add ALEToggle command (#303)

* add ALEToggle command

* stop active jobs when toggled off

* small logic cleanup & ensure ale can be ran manually while toggled off

plugin/ale.vim

@@ -49,30 +49,16 @@ let g:ale_lint_delay = get(g:, 'ale_lint_delay', 200)
 
 " This flag can be set to 0 to disable linting when text is changed.
 let g:ale_lint_on_text_changed = get(g:, 'ale_lint_on_text_changed', 1)
-if g:ale_lint_on_text_changed
-    augroup ALERunOnTextChangedGroup
-        autocmd!
-        autocmd TextChanged,TextChangedI * call ale#Queue(g:ale_lint_delay)
-    augroup END
-endif
 
 " This flag can be set to 0 to disable linting when the buffer is entered.
 let g:ale_lint_on_enter = get(g:, 'ale_lint_on_enter', 1)
-if g:ale_lint_on_enter
-    augroup ALERunOnEnterGroup
-        autocmd!
-        autocmd BufEnter,BufRead * call ale#Queue(300)
-    augroup END
-endif
 
 " This flag can be set to 1 to enable linting when a buffer is written.
 let g:ale_lint_on_save = get(g:, 'ale_lint_on_save', 0)
-if g:ale_lint_on_save
-    augroup ALERunOnSaveGroup
-        autocmd!
-        autocmd BufWrite * call ale#Queue(0)
-    augroup END
-endif
+
+" This flag may be set to 0 to disable ale. After ale is loaded, :ALEToggle
+" should be used instead.
+let g:ale_enabled = get(g:, 'ale_enabled', 1)
 
 " These flags dictates if ale uses the quickfix or the loclist (loclist is the
 " default, quickfix overrides loclist).
@@ -112,12 +98,6 @@ let g:ale_echo_msg_warning_str = get(g:, 'ale_echo_msg_warning_str', 'Warning')
 
 " 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)
-if g:ale_echo_cursor
-    augroup ALECursorGroup
-        autocmd!
-        autocmd CursorMoved,CursorHold * call ale#cursor#EchoCursorWarningWithDelay()
-    augroup END
-endif
 
 " String format for statusline
 " Its a list where:
@@ -132,12 +112,64 @@ let g:ale_statusline_format = get(g:, 'ale_statusline_format',
 let g:ale_warn_about_trailing_whitespace =
 \   get(g:, 'ale_warn_about_trailing_whitespace', 1)
 
+function! s:ALEInitAuGroups() abort
+    augroup ALERunOnTextChangedGroup
+        autocmd!
+        if g:ale_enabled && g:ale_lint_on_text_changed
+            autocmd TextChanged,TextChangedI * call ale#Queue(g:ale_lint_delay)
+        endif
+    augroup END
+
+    augroup ALERunOnEnterGroup
+        autocmd!
+        if g:ale_enabled && g:ale_lint_on_enter
+            autocmd BufEnter,BufRead * call ale#Queue(300)
+        endif
+    augroup END
+
+    augroup ALERunOnSaveGroup
+        autocmd!
+        if g:ale_enabled && g:ale_lint_on_save
+            autocmd BufWrite * call ale#Queue(0)
+        endif
+    augroup END
+
+    augroup ALECursorGroup
+        autocmd!
+        if g:ale_enabled && g:ale_echo_cursor
+            autocmd CursorMoved,CursorHold * call ale#cursor#EchoCursorWarningWithDelay()
+        endif
+    augroup END
+endfunction
+
+function! s:ALEToggle() abort
+    let g:ale_enabled = !get(g:, 'ale_enabled')
+
+    if g:ale_enabled
+        " Lint immediately
+        call ale#Queue(0)
+    else
+        for l:buffer in keys(g:ale_buffer_info)
+            " Stop jobs and delete stored buffer data
+            call ale#cleanup#Buffer(l:buffer)
+            " Clear signs, loclist, quicklist
+            call ale#engine#SetResults(l:buffer, [])
+        endfor
+    endif
+
+    call s:ALEInitAuGroups()
+endfunction
+
+call s:ALEInitAuGroups()
+
 " Define commands for moving through warnings and errors.
 command! ALEPrevious :call ale#loclist_jumping#Jump('before', 0)
 command! ALEPreviousWrap :call ale#loclist_jumping#Jump('before', 1)
 command! ALENext :call ale#loclist_jumping#Jump('after', 0)
 command! ALENextWrap :call ale#loclist_jumping#Jump('after', 1)
 
+command! ALEToggle :call s:ALEToggle()
+
 " Define command to get information about current filetype.
 command! ALEInfo :call ale#linter#Info()
 
@@ -146,6 +178,7 @@ nnoremap <silent> <Plug>(ale_previous) :ALEPrevious<Return>
 nnoremap <silent> <Plug>(ale_previous_wrap) :ALEPreviousWrap<Return>
 nnoremap <silent> <Plug>(ale_next) :ALENext<Return>
 nnoremap <silent> <Plug>(ale_next_wrap) :ALENextWrap<Return>
+nnoremap <silent> <Plug>(ale_toggle) :ALEToggle<Return>
 
 " Housekeeping