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Add mix-format function to format Elixir 1.6 files.
Co-Authored-By: Christian Kruse <[email protected]> Co-Authored-By: Peter Urbak <[email protected]>
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‎mix-format.el

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;;; mix-format.el --- Emacs plugin to mix format Elixir files
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;; Copyright (C) 2018 Anil Wadghule
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;; Author: Anil Wadghule <[email protected]>
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;; URL: https://github.com/anildigital/mix-format
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;; This file is NOT part of GNU Emacs.
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;; This program is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; This program is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;;; Commentary:
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;; The mix-format function formats the elixir files with Elixir's `mix format`
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;; command
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;;
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;; Customize the elixir and mix paths
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;;
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;; In Emacs, run following command to customize option
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;;
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;; M-x customize-option
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;;
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;; Customize-variable: mixfmt-elixir
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;; and set your elixir executable path there. After that run:
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;;
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;; M-x customize-option
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;;
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;; Customize-variable: mixfmt-mix
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;; and set your mix executable path there.
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;;
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;; Your machine's elixir and mix executable paths can be found with which command as shown below
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;;
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;; $ which mix
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;; /usr/local/bin/mix
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;;
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;; Usage
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;;
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;; Require from Emacs
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;; (require 'mix-format)
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;;
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;; Use it
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;; M-x mix-format
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;;
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;; elixir-mode hook
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;; (add-hook 'elixir-mode-hook
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;; (lambda () (add-hook 'before-save-hook 'mix-format-before-save)))
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;; To use a .formatter.exs you can either set mixfmt-args globally to a path like this:
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;; (setq mixfmt-args (list "--dot-formatter" "/path/to/.formatter.exs"))
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;; or you set mixfmt-args in a hook like this:
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;; (add-hook 'mix-format-hook '(lambda ()
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;; (if (projectile-project-p)
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;; (setq mixfmt-args (list "--dot-formatter" (concat (projectile-project-root) "/.formatter.exs")))
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;; (setq mixfmt-args nil))))
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;;
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;; In this example we use Projectile to get the project root and set mixfmt-args accordingly.
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(defcustom mixfmt-elixir "elixir"
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"Path to the Elixir interpreter."
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:type 'string
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:group 'mix-format)
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(defcustom mixfmt-mix "/usr/bin/mix"
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"Path to the 'mix' executable."
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:type 'string
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:group 'mix-format)
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(defcustom mixfmt-args nil
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"Additional arguments to 'mix format'"
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:type '(repeat string)
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:group 'mix-format)
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(defcustom mix-format-hook nil
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"Hook called by `mix-format'."
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:type 'hook
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:group 'mix-format)
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;;; Code
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;;;###autoload
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(defun mix-format-before-save ()
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"Add this to .emacs to run mix format on the current buffer when saving:
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\(add-hook 'before-save-hook 'mix-format-before-save).
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Note that this will cause ‘elixir-mode’ to get loaded the first time
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you save any file, kind of defeating the point of autoloading."
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(interactive)
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(when (eq major-mode 'elixir-mode) (mix-format)))
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(defun mixfmt--goto-line (line)
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(goto-char (point-min))
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(forward-line (1- line)))
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(defun mixfmt--delete-whole-line (&optional arg)
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"Delete the current line without putting it in the `kill-ring'.
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Derived from function `kill-whole-line'. ARG is defined as for that
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function.
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Shamelessly stolen from go-mode (https://github.com/dominikh/go-mode.el)"
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(setq arg (or arg 1))
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(if (and (> arg 0)
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(eobp)
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(save-excursion (forward-visible-line 0) (eobp)))
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(signal 'end-of-buffer nil))
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(if (and (< arg 0)
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(bobp)
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(save-excursion (end-of-visible-line) (bobp)))
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(signal 'beginning-of-buffer nil))
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(cond ((zerop arg)
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(delete-region (progn (forward-visible-line 0) (point))
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(progn (end-of-visible-line) (point))))
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((< arg 0)
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(delete-region (progn (end-of-visible-line) (point))
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(progn (forward-visible-line (1+ arg))
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(unless (bobp)
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(backward-char))
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(point))))
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(t
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(delete-region (progn (forward-visible-line 0) (point))
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(progn (forward-visible-line arg) (point))))))
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(defun mixfmt--apply-rcs-patch (patch-buffer)
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"Apply an RCS-formatted diff from PATCH-BUFFER to the current buffer.
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Shamelessly stolen from go-mode (https://github.com/dominikh/go-mode.el)"
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(let ((target-buffer (current-buffer))
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;; Relative offset between buffer line numbers and line numbers
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;; in patch.
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;;
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;; Line numbers in the patch are based on the source file, so
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;; we have to keep an offset when making changes to the
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;; buffer.
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;;
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;; Appending lines decrements the offset (possibly making it
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;; negative), deleting lines increments it. This order
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;; simplifies the forward-line invocations.
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(line-offset 0))
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(save-excursion
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(with-current-buffer patch-buffer
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(goto-char (point-min))
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(while (not (eobp))
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(unless (looking-at "^\\([ad]\\)\\([0-9]+\\) \\([0-9]+\\)")
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(error "Invalid rcs patch or internal error in mixfmt--apply-rcs-patch"))
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(forward-line)
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(let ((action (match-string 1))
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(from (string-to-number (match-string 2)))
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(len (string-to-number (match-string 3))))
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(cond
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((equal action "a")
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(let ((start (point)))
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(forward-line len)
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(let ((text (buffer-substring start (point))))
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(with-current-buffer target-buffer
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(cl-decf line-offset len)
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(goto-char (point-min))
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(forward-line (- from len line-offset))
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(insert text)))))
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((equal action "d")
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(with-current-buffer target-buffer
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(mixfmt--goto-line (- from line-offset))
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(cl-incf line-offset len)
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(mixfmt--delete-whole-line len)))
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(t
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(error "Invalid rcs patch or internal error in mixfmt--apply-rcs-patch"))))))))
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)
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;;;###autoload
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(defun mix-format (&optional is-interactive)
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(interactive "p")
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(let ((outbuff (get-buffer-create "*mix-format-output*"))
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(errbuff (get-buffer-create "*mix-format-errors*"))
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(tmpfile (make-temp-file "mix-format" nil ".ex"))
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(our-mixfmt-args (list mixfmt-mix "format"))
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(output nil))
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(unwind-protect
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(save-restriction
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(with-current-buffer outbuff
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(erase-buffer))
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(with-current-buffer errbuff
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(setq buffer-read-only nil)
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(erase-buffer))
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(write-region nil nil tmpfile)
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(run-hooks 'mix-format-hook)
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(when mixfmt-args
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(setq our-mixfmt-args (append our-mixfmt-args mixfmt-args)))
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(setq our-mixfmt-args (append our-mixfmt-args (list tmpfile)))
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(if (zerop (apply #'call-process mixfmt-elixir nil errbuff nil our-mixfmt-args))
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(progn
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(if (zerop (call-process-region (point-min) (point-max) "diff" nil outbuff nil "-n" "-" tmpfile))
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(message "File is already formatted")
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(progn
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(mixfmt--apply-rcs-patch outbuff)
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(message "mix format applied")))
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(kill-buffer errbuff))
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(progn
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(with-current-buffer errbuff
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(setq buffer-read-only t)
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(ansi-color-apply-on-region (point-min) (point-max))
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(special-mode))
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(if is-interactive
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(display-buffer errbuff)
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(message "mix-format failed: see %s" (buffer-name errbuff)))))
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(delete-file tmpfile)
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(kill-buffer outbuff)))))
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(provide 'mix-format)
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;;; mix-format.el ends here

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