Implement statix Linter and Fixer (#3969)

* Add Statix for Linting

Add `statix check` as a linter. Provides a simple set of definition
tests additionally. Variable names specify "check" to allow for later
addition of `statix fix` as a formatter once stream support is added.

Signed-off-by: David Houston <houstdav000@gmail.com>

* Fixup Supported Tools List

I didn't realise there were two separate lists of tools, so add statix
to the other list. Also, remembered "S" comes after "R", and so
re-ordered it.

Signed-off-by: David Houston <houstdav000@gmail.com>

* Fix statix Test File

I refactored the variables for statix to allow for writing a fixer
later, and forgot to update them in the test, so update them now. Also
remove a stray "i", add missing space before checks

Signed-off-by: David Houston <houstdav000@gmail.com>

* Update Output Stream for v0.4.0

statix v0.4.0 provides a breaking change of output stream from stderr to
stdout.

Signed-off-by: David Houston <houstdav000@gmail.com>

* Add statix fix Fixer

Implement statix fix as a fixer for simple Nix antipatterns.

Signed-off-by: David Houston <houstdav000@gmail.com>

* Fix statix Fixer Tests

Fix the statix fixer tests by removing the unnecessary
'read_temporary_file' value from the command, since it simply uses the
default value.

Signed-off-by: David Houston <houstdav000@gmail.com>

* Add statix Handler Test

Add a test for the statix handler per @hsanson's request.

Signed-off-by: David Houston <houstdav000@gmail.com>

* Fix to run only on stdin for linting

Signed-off-by: David Houston <houstdav000@gmail.com>

3 files changed, 46 insertions, 0 deletions

diff --git a/autoload/ale/fix/registry.vim b/autoload/ale/fix/registry.vim
index eb7d7f53..c80d2271 100644
--- a/autoload/ale/fix/registry.vim
+++ b/autoload/ale/fix/registry.vim
@@ -191,6 +191,11 @@ let s:default_registry = {
 \       'suggested_filetypes': ['ruby'],
 \       'description': 'Fix ruby files with standardrb --fix',
 \   },
+\   'statix': {
+\       'function': 'ale#fixers#statix#Fix',
+\       'suggested_filetypes': ['nix'],
+\       'description': 'Fix common Nix antipatterns with statix fix',
+\   },
 \   'stylelint': {
 \       'function': 'ale#fixers#stylelint#Fix',
 \       'suggested_filetypes': ['css', 'sass', 'scss', 'sugarss', 'stylus'],
diff --git a/autoload/ale/fixers/statix.vim b/autoload/ale/fixers/statix.vim
new file mode 100644
index 00000000..5991c925
--- /dev/null
+++ b/autoload/ale/fixers/statix.vim
@@ -0,0 +1,17 @@
+" Author: David Houston <houstdav000>
+" Description: Provide statix fix as a fixer for simple Nix antipatterns.
+
+call ale#Set('nix_statix_fix_executable', 'statix')
+call ale#Set('nix_statix_fix_options', '')
+
+function! ale#fixers#statix#Fix(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'nix_statix_fix_executable')
+    let l:options = ale#Var(a:buffer, 'nix_statix_fix_options')
+
+    return {
+    \   'command': ale#Escape(l:executable)
+    \       . ale#Pad('fix')
+    \       . ale#Pad('--stdin')
+    \       . ale#Pad(l:options),
+    \}
+endfunction
diff --git a/autoload/ale/handlers/statix.vim b/autoload/ale/handlers/statix.vim
new file mode 100644
index 00000000..eeef4107
--- /dev/null
+++ b/autoload/ale/handlers/statix.vim
@@ -0,0 +1,24 @@
+scriptencoding utf-8
+" Author: David Houston
+" Description: This file defines a handler function for statix's errorformat
+" output.
+
+function! ale#handlers#statix#Handle(buffer, lines) abort
+    " Look for lines like the following.
+    "
+    " flake.nix>46:13:W:3:This assignment is better written with `inherit`
+    let l:pattern = '\v^.*\>(\d+):(\d+):([A-Z]):(\d+):(.*)$'
+    let l:output = []
+
+    for l:match in ale#util#GetMatches(a:lines, l:pattern)
+        call add(l:output, {
+        \   'lnum': l:match[1] + 0,
+        \   'col': l:match[2] + 0,
+        \   'type': l:match[3],
+        \   'code': l:match[4],
+        \   'text': l:match[5],
+        \})
+    endfor
+
+    return l:output
+endfunction