Nicer syntax highlighting for hover (#441)

* Implement syntax highlighting for hover

* Fix signatureHelp

Author: thomasfaingnaert

autoload/lsp/ui/vim.vim

@@ -488,7 +488,7 @@ function! s:handle_location(ctx, server, type, data) abort "ctx = {counter, list
                 botright copen
             else
                 let l:lines = readfile(fnameescape(l:loc['filename']))
-                call lsp#ui#vim#output#preview(l:lines, {
+                call lsp#ui#vim#output#preview(a:server, l:lines, {
                             \   'statusline': ' LSP Peek ' . a:type,
                             \   'cursor': { 'line': l:loc['lnum'], 'col': l:loc['col'], 'align': g:lsp_peek_alignment },
                             \   'filetype': &filetype

autoload/lsp/ui/vim/hover.vim

@@ -35,7 +35,7 @@ function! s:handle_hover(server, data) abort
     endif
 
     if !empty(a:data['response']['result']) && !empty(a:data['response']['result']['contents'])
-        call lsp#ui#vim#output#preview(a:data['response']['result']['contents'], {'statusline': ' LSP Hover'})
+        call lsp#ui#vim#output#preview(a:server, a:data['response']['result']['contents'], {'statusline': ' LSP Hover'})
         return
     else
         call lsp#utils#error('No hover information found')

autoload/lsp/ui/vim/output.vim

@@ -284,7 +284,7 @@ function! s:align_preview(options) abort
     endif
 endfunction
 
-function! lsp#ui#vim#output#preview(data, options) abort
+function! lsp#ui#vim#output#preview(server, data, options) abort
     if s:winid && type(s:preview_data) == type(a:data)
        \ && s:preview_data == a:data
        \ && type(g:lsp_preview_doubletap) == 3
@@ -302,12 +302,22 @@ function! lsp#ui#vim#output#preview(data, options) abort
 
     let s:preview_data = a:data
     let l:lines = []
-    let l:ft = s:append(a:data, l:lines)
+    let l:syntax_lines = []
+    let l:ft = s:append(a:data, l:lines, l:syntax_lines)
 
     if has_key(a:options, 'filetype')
         let l:ft = a:options['filetype']
     endif
 
+    let l:server_info = lsp#get_server_info(a:server)
+    try
+        let l:do_conceal = l:server_info['config']['hover_conceal']
+    catch
+        let l:do_conceal = g:lsp_hover_conceal
+    endtry
+
+    call setbufvar(winbufnr(s:winid), 'lsp_syntax_highlights', l:syntax_lines)
+    call setbufvar(winbufnr(s:winid), 'lsp_do_conceal', l:do_conceal)
     call s:setcontent(l:lines, l:ft)
 
     " Get size information while still having the buffer active
@@ -361,10 +371,10 @@ function! lsp#ui#vim#output#preview(data, options) abort
     return ''
 endfunction
 
-function! s:append(data, lines) abort
+function! s:append(data, lines, syntax_lines) abort
     if type(a:data) == type([])
         for l:entry in a:data
-            call s:append(entry, a:lines)
+            call s:append(entry, a:lines, a:syntax_lines)
         endfor
 
         return 'markdown'
@@ -373,9 +383,15 @@ function! s:append(data, lines) abort
 
         return 'markdown'
     elseif type(a:data) == type({}) && has_key(a:data, 'language')
-        call add(a:lines, '```'.a:data.language)
-        call extend(a:lines, split(a:data.value, '\n'))
-        call add(a:lines, '```')
+        let l:new_lines = split(a:data.value, '\n')
+
+        let l:i = 1
+        while l:i <= len(l:new_lines)
+            call add(a:syntax_lines, { 'line': len(a:lines) + l:i, 'language': a:data.language })
+            let l:i += 1
+        endwhile
+
+        call extend(a:lines, l:new_lines)
 
         return 'markdown'
     elseif type(a:data) == type({}) && has_key(a:data, 'kind')

autoload/lsp/ui/vim/signature_help.vim

@@ -43,7 +43,7 @@ function! s:handle_signature_help(server, data) abort
         if has_key(l:signature, 'documentation')
             call add(l:contents, l:signature['documentation'])
         endif
-        call lsp#ui#vim#output#preview(l:contents, {'statusline': ' LSP SignatureHelp'})
+        call lsp#ui#vim#output#preview(a:server, l:contents, {'statusline': ' LSP SignatureHelp'})
         return
     else
         " signature help is used while inserting. So this must be graceful.

doc/vim-lsp.txt

@@ -34,6 +34,7 @@ CONTENTS                                                  *vim-lsp-contents*
       g:lsp_preview_max_height		    |g:lsp_preview_max_height|
       g:lsp_signature_help_enabled          |g:lsp_signature_help_enabled|
       g:lsp_fold_enabled                    |g:lsp_fold_enabled|
+      g:lsp_hover_conceal                   |g:lsp_hover_conceal|
     Functions                             |vim-lsp-functions|
       enable                                |vim-lsp-enable|
       disable                               |vim-lsp-disable|
@@ -492,6 +493,18 @@ g:lsp_fold_enabled                                    *g:lsp_fold_enabled*
     Determines whether or not folding is enabled globally. Set to `0` to
     disable sending requests.
 
+g:lsp_hover_conceal                                   *g:lsp_hover_conceal*
+    Type: |Boolean|
+    Default: `1`
+
+    If `true` (`1`), |conceallevel| is set to `2` for hover windows. This
+    means that, for example, asterisks in markdown hovers are hidden, but the
+    text is still displayed bold. You may want to disable this if the filetype
+    of the popup has custom conceals which you don't want to use, or if
+    you're using Vim in a terminal.
+
+    To override this setting per server, see |vim-lsp-hover_conceal|.
+
 ===============================================================================
 FUNCTIONS	                                        *vim-lsp-functions*
 
@@ -642,6 +655,15 @@ The vim |dict| containing information about the server.
 	'workspace_config': {'pyls': {'plugins': \
 		{'pydocstyle': {'enabled': v:true}}}}
 
+hover_conceal                                          *vim-lsp_hover_conceal*
+    Type: |Boolean|
+    Default: |g:lsp_hover_conceal|
+
+    This takes precendence over the value of |g:lsp_hover_conceal|, to allow
+    overriding this setting per server.
+
+    Example:
+        'config': { 'hover_conceal': 1 }
 
 lsp#stop_server                                        *vim-lsp-stop_server*
 

ftplugin/lsp-hover.vim

@@ -6,6 +6,11 @@ if has('patch-8.1.1517') && g:lsp_preview_float && !has('nvim')
 else
   setlocal previewwindow buftype=nofile bufhidden=wipe noswapfile nobuflisted
 endif
+
+if has('conceal') && b:lsp_do_conceal
+    setlocal conceallevel=2
+endif
+
 setlocal nocursorline nofoldenable nonumber norelativenumber
 
 if has('syntax')
@@ -15,4 +20,5 @@ endif
 let b:undo_ftplugin = 'setlocal pvw< bt< bh< swf< bl< cul< fen<' .
             \ (has('syntax') ? ' spell<' : '') .
             \ ' number< relativenumber<' .
+            \ (has('conceal') && b:lsp_do_conceal ? ' conceallevel<' : '') .
             \ ' | unlet! g:markdown_fenced_languages'

plugin/lsp.vim

@@ -36,6 +36,7 @@ let g:lsp_preview_max_width = get(g:, 'lsp_preview_max_width', -1)
 let g:lsp_preview_max_height = get(g:, 'lsp_preview_max_height', -1)
 let g:lsp_signature_help_enabled = get(g:, 'lsp_signature_help_enabled', 1)
 let g:lsp_fold_enabled = get(g:, 'lsp_fold_enabled', 1)
+let g:lsp_hover_conceal = get(g:, 'lsp_hover_conceal', 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')])

syntax/lsp-hover.vim

@@ -0,0 +1,36 @@
+" Converts a markdown language (```foo) to the corresponding Vim filetype
+function! s:get_vim_filetype(lang_markdown) abort
+    " If the user hasn't customised markdown fenced languages, just return the
+    " markdown language
+    if !exists('g:markdown_fenced_languages')
+        return a:lang_markdown
+    endif
+
+    " Otherwise, check if it has an entry for the given language
+    for l:type in g:markdown_fenced_languages
+        let l:vim_type = substitute(matchstr(l:type, '[^=]*$'), '\..*', '', '')
+        let l:markdown_type = matchstr(l:type, '[^=]*')
+
+        if l:markdown_type ==# a:lang_markdown
+            " Found entry
+            return l:vim_type
+        endif
+    endfor
+
+    " Not found
+    return a:lang_markdown
+endfunction
+
+function! s:do_highlight() abort
+    if exists('b:lsp_syntax_highlights')
+        for l:entry in b:lsp_syntax_highlights
+            let l:line = l:entry['line']
+            let l:lang = l:entry['language']
+            let l:ft = s:get_vim_filetype(l:lang)
+
+            execute printf('syntax match markdownHighlight%s contains=@markdownHighlight%s /^\%%%sl.*$/', l:ft, l:ft, l:line)
+        endfor
+    endif
+endfunction
+
+call s:do_highlight()