From 70e379cc46868916126156558486a8d8971cc5fa Mon Sep 17 00:00:00 2001
From: Eric Lehner <ericj@buffalo.edu>
Date: Tue, 13 Dec 2016 04:06:04 -0500
Subject: [PATCH] Add Elm linting via elm-make (#213)

* Add support for Elm linting

* Adding documentation for Elm

* Adjusting spacing

* Addressing concerns listed in pull request

Removed the s:FindRootDirectory function as it does not make much sense
in this context. Adjusted the rest of the code to handle the removal of
that function, including using the ale#util function to find the nearest
file.

Ensured that when an empty filepath is found, the code does not attempt
to change directories.

Ensured that the linter would take from stdin using the wrapper.
---
 README.md                |  1 +
 ale_linters/elm/make.vim | 51 ++++++++++++++++++++++++++++++++++++++++
 doc/ale.txt              |  1 +
 3 files changed, 53 insertions(+)
 create mode 100644 ale_linters/elm/make.vim

diff --git a/README.md b/README.md
index b028d8a6..8cd60a94 100644
--- a/README.md
+++ b/README.md
@@ -59,6 +59,7 @@ name. That seems to be the fairest way to arrange this table.
 | Cython (pyrex filetype) | [cython](http://cython.org/) |
 | D | [dmd](https://dlang.org/dmd-linux.html)^ |
 | Elixir | [credo](https://github.com/rrrene/credo) |
+| Elm | [elm-make](https://github.com/elm-lang/elm-make) |
 | Fortran | [gcc](https://gcc.gnu.org/) |
 | Go | [gofmt -e](https://golang.org/cmd/gofmt/), [go vet](https://golang.org/cmd/vet/), [golint](https://godoc.org/github.com/golang/lint) |
 | Haskell | [ghc](https://www.haskell.org/ghc/), [hlint](https://hackage.haskell.org/package/hlint) |
diff --git a/ale_linters/elm/make.vim b/ale_linters/elm/make.vim
new file mode 100644
index 00000000..77277b60
--- /dev/null
+++ b/ale_linters/elm/make.vim
@@ -0,0 +1,51 @@
+" Author: buffalocoder - https://github.com/buffalocoder
+" Description: Elm linting in Ale. Closely follows the Syntastic checker in https://github.com/ElmCast/elm-vim.
+
+function! ale_linters#elm#make#Handle(buffer, lines)
+    let l:output = []
+    for l:line in a:lines
+        if l:line[0] ==# '['
+            let l:errors = json_decode(l:line)
+
+            for l:error in l:errors
+                call add(l:output, {
+                \    'bufnr': a:buffer,
+                \    'lnum': l:error.region.start.line,
+                \    'vcol': 0,
+                \    'col': l:error.region.start.column,
+                \    'type': (l:error.type ==? 'error') ? 'E' : 'W',
+                \    'text': l:error.overview,
+                \    'nr': -1,
+                \})
+            endfor
+        endif
+    endfor
+
+    return l:output
+endfunction
+
+" Return the command to execute the linter in the projects directory.
+" If it doesn't, then this will fail when imports are needed.
+function! ale_linters#elm#make#GetCommand(buffer) abort
+    let l:elm_package = ale#util#FindNearestFile(a:buffer, 'elm-package.json')
+    if empty(l:elm_package)
+        let l:dir_set_cmd = ''
+    else
+        let l:root_dir = fnamemodify(l:elm_package, ':p:h')
+        let l:dir_set_cmd = 'cd ' . fnameescape(l:root_dir) . '; '
+    endif
+
+    let l:elm_cmd = 'elm-make --report=json --output='.shellescape(g:ale#util#nul_file)
+    let l:stdin_wrapper = g:ale#util#stdin_wrapper . ' .elm'
+
+    return l:dir_set_cmd . ' ' . l:stdin_wrapper . ' ' . l:elm_cmd
+endfunction
+
+call ale#linter#Define('elm', {
+\    'name': 'make',
+\    'executable': 'elm-make',
+\    'output_stream': 'both',
+\    'command_callback': 'ale_linters#elm#make#GetCommand',
+\    'callback': 'ale_linters#elm#make#Handle'
+\})
+
diff --git a/doc/ale.txt b/doc/ale.txt
index 573164d3..facc39f0 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -71,6 +71,7 @@ The following languages and tools are supported.
 * Cython (pyrex filetype): 'cython'
 * D: 'dmd'
 * Elixir: 'credo'
+* Elm: 'elm-make'
 * Fortran: 'gcc'
 * Go: 'gofmt -e', 'go vet', 'golint'
 * Haskell: 'ghc', 'hlint'