feat: add NERDTreeReverseSort option for reverse alphabetical sorting

autoload/nerdtree.vim

@@ -114,24 +114,24 @@ function! nerdtree#compareNodePaths(p1, p2) abort
         " integer type is the lesser.
         if type(sortKey1[i]) == type(sortKey2[i])
             if sortKey1[i] <# sortKey2[i]
-                return - 1
+                return g:NERDTreeReverseSort ? 1 : -1
             elseif sortKey1[i] ># sortKey2[i]
-                return 1
+                return g:NERDTreeReverseSort ? -1 : 1
             endif
         elseif type(sortKey1[i]) == type(0)
-            return -1
+            return g:NERDTreeReverseSort ? 1 : -1
         elseif type(sortKey2[i]) == type(0)
-            return 1
+            return g:NERDTreeReverseSort ? -1 : 1
         endif
         let i += 1
     endwhile
 
     " Keys are identical upto common length.
     " The key which has smaller chunks is the lesser one.
     if len(sortKey1) < len(sortKey2)
-        return -1
+        return g:NERDTreeReverseSort ? 1 : -1
     elseif len(sortKey1) > len(sortKey2)
-        return 1
+        return g:NERDTreeReverseSort ? -1 : 1
     else
         return 0
     endif

doc/NERDTree.txt

@@ -691,6 +691,9 @@ the NERDTree. These settings should be set in your vimrc, using `:let`.
 |NERDTreeNaturalSort|         Tells the NERDTree whether to use natural sort
                             order or not when sorting nodes.
 
+|NERDTreeReverseSort|         Tells the NERDTree whether to sort nodes in
+                            reverse alphabetical order.
+
 |NERDTreeSortHiddenFirst|     Tells the NERDTree whether to take the dot at
                             the beginning of the hidden file names into
                             account when sorting nodes.
@@ -1159,6 +1162,18 @@ Examples: >
 6. Files and directories matching 'foo' first, followed by other directories,
    then all other files. Each section of files is sorted by file extension.
 
+------------------------------------------------------------------------------
+                                                         *NERDTreeReverseSort*
+Values: 0 or 1.
+Default: 0
+
+If set to 1, the NERDTree will sort nodes in reverse alphabetical order within
+each group defined by |NERDTreeSortOrder|. This applies to all levels of the
+tree.
+
+Example: >
+    let NERDTreeReverseSort=1
+
 ------------------------------------------------------------------------------
                                                             *NERDTreeStatusline*
 Values: Any valid `'statusline'` setting.

plugin/NERD_tree.vim

@@ -69,6 +69,7 @@ let g:NERDTreeCascadeSingleChildDir     = get(g:, 'NERDTreeCascadeSingleChildDir
 
 let g:NERDTreeSortOrder    = get(g:, 'NERDTreeSortOrder', ['\/$', '*', '\.swp$', '\.bak$', '\~$'])
 let g:NERDTreeOldSortOrder = []
+let g:NERDTreeReverseSort  = get(g:, 'NERDTreeReverseSort',  0)
 
 let g:NERDTreeGlyphReadOnly = get(g:, 'NERDTreeGlyphReadOnly', 'RO')