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spacemacs/layers/+lang/python/local/py-yapf/py-yapf.el

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;;; py-yapf.el --- Use yapf to beautify a Python buffer
;; Copyright (C) 2015, Friedrich Paetzke <paetzke@fastmail.fm>
;; Author: Friedrich Paetzke <paetzke@fastmail.fm>
;; URL: https://github.com/paetzke/py-yapf.el
;; Version: 0.1
;; Licensed under GPLv3
;; This file is NOT part of GNU Emacs.
;;; Commentary:
;; Provides commands, which use the external "yapf"
;; tool to tidy up the current buffer according to Python's PEP8.
;; To automatically apply when saving a python file, use the
;; following code:
;; (add-hook 'python-mode-hook 'py-yapf-enable-on-save)
;;; Code:
(defgroup py-yapf nil
"Use yapf to beautify a Python buffer."
:group 'convenience
:prefix "py-yapf-")
(defcustom py-yapf-options nil
"Options used for yapf.
Note that `--in-place' is used by default."
:group 'py-yapf
:type '(repeat (string :tag "option")))
(defun py-yapf-apply-rcs-patch (patch-buffer)
"Apply an RCS-formatted diff from PATCH-BUFFER to the current buffer."
(let ((target-buffer (current-buffer))
;; Relative offset between buffer line numbers and line numbers
;; in patch.
;;
;; Line numbers in the patch are based on the source file, so
;; we have to keep an offset when making changes to the
;; buffer.
;;
;; Appending lines decrements the offset (possibly making it
;; negative), deleting lines increments it. This order
;; simplifies the forward-line invocations.
(line-offset 0))
(save-excursion
(with-current-buffer patch-buffer
(goto-char (point-min))
(while (not (eobp))
(unless (looking-at "^\\([ad]\\)\\([0-9]+\\) \\([0-9]+\\)")
(error "Invalid rcs patch or internal error in py-yapf-apply-rcs-patch"))
(forward-line)
(let ((action (match-string 1))
(from (string-to-number (match-string 2)))
(len (string-to-number (match-string 3))))
(cond
((equal action "a")
(let ((start (point)))
(forward-line len)
(let ((text (buffer-substring start (point))))
(with-current-buffer target-buffer
(setq line-offset (- line-offset len))
(goto-char (point-min))
(forward-line (- from len line-offset))
(insert text)))))
((equal action "d")
(with-current-buffer target-buffer
(goto-char (point-min))
(forward-line (- from line-offset 1))
(setq line-offset (+ line-offset len))
(kill-whole-line len)))
(t
(error "Invalid rcs patch or internal error in py-yapf-apply-rcs-patch")))))))))
(defun py-yapf ()
"Formats the current buffer according to the yapf tool."
(when (not (executable-find "yapf"))
(error "\"yapf\" command not found. Install yapf with \"pip install yapf\""))
(let ((tmpfile (make-temp-file "yapf" nil ".py"))
(patchbuf (get-buffer-create "*yapf patch*"))
(errbuf (get-buffer-create "*yapf Errors*"))
(coding-system-for-read 'utf-8)
(coding-system-for-write 'utf-8))
(with-current-buffer errbuf
(setq buffer-read-only nil)
(erase-buffer))
(with-current-buffer patchbuf
(erase-buffer))
(write-region nil nil tmpfile)
(if (zerop (apply 'call-process "yapf" nil errbuf nil
(append py-yapf-options `("--in-place" ,tmpfile))))
(if (zerop (call-process-region (point-min) (point-max) "diff" nil patchbuf nil "-n" "-" tmpfile))
(progn
(kill-buffer errbuf)
(message "Buffer is already yapfed"))
(py-yapf-apply-rcs-patch patchbuf)
(kill-buffer errbuf)
(message "Applied yapf"))
(error "Could not apply yapf. Check *yapf Errors* for details"))
(kill-buffer patchbuf)
(delete-file tmpfile)))
;;;###autoload
(defun py-yapf-buffer ()
"Uses the \"yapf\" tool to reformat the current buffer."
(interactive)
(py-yapf))
;;;###autoload
(defun py-yapf-enable-on-save ()
"Pre-save hooked to be used before running py-yapf."
(interactive)
(add-hook 'before-save-hook 'py-yapf-buffer nil t))
(provide 'py-yapf)
;;; py-yapf.el ends here