UltiSnips integration (#306)

* Implement basic UltiSnips integration

* Fix already inserted text not being removed

* Fix incorrect whitespace when nesting snippets

* Fix tabstops not working in nested snippets

* Make functions abort on error

* Check if Vim has the user_data patch

* Add basic documentation

* Add explanation UltiSnips integration to README

* Use single quoted string in plugin/lsp.vim

* Allow plugins to override get_completion_item

* Remove UltiSnips specific code to set user_data

* Remove CompleteDone autocmd from omni.vim

* Revert "Add explanation UltiSnips integration to README"

This reverts commit ee12343.

* Revert "Add basic documentation"

This reverts commit 979275b.

* Allow changing supported capabilities

* Remove g:lsp_ultisnips_integration

* Mention snippets in READE and documentation

* Add documentation for new configuration options

* Pass server_info to get_capabilities

* Change configuration variables to be a List

This way, we don't need to start them with a capital letter.

* Add lsp_complete_done autocmd

* Add documentation of lsp_complete_done

Author: thomasfaingnaert

README.md

@@ -45,6 +45,14 @@ vim-lsp supports incremental changes of Language Server Protocol.
 
 Refer to docs on configuring omnifunc or [asyncomplete.vim](https://github.com/prabirshrestha/asyncomplete.vim).
 
+## Snippets
+vim-lsp does not support snippets by default. If you want snippet integration, you will first have to install a third-party snippet plugin and a plugin that integrates it in vim-lsp.
+At the moment, you have two options:
+1. [UltiSnips](https://github.com/SirVer/ultisnips) together with [vim-lsp-ultisnips](https://github.com/thomasfaingnaert/vim-lsp-ultisnips)
+2. [neosnippet.vim](https://github.com/Shougo/neosnippet.vim) together with [vim-lsp-neosnippet](https://github.com/thomasfaingnaert/vim-lsp-neosnippet)
+
+For more information, refer to the readme and documentation of the respective plugins.
+
 ## Supported commands
 
 **Note:**

autoload/lsp.vim

@@ -369,6 +369,14 @@ function! s:ensure_start(buf, server_name, cb) abort
     endif
 endfunction
 
+function! lsp#default_get_supported_capabilities(server_info) abort
+    return {
+    \   'workspace': {
+    \       'applyEdit': v:true
+    \   }
+    \ }
+endfunction
+
 function! s:ensure_init(buf, server_name, cb) abort
     let l:server = s:servers[a:server_name]
 
@@ -406,11 +414,7 @@ function! s:ensure_init(buf, server_name, cb) abort
     if has_key(l:server_info, 'capabilities')
         let l:capabilities = l:server_info['capabilities']
     else
-        let l:capabilities = {
-        \   'workspace': {
-        \       'applyEdit': v:true
-        \   }
-        \ }
+        let l:capabilities = call(g:lsp_get_supported_capabilities[0], [server_info])
     endif
 
     let l:request = {

autoload/lsp/omni.vim

@@ -167,7 +167,7 @@ function! s:remove_typed_part(word) abort
     return strpart(a:word, l:overlap_length)
 endfunction
 
-function! lsp#omni#get_vim_completion_item(item, ...) abort
+function! lsp#omni#default_get_vim_completion_item(item, ...) abort
     let l:do_remove_typed_part = get(a:, 1, 0)
 
     if g:lsp_insert_text_enabled && has_key(a:item, 'insertText') && !empty(a:item['insertText'])
@@ -242,6 +242,10 @@ function! lsp#omni#get_vim_completion_item(item, ...) abort
     return l:completion
 endfunction
 
+function! lsp#omni#get_vim_completion_item(...) abort
+    return call(g:lsp_get_vim_completion_item[0], a:000)
+endfunction
+
 augroup lsp_completion_item_text_edit
     autocmd!
     autocmd CompleteDone * call <SID>apply_text_edits()
@@ -265,16 +269,19 @@ function! s:apply_text_edits() abort
     "       ],
     "     }
     if !g:lsp_text_edit_enabled
+        doautocmd User lsp_complete_done
         return
     endif
 
     " completion faild or not select complete item
     if empty(v:completed_item)
+        doautocmd User lsp_complete_done
         return
     endif
 
     " check user_data
     if !has_key(v:completed_item, 'user_data')
+        doautocmd User lsp_complete_done
         return
     endif
 
@@ -283,10 +290,12 @@ function! s:apply_text_edits() abort
         let l:user_data = json_decode(v:completed_item['user_data'])
     catch
         " do nothing if user_data is not json type string.
+        doautocmd User lsp_complete_done
         return
     endtry
 
     if type(l:user_data) != type({})
+        doautocmd User lsp_complete_done
         return
     endif
 
@@ -319,6 +328,8 @@ function! s:apply_text_edits() abort
     let l:pos[2] += l:col_offset
     call setpos("'a", l:saved_mark)
     call setpos('.', l:pos)
+
+    doautocmd User lsp_complete_done
 endfunction
 
 function! s:expand_range(text_edit, expand_length) abort

doc/vim-lsp.txt

@@ -22,6 +22,8 @@ CONTENTS                                                  *vim-lsp-contents*
       g:lsp_textprop_enabled                |g:lsp_textprop_enabled|
       g:lsp_use_event_queue                 |g:lsp_use_event_queue|
       g:lsp_highlight_references_enabled    |g:lsp_highlight_references_enabled|
+      g:lsp_get_vim_completion_item         |g:lsp_get_vim_completion_item|
+      g:lsp_get_supported_capabilities      |g:lsp_get_supported_capabilities|
     Functions                             |vim-lsp-functions|
       enable                                |vim-lsp-enable|
       disable                               |vim-lsp-disable|
@@ -48,10 +50,13 @@ CONTENTS                                                  *vim-lsp-contents*
       LspRename                             |LspRename|
       LspTypeDefinition                     |LspTypeDefinition|
       LspWorkspaceSymbol                    |LspWorkspaceSymbol|
+    Autocommands                          |vim-lsp-autocommands|
+      lsp_complete_done                     |lsp_complete_done|
     Mappings                              |vim-lsp-mappings|
     Autocomplete                          |vim-lsp-autocomplete|
       omnifunc                              |vim-lsp-omnifunc|
       asyncomplete.vim                      |vim-lsp-asyncomplete|
+    Snippets                              |vim-lsp-snippets|
     License                               |vim-lsp-license|
 
 
@@ -281,6 +286,32 @@ g:lsp_highlight_references_enabled         *g:lsp_highlight_references_enabled*
     highlight lspReference ctermfg=red guifg=red ctermbg=green guibg=green
 <
 
+g:lsp_get_vim_completion_item               *g:lsp_get_vim_completion_item*
+    Type: |List|
+    Default: `[function('lsp#omni#default_get_vim_completion_item')]`
+
+    A |List| containing one element of type |Funcref|. This element is a
+    reference to the function that vim-lsp should use to produce the items in
+    the completion menu. Changing this variable allows customizing how items
+    are displayed in the completion menu, or adding custom `user_data` to
+    items (see |complete-items|).
+
+    Note: You can reuse functionality provided by vim-lsp by calling
+    `lsp#omni#default_get_vim_completion_item` from within your function.
+
+g:lsp_get_supported_capabilities         *g:lsp_get_supported_capabilities*
+    Type: |List|
+    Default: `[function('lsp#default_get_supported_capabilities')]`
+
+    A |List| containing one element of type |Funcref|. This element is a
+    reference to the function that vim-lsp should use to obtain the supported
+    LSP capabilities. Changing this variable allows customizing which
+    capabilities vim-lsp sends to a language server.
+
+    Note: You can obtain the default supported capabilities of vim-lsp by
+    calling `lsp#omni#default_get_supported_capabilities` from within your
+    function.
+
 ===============================================================================
 FUNCTIONS	                                        *vim-lsp-functions*
 
@@ -455,12 +486,12 @@ Get the status of a server.
     "running", "not running".
 
 			 *vim-lsp-utils-find_nearest_parent_file_directory*
-utils#find_nearest_parent_file_directory            
+utils#find_nearest_parent_file_directory
 
-Find the nearest parent directory which contains the specific files or 
-diretories. The method has two parameters. The first is the path where 
-searching starts. The second is the files or directories names which 
-you want to find. The return value is the directory path which is found 
+Find the nearest parent directory which contains the specific files or
+diretories. The method has two parameters. The first is the path where
+searching starts. The second is the files or directories names which
+you want to find. The return value is the directory path which is found
 the most times.
 This method is mainly used to generate 'root_uri' when registering server.
 
@@ -471,7 +502,7 @@ This method is mainly used to generate 'root_uri' when registering server.
 		\ 'cmd': {server_info->['ccls']},
 		\ 'root_uri':{server_info->lsp#utils#path_to_uri(
 		\	lsp#utils#find_nearest_parent_file_directory(
-		\		lsp#utils#get_buffer_path(), 
+		\		lsp#utils#get_buffer_path(),
 		\		['.ccls', 'compile_commands.json', '.git/']
 		\	))},
 		\ 'initialization_options': {},
@@ -577,6 +608,21 @@ LspStatus                                                        *LspStatus*
 
 Prints the status of all registered servers.
 
+===============================================================================
+Autocommands                                          *vim-lsp-autocommands*
+
+lsp_complete_done                                        *lsp_complete_done*
+
+This autocommand is run after Insert mode completion is done, similar to
+|CompleteDone|. However, the difference is that |lsp_complete_done| is run
+only after vim-lsp has finished executing its internal |CompleteDone|
+autocommands (e.g. applying text edits). It is thus ideal to use for snippet
+expansion, or custom post processing of completed items. Just like
+|CompleteDone|, the Vim variable |v:completed_item| contains information about
+the completed item. It is guaranteed that vim-lsp does not change the content
+of this variable during its |CompleteDone| autocommands.
+
+
 ===============================================================================
 Mappings	                                          *vim-lsp-mappings*
 
@@ -636,6 +682,24 @@ Example:
 
 For additional configuration refer to asyncomplete.vim docs.
 
+===============================================================================
+Snippets                                                  *vim-lsp-snippets*
+
+To integrate snippets in vim-lsp, you will first have to install a third-party
+snippet plugin, and a plugin that integrates it in vim-lsp. At the moment,
+you have two options:
+
+1. UltiSnips and vim-lsp-ultisnips
+https://github.com/SirVer/ultisnips
+https://github.com/thomasfaingnaert/vim-lsp-ultisnips
+
+2. neosnippet.vim and vim-lsp-neosnippet
+https://github.com/Shougo/neosnippet.vim
+https://github.com/thomasfaingnaert/vim-lsp-neosnippet
+
+Refer to the readme and docs of vim-lsp-ultisnips and vim-lsp-neosnippet for
+more information and configuration options.
+
 ===============================================================================
 License                                                    *vim-lsp-license*
 

plugin/lsp.vim

@@ -26,6 +26,9 @@ let g:lsp_insert_text_enabled= get(g:, 'lsp_insert_text_enabled', 1)
 let g:lsp_text_edit_enabled = get(g:, 'lsp_text_edit_enabled', has('patch-8.0.1493'))
 let g:lsp_highlight_references_enabled = get(g:, 'lsp_highlight_references_enabled', 1)
 
+let g:lsp_get_vim_completion_item = get(g:, 'lsp_get_vim_completion_item', [function('lsp#omni#default_get_vim_completion_item')])
+let g:lsp_get_supported_capabilities = get(g:, 'lsp_get_supported_capabilities', [function('lsp#default_get_supported_capabilities')])
+
 if g:lsp_auto_enable
     augroup lsp_auto_enable
         autocmd!