Add pymarkdown for Markdown linting (#4906)

Add support for pymarkdown

Closes #4785

ale_linters/markdown/pymarkdown.vim

@@ -0,0 +1,73 @@
+
+call ale#Set('markdown_pymarkdown_executable', 'pymarkdown')
+call ale#Set('markdown_pymarkdown_options', '')
+call ale#Set('markdown_pymarkdown_use_global', get(g:, 'ale_use_global_executables', 0))
+call ale#Set('markdown_pymarkdown_auto_pipenv', 0)
+call ale#Set('markdown_pymarkdown_auto_poetry', 0)
+call ale#Set('markdown_pymarkdown_auto_uv', 0)
+
+function! ale_linters#markdown#pymarkdown#GetExecutable(buffer) abort
+    if (ale#Var(a:buffer, 'python_auto_pipenv') || ale#Var(a:buffer, 'markdown_pymarkdown_auto_pipenv'))
+    \ && ale#python#PipenvPresent(a:buffer)
+        return 'pipenv'
+    endif
+
+    if (ale#Var(a:buffer, 'python_auto_poetry') || ale#Var(a:buffer, 'markdown_pymarkdown_auto_poetry'))
+    \ && ale#python#PoetryPresent(a:buffer)
+        return 'poetry'
+    endif
+
+    if (ale#Var(a:buffer, 'python_auto_uv') || ale#Var(a:buffer, 'markdown_pymarkdown_auto_uv'))
+    \ && ale#python#UvPresent(a:buffer)
+        return 'uv'
+    endif
+
+    return ale#python#FindExecutable(a:buffer, 'markdown_pymarkdown', ['pymarkdown'])
+endfunction
+
+function! ale_linters#markdown#pymarkdown#GetCommand(buffer) abort
+    let l:executable = ale_linters#markdown#pymarkdown#GetExecutable(a:buffer)
+
+    let l:exec_args = l:executable =~? 'pipenv\|poetry\|uv$'
+    \   ? ' run pymarkdown'
+    \   : ''
+
+    return ale#Escape(l:executable) . l:exec_args
+    \   . ' '
+    \   . ale#Var(a:buffer, 'markdown_pymarkdown_options')
+    \   . 'scan-stdin'
+endfunction
+
+function! ale_linters#markdown#pymarkdown#Handle(buffer, lines) abort
+    let l:pattern = '\v^(\S*):(\d+):(\d+): ([A-Z]+\d+): (.*)$'
+    let l:output = []
+    " lines are formatted as follows:
+    " sample.md:1:1: MD022: Headings should be surrounded by blank lines. [Expected: 1; Actual: 0; Below] (blanks-around-headings,blanks-around-headers)
+
+    for l:match in ale#util#GetMatches(a:lines, l:pattern)
+        if(l:match[4] is# 'MD009')
+        \&& !ale#Var(a:buffer, 'warn_about_trailing_whitespace')
+            " Skip warnings for trailing whitespace if the option is off.
+            continue
+        endif
+
+        let l:item = {
+        \   'lnum': l:match[2] + 0,
+        \   'col': l:match[3] + 0,
+        \   'type': l:match[4][0],
+        \   'text': l:match[5],
+        \   'code': l:match[4],
+        \}
+
+        call add(l:output, l:item)
+    endfor
+
+    return l:output
+endfunction
+
+call ale#linter#Define('markdown', {
+\   'name': 'pymarkdown',
+\   'executable': function('ale_linters#markdown#pymarkdown#GetExecutable'),
+\   'command': function('ale_linters#markdown#pymarkdown#GetCommand'),
+\   'callback': 'ale_linters#markdown#pymarkdown#Handle',
+\})