1 364d8905 2021-11-07 op ;;; a68-mode.el --- Major mode for editing Algol 68 code
3 364d8905 2021-11-07 op ;; Copyright (C) 2011 Jose E. Marchesi
4 364d8905 2021-11-07 op ;; Copyright (C) 2021 Omar Polo <op@omarpolo.com>
6 364d8905 2021-11-07 op ;; Author: Jose E. Marchesi
7 364d8905 2021-11-07 op ;; Omar Polo <op@omarpolo.com>
8 364d8905 2021-11-07 op ;; Maintainer: Omar Polo
9 364d8905 2021-11-07 op ;; URL: https://git.omarpolo.com/a68-mode
10 364d8905 2021-11-07 op ;; Keywords: languages
12 364d8905 2021-11-07 op ;; Package-Requires: ((emacs "24.3"))
14 364d8905 2021-11-07 op ;; This file is NOT part of GNU Emacs.
16 364d8905 2021-11-07 op ;; This program is free software; you can redistribute it and/or modify
17 364d8905 2021-11-07 op ;; it under the terms of the GNU General Public License as published by
18 364d8905 2021-11-07 op ;; the Free Software Foundation; either version 3, or (at your option)
19 364d8905 2021-11-07 op ;; any later version.
21 364d8905 2021-11-07 op ;; This program is distributed in the hope that it will be useful,
22 364d8905 2021-11-07 op ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
23 364d8905 2021-11-07 op ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 364d8905 2021-11-07 op ;; GNU General Public License for more details.
26 364d8905 2021-11-07 op ;; You should have received a copy of the GNU General Public License
27 364d8905 2021-11-07 op ;; along with this program; see the file COPYING. If not, write to the
28 364d8905 2021-11-07 op ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
29 364d8905 2021-11-07 op ;; Boston, MA 02110-1301, USA.
31 364d8905 2021-11-07 op ;;; Commentary:
33 364d8905 2021-11-07 op ;; A major mode for editing Algol 68 code.
35 bb4b3a62 2021-11-07 op ;; This is an improved and modernized version of the a68-mode written
36 bb4b3a62 2021-11-07 op ;; by Jose E. Marchesi. The original code was taken from
38 bb4b3a62 2021-11-07 op ;; https://github.com/lachrymology/me/blob/master/.emacs.d/extras/algol-mode.el
40 364d8905 2021-11-07 op ;; TODO: support quote and dot stropping.
44 364d8905 2021-11-07 op (require 'syntax)
45 364d8905 2021-11-07 op (require 'font-lock)
47 364d8905 2021-11-07 op (eval-when-compile
48 364d8905 2021-11-07 op (require 'rx))
50 caaad6ea 2021-11-07 op (defgroup a68 nil
51 caaad6ea 2021-11-07 op "Major mode for editing Algol68 code."
52 caaad6ea 2021-11-07 op :prefix "a68-"
53 caaad6ea 2021-11-07 op :group 'languages)
55 caaad6ea 2021-11-07 op (defcustom a68-indent-level 3
56 caaad6ea 2021-11-07 op "Indentation step for Algol 68."
57 caaad6ea 2021-11-07 op :type 'integer
58 caaad6ea 2021-11-07 op :safe #'integerp)
60 364d8905 2021-11-07 op (defvar a68-mode-hook '()
61 364d8905 2021-11-07 op "Hook run when entering Algol68 mode.")
63 364d8905 2021-11-07 op (defvar a68-mode-map
64 8cd9fb9c 2021-11-07 op (let ((map (make-sparse-keymap)))
65 364d8905 2021-11-07 op (define-key map (kbd "C-j") #'newline-and-indent)
66 364d8905 2021-11-07 op (define-key map (kbd "RET") #'a68-electric-terminate-line)
67 364d8905 2021-11-07 op (define-key map (kbd "C-i") #'a68-electric-tab)
69 364d8905 2021-11-07 op "Keymap for Algol 68 major mode.")
71 364d8905 2021-11-07 op (defconst a68-font-lock-keywords
73 364d8905 2021-11-07 op (cons (rx word-start
74 364d8905 2021-11-07 op (or "DECS" "PROGRAM" "CONTEXT" "USE" "FINISH" "KEEP"
76 364d8905 2021-11-07 op "MODE" "OP" "PRIO" "PROC"
77 364d8905 2021-11-07 op "OF" "AT" "IS" "ISNT" "EMPTY" "SKIP"
78 364d8905 2021-11-07 op "PR" "PRAGMAT"
79 364d8905 2021-11-07 op "CASE" "IN" "OUSE" "OUT" "ESAC"
80 364d8905 2021-11-07 op "FOR" "FORALL" "FROM" "TO" "BY" "WHILE" "DO" "OD"
81 364d8905 2021-11-07 op "IF" "THEN" "ELIF" "THEN" "ELSE" "FI"
82 364d8905 2021-11-07 op "PAR" "BEGIN" "END" "GOTO" "EXIT"
83 364d8905 2021-11-07 op "LWB" "UPB" "NOT" "ABS" "BIN" "REPR" "LENG"
84 364d8905 2021-11-07 op "SHORTEN" "ODD" "SIGN" "ROUND" "ENTIER" "AND" "OR"
85 364d8905 2021-11-07 op "DIV" "OVER" "MOD" "ELEM" "SHL" "SHR" "OVERAB" "DIVAB" "MODAB"
88 364d8905 2021-11-07 op 'font-lock-keyword-face)
89 364d8905 2021-11-07 op (cons (rx word-start
90 364d8905 2021-11-07 op (or "TRUE" "FALSE")
92 364d8905 2021-11-07 op 'font-lock-constant-face)
93 364d8905 2021-11-07 op ;; only valid for bold stropping
94 364d8905 2021-11-07 op (cons (concat "\\<[A-Z]+\\>") 'font-lock-type-face)
95 364d8905 2021-11-07 op (cons "\\('\\w*'\\)"
96 364d8905 2021-11-07 op 'font-lock-variable-name-face))
97 364d8905 2021-11-07 op "Highlighting expressions for Algol 68 mode.")
99 364d8905 2021-11-07 op (defsubst a68-within-string ()
100 364d8905 2021-11-07 op "Check if inside a string."
101 364d8905 2021-11-07 op (nth 3 (syntax-ppss)))
103 364d8905 2021-11-07 op (defsubst a68-within-comment ()
104 364d8905 2021-11-07 op "Check if inside a comment."
105 364d8905 2021-11-07 op (nth 4 (syntax-ppss)))
107 364d8905 2021-11-07 op ;; Indentation rules:
109 364d8905 2021-11-07 op ;; - If we are at the beginning of the buffer, or looking at some
110 364d8905 2021-11-07 op ;; indent-0 content, indent to column 0.
112 364d8905 2021-11-07 op ;; - If we are currently at an END, ), FI or OD, then de-indent
113 364d8905 2021-11-07 op ;; relative to the previous line.
115 364d8905 2021-11-07 op ;; - If we first see and "end line" before our current line,
116 364d8905 2021-11-07 op ;; then we should indent our current line to the same indentation as
117 364d8905 2021-11-07 op ;; the end line.
119 364d8905 2021-11-07 op ;; - If we first see a "start line" like IF, then we need to increase
120 364d8905 2021-11-07 op ;; our indentation relative to that start line.
122 364d8905 2021-11-07 op ;; - If into a balanced expression, we should indent to the column
123 364d8905 2021-11-07 op ;; where the start of the innermost parenthetical group.
125 364d8905 2021-11-07 op ;; - If none of the above apply, then do not indent at all.
127 364d8905 2021-11-07 op (defun a68-indent-line ()
128 364d8905 2021-11-07 op "Indent current line as Algol 68 code."
129 364d8905 2021-11-07 op (interactive)
130 364d8905 2021-11-07 op (let ((case-fold-search nil))
131 364d8905 2021-11-07 op (save-excursion
132 364d8905 2021-11-07 op (beginning-of-line)
133 364d8905 2021-11-07 op (if (nth 1 (syntax-ppss)) ; Check for rule 5
134 364d8905 2021-11-07 op (let ((offset (save-excursion (goto-char (+ (nth 1 (syntax-ppss)) 1))
135 364d8905 2021-11-07 op (current-column))))
136 364d8905 2021-11-07 op (indent-line-to offset))
137 364d8905 2021-11-07 op (if (or (bobp) ; Check for rule 1
138 364d8905 2021-11-07 op (looking-at "^[ \t]*\\<\\(KEEP\\|FINISH\\|DECS\\|USE\\|PROGRAM\\)\\>"))
139 364d8905 2021-11-07 op (indent-line-to 0)
140 364d8905 2021-11-07 op (let ((not-indented t)
141 364d8905 2021-11-07 op (prev-indent (current-indentation))
142 364d8905 2021-11-07 op (begin-indent-re "^[ \t]*\\<\\(PAR\\|BEGIN\\|KEEP\\|IF\\|DO\\|ELSE\\|ELIF\\|THEN\\)")
143 364d8905 2021-11-07 op (deindent-line-re "^[ \t]*\\<\\(END\\|FI\\|OD\\|ELSE\\|ELIF\\)\\>")
144 364d8905 2021-11-07 op (eqindent-line-re "^[ \t]*\\<\\(THEN\\)\\>")
145 364d8905 2021-11-07 op (end-line-re "^[ \t]*\\(END\\|FI\\|OD\\)")
147 364d8905 2021-11-07 op (if (looking-at eqindent-line-re)
148 364d8905 2021-11-07 op (save-excursion
149 364d8905 2021-11-07 op (forward-line -1)
150 364d8905 2021-11-07 op (setq cur-indent (current-indentation)))
151 364d8905 2021-11-07 op (if (looking-at deindent-line-re) ; Check for rule 2
153 364d8905 2021-11-07 op (save-excursion
154 364d8905 2021-11-07 op (forward-line -1)
155 8621ed2a 2021-11-07 op (setq cur-indent (- (current-indentation) a68-indent-level)))
156 364d8905 2021-11-07 op (when (< cur-indent 0)
157 364d8905 2021-11-07 op (setq cur-indent 0)))
158 364d8905 2021-11-07 op (save-excursion
159 364d8905 2021-11-07 op (while not-indented
160 364d8905 2021-11-07 op (forward-line -1)
161 364d8905 2021-11-07 op (if (looking-at end-line-re) ; Check for rule 3
163 364d8905 2021-11-07 op (setq cur-indent (current-indentation))
164 364d8905 2021-11-07 op (setq not-indented nil))
165 364d8905 2021-11-07 op ;; Check for rule 4
166 364d8905 2021-11-07 op (if (looking-at begin-indent-re)
168 8621ed2a 2021-11-07 op (setq cur-indent (+ (current-indentation) a68-indent-level))
169 364d8905 2021-11-07 op (setq not-indented nil))
170 364d8905 2021-11-07 op (when (bobp) ; Check for rule 5
171 364d8905 2021-11-07 op (setq not-indented nil))))))))
172 364d8905 2021-11-07 op (if cur-indent
173 364d8905 2021-11-07 op (indent-line-to cur-indent)
174 364d8905 2021-11-07 op ;; If we didn't see an indentation hint, then allow no
175 364d8905 2021-11-07 op ;; indentation.
176 364d8905 2021-11-07 op (indent-line-to 0)))))))
177 364d8905 2021-11-07 op (when (< (current-column) (current-indentation))
178 364d8905 2021-11-07 op (move-to-column (current-indentation))))
180 364d8905 2021-11-07 op (defvar a68-mode-syntax-table
181 364d8905 2021-11-07 op (let ((st (make-syntax-table)))
182 364d8905 2021-11-07 op (modify-syntax-entry ?{ "<" st)
183 364d8905 2021-11-07 op (modify-syntax-entry ?# "<" st)
184 364d8905 2021-11-07 op (modify-syntax-entry ?} ">" st)
185 364d8905 2021-11-07 op (modify-syntax-entry ?# ">" st)
186 364d8905 2021-11-07 op (modify-syntax-entry ?\\ "." st)
187 364d8905 2021-11-07 op ;; (modify-syntax-entry ?C "< 13" st)
188 364d8905 2021-11-07 op ;; (modify-syntax-entry ?O "> 24" st)
189 364d8905 2021-11-07 op ;; define parentheses to match
190 364d8905 2021-11-07 op (modify-syntax-entry ?\( "()" st)
191 364d8905 2021-11-07 op (modify-syntax-entry ?\) ")(" st)
195 364d8905 2021-11-07 op ;;; Electric functions
198 364d8905 2021-11-07 op (defconst a68-autoindent-lines-re
199 364d8905 2021-11-07 op (rx word-start
200 364d8905 2021-11-07 op (or "BEGIN" "END" "ELSE" "ELIF" "DO" "OD" "CASE" "ESAC" "IN" "OUT")
203 364d8905 2021-11-07 op (defun a68-electric-terminate-line ()
204 364d8905 2021-11-07 op "Terminate line and indent next line."
205 364d8905 2021-11-07 op (interactive)
206 364d8905 2021-11-07 op ;; First, check if current line should be indented
207 364d8905 2021-11-07 op (save-excursion
208 364d8905 2021-11-07 op (beginning-of-line)
209 364d8905 2021-11-07 op (skip-chars-forward " \t")
210 364d8905 2021-11-07 op (when (looking-at a68-autoindent-lines-re)
211 364d8905 2021-11-07 op (a68-indent-line)))
212 364d8905 2021-11-07 op (delete-horizontal-space) ; Removes triling whitespaces
214 364d8905 2021-11-07 op ;; Indent next line if we are not in a string
215 364d8905 2021-11-07 op (unless (a68-within-string)
216 364d8905 2021-11-07 op (a68-indent-line)))
218 364d8905 2021-11-07 op (defun a68-electric-tab ()
219 364d8905 2021-11-07 op "Function called when TAB is pressed in Algol68 mode."
220 364d8905 2021-11-07 op (interactive)
221 364d8905 2021-11-07 op (unless (save-excursion
222 364d8905 2021-11-07 op (beginning-of-line)
223 364d8905 2021-11-07 op (a68-within-string))
224 364d8905 2021-11-07 op (a68-indent-line)))
226 e9c672cf 2021-11-07 op (defvar a68-mode-abbrev-table nil
227 e9c672cf 2021-11-07 op "Abbreviation table used in `a68-mode' buffers.")
229 e9c672cf 2021-11-07 op (define-abbrev-table 'a68-mode-abbrev-table
232 364d8905 2021-11-07 op ;;;###autoload
233 364d8905 2021-11-07 op (define-derived-mode a68-mode prog-mode "Algol68"
234 364d8905 2021-11-07 op "Major mode for editing Alogl68 files."
235 e9c672cf 2021-11-07 op :abbrev-table a68-mode-abbrev-table
236 364d8905 2021-11-07 op (setq-local font-lock-defaults '(a68-font-lock-keywords))
237 364d8905 2021-11-07 op (setq-local indent-line-function #'a68-indent-line)
238 364d8905 2021-11-07 op (setq-local comment-start "#")
239 364d8905 2021-11-07 op (setq-local comment-end "#"))
241 364d8905 2021-11-07 op ;;;###autoload
242 364d8905 2021-11-07 op (add-to-list 'auto-mode-alist '("\\.a68\\'" . a68-mode))
244 48415058 2021-11-07 op (provide 'a68-mode)
245 48415058 2021-11-07 op ;;; a68-mode.el ends here
