Add NumberSpan definition (non-DTD, but applies to enough to be useful). All widely used non-deprecated attributes have been implemented (except for rel/rev, but that's tricky). Add note about quirky COL handling and possible implementation of a workaround.

git-svn-id: http://htmlpurifier.org/svnroot/htmlpurifier/trunk@174 48356398-32a2-884e-a903-53898d9a118a

library/HTMLPurifier/AttrDef/NumberSpan.php

@@ -0,0 +1,23 @@
+<?php
+
+require_once 'HTMLPurifier/AttrDef.php';
+
+// for col and row spans, essentially, a positive integer
+class HTMLPurifier_AttrDef_NumberSpan extends HTMLPurifier_AttrDef
+{
+    
+    function validate($string) {
+        
+        $string = trim($string);
+        if ($string === '') return false;
+        if ($string === '1') return false; // this is the default value
+        if (!is_numeric($string)) return false;
+        $int = (int) $string;
+        if ($int <= 0) return false;
+        return (string) $int;
+        
+    }
+    
+}
+
+?>