Add LSClientFindCodeActions

This is very conservative for now. Edits must be enabled with a global
variable since they are risky, and they only will apply in the current
buffer.

- Allow choosing a code action following a call to `findCodeActions` and
  then call `workspace/executeCommand`
- Add dispatching for `workspace/applyEdit` to a function which selects
  the changed range and replaces the text.
- Take a server argument to dispatch so that requests can send back a
  resonse.
- Add mapping to `ga`. The default behavior is to print the ascii code
  of the character under the cursor.
- Update the client capabilities to indicate applyEdit if it is enabled.

Future Work:
- Add support for edits in other buffers.
- Allow a visual mode call which sends a range rather than a single
  character under the cursor.

CHANGELOG.md

@@ -1,4 +1,4 @@
-# 0.2.8-dev
+# 0.2.8
 
 - Don't track files which are not `modifiable`.
 - Bug Fix: Fix jumping from quickfix item to files under home directory.
@@ -9,6 +9,8 @@
 - Add support for overriding the `params` for certain methods.
 - Bug Fix: Correct paths on Windows.
 - Bug Fix: Allow restarting a server which failed to start initially.
+- Add experimental support for `textDocument/codeActions` and
+  `workspace/applyEdit`
 
 # 0.2.7
 

README.md

@@ -46,6 +46,7 @@ let g:lsc_auto_map = v:true " Use defaults
 let g:lsc_auto_map = {
     \ 'GoToDefinition': '<C-]>',
     \ 'FindReferences': 'gr',
+    \ 'FindCodeActions': 'ga',
     \ 'ShowHover': 'K',
     \ 'Completion': 'completefunc',
     \}
@@ -118,3 +119,14 @@ While the cursor is on any identifier call `LSClientShowHover` (`K` if using the
 default mappings) to request hover text and show it in a preview window.
 Override the direction of the split by setting `g:lsc_preview_split_direction`
 to either `'below'` or `'above'`.
+
+### Code Actions (experimental)
+
+While this is still experimental it is opt-in. Add
+`let g:lsc_enable_apply_edit = v:true` to allow edits to files (since these are
+the most likely result of code actions). Call `LSClientFindCodeActions` (`ga` if
+using the default mappings) to look for code actions available at the cursor
+location.
+
+Support is very limited for now. Edits can only be applied in the active buffer
+to prevent.

autoload/lsc/config.vim

@@ -1,6 +1,7 @@
 let s:default_maps = {
     \ 'GoToDefinition': '<C-]>',
     \ 'FindReferences': 'gr',
+    \ 'FindCodeActions': 'ga',
     \ 'ShowHover': 'K',
     \ 'Completion': 'completefunc',
     \}
@@ -20,7 +21,12 @@ function! lsc#config#mapKeys() abort
     return
   endif
 
-  for command in ['GoToDefinition', 'FindReferences', 'ShowHover']
+  for command in [
+      \ 'GoToDefinition',
+      \ 'FindReferences',
+      \ 'ShowHover',
+      \ 'FindCodeActions',
+      \]
     if has_key(maps, command)
       execute 'nnoremap <buffer>'.maps[command].' :LSClient'.command.'<CR>'
     endif

autoload/lsc/dispatch.vim

@@ -1,5 +1,5 @@
 " Handle messages received from the server.
-function! lsc#dispatch#message(message) abort
+function! lsc#dispatch#message(server, message) abort
   if has_key(a:message, 'method')
     if a:message['method'] ==? 'textDocument/publishDiagnostics'
       let params = a:message['params']
@@ -11,6 +11,14 @@ function! lsc#dispatch#message(message) abort
     elseif a:message['method'] ==? 'window/logMessage'
       let params = a:message['params']
       call lsc#message#log(params['message'], params['type'])
+    elseif a:message['method'] ==? 'workspace/applyEdit'
+      let params = a:message['params']
+      let applied = lsc#edit#apply(params)
+      if has_key(a:message, 'id')
+        let id = a:message['id']
+        let response = {'applied': applied}
+        call a:server.send(lsc#protocol#formatResponse(id, response))
+      endif
     else
       echom 'Got notification: '.a:message['method'].
           \ ' params: '.string(a:message['params'])

autoload/lsc/edit.vim

@@ -10,16 +10,26 @@ function! lsc#edit#findCodeActions() abort
   let find_actions_id = s:find_actions_id
   function! SelectAction(result) closure abort
     if !s:isFindActionsValid(old_pos, find_actions_id)
-      echom 'CodeActions skipped'
+      call lsc#message#show('Actions ignored')
       return
     endif
-    if type(a:result) == v:t_none ||
-        \ (type(a:result) == v:t_list && len(a:result) == 0)
+    if type(a:result) != v:t_list || len(a:result) == 0
       call lsc#message#show('No actions available')
+      return
+    endif
+    let choices = ['Choose an action:']
+    let idx = 0
+    while idx < len(a:result)
+      call add(choices, string(idx+1).' - '.a:result[idx]['title'])
+      let idx += 1
+    endwhile
+    let choice = inputlist(choices)
+    if choice > 0
+      call lsc#server#userCall('workspace/executeCommand',
+          \ {'command': a:result[choice - 1]['command'],
+          \ 'arguments': a:result[choice - 1]['arguments']},
+          \ {_->0})
     endif
-    for action in a:result
-      echom 'I found an action: '.action['title']
-    endfor
   endfunction
   call lsc#server#userCall('textDocument/codeAction',
       \ s:TextDocumentRangeParams(), function('SelectAction'))
@@ -39,3 +49,61 @@ function! s:isFindActionsValid(old_pos, find_actions_id) abort
   return a:find_actions_id == s:find_actions_id &&
       \ a:old_pos == getcurpos()
 endfunction
+
+" Applies a workspace edit and returns `v:true` if it was successful.
+function! lsc#edit#apply(params) abort
+  if !exists('g:lsc_enable_apply_edit')
+      \ || !g:lsc_enable_apply_edit
+      \ || !has_key(a:params.edit, 'changes')
+    return v:false
+  endif
+  let changes = a:params.edit.changes
+  " Only applying changes in open files for now
+  for uri in keys(changes)
+    if lsc#uri#documentPath(uri) != expand('%:p')
+      call lsc#message#error('Can only apply edits in the current buffer')
+      return v:false
+    endif
+  endfor
+  for [uri, edits] in items(changes)
+    for edit in edits
+      " Expect edit is in current buffer
+      call s:Apply(edit)
+    endfor
+  endfor
+  return v:true
+endfunction
+
+" Apply a `TextEdit` to the current buffer.
+function! s:Apply(edit) abort
+  let old_paste = &paste
+  set paste
+  if s:IsEmptyRange(a:edit.range)
+    let command = printf('%dG%d|i%s',
+        \ a:edit.range.start.line + 1,
+        \ a:edit.range.start.character + 1,
+        \ a:edit.newText
+        \)
+  else
+    " `back` handles end-exclusive range
+    let back = 'h'
+    if a:edit.range.end.character == 0
+      let back = 'k$'
+    endif
+    let command = printf('%dG%d|v%dG%d|%sc%s',
+        \ a:edit.range.start.line + 1,
+        \ a:edit.range.start.character + 1,
+        \ a:edit.range.end.line + 1,
+        \ a:edit.range.end.character + 1,
+        \ back,
+        \ a:edit.newText
+        \)
+  endif
+  execute 'normal!' command
+  let &paste = old_paste
+endfunction
+
+function! s:IsEmptyRange(range) abort
+  return a:range.start.line == a:range.end.line &&
+      \ a:range.start.character == a:range.end.character
+endfunction

autoload/lsc/protocol.vim

@@ -23,6 +23,10 @@ function! lsc#protocol#formatNotification(method, params) abort
   return s:Format(a:method, a:params, v:null)
 endfunction
 
+" Create a dictionary for the response to a call.
+function! lsc#protocol#formatResponse(id, result) abort
+  return {'id': a:id, 'result': a:result}
+endfunction
 
 function! s:Format(method, params, id) abort
   let message = {'method': a:method}
@@ -69,7 +73,7 @@ function! s:consumeMessage(server) abort
   if exists('l:content')
     call lsc#util#shift(a:server.messages, 10, content)
     try
-      call lsc#dispatch#message(content)
+      call lsc#dispatch#message(a:server, content)
     catch
       call lsc#message#error('Error dispatching message: '.string(v:exception))
     endtry

autoload/lsc/server.vim

@@ -134,7 +134,7 @@ function! s:Start(server) abort
   endif
   let params = {'processId': getpid(),
       \ 'rootUri': lsc#uri#documentUri(getcwd()),
-      \ 'capabilities': s:client_capabilities,
+      \ 'capabilities': s:ClientCapabilities(),
       \ 'trace': trace_level
       \}
   call lsc#server#call(&filetype, 'initialize',
@@ -224,9 +224,16 @@ function! lsc#server#callback(channel, message) abort
   call lsc#protocol#consumeMessage(server_info)
 endfunction
 
-" Supports no workspace capabilities - missing value means no support
-let s:client_capabilities = {
-    \ 'workspace': {},
+" Missing value means no support
+function! s:ClientCapabilities() abort
+  let applyEdit = v:false
+  if exists('g:lsc_enable_apply_edit') && g:lsc_enable_apply_edit
+    let applyEdit = v:true
+  endif
+  return {
+    \ 'workspace': {
+    \   'applyEdit': applyEdit,
+    \   },
     \ 'textDocument': {
     \   'synchronization': {
     \     'willSave': v:false,
@@ -239,6 +246,7 @@ let s:client_capabilities = {
     \   'definition': {'dynamicRegistration': v:false},
     \ }
     \}
+endfunction
 
 function! lsc#server#filetypeActive(filetype) abort
   let server = s:servers[g:lsc_servers_by_filetype[a:filetype]]

doc/lsc.txt

@@ -75,6 +75,13 @@ If the preview window is not visible it will |split| the window and size it no
 bigger than |previewheight|. Override the direction of the split by setting
 |g:lsc_preview_split_direction| to either |above| or |below|.
 
+                                                *:LSClientFindCodeActions*
+Check for available actions at the cursor's position and display them in a
+menu. Sends a "textDocument/codeAction" request to get the available choices,
+and if one is selected sends a "workspace/executeCommand". Typically actions
+end up triggering workspace edits so this command is likely only useful if
+|g:lsc_enable_apply_edit| is set to `v:true`.
+
                                                 *:LSClientRestartServer*
 Sends requests to the server for the current filetype to "shutdown" and
 "exit", and after the process exits, restarts it. If the server is
@@ -194,6 +201,11 @@ edits which simultaneously change content near the beginning and end of the
 buffer can cause large changes to be sent, but in most cases the messages will
 be smaller than with full syncs.
 
+                                                *lsc-configure-edits*
+                                                *g:lsc_enable_apply_edit*
+By default the client will not modify any buffer in response to
+`workspace/applyEdit` calls. To enable edits set to `v:true`.
+
 AUTOCMDS                                        *lsc-autocmds*
 
                                                 *autocmd-LSCAutocomplete*

plugin/lsc.vim

@@ -14,6 +14,7 @@ endif
 command! LSClientGoToDefinition call lsc#reference#goToDefinition()
 command! LSClientFindReferences call lsc#reference#findReferences()
 command! LSClientShowHover call lsc#reference#hover()
+command! LSClientFindCodeActions call lsc#edit#findCodeActions()
 command! LSClientRestartServer call <SID>IfEnabled('lsc#server#restart')
 command! LSClientDisable call lsc#server#disable()
 command! LSClientEnable call lsc#server#enable()