Fix #516 - Add support for pyflakes for Python

ale_linters/python/pyflakes.vim

@@ -0,0 +1,38 @@
+" Author: w0rp <devw0rp@gmail.com>
+" Description: pyflakes for python files
+
+call ale#Set('python_pyflakes_executable', 'pyflakes')
+call ale#Set('python_pyflakes_use_global', 0)
+
+function! ale_linters#python#pyflakes#GetExecutable(buffer) abort
+    return ale#python#FindExecutable(a:buffer, 'python_pyflakes', ['pyflakes'])
+endfunction
+
+function! ale_linters#python#pyflakes#GetCommand(buffer) abort
+    let l:executable = ale_linters#python#pyflakes#GetExecutable(a:buffer)
+
+    return ale#Escape(l:executable) . ' %t'
+endfunction
+
+function! ale_linters#python#pyflakes#Handle(buffer, lines) abort
+    let l:pattern = '\v^[a-zA-Z]?:?[^:]+:(\d+):(\d+)?:? (.+)$'
+    let l:output = []
+
+    for l:match in ale#util#GetMatches(a:lines, l:pattern)
+        call add(l:output, {
+        \   'lnum': l:match[1] + 0,
+        \   'col': l:match[2] + 0,
+        \   'text': l:match[3],
+        \})
+    endfor
+
+    return l:output
+endfunction
+
+call ale#linter#Define('python', {
+\   'name': 'pyflakes',
+\   'executable_callback': 'ale_linters#python#pyflakes#GetExecutable',
+\   'command_callback': 'ale_linters#python#pyflakes#GetCommand',
+\   'callback': 'ale_linters#python#pyflakes#Handle',
+\   'output_stream': 'both',
+\})