Fix #39 - "Buffer with this name already exists"

This usually happens when you try to open the Merginal buffer from
another tab.

CHANGELOG.md

@@ -5,6 +5,13 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
+### Added
+- Support separate Meginal buffers on multiple tabs.
+
+### Changed
+- Calling `Merginal` or `MerginalToggle` when the merginal buffer is open but not in the main mode (branch list by default, or changes if in special Git status) will:
+  - Jump to it, if the user is in another window.
+  - Change it to the main mode, if the user is in it.
 
 ## [2.1.2] - 2020-01-29
 ### Fixed

autoload/merginal.vim

@@ -169,5 +169,10 @@ function! merginal#openMerginalBuffer() abort
     if empty(l:mode)
         let l:mode = 'branchList'
     endif
-    call merginal#modulelib#createObject(l:mode).openTuiBuffer(-1)
+    if exists('b:merginal')
+        let l:targetWindow = winnr()
+    else
+        let l:targetWindow = -1
+    endif
+    call merginal#modulelib#createObject(l:mode).openTuiBuffer(l:targetWindow)
 endfunction

autoload/merginal/buffers/base.vim

@@ -28,12 +28,21 @@ function! s:f.generateBody() dict abort
     throw 'generateBody() Not implemented for '.self.name
 endfunction
 
+function! s:bufferNameFor(role) abort
+    if !exists('t:merginal_tabpageUniqueIdentifier')
+        let t:merginal_tabpageUniqueIdentifier = reltimestr(reltime())
+    endif
+    return printf('Merginal:%s:%s', a:role, t:merginal_tabpageUniqueIdentifier)
+endfunction
+
 function! s:f.bufferName() dict abort
-    return 'Merginal:'.self.name
+    return s:bufferNameFor(self.name)
 endfunction
 
 function! s:f.existingWindowNumber() dict abort
-    return bufwinnr(bufnr(self.bufferName()))
+    " return bufwinnr(bufnr(self.bufferName()))
+    " return bufwinnr(bufnr(s:bufferNameFor('*')))
+    return bufwinnr('Merginal:')
 endfunction
 
 function! s:f.gitRun(...) dict abort
@@ -77,7 +86,6 @@ function! s:f.gitBang(...) dict abort
     endtry
 endfunction
 
-
 "Returns 1 if a new window was opened, 0 if it already existed
 function! s:f.openTuiBuffer(targetWindow) dict abort
     let self.repo = fugitive#repo()

doc/merginal.txt

@@ -4,7 +4,7 @@
 Author:  Idan Arye <https://github.com/idanarye/>
 License: Same terms as Vim itself (see |license|)
 
-Version: 2.1.2
+Version: 2.1.2+
 
 INTRODUCTION                                                      *merginal*
 

plugin/merginal.vim

@@ -10,8 +10,10 @@ function! s:toggleBasedOnMergeMode() abort
         if l:bufferObject.name == l:mode
             call merginal#closeMerginalBuffer()
             return
-        else
+        elseif l:merginalWindowNumber == winnr()
             call l:bufferObject.gotoBuffer(l:mode)
+        else
+            execute l:merginalWindowNumber.'wincmd w'
         endif
     else
         call merginal#openMerginalBuffer()