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purescript-simple-indent.el
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purescript-simple-indent.el
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;;; purescript-simple-indent.el --- Simple indentation module for PureScript Mode -*- lexical-binding: t -*-
;; Copyright (C) 1998 Heribert Schuetz, Graeme E Moss
;; Author: Heribert Schuetz <[email protected]>
;; Graeme E Moss <[email protected]>
;; Keywords: indentation files PureScript
;; This file is not part of GNU Emacs.
;; This file is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 3, or (at your option)
;; any later version.
;; This file is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with this program. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; Purpose:
;;
;; To support simple indentation of PureScript scripts.
;;
;;
;; Installation:
;;
;; To bind TAB to the indentation command for all PureScript buffers, add
;; this to .emacs:
;;
;; (add-hook 'purescript-mode-hook 'turn-on-purescript-simple-indent)
;;
;; Otherwise, call `turn-on-purescript-simple-indent'.
;;
;;
;; Customisation:
;;
;; None supported.
;;
;;
;; History:
;;
;; If you have any problems or suggestions, after consulting the list
;; below, email [email protected] quoting the version of you are
;; using, the version of Emacs you are using, and a small example of
;; the problem or suggestion.
;;
;; Version 1.0:
;; Brought over from PureScript mode v1.1.
;;
;; Present Limitations/Future Work (contributions are most welcome!):
;;
;; (None so far.)
;;; Code:
;; All functions/variables start with
;; `(turn-(on/off)-)purescript-simple-indent'.
(require 'purescript-mode)
(defgroup purescript-simple-indent nil
"Simple PureScript indentation."
:link '(custom-manual "(purescript-mode)Indentation")
:group 'purescript
:prefix "purescript-simple-indent-")
;; Version.
(defconst purescript-simple-indent-version "1.2"
"`purescript-simple-indent' version number.")
(defun purescript-simple-indent-version ()
"Echo the current version of `purescript-simple-indent' in the minibuffer."
(interactive)
(message "Using purescript-simple-indent version %s"
purescript-simple-indent-version))
;; Partly stolen from `indent-relative' in indent.el:
(defun purescript-simple-indent ()
"Space out to under next visible indent point.
Indent points are positions of non-whitespace following whitespace in
lines preceeding point. A position is visible if it is to the left of
the first non-whitespace of every nonblank line between the position and
the current line. If there is no visible indent point beyond the current
column, `tab-to-tab-stop' is done instead."
(interactive)
(let* ((start-column (current-column))
(invisible-from nil) ; `nil' means infinity here
(indent
(catch 'purescript-simple-indent-break
(save-excursion
(while (progn (beginning-of-line)
(not (bobp)))
(forward-line -1)
(if (not (looking-at "[ \t]*\n"))
(let ((this-indentation (current-indentation)))
(if (or (not invisible-from)
(< this-indentation invisible-from))
(if (> this-indentation start-column)
(setq invisible-from this-indentation)
(let ((end (line-beginning-position 2)))
(move-to-column start-column)
;; Is start-column inside a tab on this line?
(if (> (current-column) start-column)
(backward-char 1))
(or (looking-at "[ \t]")
(skip-chars-forward "^ \t" end))
(skip-chars-forward " \t" end)
(let ((col (current-column)))
(throw 'purescript-simple-indent-break
(if (or (= (point) end)
(and invisible-from
(> col invisible-from)))
invisible-from
col)))))))))))))
(if indent
(let ((opoint (point-marker)))
(indent-line-to indent)
(if (> opoint (point))
(goto-char opoint))
(set-marker opoint nil))
(tab-to-tab-stop))))
(defun purescript-simple-indent-backtab ()
"Indent backwards. Dual to `purescript-simple-indent'."
(interactive)
(let ((current-point (point))
(i 0)
(x 0))
(goto-char (line-beginning-position))
(save-excursion
(while (< (point) current-point)
(purescript-simple-indent)
(setq i (+ i 1))))
(while (< x (- i 1))
(purescript-simple-indent)
(setq x (+ x 1)))))
(defun purescript-simple-indent-newline-same-col ()
"Make a newline and go to the same column as the current line."
(interactive)
(let ((start-end
(save-excursion
(let* ((start (line-beginning-position))
(end (progn (goto-char start)
(search-forward-regexp
"[^ ]" (line-end-position) t 1))))
(when end (cons start (1- end)))))))
(if start-end
(progn (newline)
(insert (buffer-substring-no-properties
(car start-end) (cdr start-end))))
(newline))))
(defun purescript-simple-indent-newline-indent ()
"Make a newline on the current column and indent on step."
(interactive)
(purescript-simple-indent-newline-same-col)
(insert (make-string purescript-indent-spaces ? )))
;;;###autoload
(define-minor-mode purescript-simple-indent-mode
"Simple PureScript indentation mode that uses simple heuristic.
In this minor mode, `indent-for-tab-command' (bound to <tab> by
default) will move the cursor to the next indent point in the
previous nonblank line, whereas `purescript-simple-indent-backtab'
\ (bound to <backtab> by default) will move the cursor the
previous indent point. An indent point is a non-whitespace
character following whitespace.
Runs `purescript-simple-indent-hook' on activation."
:lighter " Ind"
:group 'purescript-simple-indent
:keymap '(([backtab] . purescript-simple-indent-backtab))
(kill-local-variable 'indent-line-function)
(when purescript-simple-indent-mode
(set (make-local-variable 'indent-line-function) 'purescript-simple-indent)
(run-hooks 'purescript-simple-indent-hook)))
;; The main functions.
;;;###autoload
(defun turn-on-purescript-simple-indent ()
"Turn on function `purescript-simple-indent-mode'."
(interactive)
(purescript-simple-indent-mode))
(defun turn-off-purescript-simple-indent ()
"Turn off function `purescript-simple-indent-mode'."
(interactive)
(purescript-simple-indent-mode 0))
;; Provide ourselves:
(provide 'purescript-simple-indent)
;;; purescript-simple-indent.el ends here