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 ).