Add option to exclusively MRU cycle through the two MRU buffers

autoload/buffergator.vim

@@ -350,6 +350,9 @@ function! s:_is_full_height_window(win_num)
     endif
 endfunction!
 
+let g:buffergator__has_cycled = 0
+let g:buffergator__buf_prev = 0
+
 function! s:_find_mru_bufnr(dir)
     let l:cur_buf_idx = index(w:buffergator_mru, bufnr("%"))
     if len(w:buffergator_mru) < 1 " maybe should be 2?
@@ -359,9 +362,31 @@ function! s:_find_mru_bufnr(dir)
         let l:target_buf_idx = 0
     else
         if a:dir < 0
-            let l:target_buf_idx = l:cur_buf_idx + 1 " deeper in list = older
+            if g:buffergator_mru_cycle_loop_last_two
+                if !g:buffergator__has_cycled
+                    let l:target_buf_idx = l:cur_buf_idx + 1 " deeper in list = older
+                    let g:buffergator__buf_prev = l:cur_buf_idx
+                    let g:buffergator__has_cycled = 1
+                else
+                    let l:target_buf_idx = g:buffergator__buf_prev
+                    let g:buffergator__buf_prev = l:cur_buf_idx
+                endif
+            else
+                let l:target_buf_idx = l:cur_buf_idx + 1 " deeper in list = older
+            endif
         else
-            let l:target_buf_idx = l:cur_buf_idx - 1 " up list = newer
+            if g:buffergator_mru_cycle_loop_last_two
+                if !g:buffergator__has_cycled
+                    let l:target_buf_idx = l:cur_buf_idx - 1 " up list = newer
+                    let g:buffergator__buf_prev = l:cur_buf_idx
+                    let g:buffergator__has_cycled = 1
+                else
+                    let l:target_buf_idx = g:buffergator__buf_prev
+                    let g:buffergator__buf_prev = l:cur_buf_idx
+                endif
+            else
+                let l:target_buf_idx = l:cur_buf_idx - 1 " up list = newer
+            endif
         endif
     endif
     if l:target_buf_idx < 0

doc/buffergator.txt

@@ -91,13 +91,21 @@ key mappings are defined:
                           (default), then this will loop, i.e. returning to
                           the initial buffer after reaching the oldest buffer.
 
+                          If "g:buffergator_mru_cycle_loop_last_two" is set to
+                          1, then only the last two accessed buffers will be
+                          cycled.
+
 ]b, <M-S-B>               Invokes ":BuffergatorMruCycleNext": cycle to a newer
                           buffer in the most-recently used (MRU) buffer list.
                           most-recently used buffer. If
                           "g:buffergator_mru_cycle_loop" is set to 1
                           (default), then this will loop, i.e. returning to
                           the oldest buffer after reaching the newest buffer.
 
+                          If "g:buffergator_mru_cycle_loop_last_two" is set to
+                          1, then only the last two accessed buffers will be
+                          cycled.
+
 Unless either "g:buffergator_suppress_keymaps" or
 "g:buffergator_suppress_mru_switching_keymaps" is set to 1, then the following
 key mappings are defined:

plugin/buffergator.vim

@@ -36,6 +36,9 @@ set cpo&vim
 if !exists("g:buffergator_mru_cycle_loop")
     let g:buffergator_mru_cycle_loop = 1
 endif
+if !exists("g:buffergator_mru_cycle_loop_last_two")
+    let g:buffergator_mru_cycle_loop_last_two = 0
+endif
 let g:buffergator_track_mru = 1
 let g:buffergator_mru = []
 function! BuffergatorUpdateMRU(acmd_bufnr)