Fix GlobalizationExtension RTL detection

src/Markdig.Tests/Specs/GlobalizationSpecs.generated.cs

@@ -226,5 +226,27 @@ namespace Markdig.Tests.Specs.Globalization
 
             TestParser.TestSpec("Nutrition |Apple | Oranges\n--|-- | --\nCalories|52|47\nSugar|10g|9g\n\n پێکهاتە |سێو | پڕتەقاڵ\n--|-- | --\nکالۆری|٥٢|٤٧\nشەکر| ١٠گ|٩گ", "<table>\n<thead>\n<tr>\n<th>Nutrition</th>\n<th>Apple</th>\n<th>Oranges</th>\n</tr>\n</thead>\n<tbody>\n<tr>\n<td>Calories</td>\n<td>52</td>\n<td>47</td>\n</tr>\n<tr>\n<td>Sugar</td>\n<td>10g</td>\n<td>9g</td>\n</tr>\n</tbody>\n</table>\n<table dir=\"rtl\" align=\"right\">\n<thead>\n<tr>\n<th>پێکهاتە</th>\n<th>سێو</th>\n<th>پڕتەقاڵ</th>\n</tr>\n</thead>\n<tbody>\n<tr>\n<td>کالۆری</td>\n<td>٥٢</td>\n<td>٤٧</td>\n</tr>\n<tr>\n<td>شەکر</td>\n<td>١٠گ</td>\n<td>٩گ</td>\n</tr>\n</tbody>\n</table>", "globalization+advanced+emojis", context: "Example 3\nSection Extensions / Globalization\n");
         }
+
+        // But if text starts with LTR characters, no attributes are added.
+        [Test]
+        public void ExtensionsGlobalization_Example004()
+        {
+            // Example 4
+            // Section: Extensions / Globalization
+            //
+            // The following Markdown:
+            //     Foo میوە
+            //     
+            //     میوە bar
+            //     
+            //     Baz میوە
+            //
+            // Should be rendered as:
+            //     <p>Foo میوە</p>
+            //     <p dir="rtl">میوە bar</p>
+            //     <p>Baz میوە</p>
+
+            TestParser.TestSpec("Foo میوە\n\nمیوە bar\n\nBaz میوە", "<p>Foo میوە</p>\n<p dir=\"rtl\">میوە bar</p>\n<p>Baz میوە</p>", "globalization+advanced+emojis", context: "Example 4\nSection Extensions / Globalization\n");
+        }
     }
 }

src/Markdig.Tests/Specs/GlobalizationSpecs.md

@@ -186,4 +186,18 @@ Sugar|10g|9g
 </tr>
 </tbody>
 </table>
+````````````````````````````````
+
+But if text starts with LTR characters, no attributes are added.
+
+```````````````````````````````` example
+Foo میوە
+
+میوە bar
+
+Baz میوە
+.
+<p>Foo میوە</p>
+<p dir="rtl">میوە bar</p>
+<p>Baz میوە</p>
 ````````````````````````````````

src/Markdig/Extensions/Globalization/GlobalizationExtension.cs

@@ -93,20 +93,23 @@ namespace Markdig.Extensions.Globalization
         {
             for (int i = slice.Start; i <= slice.End; i++)
             {
-                if (slice[i] < 128)
+                char c = slice[i];
+                if (c < 128)
                 {
+                    if (CharHelper.IsAlpha(c))
+                    {
+                        return false;
+                    }
+
                     continue;
                 }
 
-                int rune;
-                if (CharHelper.IsHighSurrogate(slice[i]) && i < slice.End && CharHelper.IsLowSurrogate(slice[i + 1]))
+                int rune = c;
+                if (CharHelper.IsHighSurrogate(c) && i < slice.End && CharHelper.IsLowSurrogate(slice[i + 1]))
                 {
-                    Debug.Assert(char.IsSurrogatePair(slice[i], slice[i + 1]));
-                    rune = char.ConvertToUtf32(slice[i], slice[i + 1]);
-                }
-                else
-                {
-                    rune = slice[i];
+                    Debug.Assert(char.IsSurrogatePair(c, slice[i + 1]));
+                    rune = char.ConvertToUtf32(c, slice[i + 1]);
+                    i++;
                 }
 
                 if (CharHelper.IsRightToLeft(rune))