Close #3274 - Handle basic LSP markdown formatting

3 files changed, 163 insertions, 38 deletions

diff --git a/autoload/ale/hover.vim b/autoload/ale/hover.vim
index a6462227..fe4e5da7 100644
--- a/autoload/ale/hover.vim
+++ b/autoload/ale/hover.vim
@@ -56,6 +56,137 @@ function! ale#hover#HandleTSServerResponse(conn_id, response) abort
     endif
 endfunction
 
+" Convert a language name to another one.
+" The language name could be an empty string or v:null
+function! s:ConvertLanguageName(language) abort
+    return a:language
+endfunction
+
+function! ale#hover#ParseLSPResult(contents) abort
+    let l:includes = {}
+    let l:highlights = []
+    let l:lines = []
+    let l:list = type(a:contents) is v:t_list ? a:contents : [a:contents]
+    let l:region_index = 0
+
+    for l:item in l:list
+        if !empty(l:lines)
+            call add(l:lines, '')
+        endif
+
+        if type(l:item) is v:t_dict && has_key(l:item, 'kind')
+            if l:item.kind is# 'markdown'
+                " Handle markdown values as we handle strings below.
+                let l:item = get(l:item, 'value', '')
+            elseif l:item.kind is# 'plaintext'
+                " We shouldn't try to parse plaintext as markdown.
+                " Pass the lines on and skip parsing them.
+                call extend(l:lines, split(get(l:item, 'value', ''), "\n"))
+
+                continue
+            endif
+        endif
+
+        let l:marked_list = []
+
+        " If the item is a string, then we should parse it as Markdown text.
+        if type(l:item) is v:t_string
+            let l:fence_language = v:null
+            let l:fence_lines = []
+
+            for l:line in split(l:item, "\n")
+                if l:fence_language is v:null
+                    " Look for the start of a code fence. (```python, etc.)
+                    let l:match = matchlist(l:line, '^```\(.*\)$')
+
+                    if !empty(l:match)
+                        let l:fence_language = l:match[1]
+
+                        if !empty(l:marked_list)
+                            call add(l:fence_lines, '')
+                        endif
+                    else
+                        if !empty(l:marked_list)
+                        \&& l:marked_list[-1][0] isnot v:null
+                            call add(l:marked_list, [v:null, ['']])
+                        endif
+
+                        call add(l:marked_list, [v:null, [l:line]])
+                    endif
+                elseif l:line =~# '^```$'
+                    " When we hit the end of a code fence, pass the fenced
+                    " lines on to the next steps below.
+                    call add(l:marked_list, [l:fence_language, l:fence_lines])
+                    let l:fence_language = v:null
+                    let l:fence_lines = []
+                else
+                    " Gather lines inside of a code fence.
+                    call add(l:fence_lines, l:line)
+                endif
+            endfor
+        " If the result from the LSP server is a {language: ..., value: ...}
+        " Dictionary, then that should be interpreted as if it was:
+        "
+        " ```${language}
+        " ${value}
+        " ```
+        elseif type(l:item) is v:t_dict
+        \&& has_key(l:item, 'language')
+        \&& type(l:item.language) is v:t_string
+        \&& has_key(l:item, 'value')
+        \&& type(l:item.value) is v:t_string
+            call add(
+            \   l:marked_list,
+            \   [l:item.language, split(l:item.value, "\n")],
+            \)
+        endif
+
+        for [l:language, l:marked_lines] in l:marked_list
+            if l:language is v:null
+                " NOTE: We could handle other Markdown formatting here.
+                call map(
+                \   l:marked_lines,
+                \   'substitute(v:val, ''\\_'', ''_'', ''g'')',
+                \)
+            else
+                let l:language = s:ConvertLanguageName(l:language)
+
+                if !empty(l:language)
+                    let l:includes[l:language] = printf(
+                    \   'syntax/%s.vim',
+                    \   l:language,
+                    \)
+
+                    let l:start = len(l:lines) + 1
+                    let l:end = l:start + len(l:marked_lines)
+                    let l:region_index += 1
+
+                    call add(l:highlights, 'syntax region'
+                    \   . ' ALE_hover_' . l:region_index
+                    \   . ' start=/\%' . l:start . 'l/'
+                    \   . ' end=/\%' . l:end . 'l/'
+                    \   . ' contains=@ALE_hover_' . l:language
+                    \)
+                endif
+            endif
+
+            call extend(l:lines, l:marked_lines)
+        endfor
+    endfor
+
+    let l:include_commands = []
+
+    for [l:language, l:lang_path] in sort(items(l:includes))
+        call add(l:include_commands, 'unlet! b:current_syntax')
+        call add(
+        \   l:include_commands,
+        \   printf('syntax include @ALE_hover_%s %s', l:language, l:lang_path),
+        \)
+    endfor
+
+    return [l:include_commands + l:highlights, l:lines]
+endfunction
+
 function! ale#hover#HandleLSPResponse(conn_id, response) abort
     if has_key(a:response, 'id')
     \&& has_key(s:hover_map, a:response.id)
@@ -82,40 +213,25 @@ function! ale#hover#HandleLSPResponse(conn_id, response) abort
             return
         endif
 
-        let l:result = l:result.contents
+        let [l:commands, l:lines] = ale#hover#ParseLSPResult(l:result.contents)
 
-        if type(l:result) is v:t_string
-            " The result can be just a string.
-            let l:result = [l:result]
-        endif
-
-        if type(l:result) is v:t_dict
-            " If the result is an object, then it's markup content.
-            let l:result = has_key(l:result, 'value') ? [l:result.value] : []
-        endif
-
-        if type(l:result) is v:t_list
-            " Replace objects with text values.
-            call filter(l:result, '!(type(v:val) is v:t_dict && !has_key(v:val, ''value''))')
-            call map(l:result, 'type(v:val) is v:t_string ? v:val : v:val.value')
-            let l:str = join(l:result, "\n")
-            let l:str = substitute(l:str, '^\s*\(.\{-}\)\s*$', '\1', '')
-
-            if !empty(l:str)
-                if get(l:options, 'hover_from_balloonexpr', 0)
-                \&& exists('*balloon_show')
-                \&& ale#Var(l:options.buffer, 'set_balloons')
-                    call balloon_show(l:str)
-                elseif get(l:options, 'truncated_echo', 0)
-                    call ale#cursor#TruncatedEcho(split(l:str, "\n")[0])
-                elseif g:ale_hover_to_preview
-                    call ale#preview#Show(split(l:str, "\n"), {
-                    \   'filetype': 'ale-preview.message',
-                    \   'stay_here': 1,
-                    \})
-                else
-                    call ale#util#ShowMessage(l:str)
-                endif
+        if !empty(l:lines)
+            if get(l:options, 'hover_from_balloonexpr', 0)
+            \&& exists('*balloon_show')
+            \&& ale#Var(l:options.buffer, 'set_balloons')
+                call balloon_show(join(l:lines, "\n"))
+            elseif get(l:options, 'truncated_echo', 0)
+                call ale#cursor#TruncatedEcho(l:lines[0])
+            elseif g:ale_hover_to_preview
+                call ale#preview#Show(l:lines, {
+                \   'filetype': 'ale-preview.message',
+                \   'stay_here': 1,
+                \   'commands': l:commands,
+                \})
+            else
+                call ale#util#ShowMessage(join(l:lines, "\n"), {
+                \   'commands': l:commands,
+                \})
             endif
         endif
     endif
diff --git a/autoload/ale/preview.vim b/autoload/ale/preview.vim
index 7902ec63..faf45cb0 100644
--- a/autoload/ale/preview.vim
+++ b/autoload/ale/preview.vim
@@ -31,6 +31,10 @@ function! ale#preview#Show(lines, ...) abort
     setlocal readonly
     let &l:filetype = get(l:options, 'filetype', 'ale-preview')
 
+    for l:command in get(l:options, 'commands', [])
+        call execute(l:command)
+    endfor
+
     if get(l:options, 'stay_here')
         wincmd p
     endif
diff --git a/autoload/ale/util.vim b/autoload/ale/util.vim
index ee62af28..bb9c1961 100644
--- a/autoload/ale/util.vim
+++ b/autoload/ale/util.vim
@@ -16,7 +16,9 @@ endfunction
 " Vim 8 does not support echoing long messages from asynchronous callbacks,
 " but NeoVim does. Small messages can be echoed in Vim 8, and larger messages
 " have to be shown in preview windows.
-function! ale#util#ShowMessage(string) abort
+function! ale#util#ShowMessage(string, ...) abort
+    let l:options = get(a:000, 0, {})
+
     if !has('nvim')
         call ale#preview#CloseIfTypeMatches('ale-preview.message')
     endif
@@ -25,10 +27,13 @@ function! ale#util#ShowMessage(string) abort
     if has('nvim') || (a:string !~? "\n" && len(a:string) < &columns)
         execute 'echo a:string'
     else
-        call ale#preview#Show(split(a:string, "\n"), {
-        \   'filetype': 'ale-preview.message',
-        \   'stay_here': 1,
-        \})
+        call ale#preview#Show(split(a:string, "\n"), extend(
+        \   {
+        \       'filetype': 'ale-preview.message',
+        \       'stay_here': 1,
+        \   },
+        \   l:options,
+        \))
     endif
 endfunction