return elem.disabled === false;
                    },

                    "disabled": function (elem) {
                        return elem.disabled === true;
                    },

                    "checked": function (elem) {
                        // In CSS3, :checked should return both checked and selected elements
                        // http://www.w3.org/TR/2011/REC-css3-selectors-20110929/#checked
                        var nodeName = elem.nodeName.toLowerCase();
                        return (nodeName === "input" && !!elem.checked) || (nodeName === "option" && !!elem.selected);
                    },

                    "selected": function (elem) {
                        // Accessing this property makes selected-by-default
                        // options in Safari work properly
                        if (elem.parentNode) {
                            elem.parentNode.selectedIndex;
                        }

                        return elem.selected === true;
                    },

                    // Contents
                    "empty": function (elem) {
                        // http://www.w3.org/TR/selectors/#empty-pseudo
                        // :empty is negated by element (1) or content nodes (text: 3; cdata: 4; entity ref: 5),
                        //   but not by others (comment: 8; processing instruction: 7; etc.)
                        // nodeType < 6 works because attributes (2) do not appear as children
                        for (elem = elem.firstChild; elem; elem = elem.nextSibling) {
                            if (elem.nodeType < 6) {
                                return false;
                            }
                        }
                        return true;
                    },

                    "parent": function (elem) {
                        return !Expr.pseudos["empty"](elem);
                    },

                    // Element/input types
                    "header": function (elem) {
                        return rheader.test(elem.nodeName);
                    },

                    "input": function (elem) {
                        return rinputs.test(elem.nodeName);
                    },

                    "button": function (elem) {
                        var name = elem.nodeName.toLowerCase();
                        return name === "input" && elem.type === "button" || name === "button";
                    },

                    "text": function (elem) {
                        var attr;
                        return elem.nodeName.toLowerCase() === "input" &&
                            elem.type === "text" &&

                            // Support: IE<8
                            // New HTML5 attribute values (e.g., "search") appear with elem.type === "text"
                            ((attr = elem.getAttribute("type")) == null || attr.toLowerCase() === "text");
                    },

                    // Position-in-collection
                    "first": createPositionalPseudo(function () {
                        return [0];
                    }),

                    "last": createPositionalPseudo(function (matchIndexes, length) {
                        return [length - 1];
                    }),

                    "eq": createPositionalPseudo(function (matchIndexes, length, argument) {
                        return [argument < 0 ? argument + length : argument];
                    }),

                    "even": createPositionalPseudo(function (matchIndexes, length) {
                        var i = 0;
                        for (; i < length; i += 2) {
                            matchIndexes.push(i);
                        }
                        return matchIndexes;
                    }),

                    "odd": createPositionalPseudo(function (matchIndexes, length) {
                        var i = 1;
                        for (; i < length; i += 2) {
                            matchIndexes.push(i);
                        }
                        return matchIndexes;
                    }),

                    "lt": createPositionalPseudo(function (matchIndexes, length, argument) {
                        var i = argument < 0 ? argument + length : argument;
                        for (; --i >= 0;) {
                            matchIndexes.push(i);
                        }
                        return matchIndexes;
                    }),

                    "gt": createPositionalPseudo(function (matchIndexes, length, argument) {
                        var i = argument < 0 ? argument + length : argument;
                        for (; ++i < length;) {
                            matchIndexes.push(i);
                        }
                        return matchIndexes;
                    })
                }
            };

            Expr.pseudos["nth"] = Expr.pseudos["eq"];

            // Add button/input type pseudos
            for (i in { radio: true, checkbox: true, file: true, password: true, image: true }) {
                Expr.pseudos[i] = createInputPseudo(i);
            }
            for (i in { submit: true, reset: true }) {
                Expr.pseudos[i] = createButtonPseudo(i);
            }

            // Easy API for creating new setFilters
            function setFilters() { }
            setFilters.prototype = Expr.filters = Expr.pseudos;
            Expr.setFilters = new setFilters();

            tokenize = Sizzle.tokenize = function (selector, parseOnly) {
                var matched, match, tokens, type,
                    soFar, groups, preFilters,
                    cached = tokenCache[selector + " "];

                if (cached) {
                    return parseOnly ? 0 : cached.slice(0);
                }

                soFar = selector;
                groups = [];
                preFilters = Expr.preFilter;

                while (soFar) {

                    // Comma and first run
                    if (!matched || (match = rcomma.exec(soFar))) {
                        if (match) {
                            // Don't consume trailing commas as valid
                            soFar = soFar.slice(match[0].length) || soFar;
                        }
                        groups.push((tokens = []));
                    }

                    matched = false;

                    // Combinators
                    if ((match = rcombinators.exec(soFar))) {
                        matched = match.shift();
                        tokens.push({
                            value: matched,
                            // Cast descendant combinators to space
                            type: match[0].replace(rtrim, " ")
                        });
                        soFar = soFar.slice(matched.length);
                    }

                    // Filters
                    for (type in Expr.filter) {
                        if ((match = matchExpr[type].exec(soFar)) && (!preFilters[type] ||
                            (match = preFilters[type](match)))) {
                            matched = match.shift();
                            tokens.push({
                                value: matched,
                                type: type,
                                matches: match
                            });
                            soFar = soFar.slice(matched.length);
                        }
                    }

                    if (!matched) {
                        break;
                    }
                }

                // Return the length of the invalid excess
                // if we're just parsing
                // Otherwise, throw an error or return tokens
                return parseOnly ?
                    soFar.length :
                    soFar ?
                    Sizzle.error(selector) :
                    // Cache the tokens
                    tokenCache(selector, groups).slice(0);
            };

            function toSelector(tokens) {
                var i = 0,
                    len = tokens.length,
                    selector = "";
                for (; i < len; i++) {
                    selector += tokens[i].value;
                }
                return selector;
            }

            function addCombinator(matcher, combinator, base) {
                var dir = combinator.dir,
                    checkNonElements = base && dir === "parentNode",
                    doneName = done++;

                return combinator.first ?
                    // Check against closest ancestor/preceding element
                    function (elem, context, xml) {
                        while ((elem = elem[dir])) {
                            if (elem.nodeType === 1 || checkNonElements) {
                                return matcher(elem, context, xml);
                            }
                        }
                    } :

                    // Check against all ancestor/preceding elements
                    function (elem, context, xml) {
                        var oldCache, outerCache,
                            newCache = [dirruns, doneName];

                        // We can't set arbitrary data on XML nodes, so they don't benefit from dir caching
                        if (xml) {
                            while ((elem = elem[dir])) {
                                if (elem.nodeType === 1 || checkNonElements) {
                                    if (matcher(elem, context, xml)) {
                                        return true;
                                    }
                                }
                            }
                        } else {
                            while ((elem = elem[dir])) {
                                if (elem.nodeType === 1 || checkNonElements) {
                                    outerCache = elem[expando] || (elem[expando] = {});
                                    if ((oldCache = outerCache[dir]) &&
                                        oldCache[0] === dirruns && oldCache[1] === doneName) {

                                        // Assign to newCache so results back-propagate to previous elements
                                        return (newCache[2] = oldCache[2]);
                                    } else {
                                        // Reuse newcache so results back-propagate to previous elements
                                        outerCache[dir] = newCache;

                                        // A match means we're done; a fail means we have to keep checking
                                        if ((newCache[2] = matcher(elem, context, xml))) {
                                            return true;
                                        }
                                    }
                                }
                            }
                        }
                    };
            }

            function elementMatcher(matchers) {
                return matchers.length > 1 ?
                    function (elem, context, xml) {
                        var i = matchers.length;
                        while (i--) {
                            if (!matchers[i](elem, context, xml)) {
                                return false;
                            }
                        }
                        return true;
                    } :
                    matchers[0];
            }

            function multipleContexts(selector, contexts, results) {
                var i = 0,
                    len = contexts.length;
                for (; i < len; i++) {
                    Sizzle(selector, contexts[i], results);
                }
                return results;
            }

            function condense(unmatched, map, filter, context, xml) {
                var elem,
                    newUnmatched = [],
                    i = 0,
                    len = unmatched.length,
                    mapped = map != null;

                for (; i < len; i++) {
                    if ((elem = unmatched[i])) {
                        if (!filter || filter(elem, context, xml)) {
                            newUnmatched.push(elem);
                            if (mapped) {
                                map.push(i);
                            }
                        }
                    }
                }

                return newUnmatched;
            }

            function setMatcher(preFilter, selector, matcher, postFilter, postFinder, postSelector) {
                if (postFilter && !postFilter[expando]) {
                    postFilter = setMatcher(postFilter);
                }
                if (postFinder && !postFinder[expando]) {
                    postFinder = setMatcher(postFinder, postSelector);
                }
                return markFunction(function (seed, results, context, xml) {
                    var temp, i, elem,
                        preMap = [],
                        postMap = [],
                        preexisting = results.length,

                        // Get initial elements from seed or context
                        elems = seed || multipleContexts(selector || "*", context.nodeType ? [context] : context, []),

                        // Prefilter to get matcher input, preserving a map for seed-results synchronization
                        matcherIn = preFilter && (seed || !selector) ?
                            condense(elems, preMap, preFilter, context, xml) :
                            elems,

                        matcherOut = matcher ?
                            // If we have a postFinder, or filtered seed, or non-seed postFilter or preexisting results,
                            postFinder || (seed ? preFilter : preexisting || postFilter) ?

                            // ...intermediate processing is necessary
                            [] :

                            // ...otherwise use results directly
                            results :
                            matcherIn;

                    // Find primary matches
                    if (matcher) {
                        matcher(matcherIn, matcherOut, context, xml);
                    }

                    // Apply postFilter
                    if (postFilter) {
                        temp = condense(matcherOut, postMap);
                        postFilter(temp, [], context, xml);

                        // Un-match failing elements by moving them back to matcherIn
                        i = temp.length;
                        while (i--) {
                            if ((elem = temp[i])) {
                                matcherOut[postMap[i]] = !(matcherIn[postMap[i]] = elem);
                            }
                        }
                    }

                    if (seed) {
                        if (postFinder || preFilter) {
                            if (postFinder) {
                                // Get the final matcherOut by condensing this intermediate into postFinder contexts
                                temp = [];
                                i = matcherOut.length;
                                while (i--) {
                                    if ((elem = matcherOut[i])) {
                                        // Restore matcherIn since elem is not yet a final match
                                        temp.push((matcherIn[i] = elem));
                                    }
                                }
                                postFinder(null, (matcherOut = []), temp, xml);
                            }

                            // Move matched elements from seed to results to keep them synchronized
                            i = matcherOut.length;
                            while (i--) {
                                if ((elem = matcherOut[i]) &&
                                    (temp = postFinder ? indexOf(seed, elem) : preMap[i]) > -1) {

                                    seed[temp] = !(results[temp] = elem);
                                }
                            }
                        }

                        // Add elements to results, through postFinder if defined
                    } else {
                        matcherOut = condense(
                            matcherOut === results ?
                            matcherOut.splice(preexisting, matcherOut.length) :
                            matcherOut
                        );
                        if (postFinder) {
                            postFinder(null, results, matcherOut, xml);
                        } else {
                            push.apply(results, matcherOut);
                        }
                    }
                });
            }

            function matcherFromTokens(tokens) {
                var checkContext, matcher, j,
                    len = tokens.length,
                    leadingRelative = Expr.relative[tokens[0].type],
                    implicitRelative = leadingRelative || Expr.relative[" "],
                    i = leadingRelative ? 1 : 0,

                    // The foundational matcher ensures that elements are reachable from top-level context(s)
                    matchContext = addCombinator(function (elem) {
                        return elem === checkContext;
                    }, implicitRelative, true),
                    matchAnyContext = addCombinator(function (elem) {
                        return indexOf(checkContext, elem) > -1;
                    }, implicitRelative, true),
                    matchers = [function (elem, context, xml) {
                        var ret = (!leadingRelative && (xml || context !== outermostContext)) || (
                            (checkContext = context).nodeType ?
                                matchContext(elem, context, xml) :
                                matchAnyContext(elem, context, xml));
                        // Avoid hanging onto element (issue #299)
                        checkContext = null;
                        return ret;
                    }];

                for (; i < len; i++) {
                    if ((matcher = Expr.relative[tokens[i].type])) {
                        matchers = [addCombinator(elementMatcher(matchers), matcher)];
                    } else {
                        matcher = Expr.filter[tokens[i].type].apply(null, tokens[i].matches);

                        // Return special upon seeing a positional matcher
                        if (matcher[expando]) {
                            // Find the next relative operator (if any) for proper handling
                            j = ++i;
                            for (; j < len; j++) {
                                if (Expr.relative[tokens[j].type]) {
                                    break;
                                }
                            }
                            return setMatcher(
                                i > 1 && elementMatcher(matchers),
                                i > 1 && toSelector(
                                    // If the preceding token was a descendant combinator, insert an implicit any-element `*`
                                    tokens.slice(0, i - 1).concat({ value: tokens[i - 2].type === " " ? "*" : "" })
                                ).replace(rtrim, "$1"),
                                matcher,
                                i < j && matcherFromTokens(tokens.slice(i, j)),
                                j < len && matcherFromTokens((tokens = tokens.slice(j))),
                                j < len && toSelector(tokens)
                            );
                        }
                        matchers.push(matcher);
                    }
                }

                return elementMatcher(matchers);
            }

            function matcherFromGroupMatchers(elementMatchers, setMatchers) {
                var bySet = setMatchers.length > 0,
                    byElement = elementMatchers.length > 0,
                    superMatcher = function (seed, context, xml, results, outermost) {
                        var elem, j, matcher,
                            matchedCount = 0,
                            i = "0",
                            unmatched = seed && [],
                            setMatched = [],
                            contextBackup = outermostContext,
                            // We must always have either seed elements or outermost context
                            elems = seed || byElement && Expr.find["TAG"]("*", outermost),
                            // Use integer dirruns iff this is the outermost matcher
                            dirrunsUnique = (dirruns += contextBackup == null ? 1 : Math.random() || 0.1),
                            len = elems.length;

                        if (outermost) {
                            outermostContext = context !== document && context;
                        }

                        // Add elements passing elementMatchers directly to results
                        // Keep `i` a string if there are no elements so `matchedCount` will be "00" below
                        // Support: IE<9, Safari
                        // Tolerate NodeList properties (IE: "length"; Safari: ) matching elements by id
                        for (; i !== len && (elem = elems[i]) != null; i++) {
                            if (byElement && elem) {
                                j = 0;
                                while ((matcher = elementMatchers[j++])) {
                                    if (matcher(elem, context, xml)) {
                                        results.push(elem);
                                        break;
                                    }
                                }
                                if (outermost) {
                                    dirruns = dirrunsUnique;
                                }
                            }

                            // Track unmatched elements for set filters
                            if (bySet) {
                                // They will have gone through all possible matchers
                                if ((elem = !matcher && elem)) {
                                    matchedCount--;
                                }

                                // Lengthen the array for every element, matched or not
                                if (seed) {
                                    unmatched.push(elem);
                                }
                            }
                        }

                        // Apply set filters to unmatched elements
                        matchedCount += i;
                        if (bySet && i !== matchedCount) {
                            j = 0;
                            while ((matcher = setMatchers[j++])) {
                                matcher(unmatched, setMatched, context, xml);
                            }

                            if (seed) {
                                // Reintegrate element matches to eliminate the need for sorting
                                if (matchedCount > 0) {
                                    while (i--) {
                                        if (!(unmatched[i] || setMatched[i])) {
                                            setMatched[i] = pop.call(results);
                                        }
                                    }
                                }

                                // Discard index placeholder values to get only actual matches
                                setMatched = condense(setMatched);
                            }

                            // Add matches to results
                            push.apply(results, setMatched);

                            // Seedless set matches succeeding multiple successful matchers stipulate sorting
                            if (outermost && !seed && setMatched.length > 0 &&
                                (matchedCount + setMatchers.length) > 1) {

                                Sizzle.uniqueSort(results);
                            }
                        }

                        // Override manipulation of globals by nested matchers
                        if (outermost) {
                            dirruns = dirrunsUnique;
                            outermostContext = contextBackup;
                        }

                        return unmatched;
                    };

                return bySet ?
                    markFunction(superMatcher) :
                    superMatcher;
            }

            compile = Sizzle.compile = function (selector, match /* Internal Use Only */) {
                var i,
                    setMatchers = [],
                    elementMatchers = [],
                    cached = compilerCache[selector + " "];

                if (!cached) {
                    // Generate a function of recursive functions that can be used to check each element
                    if (!match) {
                        match = tokenize(selector);
                    }
                    i = match.length;
                    while (i--) {
                        cached = matcherFromTokens(match[i]);
                        if (cached[expando]) {
                            setMatchers.push(cached);
                        } else {
                            elementMatchers.push(cached);
                        }
                    }

                    // Cache the compiled function
                    cached = compilerCache(selector, matcherFromGroupMatchers(elementMatchers, setMatchers));

                    // Save selector and tokenization
                    cached.selector = selector;
                }
                return cached;
            };

            /**
             * A low-level selection function that works with Sizzle's compiled
             *  selector functions
             * @param {String|Function} selector A selector or a pre-compiled
             *  selector function built with Sizzle.compile
             * @param {Element} context
             * @param {Array} [results]
             * @param {Array} [seed] A set of elements to match against
             */
            select = Sizzle.select = function (selector, context, results, seed) {
                var i, tokens, token, type, find,
                    compiled = typeof selector === "function" && selector,
                    match = !seed && tokenize((selector = compiled.selector || selector));

                results = results || [];

                // Try to minimize operations if there is no seed and only one group
                if (match.length === 1) {

                    // Take a shortcut and set the context if the root selector is an ID
                    tokens = match[0] = match[0].slice(0);
                    if (tokens.length > 2 && (token = tokens[0]).type === "ID" &&
                        support.getById && context.nodeType === 9 && documentIsHTML &&
                        Expr.relative[tokens[1].type]) {

                        context = (Expr.find["ID"](token.matches[0].replace(runescape, funescape), context) || [])[0];
                        if (!context) {
                            return results;

                            // Precompiled matchers will still verify ancestry, so step up a level
                        } else if (compiled) {
                            context = context.parentNode;
                        }

                        selector = selector.slice(tokens.shift().value.length);
                    }

                    // Fetch a seed set for right-to-left matching
                    i = matchExpr["needsContext"].test(selector) ? 0 : tokens.length;
                    while (i--) {
                        token = tokens[i];

                        // Abort if we hit a combinator
                        if (Expr.relative[(type = token.type)]) {
                            break;
                        }
                        if ((find = Expr.find[type])) {
                            // Search, expanding context for leading sibling combinators
                            if ((seed = find(
                                token.matches[0].replace(runescape, funescape),
                                rsibling.test(tokens[0].type) && testContext(context.parentNode) || context
                            ))) {

                                // If seed is empty or no tokens remain, we can return early
                                tokens.splice(i, 1);
                                selector = seed.length && toSelector(tokens);
                                if (!selector) {
                                    push.apply(results, seed);
                                    return results;
                                }

                                break;
                            }
                        }
                    }
                }

                // Compile and execute a filtering function if one is not provided
                // Provide `match` to avoid retokenization if we modified the selector above
                (compiled || compile(selector, match))(
                    seed,
                    context,
                    !documentIsHTML,
                    results,
                    rsibling.test(selector) && testContext(context.parentNode) || context
                );
                return results;
            };

            // One-time assignments

            // Sort stability
            support.sortStable = expando.split("").sort(sortOrder).join("") === expando;

            // Support: Chrome 14-35+
            // Always assume duplicates if they aren't passed to the comparison function
            support.detectDuplicates = !!hasDuplicate;

            // Initialize against the default document
            setDocument();

            // Support: Webkit<537.32 - Safari 6.0.3/Chrome 25 (fixed in Chrome 27)
            // Detached nodes confoundingly follow *each other*
            support.sortDetached = assert(function (div1) {
                // Should return 1, but returns 4 (following)
                return div1.compareDocumentPosition(document.createElement("div")) & 1;
            });

            // Support: IE<8
            // Prevent attribute/property "interpolation"
            // http://msdn.microsoft.com/en-us/library/ms536429%28VS.85%29.aspx
            if (!assert(function (div) {
                div.innerHTML = "";
                return div.firstChild.getAttribute("href") === "#";
            })) {
                addHandle("type|href|height|width", function (elem, name, isXML) {
                    if (!isXML) {
                        return elem.getAttribute(name, name.toLowerCase() === "type" ? 1 : 2);
                    }
                });
            }

            // Support: IE<9
            // Use defaultValue in place of getAttribute("value")
            if (!support.attributes || !assert(function (div) {
                div.innerHTML = "";
                div.firstChild.setAttribute("value", "");
                return div.firstChild.getAttribute("value") === "";
            })) {
                addHandle("value", function (elem, name, isXML) {
                    if (!isXML && elem.nodeName.toLowerCase() === "input") {
                        return elem.defaultValue;
                    }
                });
            }

            // Support: IE<9
            // Use getAttributeNode to fetch booleans when getAttribute lies
            if (!assert(function (div) {
                return div.getAttribute("disabled") == null;
            })) {
                addHandle(booleans, function (elem, name, isXML) {
                    var val;
                    if (!isXML) {
                        return elem[name] === true ? name.toLowerCase() :
                            (val = elem.getAttributeNode(name)) && val.specified ?
                            val.value :
                            null;
                    }
                });
            }

            return Sizzle;

        })(window);

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

你可能感兴趣的:(Jquery源码)