Close #2522 - Check pylint on the fly

Newer versions of pylint will now check your code as you type. Older
versions will still only check the file on disk.

Co-authored-by: Oliver Wiegers <oliver.wiegers@gmail.com>

5 files changed, 119 insertions, 54 deletions

diff --git a/ale_linters/python/pylint.vim b/ale_linters/python/pylint.vim
index b16d5355..44eea246 100644
--- a/ale_linters/python/pylint.vim
+++ b/ale_linters/python/pylint.vim
@@ -17,7 +17,7 @@ function! ale_linters#python#pylint#GetExecutable(buffer) abort
     return ale#python#FindExecutable(a:buffer, 'python_pylint', ['pylint'])
 endfunction
 
-function! ale_linters#python#pylint#GetCommand(buffer) abort
+function! ale_linters#python#pylint#GetCommand(buffer, version) abort
     let l:cd_string = ''
 
     if ale#Var(a:buffer, 'python_pylint_change_directory')
@@ -38,17 +38,23 @@ function! ale_linters#python#pylint#GetCommand(buffer) abort
 
     return l:cd_string
     \   . ale#Escape(l:executable) . l:exec_args
-    \   . ' ' . ale#Var(a:buffer, 'python_pylint_options')
+    \   . ale#Pad(ale#Var(a:buffer, 'python_pylint_options'))
     \   . ' --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n'
+    \   .  (ale#semver#GTE(a:version, [2, 4, 0]) ? ' --from-stdin' : '')
     \   . ' %s'
 endfunction
 
 function! ale_linters#python#pylint#Handle(buffer, lines) abort
+    let l:output = ale#python#HandleTraceback(a:lines, 10)
+
+    if !empty(l:output)
+        return l:output
+    endif
+
     " Matches patterns like the following:
     "
     " test.py:4:4: W0101 (unreachable) Unreachable code
     let l:pattern = '\v^[a-zA-Z]?:?[^:]+:(\d+):(\d+): ([[:alnum:]]+) \(([^(]*)\) (.*)$'
-    let l:output = []
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         "let l:failed = append(0, l:match)
@@ -71,13 +77,19 @@ function! ale_linters#python#pylint#Handle(buffer, lines) abort
             let l:code_out = l:match[4]
         endif
 
-        call add(l:output, {
+        let l:item = {
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 1,
         \   'text': l:match[5],
         \   'code': l:code_out,
-        \   'type': l:code[:0] is# 'E' ? 'E' : 'W',
-        \})
+        \   'type': 'W',
+        \}
+
+        if l:code[:0] is# 'E'
+            let l:item.type = 'E'
+        endif
+
+        call add(l:output, l:item)
     endfor
 
     return l:output
@@ -86,7 +98,17 @@ endfunction
 call ale#linter#Define('python', {
 \   'name': 'pylint',
 \   'executable': function('ale_linters#python#pylint#GetExecutable'),
-\   'command': function('ale_linters#python#pylint#GetCommand'),
+\   'lint_file': {buffer -> ale#semver#RunWithVersionCheck(
+\       buffer,
+\       ale#Var(buffer, 'python_pylint_executable'),
+\       '%e --version',
+\       {buffer, version -> !ale#semver#GTE(version, [2, 4, 0])},
+\   )},
+\   'command': {buffer -> ale#semver#RunWithVersionCheck(
+\       buffer,
+\       ale#Var(buffer, 'python_pylint_executable'),
+\       '%e --version',
+\       function('ale_linters#python#pylint#GetCommand'),
+\   )},
 \   'callback': 'ale_linters#python#pylint#Handle',
-\   'lint_file': 1,
 \})
diff --git a/autoload/ale/engine.vim b/autoload/ale/engine.vim
index 63195d0f..3cafa25c 100644
--- a/autoload/ale/engine.vim
+++ b/autoload/ale/engine.vim
@@ -444,7 +444,7 @@ function! s:RunJob(command, options) abort
     return 1
 endfunction
 
-function! s:StopCurrentJobs(buffer, clear_lint_file_jobs) abort
+function! s:StopCurrentJobs(buffer, clear_lint_file_jobs, linter_slots) abort
     let l:info = get(g:ale_buffer_info, a:buffer, {})
     call ale#command#StopJobs(a:buffer, 'linter')
 
@@ -453,13 +453,23 @@ function! s:StopCurrentJobs(buffer, clear_lint_file_jobs) abort
         call ale#command#StopJobs(a:buffer, 'file_linter')
         let l:info.active_linter_list = []
     else
+        let l:lint_file_map = {}
+
+        " Use a previously computed map of `lint_file` values to find
+        " linters that are used for linting files.
+        for [l:lint_file, l:linter] in a:linter_slots
+            if l:lint_file is 1
+                let l:lint_file_map[l:linter.name] = 1
+            endif
+        endfor
+
         " Keep jobs for linting files when we're only linting buffers.
-        call filter(l:info.active_linter_list, 'get(v:val, ''lint_file'')')
+        call filter(l:info.active_linter_list, 'get(l:lint_file_map, v:val.name)')
     endif
 endfunction
 
 function! ale#engine#Stop(buffer) abort
-    call s:StopCurrentJobs(a:buffer, 1)
+    call s:StopCurrentJobs(a:buffer, 1, [])
 endfunction
 
 function! s:RemoveProblemsForDisabledLinters(buffer, linters) abort
@@ -562,6 +572,22 @@ function! s:RunLinter(buffer, linter, lint_file) abort
     return 0
 endfunction
 
+function! s:GetLintFileSlots(buffer, linters) abort
+    let l:linter_slots = []
+
+    for l:linter in a:linters
+        let l:LintFile = l:linter.lint_file
+
+        if type(l:LintFile) is v:t_func
+            let l:LintFile = l:LintFile(a:buffer)
+        endif
+
+        call add(l:linter_slots, [l:LintFile, l:linter])
+    endfor
+
+    return l:linter_slots
+endfunction
+
 function! s:GetLintFileValues(slots, Callback) abort
     let l:deferred_list = []
     let l:new_slots = []
@@ -595,12 +621,18 @@ endfunction
 
 function! s:RunLinters(
 \   buffer,
+\   linters,
 \   slots,
 \   should_lint_file,
 \   new_buffer,
-\   can_clear_results
 \) abort
-    let l:can_clear_results = a:can_clear_results
+    call s:StopCurrentJobs(a:buffer, a:should_lint_file, a:slots)
+    call s:RemoveProblemsForDisabledLinters(a:buffer, a:linters)
+
+    " We can only clear the results if we aren't checking the buffer.
+    let l:can_clear_results = !ale#engine#IsCheckingBuffer(a:buffer)
+
+    silent doautocmd <nomodeline> User ALELintPre
 
     for [l:lint_file, l:linter] in a:slots
         " Only run lint_file linters if we should.
@@ -631,36 +663,19 @@ endfunction
 function! ale#engine#RunLinters(buffer, linters, should_lint_file) abort
     " Initialise the buffer information if needed.
     let l:new_buffer = ale#engine#InitBufferInfo(a:buffer)
-    call s:StopCurrentJobs(a:buffer, a:should_lint_file)
-    call s:RemoveProblemsForDisabledLinters(a:buffer, a:linters)
-
-    " We can only clear the results if we aren't checking the buffer.
-    let l:can_clear_results = !ale#engine#IsCheckingBuffer(a:buffer)
-
-    silent doautocmd <nomodeline> User ALELintPre
-
-    " Handle `lint_file` callbacks first.
-    let l:linter_slots = []
-
-    for l:linter in a:linters
-        let l:LintFile = l:linter.lint_file
-
-        if type(l:LintFile) is v:t_func
-            let l:LintFile = l:LintFile(a:buffer)
-        endif
 
-        call add(l:linter_slots, [l:LintFile, l:linter])
-    endfor
-
-    call s:GetLintFileValues(l:linter_slots, {
-    \   new_slots -> s:RunLinters(
-    \       a:buffer,
-    \       new_slots,
-    \       a:should_lint_file,
-    \       l:new_buffer,
-    \       l:can_clear_results,
-    \   )
-    \})
+    call s:GetLintFileValues(
+    \   s:GetLintFileSlots(a:buffer, a:linters),
+    \   {
+    \       slots -> s:RunLinters(
+    \           a:buffer,
+    \           a:linters,
+    \           slots,
+    \           a:should_lint_file,
+    \           l:new_buffer,
+    \       )
+    \   }
+    \)
 endfunction
 
 " Clean up a buffer.
diff --git a/doc/ale.txt b/doc/ale.txt
index e6b91be8..6ef137c1 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -179,8 +179,11 @@ script like so. >
 
   #!/usr/bin/env bash
 
-  exec docker run --rm -v "$(pwd):/data" cytopia/pylint "$@"
+  exec docker run -i --rm -v "$(pwd):/data" cytopia/pylint "$@"
 <
+
+You will run to run Docker commands with `-i` in order to read from stdin.
+
 With the above script in mind, you might configure ALE to lint your Python
 project with `pylint` by providing the path to the script to execute, and
 mappings which describe how to between the two file systems in your
diff --git a/test/command_callback/test_pylint_command_callback.vader b/test/command_callback/test_pylint_command_callback.vader
index 755dd292..15f004b6 100644
--- a/test/command_callback/test_pylint_command_callback.vader
+++ b/test/command_callback/test_pylint_command_callback.vader
@@ -8,6 +8,8 @@ Before:
   let b:bin_dir = has('win32') ? 'Scripts' : 'bin'
   let b:command_tail = ' --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n %s'
 
+  GivenCommandOutput ['pylint 2.3.0']
+
 After:
   unlet! b:bin_dir
   unlet! b:executable
@@ -17,26 +19,33 @@ After:
 
 Execute(The pylint callbacks should return the correct default values):
   AssertLinter 'pylint',
-  \ ale#path#CdString(expand('#' . bufnr('') . ':p:h'))
-  \   . ale#Escape('pylint') . ' ' . b:command_tail
+  \ ale#path#CdString(expand('%:p:h'))
+  \   . ale#Escape('pylint') . b:command_tail
+
+Execute(Pylint should run with the --from-stdin in new enough versions):
+  GivenCommandOutput ['pylint 2.4.0']
+
+  AssertLinter 'pylint',
+  \ ale#path#CdString(expand('%:p:h'))
+  \   . ale#Escape('pylint') . b:command_tail[:-3] . '--from-stdin %s'
 
 Execute(The option for disabling changing directories should work):
   let g:ale_python_pylint_change_directory = 0
 
-  AssertLinter 'pylint', ale#Escape('pylint') . ' ' . b:command_tail
+  AssertLinter 'pylint', ale#Escape('pylint') . b:command_tail
 
 Execute(The pylint executable should be configurable, and escaped properly):
   let g:ale_python_pylint_executable = 'executable with spaces'
 
   AssertLinter 'executable with spaces',
-  \ ale#path#CdString(expand('#' . bufnr('') . ':p:h'))
-  \   . ale#Escape('executable with spaces') . ' ' . b:command_tail
+  \ ale#path#CdString(expand('%:p:h'))
+  \   . ale#Escape('executable with spaces') . b:command_tail
 
 Execute(The pylint command callback should let you set options):
   let g:ale_python_pylint_options = '--some-option'
 
   AssertLinter 'pylint',
-  \ ale#path#CdString(expand('#' . bufnr('') . ':p:h'))
+  \ ale#path#CdString(expand('%:p:h'))
   \   . ale#Escape('pylint') . ' --some-option' . b:command_tail
 
 Execute(The pylint callbacks shouldn't detect virtualenv directories where they don't exist):
@@ -44,7 +53,7 @@ Execute(The pylint callbacks shouldn't detect virtualenv directories where they
 
   AssertLinter 'pylint',
   \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/no_virtualenv/subdir'))
-  \   . ale#Escape('pylint') . ' ' . b:command_tail
+  \   . ale#Escape('pylint') . b:command_tail
 
 Execute(The pylint callbacks should detect virtualenv directories):
   silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py')
@@ -55,7 +64,7 @@ Execute(The pylint callbacks should detect virtualenv directories):
 
   AssertLinter b:executable,
   \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/subdir'))
-  \   . ale#Escape(b:executable) . ' ' . b:command_tail
+  \   . ale#Escape(b:executable) . b:command_tail
 
 Execute(You should able able to use the global pylint instead):
   silent execute 'file ' . fnameescape(g:dir . '/python_paths/with_virtualenv/subdir/foo/bar.py')
@@ -63,7 +72,7 @@ Execute(You should able able to use the global pylint instead):
 
   AssertLinter 'pylint',
   \ ale#path#CdString(ale#path#Simplify(g:dir . '/python_paths/with_virtualenv/subdir'))
-  \   . ale#Escape('pylint') . ' ' . b:command_tail
+  \   . ale#Escape('pylint') . b:command_tail
 
 Execute(Setting executable to 'pipenv' appends 'run pylint'):
   let g:ale_python_pylint_executable = 'path/to/pipenv'
@@ -71,7 +80,7 @@ Execute(Setting executable to 'pipenv' appends 'run pylint'):
   AssertLinter 'path/to/pipenv',
   \ ale#path#CdString(expand('#' . bufnr('') . ':p:h'))
   \   . ale#Escape('path/to/pipenv') . ' run pylint'
-  \   . '  --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n %s'
+  \   . ' --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n %s'
 
 Execute(Pipenv is detected when python_pylint_auto_pipenv is set):
   let g:ale_python_pylint_auto_pipenv = 1
@@ -80,4 +89,4 @@ Execute(Pipenv is detected when python_pylint_auto_pipenv is set):
   AssertLinter 'pipenv',
   \ ale#path#CdString(expand('#' . bufnr('') . ':p:h'))
   \   . ale#Escape('pipenv') . ' run pylint'
-  \   . '  --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n %s'
+  \   . ' --output-format text --msg-template="{path}:{line}:{column}: {msg_id} ({symbol}) {msg}" --reports n %s'
diff --git a/test/test_computed_lint_file_values.vader b/test/test_computed_lint_file_values.vader
index 399e96fe..ed0d4c0c 100644
--- a/test/test_computed_lint_file_values.vader
+++ b/test/test_computed_lint_file_values.vader
@@ -132,3 +132,19 @@ Execute(Linters where lint_file eventually evaluates to 1 shouldn't be run if we
   call ale#test#FlushJobs()
 
   AssertEqual [], ale#test#GetLoclistWithoutModule()
+
+Execute(Keeping computed lint_file jobs running should work):
+  AssertEqual 'testlinter2', ale#linter#Get('foobar')[1].name
+
+  call ale#engine#InitBufferInfo(bufnr(''))
+
+  call ale#engine#MarkLinterActive(
+  \ g:ale_buffer_info[bufnr('')],
+  \ ale#linter#Get('foobar')[1]
+  \)
+  call ale#engine#RunLinters(bufnr(''), ale#linter#Get('foobar'), 0)
+
+  Assert !empty(g:ale_buffer_info[bufnr('')].active_linter_list),
+  \ 'The active linter list was empty'
+  Assert ale#engine#IsCheckingBuffer(bufnr('')),
+  \ 'The IsCheckingBuffer function returned 0'