Add support for LilyPond syntax (#5117)

Add support for LilyPond syntax

See: https://lilypond.org/

Fix alpha order of LilyPond
Add support for custom executable and options to lilypond linter

Enhances the lilypond linter with configurable options:
- Add g:alelilypondlilypondexecutable for custom lilypond binary path
- Add g:alelilypondlilypondoptions for additional command-line flags
- Refactor linter to use GetCommand() function for dynamic command building
- Add linter tests covering configuration scenarios
- Update documentation with usage examples and proper formatting

Co-authored-by: samb0t <sambottoni@gmail.com>

7 files changed, 159 insertions, 0 deletions

diff --git a/ale_linters/lilypond/lilypond.vim b/ale_linters/lilypond/lilypond.vim
new file mode 100644
index 000000000..8469b5d61
--- /dev/null
+++ b/ale_linters/lilypond/lilypond.vim
@@ -0,0 +1,40 @@
+" Author: Sam Bottoni
+" Description: lilypond linter for LilyPond files
+
+call ale#Set('lilypond_lilypond_executable', 'lilypond')
+
+let g:ale_lilypond_lilypond_options = get(g:, 'ale_lilypond_lilypond_options', '')
+
+function! ale_linters#lilypond#lilypond#GetCommand(buffer) abort
+    return '%e --loglevel=WARNING -dbackend=null -dno-print-pages -o /tmp'
+    \   . ale#Pad(ale#Var(a:buffer, 'lilypond_lilypond_options'))
+    \   . ' %t 2>&1'
+endfunction
+
+function! ale_linters#lilypond#lilypond#Handle(buffer, lines) abort
+    let l:output = []
+
+    for l:line in a:lines
+        " Match: file:line:col: error|warning|programming error: message
+        let l:match = matchlist(l:line,
+        \   '\v^.*:(\d+):(\d+): (error|warning|programming error): (.*)$')
+
+        if !empty(l:match)
+            call add(l:output, {
+            \   'lnum': str2nr(l:match[1]),
+            \   'col': str2nr(l:match[2]),
+            \   'type': l:match[3] =~? 'error' ? 'E' : 'W',
+            \   'text': l:match[4]
+            \})
+        endif
+    endfor
+
+    return l:output
+endfunction
+
+call ale#linter#Define('lilypond', {
+\   'name': 'lilypond',
+\   'executable': {b -> ale#Var(b, 'lilypond_lilypond_executable')},
+\   'command': function('ale_linters#lilypond#lilypond#GetCommand'),
+\   'callback': 'ale_linters#lilypond#lilypond#Handle',
+\})
diff --git a/doc/ale-lilypond.txt b/doc/ale-lilypond.txt
new file mode 100644
index 000000000..0b4d51a56
--- /dev/null
+++ b/doc/ale-lilypond.txt
@@ -0,0 +1,29 @@
+===============================================================================
+ALE LilyPond Integration                                 *ale-lilypond-options*
+
+
+===============================================================================
+lilypond                                                         *ale-lilypond*
+
+g:ale_lilypond_lilypond_executable           *g:ale_lilypond_lilypond_executable*
+                                             *b:ale_lilypond_lilypond_executable*
+  Type: |String|
+  Default: `'lilypond'`
+
+  This variable can be changed to modify the executable used for lilypond.
+
+
+g:ale_lilypond_lilypond_options                 *g:ale_lilypond_lilypond_options*
+                                                *b:ale_lilypond_lilypond_options*
+  Type: |String|
+  Default: `''`
+
+  This variable can be changed to modify flags given to lilypond.
+
+  For example, to add custom include paths: >
+
+    let g:ale_lilypond_lilypond_options = '--include=/path/to/includes'
+<
+
+===============================================================================
+  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl:
diff --git a/doc/ale-supported-languages-and-tools.txt b/doc/ale-supported-languages-and-tools.txt
index fdd8f24dc..44812b93f 100644
--- a/doc/ale-supported-languages-and-tools.txt
+++ b/doc/ale-supported-languages-and-tools.txt
@@ -383,6 +383,8 @@ Notes:
   * `lessc`
   * `prettier`
   * `stylelint`
+* LilyPond
+  * `lilypond`
 * LLVM
   * `llc`
 * Lua
diff --git a/doc/ale.txt b/doc/ale.txt
index e0192177a..f7a52df63 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -3722,6 +3722,8 @@ documented in additional help files.
     lessc.................................|ale-less-lessc|
     prettier..............................|ale-less-prettier|
     stylelint.............................|ale-less-stylelint|
+  lilypond................................|ale-lilypond-options|
+    lilypond..............................|ale-lilypond|
   llvm....................................|ale-llvm-options|
     llc...................................|ale-llvm-llc|
   lua.....................................|ale-lua-options|
diff --git a/supported-tools.md b/supported-tools.md
index 8988fa72b..94670d15f 100644
--- a/supported-tools.md
+++ b/supported-tools.md
@@ -393,6 +393,8 @@ formatting.
   * [lessc](https://www.npmjs.com/package/less)
   * [prettier](https://github.com/prettier/prettier)
   * [stylelint](https://github.com/stylelint/stylelint)
+* LilyPond
+  * [lilypond](https://lilypond.org/)
 * LLVM
   * [llc](https://llvm.org/docs/CommandGuide/llc.html)
 * Lua
diff --git a/test/handler/test_lilypond.vader b/test/handler/test_lilypond.vader
new file mode 100644
index 000000000..b3f92d902
--- /dev/null
+++ b/test/handler/test_lilypond.vader
@@ -0,0 +1,49 @@
+Before:
+  runtime ale_linters/lilypond/lilypond.vim
+  call ale#linter#Reset()
+
+Execute(The lilypond handler should parse a single error correctly):
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 2,
+  \     'col': 5,
+  \     'type': 'E',
+  \     'text': 'syntax error, unexpected NOT_A_TOKEN',
+  \   }
+  \ ],
+  \ ale_linters#lilypond#lilypond#Handle(0, [
+  \   'test.ly:2:5: error: syntax error, unexpected NOT_A_TOKEN'
+  \ ])
+
+Execute(The lilypond handler should parse warnings and errors):
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 3,
+  \     'col': 1,
+  \     'type': 'W',
+  \     'text': 'deprecated syntax',
+  \   },
+  \   {
+  \     'lnum': 5,
+  \     'col': 12,
+  \     'type': 'E',
+  \     'text': 'unknown symbol',
+  \   }
+  \ ],
+  \ ale_linters#lilypond#lilypond#Handle(0, [
+  \   'test.ly:3:1: warning: deprecated syntax',
+  \   'test.ly:5:12: error: unknown symbol'
+  \ ])
+
+Execute(The lilypond handler should ignore non-matching lines):
+  AssertEqual
+  \ [],
+  \ ale_linters#lilypond#lilypond#Handle(0, [
+  \   'This is some unrelated output',
+  \   'Another line without structure'
+  \ ])
+
+After:
+  call ale#linter#Reset()
diff --git a/test/linter/test_lilypond.vader b/test/linter/test_lilypond.vader
new file mode 100644
index 000000000..90983ba21
--- /dev/null
+++ b/test/linter/test_lilypond.vader
@@ -0,0 +1,35 @@
+Before:
+  call ale#assert#SetUpLinterTest('lilypond', 'lilypond')
+  call ale#test#SetFilename('test.ly')
+
+  let g:ale_lilypond_lilypond_executable = 'lilypond'
+  let g:ale_lilypond_lilypond_options = ''
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(The executable should default to lilypond):
+  AssertLinter 'lilypond',
+  \ ale#Escape('lilypond') . ' --loglevel=WARNING -dbackend=null -dno-print-pages -o /tmp %t 2>&1'
+
+Execute(Should be able to set a custom executable):
+  let g:ale_lilypond_lilypond_executable = 'bin/lilypond'
+
+  AssertLinter 'bin/lilypond',
+  \ ale#Escape('bin/lilypond') . ' --loglevel=WARNING -dbackend=null -dno-print-pages -o /tmp %t 2>&1'
+
+Execute(Should be able to set custom options):
+  let g:ale_lilypond_lilypond_options = '--include=/path/to/includes'
+
+  AssertLinter 'lilypond',
+  \ ale#Escape('lilypond') . ' --loglevel=WARNING -dbackend=null -dno-print-pages -o /tmp'
+  \ . ' --include=/path/to/includes %t 2>&1'
+
+Execute(Should be able to set both custom executable and options):
+  let g:ale_lilypond_lilypond_executable = '/usr/local/bin/lilypond'
+  let g:ale_lilypond_lilypond_options = '--include=/custom/path -dlog-file=/tmp/lily.log'
+
+  AssertLinter '/usr/local/bin/lilypond',
+  \ ale#Escape('/usr/local/bin/lilypond') . ' --loglevel=WARNING -dbackend=null -dno-print-pages -o /tmp'
+  \ . ' --include=/custom/path -dlog-file=/tmp/lily.log %t 2>&1'
+