Add initial ameba (crystal linter) support (#2174)

* Add initial ameba (crystal linter) support

Note that this depends on saved file as `ameba` does not have STDIN
support

* Fix formatting of crystal linter documentation
* Add tests for ameba executable customization

1 files changed, 56 insertions, 0 deletions

diff --git a/ale_linters/crystal/ameba.vim b/ale_linters/crystal/ameba.vim
new file mode 100644
index 00000000..d50d9fd3
--- /dev/null
+++ b/ale_linters/crystal/ameba.vim
@@ -0,0 +1,56 @@
+" Author: Harrison Bachrach - https://github.com/HarrisonB
+" Description: Ameba, a linter for crystal files
+
+call ale#Set('crystal_ameba_executable', 'bin/ameba')
+
+function! ale_linters#crystal#ameba#GetCommand(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'crystal_ameba_executable')
+
+    return ale#Escape(l:executable)
+    \   . ' --format json '
+    \   .  ale#Escape(expand('#' . a:buffer . ':p'))
+endfunction
+
+call ale#linter#Define('crystal', {
+\   'name': 'ameba',
+\   'executable_callback': ale#VarFunc('crystal_ameba_executable'),
+\   'command_callback': 'ale_linters#crystal#ameba#GetCommand',
+\   'callback': 'ale_linters#crystal#ameba#HandleAmebaOutput',
+\})
+
+" Handle output from ameba
+function! ale_linters#crystal#ameba#HandleAmebaOutput(buffer, lines) abort
+    if len(a:lines) == 0
+      return []
+    endif
+
+    let l:errors = ale#util#FuzzyJSONDecode(a:lines[0], {})
+
+    if !has_key(l:errors, 'summary')
+    \|| l:errors['summary']['issues_count'] == 0
+    \|| empty(l:errors['sources'])
+        return []
+    endif
+
+    let l:output = []
+
+    for l:error in l:errors['sources'][0]['issues']
+        let l:start_col = str2nr(l:error['location']['column'])
+        let l:end_col = str2nr(l:error['end_location']['column'])
+
+        if !l:end_col
+          let l:end_col = l:start_col + 1
+        endif
+
+        call add(l:output, {
+        \   'lnum': str2nr(l:error['location']['line']),
+        \   'col': l:start_col,
+        \   'end_col': l:end_col,
+        \   'code': l:error['rule_name'],
+        \   'text': l:error['message'],
+        \   'type': 'W',
+        \})
+    endfor
+
+    return l:output
+endfunction