Adds standardrb linter (#2133)

See: https://github.com/testdouble/standard

StandardRB is to RuboCop what StandardJS is to ESLint. This commit 
naively copies the RuboCop linter and fixer to point at the standardrb
executable. Any other adjustments are very minor (the only I can think 
of is that standardrb takes a `--fix` option instead of 
`--auto-correct`).

This raises a confusing point to me as both developer and a user: since
ale enables all linters by default, won't this run both RuboCop and 
StandardRB (the results of which will almost always be in conflict with
one another)? How does ale already solve for this for the similar case
of StandardJS and ESLint?

2 files changed, 24 insertions, 31 deletions

diff --git a/ale_linters/ruby/rubocop.vim b/ale_linters/ruby/rubocop.vim
index 45218394..790ca82c 100644
--- a/ale_linters/ruby/rubocop.vim
+++ b/ale_linters/ruby/rubocop.vim
@@ -13,36 +13,6 @@ function! ale_linters#ruby#rubocop#GetCommand(buffer) abort
     \   . ' --stdin ' . ale#Escape(expand('#' . a:buffer . ':p'))
 endfunction
 
-function! ale_linters#ruby#rubocop#Handle(buffer, lines) abort
-    try
-        let l:errors = json_decode(a:lines[0])
-    catch
-        return []
-    endtry
-
-    if !has_key(l:errors, 'summary')
-    \|| l:errors['summary']['offense_count'] == 0
-    \|| empty(l:errors['files'])
-        return []
-    endif
-
-    let l:output = []
-
-    for l:error in l:errors['files'][0]['offenses']
-        let l:start_col = l:error['location']['column'] + 0
-        call add(l:output, {
-        \   'lnum': l:error['location']['line'] + 0,
-        \   'col': l:start_col,
-        \   'end_col': l:start_col + l:error['location']['length'] - 1,
-        \   'code': l:error['cop_name'],
-        \   'text': l:error['message'],
-        \   'type': ale_linters#ruby#rubocop#GetType(l:error['severity']),
-        \})
-    endfor
-
-    return l:output
-endfunction
-
 function! ale_linters#ruby#rubocop#GetType(severity) abort
     if a:severity is? 'convention'
     \|| a:severity is? 'warning'
@@ -57,5 +27,5 @@ call ale#linter#Define('ruby', {
 \   'name': 'rubocop',
 \   'executable_callback': ale#VarFunc('ruby_rubocop_executable'),
 \   'command_callback': 'ale_linters#ruby#rubocop#GetCommand',
-\   'callback': 'ale_linters#ruby#rubocop#Handle',
+\   'callback': 'ale#ruby#HandleRubocopOutput',
 \})
diff --git a/ale_linters/ruby/standardrb.vim b/ale_linters/ruby/standardrb.vim
new file mode 100644
index 00000000..95e10934
--- /dev/null
+++ b/ale_linters/ruby/standardrb.vim
@@ -0,0 +1,23 @@
+" Author: Justin Searls https://github.com/searls, ynonp - https://github.com/ynonp, Eddie Lebow https://github.com/elebow
+" based on the ale rubocop linter
+" Description: StandardRB - Ruby Style Guide, with linter & automatic code fixer
+
+call ale#Set('ruby_standardrb_executable', 'standardrb')
+call ale#Set('ruby_standardrb_options', '')
+
+function! ale_linters#ruby#standardrb#GetCommand(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'ruby_standardrb_executable')
+
+    return ale#handlers#ruby#EscapeExecutable(l:executable, 'standardrb')
+    \   . ' --format json --force-exclusion '
+    \   . ale#Var(a:buffer, 'ruby_standardrb_options')
+    \   . ' --stdin ' . ale#Escape(expand('#' . a:buffer . ':p'))
+endfunction
+
+" standardrb is based on RuboCop so the callback is the same
+call ale#linter#Define('ruby', {
+\   'name': 'standardrb',
+\   'executable_callback': ale#VarFunc('ruby_standardrb_executable'),
+\   'command_callback': 'ale_linters#ruby#standardrb#GetCommand',
+\   'callback': 'ale#ruby#HandleRubocopOutput',
+\})