Selector: reduce size, simplify setDocument

With new selector code doing less convoluted support tests, it was possible
to extract a lot of logic out of setDocument & also reduce size.

This commit also backports jquery/sizzle#439 that was reverted by mistake
during a switch from JSHint + JSCS to ESLint.

Closes gh-4462
Ref jquery/sizzle#442
Ref jquery/sizzle#439

3 files changed, 128 insertions, 130 deletions

diff --git a/src/selector.js b/src/selector.js
index 3e187a159..847d3a448 100644
--- a/src/selector.js
+++ b/src/selector.js
@@ -1,20 +1,23 @@
 define( [
 	"./core",
 	"./var/document",
+	"./var/documentElement",
 	"./var/indexOf",
 	"./var/pop",
 	"./var/push",
+	"./selector/rbuggyQSA",
 	"./selector/support",
 
 	// The following utils are attached directly to the jQuery object.
 	"./selector/contains",
 	"./selector/escapeSelector",
 	"./selector/uniqueSort"
-], function( jQuery, document, indexOf, pop, push, support ) {
+], function( jQuery, document, documentElement, indexOf, pop, push, rbuggyQSA, support ) {
 
 "use strict";
 
-var preferredDoc = document;
+var preferredDoc = document,
+	matches = documentElement.matches || documentElement.msMatchesSelector;
 
 ( function() {
 
@@ -24,10 +27,8 @@ var i,
 
 	// Local document vars
 	document,
-	docElem,
+	documentElement,
 	documentIsHTML,
-	rbuggyQSA,
-	matches,
 
 	// Instance-specific data
 	expando = jQuery.expando,
@@ -86,20 +87,20 @@ var i,
 	ridentifier = new RegExp( "^" + identifier + "$" ),
 
 	matchExpr = {
-		"ID": new RegExp( "^#(" + identifier + ")" ),
-		"CLASS": new RegExp( "^\\.(" + identifier + ")" ),
-		"TAG": new RegExp( "^(" + identifier + "|[*])" ),
-		"ATTR": new RegExp( "^" + attributes ),
-		"PSEUDO": new RegExp( "^" + pseudos ),
-		"CHILD": new RegExp(
+		ID: new RegExp( "^#(" + identifier + ")" ),
+		CLASS: new RegExp( "^\\.(" + identifier + ")" ),
+		TAG: new RegExp( "^(" + identifier + "|[*])" ),
+		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 + ")$", "i" ),
+		bool: new RegExp( "^(?:" + booleans + ")$", "i" ),
 
 		// For use in libraries implementing .is()
 		// We use this for POS matching in `select`
-		"needsContext": new RegExp( "^" + whitespace +
+		needsContext: new RegExp( "^" + whitespace +
 			"*[>+~]|:(even|odd|eq|gt|lt|nth|first|last)(?:\\(" + whitespace +
 			"*((?:-\\d)?\\d*)" + whitespace + "*\\)|)(?=[^-]|$)", "i" )
 	},
@@ -190,10 +191,8 @@ function find( selector, context, results, seed ) {
 					if ( nodeType === 9 ) {
 						if ( ( elem = context.getElementById( m ) ) ) {
 							results.push( elem );
-							return results;
-						} else {
-							return results;
 						}
+						return results;
 
 					// Element context
 					} else {
@@ -420,20 +419,19 @@ function testContext( context ) {
 /**
  * Sets document-related variables once based on the current document
  * @param {Element|Object} [node] An element or document object to use to set the document
- * @returns {Object} Returns the current document
  */
 function setDocument( node ) {
 	var subWindow,
 		doc = node ? node.ownerDocument || node : preferredDoc;
 
 	// Return early if doc is invalid or already selected
-	if ( doc === document || doc.nodeType !== 9 || !doc.documentElement ) {
-		return document;
+	if ( doc === document || doc.nodeType !== 9 ) {
+		return;
 	}
 
 	// Update global variables
 	document = doc;
-	docElem = document.documentElement;
+	documentElement = document.documentElement;
 	documentIsHTML = !jQuery.isXMLDoc( document );
 
 	// Support: IE 9 - 11+, Edge 12 - 18+
@@ -444,77 +442,6 @@ function setDocument( node ) {
 		// Support: IE 9 - 11+, Edge 12 - 18+
 		subWindow.addEventListener( "unload", unloadHandler );
 	}
-
-	// ID filter and find
-	Expr.filter.ID = function( id ) {
-		var attrId = id.replace( runescape, funescape );
-		return function( elem ) {
-			return elem.getAttribute( "id" ) === attrId;
-		};
-	};
-	Expr.find.ID = function( id, context ) {
-		if ( typeof context.getElementById !== "undefined" && documentIsHTML ) {
-			var elem = context.getElementById( id );
-			return elem ? [ elem ] : [];
-		}
-	};
-
-	// Tag
-	Expr.find.TAG = function( tag, context ) {
-		if ( typeof context.getElementsByTagName !== "undefined" ) {
-			return context.getElementsByTagName( tag );
-
-		// DocumentFragment nodes don't have gEBTN
-		} else {
-			return context.querySelectorAll( tag );
-		}
-	};
-
-	// Class
-	Expr.find.CLASS = function( className, context ) {
-		if ( typeof context.getElementsByClassName !== "undefined" && documentIsHTML ) {
-			return context.getElementsByClassName( className );
-		}
-	};
-
-	/* QSA/matchesSelector
-	---------------------------------------------------------------------- */
-
-	// QSA and matchesSelector support
-
-	rbuggyQSA = [];
-
-	var testEl = document.createElement( "fieldset" );
-
-	testEl.innerHTML = "<a href='' disabled='disabled'></a>" +
-		"<select disabled='disabled'><option/></select>";
-
-	// Support: Windows 8 Native Apps
-	// The type and name attributes are restricted during .innerHTML assignment
-	var input = document.createElement( "input" );
-	input.setAttribute( "type", "hidden" );
-	testEl.appendChild( input ).setAttribute( "name", "D" );
-
-	// Support: Chrome 74+
-	// :enabled/:disabled and hidden elements (hidden elements are still enabled)
-	if ( testEl.querySelectorAll( ":enabled" ).length !== 2 ) {
-		rbuggyQSA.push( ":enabled", ":disabled" );
-	}
-
-	// Support: IE 9 - 11+
-	// IE's :disabled selector does not pick up the children of disabled fieldsets
-	docElem.appendChild( testEl ).disabled = true;
-	if ( testEl.querySelectorAll( ":disabled" ).length !== 2 ) {
-		rbuggyQSA.push( ":enabled", ":disabled" );
-	}
-
-	docElem.removeChild( testEl );
-
-	matches = docElem.matches || docElem.msMatchesSelector;
-
-	rbuggyQSA = rbuggyQSA.length && new RegExp( rbuggyQSA.join( "|" ) );
-
-	return document;
 }
 
 find.matches = function( expr, elements ) {
@@ -551,7 +478,30 @@ Expr = jQuery.expr = {
 
 	match: matchExpr,
 
-	find: {},
+	find: {
+		ID: function( id, context ) {
+			if ( typeof context.getElementById !== "undefined" && documentIsHTML ) {
+				var elem = context.getElementById( id );
+				return elem ? [ elem ] : [];
+			}
+		},
+
+		TAG: function( tag, context ) {
+			if ( typeof context.getElementsByTagName !== "undefined" ) {
+				return context.getElementsByTagName( tag );
+
+				// DocumentFragment nodes don't have gEBTN
+			} else {
+				return context.querySelectorAll( tag );
+			}
+		},
+
+		CLASS: function( className, context ) {
+			if ( typeof context.getElementsByClassName !== "undefined" && documentIsHTML ) {
+				return context.getElementsByClassName( className );
+			}
+		}
+	},
 
 	relative: {
 		">": { dir: "parentNode", first: true },
@@ -561,7 +511,7 @@ Expr = jQuery.expr = {
 	},
 
 	preFilter: {
-		"ATTR": function( match ) {
+		ATTR: function( match ) {
 			match[ 1 ] = match[ 1 ].replace( runescape, funescape );
 
 			// Move the given value to match[3] whether quoted or unquoted
@@ -575,7 +525,7 @@ Expr = jQuery.expr = {
 			return match.slice( 0, 4 );
 		},
 
-		"CHILD": function( match ) {
+		CHILD: function( match ) {
 
 			/* matches from matchExpr["CHILD"]
 				1 type (only|nth|...)
@@ -612,7 +562,7 @@ Expr = jQuery.expr = {
 			return match;
 		},
 
-		"PSEUDO": function( match ) {
+		PSEUDO: function( match ) {
 			var excess,
 				unquoted = !match[ 6 ] && match[ 2 ];
 
@@ -644,8 +594,14 @@ Expr = jQuery.expr = {
 	},
 
 	filter: {
+		ID: function( id ) {
+			var attrId = id.replace( runescape, funescape );
+			return function( elem ) {
+				return elem.getAttribute( "id" ) === attrId;
+			};
+		},
 
-		"TAG": function( nodeNameSelector ) {
+		TAG: function( nodeNameSelector ) {
 			var nodeName = nodeNameSelector.replace( runescape, funescape ).toLowerCase();
 			return nodeNameSelector === "*" ?
 				function() {
@@ -656,7 +612,7 @@ Expr = jQuery.expr = {
 				};
 		},
 
-		"CLASS": function( className ) {
+		CLASS: function( className ) {
 			var pattern = classCache[ className + " " ];
 
 			return pattern ||
@@ -672,7 +628,7 @@ Expr = jQuery.expr = {
 				} );
 		},
 
-		"ATTR": function( name, operator, check ) {
+		ATTR: function( name, operator, check ) {
 			return function( elem ) {
 				var result = jQuery.attr( elem, name );
 
@@ -712,7 +668,7 @@ Expr = jQuery.expr = {
 			};
 		},
 
-		"CHILD": function( type, what, _argument, first, last ) {
+		CHILD: function( type, what, _argument, first, last ) {
 			var simple = type.slice( 0, 3 ) !== "nth",
 				forward = type.slice( -4 ) !== "last",
 				ofType = what === "of-type";
@@ -822,7 +778,7 @@ Expr = jQuery.expr = {
 				};
 		},
 
-		"PSEUDO": function( pseudo, argument ) {
+		PSEUDO: function( pseudo, argument ) {
 
 			// pseudo-class names are case-insensitive
 			// http://www.w3.org/TR/selectors/#pseudo-classes
@@ -864,7 +820,7 @@ Expr = jQuery.expr = {
 	pseudos: {
 
 		// Potentially complex pseudos
-		"not": markFunction( function( selector ) {
+		not: markFunction( function( selector ) {
 
 			// Trim the selector passed to compile
 			// to avoid treating leading and trailing
@@ -896,13 +852,13 @@ Expr = jQuery.expr = {
 				};
 		} ),
 
-		"has": markFunction( function( selector ) {
+		has: markFunction( function( selector ) {
 			return function( elem ) {
 				return find( selector, elem ).length > 0;
 			};
 		} ),
 
-		"contains": markFunction( function( text ) {
+		contains: markFunction( function( text ) {
 			text = text.replace( runescape, funescape );
 			return function( elem ) {
 				return ( elem.textContent || jQuery.text( elem ) ).indexOf( text ) > -1;
@@ -916,7 +872,7 @@ Expr = jQuery.expr = {
 		// 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: markFunction( function( lang ) {
 
 			// lang value must be a valid identifier
 			if ( !ridentifier.test( lang || "" ) ) {
@@ -939,26 +895,26 @@ Expr = jQuery.expr = {
 		} ),
 
 		// Miscellaneous
-		"target": function( elem ) {
+		target: function( elem ) {
 			var hash = window.location && window.location.hash;
 			return hash && hash.slice( 1 ) === elem.id;
 		},
 
-		"root": function( elem ) {
-			return elem === docElem;
+		root: function( elem ) {
+			return elem === documentElement;
 		},
 
-		"focus": function( elem ) {
+		focus: function( elem ) {
 			return elem === document.activeElement &&
-				( !document.hasFocus || document.hasFocus() ) &&
+				document.hasFocus() &&
 				!!( elem.type || elem.href || ~elem.tabIndex );
 		},
 
 		// Boolean properties
-		"enabled": createDisabledPseudo( false ),
-		"disabled": createDisabledPseudo( true ),
+		enabled: createDisabledPseudo( false ),
+		disabled: createDisabledPseudo( true ),
 
-		"checked": function( elem ) {
+		checked: function( elem ) {
 
 			// In CSS3, :checked should return both checked and selected elements
 			// http://www.w3.org/TR/2011/REC-css3-selectors-20110929/#checked
@@ -967,7 +923,7 @@ Expr = jQuery.expr = {
 				( nodeName === "option" && !!elem.selected );
 		},
 
-		"selected": function( elem ) {
+		selected: function( elem ) {
 
 			// Support: IE <=11+
 			// Accessing the selectedIndex property
@@ -982,7 +938,7 @@ Expr = jQuery.expr = {
 		},
 
 		// Contents
-		"empty": function( elem ) {
+		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),
@@ -996,43 +952,43 @@ Expr = jQuery.expr = {
 			return true;
 		},
 
-		"parent": function( elem ) {
+		parent: function( elem ) {
 			return !Expr.pseudos.empty( elem );
 		},
 
 		// Element/input types
-		"header": function( elem ) {
+		header: function( elem ) {
 			return rheader.test( elem.nodeName );
 		},
 
-		"input": function( elem ) {
+		input: function( elem ) {
 			return rinputs.test( elem.nodeName );
 		},
 
-		"button": function( elem ) {
+		button: function( elem ) {
 			var name = elem.nodeName.toLowerCase();
 			return name === "input" && elem.type === "button" || name === "button";
 		},
 
-		"text": function( elem ) {
+		text: function( elem ) {
 			return elem.nodeName.toLowerCase() === "input" &&
 				elem.type === "text";
 		},
 
 		// Position-in-collection
-		"first": createPositionalPseudo( function() {
+		first: createPositionalPseudo( function() {
 			return [ 0 ];
 		} ),
 
-		"last": createPositionalPseudo( function( _matchIndexes, length ) {
+		last: createPositionalPseudo( function( _matchIndexes, length ) {
 			return [ length - 1 ];
 		} ),
 
-		"eq": createPositionalPseudo( function( _matchIndexes, length, argument ) {
+		eq: createPositionalPseudo( function( _matchIndexes, length, argument ) {
 			return [ argument < 0 ? argument + length : argument ];
 		} ),
 
-		"even": createPositionalPseudo( function( matchIndexes, length ) {
+		even: createPositionalPseudo( function( matchIndexes, length ) {
 			var i = 0;
 			for ( ; i < length; i += 2 ) {
 				matchIndexes.push( i );
@@ -1040,7 +996,7 @@ Expr = jQuery.expr = {
 			return matchIndexes;
 		} ),
 
-		"odd": createPositionalPseudo( function( matchIndexes, length ) {
+		odd: createPositionalPseudo( function( matchIndexes, length ) {
 			var i = 1;
 			for ( ; i < length; i += 2 ) {
 				matchIndexes.push( i );
@@ -1048,7 +1004,7 @@ Expr = jQuery.expr = {
 			return matchIndexes;
 		} ),
 
-		"lt": createPositionalPseudo( function( matchIndexes, length, argument ) {
+		lt: createPositionalPseudo( function( matchIndexes, length, argument ) {
 			var i;
 
 			if ( argument < 0 ) {
@@ -1065,7 +1021,7 @@ Expr = jQuery.expr = {
 			return matchIndexes;
 		} ),
 
-		"gt": createPositionalPseudo( function( matchIndexes, length, argument ) {
+		gt: createPositionalPseudo( function( matchIndexes, length, argument ) {
 			var i = argument < 0 ? argument + length : argument;
 			for ( ; ++i < length; ) {
 				matchIndexes.push( i );
@@ -1672,8 +1628,6 @@ setDocument();
 
 jQuery.find = find;
 
-/* eslint-enable */
-
 } )();
 
 } );
diff --git a/src/selector/rbuggyQSA.js b/src/selector/rbuggyQSA.js
new file mode 100644
index 000000000..eee151afb
--- /dev/null
+++ b/src/selector/rbuggyQSA.js
@@ -0,0 +1,30 @@
+define( [
+	"../var/document",
+	"../var/isIE"
+], function( document, isIE ) {
+
+"use strict";
+
+var rbuggyQSA = [],
+	testEl = document.createElement( "div" );
+
+testEl.innerHTML = "<a href=''></a>";
+
+// Support: Chrome 38 - 77 only
+// Chrome considers anchor elements with href to match ":enabled"
+// See https://bugs.chromium.org/p/chromium/issues/detail?id=993387
+if ( testEl.querySelectorAll( ":enabled" ).length ) {
+	rbuggyQSA.push( ":enabled" );
+}
+
+// Support: IE 9 - 11+
+// IE's :disabled selector does not pick up the children of disabled fieldsets
+if ( isIE ) {
+	rbuggyQSA.push( ":enabled", ":disabled" );
+}
+
+rbuggyQSA = rbuggyQSA.length && new RegExp( rbuggyQSA.join( "|" ) );
+
+return rbuggyQSA;
+
+} );
diff --git a/test/unit/selector.js b/test/unit/selector.js
index 779b554e7..f015fc933 100644
--- a/test/unit/selector.js
+++ b/test/unit/selector.js
@@ -1408,8 +1408,6 @@ QUnit.test( "pseudo - fieldset:(dis|en)abled", function( assert ) {
 QUnit.test( "pseudo - :disabled by ancestry", function( assert ) {
 	assert.expect( 1 );
 
-	// Don't test for presence of select
-	// IE6 doesn't visibly or functionally disable them when the fieldset is disabled
 	assert.t(
 		"Inputs inherit disabled from fieldset",
 		"#disabled-fieldset :disabled",
@@ -1418,6 +1416,22 @@ QUnit.test( "pseudo - :disabled by ancestry", function( assert ) {
 	);
 } );
 
+QUnit.test( "pseudo - a:(dis|en)abled", function( assert ) {
+	assert.expect( 2 );
+
+	var enabled, disabled,
+		container = jQuery( "<div/>" ),
+		anchor = jQuery( "<a href='#'>Link</a>" );
+
+	container.appendTo( "#qunit-fixture" );
+
+	enabled = container.find( "a:enabled" );
+	disabled = container.find( "a:disabled" );
+
+	assert.strictEqual( enabled.length, 0, ":enabled doesn't match anchor elements" );
+	assert.strictEqual( disabled.length, 0, ":disabled doesn't match anchor elements" );
+} );
+
 QUnit.test( "pseudo - :target and :root", function( assert ) {
 	assert.expect( 2 );