#1889 Add support for automatically previewing messages based on the cursor position

autoload/ale/cursor.vim

@@ -1,4 +1,6 @@
+scriptencoding utf-8
 " Author: w0rp <devw0rp@gmail.com>
+" Author: João Paulo S. de Souza <joao.paulo.silvasouza@hotmail.com>
 " Description: Echoes lint message for the current line, if any
 
 " Controls the milliseconds delay before echoing a message.
@@ -37,12 +39,11 @@ function! ale#cursor#TruncatedEcho(original_message) abort
     endtry
 endfunction
 
-function! s:FindItemAtCursor() abort
+function! s:FindItemAtCursor(buffer) abort
-    let l:buf = bufnr('')
+    let l:info = get(g:ale_buffer_info, a:buffer, {})
-    let l:info = get(g:ale_buffer_info, l:buf, {})
     let l:loclist = get(l:info, 'loclist', [])
     let l:pos = getcurpos()
-    let l:index = ale#util#BinarySearch(l:loclist, l:buf, l:pos[1], l:pos[2])
+    let l:index = ale#util#BinarySearch(l:loclist, a:buffer, l:pos[1], l:pos[2])
     let l:loc = l:index >= 0 ? l:loclist[l:index] : {}
 
     return [l:info, l:loc]
@@ -56,7 +57,9 @@ function! s:StopCursorTimer() abort
 endfunction
 
 function! ale#cursor#EchoCursorWarning(...) abort
-    if !g:ale_echo_cursor
+    let l:buffer = bufnr('')
+
+    if !g:ale_echo_cursor && !g:ale_cursor_detail
         return
     endif
 
@@ -65,13 +68,13 @@ function! ale#cursor#EchoCursorWarning(...) abort
         return
     endif
 
-    if ale#ShouldDoNothing(bufnr(''))
+    if ale#ShouldDoNothing(l:buffer)
         return
     endif
 
-    let l:buffer = bufnr('')
+    let [l:info, l:loc] = s:FindItemAtCursor(l:buffer)
-    let [l:info, l:loc] = s:FindItemAtCursor()
 
+    if g:ale_echo_cursor
         if !empty(l:loc)
             let l:format = ale#Var(l:buffer, 'echo_msg_format')
             let l:msg = ale#GetLocItemMessage(l:loc, l:format)
@@ -83,10 +86,21 @@ function! ale#cursor#EchoCursorWarning(...) abort
             execute 'echo'
             let l:info.echoed = 0
         endif
+    endif
+
+    if g:ale_cursor_detail
+        if !empty(l:loc)
+            call s:ShowCursorDetailForItem(l:loc, {'stay_here': 1})
+        else
+            call ale#preview#CloseIfTypeMatches('ale-preview')
+        endif
+    endif
 endfunction
 
 function! ale#cursor#EchoCursorWarningWithDelay() abort
-    if !g:ale_echo_cursor
+    let l:buffer = bufnr('')
+
+    if !g:ale_echo_cursor && !g:ale_cursor_detail
         return
     endif
 
@@ -104,7 +118,7 @@ function! ale#cursor#EchoCursorWarningWithDelay() abort
     " we should echo something. Otherwise we can end up doing processing
     " the echo message far too frequently.
     if l:pos != s:last_pos
-        let l:delay = ale#Var(bufnr(''), 'echo_delay')
+        let l:delay = ale#Var(l:buffer, 'echo_delay')
 
         let s:last_pos = l:pos
         let s:cursor_timer = timer_start(
@@ -114,24 +128,37 @@ function! ale#cursor#EchoCursorWarningWithDelay() abort
     endif
 endfunction
 
+function! s:ShowCursorDetailForItem(loc, options) abort
+    let l:stay_here = get(a:options, 'stay_here', 0)
+
+    let s:last_detailed_line = line('.')
+    let l:message = get(a:loc, 'detail', a:loc.text)
+    let l:lines = split(l:message, "\n")
+    call ale#preview#Show(l:lines, {'stay_here': l:stay_here})
+
+    " Clear the echo message if we manually displayed details.
+    if !l:stay_here
+        execute 'echo'
+    endif
+endfunction
+
 function! ale#cursor#ShowCursorDetail() abort
+    let l:buffer = bufnr('')
+
     " Only echo the warnings in normal mode, otherwise we will get problems.
     if mode() isnot# 'n'
         return
     endif
 
-    if ale#ShouldDoNothing(bufnr(''))
+    if ale#ShouldDoNothing(l:buffer)
         return
     endif
 
     call s:StopCursorTimer()
 
-    let [l:info, l:loc] = s:FindItemAtCursor()
+    let [l:info, l:loc] = s:FindItemAtCursor(l:buffer)
 
     if !empty(l:loc)
-        let l:message = get(l:loc, 'detail', l:loc.text)
+        call s:ShowCursorDetailForItem(l:loc, {'stay_here': 0})
-
-        call ale#preview#Show(split(l:message, "\n"))
-        execute 'echo'
     endif
 endfunction

autoload/ale/events.vim

@@ -131,13 +131,17 @@ function! ale#events#Init() abort
                 autocmd InsertLeave * call ale#Queue(0)
             endif
 
-            if g:ale_echo_cursor
+            if g:ale_echo_cursor || g:ale_cursor_detail
                 autocmd CursorMoved,CursorHold * if exists('*ale#engine#Cleanup') | call ale#cursor#EchoCursorWarningWithDelay() | endif
                 " Look for a warning to echo as soon as we leave Insert mode.
                 " The script's position variable used when moving the cursor will
                 " not be changed here.
                 autocmd InsertLeave * if exists('*ale#engine#Cleanup') | call ale#cursor#EchoCursorWarning() | endif
             endif
+
+            if g:ale_close_preview_on_insert
+                autocmd InsertEnter * if exists('*ale#preview#CloseIfTypeMatches') | call ale#preview#CloseIfTypeMatches('ale-preview') | endif
+            endif
         endif
     augroup END
 endfunction

autoload/ale/preview.vim

@@ -15,13 +15,13 @@ function! ale#preview#Show(lines, ...) abort
     setlocal modifiable
     setlocal noreadonly
     setlocal nobuflisted
-    let &l:filetype = get(l:options, 'filetype', 'ale-preview')
     setlocal buftype=nofile
     setlocal bufhidden=wipe
     :%d
     call setline(1, a:lines)
     setlocal nomodifiable
     setlocal readonly
+    let &l:filetype = get(l:options, 'filetype', 'ale-preview')
 
     if get(l:options, 'stay_here')
         wincmd p

doc/ale.txt

@@ -532,6 +532,7 @@ their relevant options.
 * By setting error highlights.                     - |g:ale_set_highlights|
 * By creating signs in the sign column.            - |g:ale_set_signs|
 * By echoing messages based on your cursor.        - |g:ale_echo_cursor|
+* By displaying the preview based on your cursor.  - |g:ale_cursor_detail|
 * By showing balloons for your mouse cursor        - |g:ale_set_balloons|
 
 Please consult the documentation for each option, which can reveal some other
@@ -805,6 +806,20 @@ g:ale_change_sign_column_color                 *g:ale_change_sign_column_color*
   windows.
 
 
+g:ale_close_preview_on_insert                   *g:ale_close_preview_on_insert*
+
+  Type: |Number|
+  Default: `0`
+
+  When this option is set to `1`, ALE's |preview-window| will be automatically
+  closed upon entering Insert Mode. This option can be used in combination
+  with |g:ale_cursor_detail| for automatically displaying the preview window
+  on problem lines, and automatically closing it again when editing text.
+
+  This setting must be set to `1` before ALE is loaded for this behavior
+  to be enabled. See |ale-lint-settings-on-startup|.
+
+
 g:ale_command_wrapper                                   *g:ale_command_wrapper*
                                                         *b:ale_command_wrapper*
   Type: |String|
@@ -893,6 +908,27 @@ g:ale_completion_max_suggestions             *g:ale_completion_max_suggestions*
   Adjust this option as needed, depending on the complexity of your codebase
   and your available processing power.
 
+g:ale_cursor_detail                                       *g:ale_cursor_detail*
+
+  Type: |Number|
+  Default: `0`
+
+  When this option is set to `1`, ALE's |preview-window| will be automatically
+  opened when the cursor moves onto lines with problems. ALE will search for
+  problems using the same logic that |g:ale_echo_cursor| uses. The preview
+  window will be closed automatically when you move away from the line.
+
+  Messages are only displayed after a short delay. See |g:ale_echo_delay|.
+
+  The preview window is opened without stealing focus, which means your cursor
+  will stay in the same buffer as it currently is.
+
+  The preview window can be closed automatically upon entering Insert mode
+  by setting |g:ale_close_preview_on_insert| to `1`.
+
+  Either this setting or |g:ale_echo_cursor| must be set to `1` before ALE is
+  loaded for messages to be displayed. See |ale-lint-settings-on-startup|.
+
 
 g:ale_echo_cursor                                           *g:ale_echo_cursor*
 
@@ -903,11 +939,14 @@ g:ale_echo_cursor                                           *g:ale_echo_cursor*
   cursor is near a warning or error. ALE will attempt to find the warning or
   error at a column nearest to the cursor when the cursor is resting on a line
   which contains a warning or error. This option can be set to `0` to disable
-  this behaviour.
+  this behavior.
-  The format of the message can be customizable in |g:ale_echo_msg_format|.
 
-  You should set this setting once before ALE is loaded, and restart Vim if
+  Messages are only displayed after a short delay. See |g:ale_echo_delay|.
-  you want to change your preferences. See |ale-lint-settings-on-startup|.
+
+  The format of the message can be customized with |g:ale_echo_msg_format|.
+
+  Either this setting or |g:ale_cursor_detail| must be set to `1` before ALE
+  is loaded for messages to be displayed. See |ale-lint-settings-on-startup|.
 
 
 g:ale_echo_delay                                             *g:ale_echo_delay*
@@ -916,7 +955,7 @@ g:ale_echo_delay                                             *g:ale_echo_delay*
   Default: `10`
 
   Given any integer, this option controls the number of milliseconds before
-  ALE will echo a message for a problem near the cursor.
+  ALE will echo or preview a message for a problem near the cursor.
 
   The value can be increased to decrease the amount of processing ALE will do
   for files displaying a large number of problems.

plugin/ale.vim

@@ -109,6 +109,13 @@ let g:ale_set_highlights = get(g:, 'ale_set_highlights', has('syntax'))
 " This flag can be set to 0 to disable echoing when the cursor moves.
 let g:ale_echo_cursor = get(g:, 'ale_echo_cursor', 1)
 
+" This flag can be set to 1 to automatically show errors in the preview window.
+let g:ale_cursor_detail = get(g:, 'ale_cursor_detail', 0)
+
+" This flag can be set to 1 to automatically close the preview window upon
+" entering Insert Mode.
+let g:ale_close_preview_on_insert = get(g:, 'ale_close_preview_on_insert', 0)
+
 " This flag can be set to 0 to disable balloon support.
 let g:ale_set_balloons = get(g:, 'ale_set_balloons', has('balloon_eval') && has('gui_running'))