Allow configuring which_key per buffer

autoload/which_key.vim

@@ -13,6 +13,12 @@ let g:which_key#TYPE = s:TYPE
 
 let s:should_note_winid = exists('*win_getid')
 
+let s:buffer_cache = {}
+let s:cur_dir = fnamemodify(resolve(expand('<sfile>:p')), ':h')
+let g:which_key#extensions = map(
+      \ split(globpath(s:cur_dir.'/which_key/extensions', '*'), '\n'),
+      \ 'fnamemodify(v:val, '':t:r'')')
+
 function! which_key#register(prefix, dict) abort
   let key = a:prefix ==? '<Space>' ? ' ' : a:prefix
   let val = a:dict
@@ -43,6 +49,50 @@ function! s:handle_char_on_start_is_ok(c) abort
   endif
 endfunction
 
+function! which_key#start_buffer(vis, ...) abort
+  let key = '<buffer>'
+  if empty(s:buffer_cache) || g:which_key_run_map_on_popup
+    let s:buffer_cache = {}
+    call which_key#mappings#parse(key, s:buffer_cache, s:vis ==# 'gv' ? 1 : 0)
+  endif
+
+  let native = s:buffer_cache
+
+  try
+    let l:extension_name = s:get_extension_name()
+    let l:ext_config = g:which_key#extensions#{l:extension_name}#config
+  catch /^Vim\%((\a\+)\)\=:E121/
+    echom v:exception
+  endtry
+
+  if exists('b:which_key')
+    let buffer_which_key = copy(b:which_key)
+    if get(b:, 'which_key_no_native', 0)
+      let s:runtime = buffer_which_key
+    else
+      call s:merge(buffer_which_key, native)
+      let s:runtime = buffer_which_key
+    endif
+  else
+
+    if exists('l:ext_config')
+      if !get(l:ext_config, 'no_native', v:false)
+        call s:merge(l:ext_config['mappings'], native)
+      endif
+      let s:runtime = l:ext_config['mappings']
+    else
+      let s:runtime = native
+    endif
+  endif
+
+  call which_key#window#show(s:runtime)
+endfunction
+
+" Some plugins use the filetype name like coc-explorer.
+function! s:get_extension_name() abort
+  return substitute(&filetype, '-', '_', 'g')
+endfunction
+
 function! which_key#start(vis, bang, prefix) " {{{
   let s:vis = a:vis ? 'gv' : ''
   let s:count = v:count != 0 ? v:count : ''
@@ -52,6 +102,13 @@ function! which_key#start(vis, bang, prefix) " {{{
     let g:which_key_origin_winid = win_getid()
   endif
 
+  if a:prefix == '<buffer>'
+        \ || exists('b:which_key')
+        \ || index(g:which_key#extensions, s:get_extension_name()) > -1
+    call which_key#start_buffer(a:vis)
+    return
+  endif
+
   if a:bang
     let s:runtime = a:prefix
     let s:last_runtime_stack = [copy(s:runtime)]

autoload/which_key/extensions/coc_explorer.vim

@@ -0,0 +1,25 @@
+let s:mappings = {
+      \ 'h': ['<Plug>(coc-explorer-key-n-h)', 'collapse node'],
+      \ 'l': ['<Plug>(coc-explorer-key-n-l)', 'expand node'],
+      \ 'o': ['<Plug>(coc-explorer-key-n-o)', 'expand & collapse node'],
+      \ 'e': ['<Plug>(coc-explorer-key-n-e)', 'open'],
+      \ 'gs': ['<Plug>(coc-explorer-key-n-gs)', 'reveal buffer in explorer'],
+      \ 'gp': ['<Plug>(coc-explorer-key-n-gp)', 'preview'],
+      \ 'y': ['<Plug>(coc-explorer-key-n-y)', 'copy full filepath to clipboard'],
+      \ 'Y': ['<Plug>(coc-explorer-key-n-Y)', 'copy filename to clipboard'],
+      \ 'c': ['<Plug>(coc-explorer-key-n-c)', 'copy file for paste'],
+      \ 'x': ['<Plug>(coc-explorer-key-n-x)', 'cut file for paste'],
+      \ 'p': ['<Plug>(coc-explorer-key-n-p)', 'paste files to here'],
+      \ 'd': ['<Plug>(coc-explorer-key-n-d)', 'move file or directory to trash'],
+      \ 'D': ['<Plug>(coc-explorer-key-n-D)', 'delete file or directory forever'],
+      \ 'a': ['<Plug>(coc-explorer-key-n-a)', 'add a new file'],
+      \ 'A': ['<Plug>(coc-explorer-key-n-A)', 'add a new directory'],
+      \ 'r': ['<Plug>(coc-explorer-key-n-r)', 'rename'],
+      \ '.': ['<Plug>(coc-explorer-key-n-.)', 'toggle hidden'],
+      \ 'R': ['<Plug>(coc-explorer-key-n-R)', 'refresh'],
+      \ }
+
+let g:which_key#extensions#coc_explorer#config = {
+      \ 'no_native': v:true,
+      \ 'mappings': s:mappings,
+      \ }

autoload/which_key/extensions/nerdtree.vim

@@ -0,0 +1,30 @@
+let s:mappings = {
+      \ 't': 'open in new tab',
+      \ 'T': 'open in new tab silently',
+      \ 'i': 'open split',
+      \ 's': 'open vsplit',
+      \ 'gs': 'preview vsplit',
+      \ 'o': 'open & close node',
+      \ 'O': 'recursively open node',
+      \ 'x': 'close parent of node',
+      \ 'X': 'close all child nodes of current node recursively',
+      \ 'e': 'explore selected dir',
+      \ 'P': 'go to root',
+      \ 'p': 'go to parent',
+      \ 'K': 'go to first child',
+      \ 'J': 'go to last child',
+      \ 'C': 'change tree root to the selected dir',
+      \ 'u': 'move tree root up a dir',
+      \ 'U': 'move tree root up a dir but leave old root open',
+      \ 'r': 'refresh cursur dir',
+      \ 'R': 'refresh current root',
+      \ 'm': 'Show menu',
+      \ 'q': 'Close the NERDTree window',
+      \ 'A': 'Zoom (maximize-minimize) the NERDTree window',
+      \ '?': 'toggle help',
+      \ }
+
+let g:which_key#extensions#nerdtree#config = {
+      \ 'no_native': v:false,
+      \ 'mappings': s:mappings,
+      \ }

autoload/which_key/extensions/vista.vim

@@ -0,0 +1,7 @@
+let g:which_key#extensions#vista#config = {
+      \ 'mappings': {
+        \ '/': 'open-symbols-finder',
+        \ 'q': 'close-vista-sidebar',
+        \ '<CR>': 'jump-or-fold',
+        \ }
+      \ }

autoload/which_key/extensions/vista_kind.vim

@@ -0,0 +1,7 @@
+let g:which_key#extensions#vista_kind#config = {
+      \ 'mappings': {
+        \ '/': 'open-symbols-finder',
+        \ 'q': 'close-vista-sidebar',
+        \ '<CR>': 'jump-or-fold',
+        \ }
+      \ }