From 2c14233057d689cd9fb1b6bda028682103dcc290 Mon Sep 17 00:00:00 2001
From: Allan Jardine <allan.jardine@sprymedia.co.uk>
Date: Sat, 19 Nov 2011 09:53:11 +0000
Subject: [PATCH] New: Optimisation for sorting - when the sorting runs it will
 execute the sorting function a lot, particularly for large tables, so we want
 these functions to be as fast as possible. As it stood, each time the
 function ran it would prep the data and then do the required comparison - and
 it would do that data prep every time. This is pointless since toLowerCase
 (for example) is always going to give the same result when using the same
 input - so now introduced a third sorting function type (in addition to 'asc'
 and 'desc') called 'pre', which will pre-format the data to be sorted, only
 once for each item to be sorted, allowing the sorting comparison function
 itself to be really fast (simply just the comparison). This is also backwards
 compatible, if the sorting type doesn't have a 'pre'-formatting method then
 it will just use the two sorting functions as normal.

---
 media/js/jquery.dataTables.js | 104 +++++++++++++++++++---------------
 1 file changed, 58 insertions(+), 46 deletions(-)

diff --git a/media/js/jquery.dataTables.js b/media/js/jquery.dataTables.js
index fd0cc201..e3b033c3 100644
--- a/media/js/jquery.dataTables.js
+++ b/media/js/jquery.dataTables.js
@@ -581,21 +581,19 @@
 		/*
 		 * text sorting
 		 */
-		"string-asc": function ( a, b )
+		"string-pre": function ( a )
 		{
 			if ( typeof a != 'string' ) { a = ''; }
-			if ( typeof b != 'string' ) { b = ''; }
-			var x = a.toLowerCase();
-			var y = b.toLowerCase();
+			return a.toLowerCase();
+		},
+
+		"string-asc": function ( x, y )
+		{
 			return ((x < y) ? -1 : ((x > y) ? 1 : 0));
 		},
 		
-		"string-desc": function ( a, b )
+		"string-desc": function ( x, y )
 		{
-			if ( typeof a != 'string' ) { a = ''; }
-			if ( typeof b != 'string' ) { b = ''; }
-			var x = a.toLowerCase();
-			var y = b.toLowerCase();
 			return ((x < y) ? 1 : ((x > y) ? -1 : 0));
 		},
 		
@@ -603,17 +601,18 @@
 		/*
 		 * html sorting (ignore html tags)
 		 */
-		"html-asc": function ( a, b )
+		"html-pre": function ( a )
+		{
+			return a.replace( /<.*?>/g, "" ).toLowerCase();
+		},
+		
+		"html-asc": function ( x, y )
 		{
-			var x = a.replace( /<.*?>/g, "" ).toLowerCase();
-			var y = b.replace( /<.*?>/g, "" ).toLowerCase();
 			return ((x < y) ? -1 : ((x > y) ? 1 : 0));
 		},
 		
-		"html-desc": function ( a, b )
+		"html-desc": function ( x, y )
 		{
-			var x = a.replace( /<.*?>/g, "" ).toLowerCase();
-			var y = b.replace( /<.*?>/g, "" ).toLowerCase();
 			return ((x < y) ? 1 : ((x > y) ? -1 : 0));
 		},
 		
@@ -621,37 +620,24 @@
 		/*
 		 * date sorting
 		 */
-		"date-asc": function ( a, b )
+		"date-pre": function ( a )
 		{
 			var x = Date.parse( a );
-			var y = Date.parse( b );
 			
 			if ( isNaN(x) || x==="" )
 			{
-			x = Date.parse( "01/01/1970 00:00:00" );
+				x = Date.parse( "01/01/1970 00:00:00" );
 			}
-			if ( isNaN(y) || y==="" )
-			{
-				y =	Date.parse( "01/01/1970 00:00:00" );
-			}
-			
+			return x;
+		},
+
+		"date-asc": function ( x, y )
+		{
 			return x - y;
 		},
 		
-		"date-desc": function ( a, b )
+		"date-desc": function ( x, y )
 		{
-			var x = Date.parse( a );
-			var y = Date.parse( b );
-			
-			if ( isNaN(x) || x==="" )
-			{
-			x = Date.parse( "01/01/1970 00:00:00" );
-			}
-			if ( isNaN(y) || y==="" )
-			{
-				y =	Date.parse( "01/01/1970 00:00:00" );
-			}
-			
 			return y - x;
 		},
 		
@@ -659,17 +645,18 @@
 		/*
 		 * numerical sorting
 		 */
-		"numeric-asc": function ( a, b )
+		"numeric-asc": function ( a )
+		{
+			return (a=="-" || a==="") ? 0 : a*1;
+		},
+
+		"numeric-asc": function ( x, y )
 		{
-			var x = (a=="-" || a==="") ? 0 : a*1;
-			var y = (b=="-" || b==="") ? 0 : b*1;
 			return x - y;
 		},
 		
-		"numeric-desc": function ( a, b )
+		"numeric-desc": function ( x, y )
 		{
-			var x = (a=="-" || a==="") ? 0 : a*1;
-			var y = (b=="-" || b==="") ? 0 : b*1;
 			return y - x;
 		}
 	};
@@ -2688,6 +2675,7 @@
 				"nTr": null,
 				"_iId": oSettings.iNextId++,
 				"_aData": aDataIn,
+				"_aSortData": [],
 				"_anHidden": [],
 				"_sRowStripe": ""
 			};
@@ -2843,6 +2831,7 @@
 							"nTr": nTrs[i],
 							"_iId": oSettings.iNextId++,
 							"_aData": [],
+							"_aSortData": [],
 							"_anHidden": [],
 							"_sRowStripe": ''
 						} );
@@ -4649,7 +4638,7 @@
 		function _fnSort ( oSettings, bApplyClasses )
 		{
 			var
-				i, iLen, j, jLen,
+				i, iLen, j, jLen, k, kLen,
 				aaSort = [],
 			 	aiOrig = [],
 				oSort = _oExt.oSort,
@@ -4694,6 +4683,30 @@
 				{
 					aiOrig[ oSettings.aiDisplayMaster[i] ] = i;
 				}
+
+				/* Build an internal data array which is specific to the sort, so we can get and prep
+				 * the data to be sorted only once, rather than needing to do it every time the sorting
+				 * function runs. This make the sorting function a very simple comparison
+				 */
+				var iSortLen = aaSort.length;
+				var fnSortFormat;
+				for ( i=0, iLen=aoData.length ; i<iLen ; i++ )
+				{
+					for ( j=0 ; j<iSortLen ; j++ )
+					{
+						aDataSort = aoColumns[ aaSort[j][0] ].aDataSort;
+
+						for ( k=0, kLen=aDataSort.length ; k<kLen ; k++ )
+						{
+							sDataType = aoColumns[ aDataSort[k] ].sType;
+							fnSortFormat = oSort[ (sDataType ? sDataType : 'string')+"-pre" ];
+							
+							aoData[i]._aSortData[ aDataSort[k] ] = fnSortFormat ?
+								fnSortFormat( _fnGetCellData( oSettings, i, aDataSort[k], 'sort' ) ) :
+								_fnGetCellData( oSettings, i, aDataSort[k], 'sort' );
+						}
+					}
+				}
 				
 				/* Do the sort - here we want multi-column sorting based on a given data source (column)
 				 * and sorting function (from oSort) in a certain direction. It's reasonably complex to
@@ -4712,7 +4725,6 @@
 				 * test the next column. If all columns match, then we use a numeric sort on the row 
 				 * positions in the original data array to provide a stable sort.
 				 */
-				var iSortLen = aaSort.length;
 				oSettings.aiDisplayMaster.sort( function ( a, b ) {
 					var k, l, lLen, iTest, aDataSort, sDataType;
 					for ( k=0 ; k<iSortLen ; k++ )
@@ -4724,8 +4736,8 @@
 							sDataType = aoColumns[ aDataSort[l] ].sType;
 							
 							iTest = oSort[ (sDataType ? sDataType : 'string')+"-"+aaSort[k][1] ](
-								_fnGetCellData( oSettings, a, aDataSort[l], 'sort' ),
-								_fnGetCellData( oSettings, b, aDataSort[l], 'sort' )
+								aoData[a]._aSortData[ aDataSort[l] ],
+								aoData[b]._aSortData[ aDataSort[l] ]
 							);
 						
 							if ( iTest !== 0 )