lisp/emacs-lisp/sregex.el

   1 ;;; sregex.el --- symbolic regular expressions
   2
   3 ;; Copyright (C) 1997, 1998, 2000 Free Software Foundation, Inc.
   4
   5 ;; Author: Bob Glickstein <bobg+sregex@zanshin.com>
   6 ;; Maintainer: Bob Glickstein <bobg+sregex@zanshin.com>
   7 ;; Keywords: extensions
   8
   9 ;; This file is part of GNU Emacs.
  10
  11 ;; GNU Emacs is free software; you can redistribute it and/or modify
  12 ;; it under the terms of the GNU General Public License as published by
  13 ;; the Free Software Foundation; either version 2, or (at your option)
  14 ;; any later version.
  15
  16 ;; GNU Emacs is distributed in the hope that it will be useful,
  17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19 ;; GNU General Public License for more details.
  20
  21 ;; You should have received a copy of the GNU General Public License
  22 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  24 ;; Boston, MA 02111-1307, USA.
  25
  26 ;;; Commentary:
  27
  28 ;; This package allows you to write regular expressions using a
  29 ;; totally new, Lisp-like syntax.
  30
  31 ;; A "symbolic regular expression" (sregex for short) is a Lisp form
  32 ;; that, when evaluated, produces the string form of the specified
  33 ;; regular expression.  Here's a simple example:
  34
  35 ;;   (sregexq (or "Bob" "Robert"))  =>  "Bob\\|Robert"
  36
  37 ;; As you can see, an sregex is specified by placing one or more
  38 ;; special clauses in a call to `sregexq'.  The clause in this case is
  39 ;; the `or' of two strings (not to be confused with the Lisp function
  40 ;; `or').  The list of allowable clauses appears below.
  41
  42 ;; With sregex, it is never necessary to "escape" magic characters
  43 ;; that are meant to be taken literally; that happens automatically.
  44 ;; For example:
  45
  46 ;;   (sregexq "M*A*S*H")  =>  "M\\*A\\*S\\*H"
  47
  48 ;; It is also unnecessary to "group" parts of the expression together
  49 ;; to overcome operator precedence; that also happens automatically.
  50 ;; For example:
  51
  52 ;;   (sregexq (opt (or "Bob" "Robert")))  =>  "\\(?:Bob\\|Robert\\)?"
  53
  54 ;; It *is* possible to group parts of the expression in order to refer
  55 ;; to them with numbered backreferences:
  56
  57 ;;   (sregexq (group (or "Go" "Run"))
  58 ;;            ", Spot, "
  59 ;;            (backref 1))             =>  "\\(Go\\|Run\\), Spot, \\1"
  60
  61 ;; `sregexq' is a macro.  Each time it is used, it constructs a simple
  62 ;; Lisp expression that then invokes a moderately complex engine to
  63 ;; interpret the sregex and render the string form.  Because of this,
  64 ;; I don't recommend sprinkling calls to `sregexq' throughout your
  65 ;; code, the way one normally does with string regexes (which are
  66 ;; cheap to evaluate).  Instead, it's wiser to precompute the regexes
  67 ;; you need wherever possible instead of repeatedly constructing the
  68 ;; same ones over and over.  Example:
  69
  70 ;;    (let ((field-regex (sregexq (opt "resent-")
  71 ;;                                (or "to" "cc" "bcc"))))
  72 ;;      ...
  73 ;;      (while ...
  74 ;;        ...
  75 ;;        (re-search-forward field-regex ...)
  76 ;;        ...))
  77
  78 ;; The arguments to `sregexq' are automatically quoted, but the
  79 ;; flipside of this is that it is not straightforward to include
  80 ;; computed (i.e., non-constant) values in `sregexq' expressions.  So
  81 ;; `sregex' is a function that is like `sregexq' but which does not
  82 ;; automatically quote its values.  Literal sregex clauses must be
  83 ;; explicitly quoted like so:
  84
  85 ;;   (sregex '(or "Bob" "Robert"))  =>  "Bob\\|Robert"
  86
  87 ;; but computed clauses can be included easily, allowing for the reuse
  88 ;; of common clauses:
  89
  90 ;;  (let ((dotstar '(0+ any))
  91 ;;        (whitespace '(1+ (syntax ?-)))
  92 ;;        (digits '(1+ (char (?0 . ?9)))))
  93 ;;    (sregex 'bol dotstar ":" whitespace digits))  =>  "^.*:\\s-+[0-9]+"
  94
  95 ;; To use this package in a Lisp program, simply (require 'sregex).
  96
  97 ;; Here are the clauses allowed in an `sregex' or `sregexq'
  98 ;; expression:
  99
 100 ;; - a string
 101 ;;   This stands for the literal string.  If it contains
 102 ;;   metacharacters, they will be escaped in the resulting regex
 103 ;;   (using `regexp-quote').
 104
 105 ;; - the symbol `any'
 106 ;;   This stands for ".", a regex matching any character except
 107 ;;   newline.
 108
 109 ;; - the symbol `bol'
 110 ;;   Stands for "^", matching the empty string at the beginning of a line
 111
 112 ;; - the symbol `eol'
 113 ;;   Stands for "$", matching the empty string at the end of a line
 114
 115 ;; - (group CLAUSE ...)
 116 ;;   Groups the given CLAUSEs using "\\(" and "\\)".
 117
 118 ;; - (sequence CLAUSE ...)
 119
 120 ;;   Groups the given CLAUSEs; may or may not use "\\(?:" and "\\)".
 121 ;;   Clauses grouped by `sequence' do not count for purposes of
 122 ;;   numbering backreferences.  Use `sequence' in situations like
 123 ;;   this:
 124
 125 ;;     (sregexq (or "dog" "cat"
 126 ;;                  (sequence (opt "sea ") "monkey")))
 127 ;;                                  =>  "dog\\|cat\\|\\(?:sea \\)?monkey"
 128
 129 ;;   where a single `or' alternate needs to contain multiple
 130 ;;   subclauses.
 131
 132 ;; - (backref N)
 133 ;;   Matches the same string previously matched by the Nth "group" in
 134 ;;   the same sregex.  N is a positive integer.
 135
 136 ;; - (or CLAUSE ...)
 137 ;;   Matches any one of the CLAUSEs by separating them with "\\|".
 138
 139 ;; - (0+ CLAUSE ...)
 140 ;;   Concatenates the given CLAUSEs and matches zero or more
 141 ;;   occurrences by appending "*".
 142
 143 ;; - (1+ CLAUSE ...)
 144 ;;   Concatenates the given CLAUSEs and matches one or more
 145 ;;   occurrences by appending "+".
 146
 147 ;; - (opt CLAUSE ...)
 148 ;;   Concatenates the given CLAUSEs and matches zero or one occurrence
 149 ;;   by appending "?".
 150
 151 ;; - (repeat MIN MAX CLAUSE ...)
 152 ;;   Concatenates the given CLAUSEs and constructs a regex matching at
 153 ;;   least MIN occurrences and at most MAX occurrences.  MIN must be a
 154 ;;   non-negative integer.  MAX must be a non-negative integer greater
 155 ;;   than or equal to MIN; or MAX can be nil to mean "infinity."
 156
 157 ;; - (char CHAR-CLAUSE ...)
 158 ;;   Creates a "character class" matching one character from the given
 159 ;;   set.  See below for how to construct a CHAR-CLAUSE.
 160
 161 ;; - (not-char CHAR-CLAUSE ...)
 162 ;;   Creates a "character class" matching any one character not in the
 163 ;;   given set.  See below for how to construct a CHAR-CLAUSE.
 164
 165 ;; - the symbol `bot'
 166 ;;   Stands for "\\`", matching the empty string at the beginning of
 167 ;;   text (beginning of a string or of a buffer).
 168
 169 ;; - the symbol `eot'
 170 ;;   Stands for "\\'", matching the empty string at the end of text.
 171
 172 ;; - the symbol `point'
 173 ;;   Stands for "\\=", matching the empty string at point.
 174
 175 ;; - the symbol `word-boundary'
 176 ;;   Stands for "\\b", matching the empty string at the beginning or
 177 ;;   end of a word.
 178
 179 ;; - the symbol `not-word-boundary'
 180 ;;   Stands for "\\B", matching the empty string not at the beginning
 181 ;;   or end of a word.
 182
 183 ;; - the symbol `bow'
 184 ;;   Stands for "\\<", matching the empty string at the beginning of a
 185 ;;   word.
 186
 187 ;; - the symbol `eow'
 188 ;;   Stands for "\\>", matching the empty string at the end of a word.
 189
 190 ;; - the symbol `wordchar'
 191 ;;   Stands for the regex "\\w", matching a word-constituent character
 192 ;;   (as determined by the current syntax table)
 193
 194 ;; - the symbol `not-wordchar'
 195 ;;   Stands for the regex "\\W", matching a non-word-constituent
 196 ;;   character.
 197
 198 ;; - (syntax CODE)
 199 ;;   Stands for the regex "\\sCODE", where CODE is a syntax table code
 200 ;;   (a single character).  Matches any character with the requested
 201 ;;   syntax.
 202
 203 ;; - (not-syntax CODE)
 204 ;;   Stands for the regex "\\SCODE", where CODE is a syntax table code
 205 ;;   (a single character).  Matches any character without the
 206 ;;   requested syntax.
 207
 208 ;; - (regex REGEX)
 209 ;;   This is a "trapdoor" for including ordinary regular expression
 210 ;;   strings in the result.  Some regular expressions are clearer when
 211 ;;   written the old way: "[a-z]" vs. (sregexq (char (?a . ?z))), for
 212 ;;   instance.  However, see the note under "Bugs," below.
 213
 214 ;; Each CHAR-CLAUSE that is passed to (char ...) and (not-char ...)
 215 ;; has one of the following forms:
 216
 217 ;; - a character
 218 ;;   Adds that character to the set.
 219
 220 ;; - a string
 221 ;;   Adds all the characters in the string to the set.
 222
 223 ;; - A pair (MIN . MAX)
 224 ;;   Where MIN and MAX are characters, adds the range of characters
 225 ;;   from MIN through MAX to the set.
 226
 227 ;;; To do:
 228
 229 ;; An earlier version of this package could optionally translate the
 230 ;; symbolic regex into other languages' syntaxes, e.g. Perl.  For
 231 ;; instance, with Perl syntax selected, (sregexq (or "ab" "cd")) would
 232 ;; yield "ab|cd" instead of "ab\\|cd".  It might be useful to restore
 233 ;; such a facility.
 234
 235 ;; - handle multibyte chars in sregex--char-aux
 236 ;; - add support for character classes ([:blank:], ...)
 237 ;; - add support for non-greedy operators *? and +?
 238 ;; - bug: (sregexq (opt (opt ?a))) returns "a??" which is a non-greedy "a?"
 239
 240 ;;; Bugs:
 241
 242 ;;; Code:
 243
 244 (eval-when-compile (require 'cl))
 245
 246 ;; Compatibility code for when we didn't have shy-groups
 247 (defvar sregex--current-sregex nil)
 248 (defun sregex-info () nil)
 249 (defmacro sregex-save-match-data (&rest forms) (cons 'save-match-data forms))
 250 (defun sregex-replace-match (r &optional f l str subexp x)
 251   (replace-match r f l str subexp))
 252 (defun sregex-match-string (c &optional i x) (match-string c i))
 253 (defun sregex-match-string-no-properties (count &optional in-string sregex)
 254   (match-string-no-properties count in-string))
 255 (defun sregex-match-beginning (count &optional sregex) (match-beginning count))
 256 (defun sregex-match-end (count &optional sregex) (match-end count))
 257 (defun sregex-match-data (&optional sregex) (match-data))
 258 (defun sregex-backref-num (n &optional sregex) n)
 259
 260
 261 (defun sregex (&rest exps)
 262   "Symbolic regular expression interpreter.
 263 This is exactly like `sregexq' (q.v.) except that it evaluates all its
 264 arguments, so literal sregex clauses must be quoted.  For example:
 265
 266   (sregex '(or \"Bob\" \"Robert\"))  =>  \"Bob\\\\|Robert\"
 267
 268 An argument-evaluating sregex interpreter lets you reuse sregex
 269 subexpressions:
 270
 271   (let ((dotstar '(0+ any))
 272         (whitespace '(1+ (syntax ?-)))
 273         (digits '(1+ (char (?0 . ?9)))))
 274     (sregex 'bol dotstar \":\" whitespace digits))  =>  \"^.*:\\\\s-+[0-9]+\""
 275   (sregex--sequence exps nil))
 276
 277 (defmacro sregexq (&rest exps)
 278   "Symbolic regular expression interpreter.
 279 This macro allows you to specify a regular expression (regexp) in
 280 symbolic form, and converts it into the string form required by Emacs's
 281 regex functions such as `re-search-forward' and `looking-at'.  Here is
 282 a simple example:
 283
 284   (sregexq (or \"Bob\" \"Robert\"))  =>  \"Bob\\\\|Robert\"
 285
 286 As you can see, an sregex is specified by placing one or more special
 287 clauses in a call to `sregexq'.  The clause in this case is the `or'
 288 of two strings (not to be confused with the Lisp function `or').  The
 289 list of allowable clauses appears below.
 290
 291 With `sregex', it is never necessary to \"escape\" magic characters
 292 that are meant to be taken literally; that happens automatically.
 293 For example:
 294
 295   (sregexq \"M*A*S*H\")  =>  \"M\\\\*A\\\\*S\\\\*H\"
 296
 297 It is also unnecessary to \"group\" parts of the expression together
 298 to overcome operator precedence; that also happens automatically.
 299 For example:
 300
 301   (sregexq (opt (or \"Bob\" \"Robert\")))  =>  \"\\\\(Bob\\\\|Robert\\\\)?\"
 302
 303 It *is* possible to group parts of the expression in order to refer
 304 to them with numbered backreferences:
 305
 306   (sregexq (group (or \"Go\" \"Run\"))
 307            \", Spot, \"
 308            (backref 1))             =>  \"\\\\(Go\\\\|Run\\\\), Spot, \\\\1\"
 309
 310 If `sregexq' needs to introduce its own grouping parentheses, it will
 311 automatically renumber your backreferences:
 312
 313   (sregexq (opt \"resent-\")
 314            (group (or \"to\" \"cc\" \"bcc\"))
 315            \": \"
 316            (backref 1))  =>  \"\\\\(resent-\\\\)?\\\\(to\\\\|cc\\\\|bcc\\\\): \\\\2\"
 317
 318 `sregexq' is a macro.  Each time it is used, it constructs a simple
 319 Lisp expression that then invokes a moderately complex engine to
 320 interpret the sregex and render the string form.  Because of this, I
 321 don't recommend sprinkling calls to `sregexq' throughout your code,
 322 the way one normally does with string regexes (which are cheap to
 323 evaluate).  Instead, it's wiser to precompute the regexes you need
 324 wherever possible instead of repeatedly constructing the same ones
 325 over and over.  Example:
 326
 327    (let ((field-regex (sregexq (opt \"resent-\")
 328                                (or \"to\" \"cc\" \"bcc\"))))
 329      ...
 330      (while ...
 331        ...
 332        (re-search-forward field-regex ...)
 333        ...))
 334
 335 The arguments to `sregexq' are automatically quoted, but the
 336 flipside of this is that it is not straightforward to include
 337 computed (i.e., non-constant) values in `sregexq' expressions.  So
 338 `sregex' is a function that is like `sregexq' but which does not
 339 automatically quote its values.  Literal sregex clauses must be
 340 explicitly quoted like so:
 341
 342   (sregex '(or \"Bob\" \"Robert\"))  =>  \"Bob\\\\|Robert\"
 343
 344 but computed clauses can be included easily, allowing for the reuse
 345 of common clauses:
 346
 347   (let ((dotstar '(0+ any))
 348         (whitespace '(1+ (syntax ?-)))
 349         (digits '(1+ (char (?0 . ?9)))))
 350     (sregex 'bol dotstar \":\" whitespace digits))  =>  \"^.*:\\\\s-+[0-9]+\"
 351
 352 Here are the clauses allowed in an `sregex' or `sregexq' expression:
 353
 354 - a string
 355   This stands for the literal string.  If it contains
 356   metacharacters, they will be escaped in the resulting regex
 357   (using `regexp-quote').
 358
 359 - the symbol `any'
 360   This stands for \".\", a regex matching any character except
 361   newline.
 362
 363 - the symbol `bol'
 364   Stands for \"^\", matching the empty string at the beginning of a line
 365
 366 - the symbol `eol'
 367   Stands for \"$\", matching the empty string at the end of a line
 368
 369 - (group CLAUSE ...)
 370   Groups the given CLAUSEs using \"\\\\(\" and \"\\\\)\".
 371
 372 - (sequence CLAUSE ...)
 373
 374   Groups the given CLAUSEs; may or may not use \"\\\\(\" and \"\\\\)\".
 375   Clauses grouped by `sequence' do not count for purposes of
 376   numbering backreferences.  Use `sequence' in situations like
 377   this:
 378
 379     (sregexq (or \"dog\" \"cat\"
 380                  (sequence (opt \"sea \") \"monkey\")))
 381                                  =>  \"dog\\\\|cat\\\\|\\\\(?:sea \\\\)?monkey\"
 382
 383   where a single `or' alternate needs to contain multiple
 384   subclauses.
 385
 386 - (backref N)
 387   Matches the same string previously matched by the Nth \"group\" in
 388   the same sregex.  N is a positive integer.
 389
 390 - (or CLAUSE ...)
 391   Matches any one of the CLAUSEs by separating them with \"\\\\|\".
 392
 393 - (0+ CLAUSE ...)
 394   Concatenates the given CLAUSEs and matches zero or more
 395   occurrences by appending \"*\".
 396
 397 - (1+ CLAUSE ...)
 398   Concatenates the given CLAUSEs and matches one or more
 399   occurrences by appending \"+\".
 400
 401 - (opt CLAUSE ...)
 402   Concatenates the given CLAUSEs and matches zero or one occurrence
 403   by appending \"?\".
 404
 405 - (repeat MIN MAX CLAUSE ...)
 406   Concatenates the given CLAUSEs and constructs a regex matching at
 407   least MIN occurrences and at most MAX occurrences.  MIN must be a
 408   non-negative integer.  MAX must be a non-negative integer greater
 409   than or equal to MIN; or MAX can be nil to mean \"infinity.\"
 410
 411 - (char CHAR-CLAUSE ...)
 412   Creates a \"character class\" matching one character from the given
 413   set.  See below for how to construct a CHAR-CLAUSE.
 414
 415 - (not-char CHAR-CLAUSE ...)
 416   Creates a \"character class\" matching any one character not in the
 417   given set.  See below for how to construct a CHAR-CLAUSE.
 418
 419 - the symbol `bot'
 420   Stands for \"\\\\`\", matching the empty string at the beginning of
 421   text (beginning of a string or of a buffer).
 422
 423 - the symbol `eot'
 424   Stands for \"\\\\'\", matching the empty string at the end of text.
 425
 426 - the symbol `point'
 427   Stands for \"\\\\=\", matching the empty string at point.
 428
 429 - the symbol `word-boundary'
 430   Stands for \"\\\\b\", matching the empty string at the beginning or
 431   end of a word.
 432
 433 - the symbol `not-word-boundary'
 434   Stands for \"\\\\B\", matching the empty string not at the beginning
 435   or end of a word.
 436
 437 - the symbol `bow'
 438   Stands for \"\\\\\\=<\", matching the empty string at the beginning of a
 439   word.
 440
 441 - the symbol `eow'
 442   Stands for \"\\\\\\=>\", matching the empty string at the end of a word.
 443
 444 - the symbol `wordchar'
 445   Stands for the regex \"\\\\w\", matching a word-constituent character
 446   (as determined by the current syntax table)
 447
 448 - the symbol `not-wordchar'
 449   Stands for the regex \"\\\\W\", matching a non-word-constituent
 450   character.
 451
 452 - (syntax CODE)
 453   Stands for the regex \"\\\\sCODE\", where CODE is a syntax table code
 454   (a single character).  Matches any character with the requested
 455   syntax.
 456
 457 - (not-syntax CODE)
 458   Stands for the regex \"\\\\SCODE\", where CODE is a syntax table code
 459   (a single character).  Matches any character without the
 460   requested syntax.
 461
 462 - (regex REGEX)
 463   This is a \"trapdoor\" for including ordinary regular expression
 464   strings in the result.  Some regular expressions are clearer when
 465   written the old way: \"[a-z]\" vs. (sregexq (char (?a . ?z))), for
 466   instance.
 467
 468 Each CHAR-CLAUSE that is passed to (char ...) and (not-char ...)
 469 has one of the following forms:
 470
 471 - a character
 472   Adds that character to the set.
 473
 474 - a string
 475   Adds all the characters in the string to the set.
 476
 477 - A pair (MIN . MAX)
 478   Where MIN and MAX are characters, adds the range of characters
 479   from MIN through MAX to the set."
 480   `(apply 'sregex ',exps))
 481
 482 (defun sregex--engine (exp combine)
 483   (cond
 484    ((stringp exp)
 485     (if (and combine
 486              (eq combine 'suffix)
 487              (/= (length exp) 1))
 488         (concat "\\(?:" (regexp-quote exp) "\\)")
 489       (regexp-quote exp)))
 490    ((symbolp exp)
 491     (ecase exp
 492       (any ".")
 493       (bol "^")
 494       (eol "$")
 495       (wordchar "\\w")
 496       (not-wordchar "\\W")
 497       (bot "\\`")
 498       (eot "\\'")
 499       (point "\\=")
 500       (word-boundary "\\b")
 501       (not-word-boundary "\\B")
 502       (bow "\\<")
 503       (eow "\\>")))
 504    ((consp exp)
 505     (funcall (intern (concat "sregex--"
 506                              (symbol-name (car exp))))
 507              (cdr exp)
 508              combine))
 509    (t (error "Invalid expression: %s" exp))))
 510
 511 (defun sregex--sequence (exps combine)
 512   (if (= (length exps) 1) (sregex--engine (car exps) combine)
 513     (let ((re (mapconcat
 514                (lambda (e) (sregex--engine e 'concat))
 515                exps "")))
 516       (if (eq combine 'suffix)
 517           (concat "\\(?:" re "\\)")
 518         re))))
 519
 520 (defun sregex--or (exps combine)
 521   (if (= (length exps) 1) (sregex--engine (car exps) combine)
 522     (let ((re (mapconcat
 523                (lambda (e) (sregex--engine e 'or))
 524                exps "\\|")))
 525       (if (not (eq combine 'or))
 526           (concat "\\(?:" re "\\)")
 527         re))))
 528
 529 (defun sregex--group (exps combine) (concat "\\(" (sregex--sequence exps nil) "\\)"))
 530
 531 (defun sregex--backref (exps combine) (concat "\\" (int-to-string (car exps))))
 532 (defun sregex--opt (exps combine) (concat (sregex--sequence exps 'suffix) "?"))
 533 (defun sregex--0+ (exps combine) (concat (sregex--sequence exps 'suffix) "*"))
 534 (defun sregex--1+ (exps combine) (concat (sregex--sequence exps 'suffix) "+"))
 535
 536 (defun sregex--char (exps combine) (sregex--char-aux nil exps))
 537 (defun sregex--not-char (exps combine) (sregex--char-aux t exps))
 538
 539 (defun sregex--syntax (exps combine) (format "\\s%c" (car exps)))
 540 (defun sregex--not-syntax (exps combine) (format "\\S%c" (car exps)))
 541
 542 (defun sregex--regex (exps combine)
 543   (if combine (concat "\\(?:" (car exps) "\\)") (car exps)))
 544
 545 (defun sregex--repeat (exps combine)
 546   (let* ((min (or (pop exps) 0))
 547          (minstr (number-to-string min))
 548          (max (pop exps)))
 549     (concat (sregex--sequence exps 'suffix)
 550             (concat "\\{" minstr ","
 551                     (when max (number-to-string max)) "\\}"))))
 552
 553 (defun sregex--char-range (start end)
 554   (let ((startc (char-to-string start))
 555         (endc (char-to-string end)))
 556     (cond
 557      ((> end (+ start 2)) (concat startc "-" endc))
 558      ((> end (+ start 1)) (concat startc (char-to-string (1+ start)) endc))
 559      ((> end start) (concat startc endc))
 560      (t startc))))
 561
 562 (defun sregex--char-aux (complement args)
 563   ;; regex-opt does the same, we should join effort.
 564   (let ((chars (make-bool-vector 256 nil))) ; Yeah, right!
 565     (dolist (arg args)
 566       (cond ((integerp arg) (aset chars arg t))
 567             ((stringp arg) (mapcar (lambda (c) (aset chars c t)) arg))
 568             ((consp arg)
 569              (let ((start (car arg))
 570                    (end (cdr arg)))
 571                (when (> start end)
 572                  (let ((tmp start)) (setq start end) (setq end tmp)))
 573                ;; now start <= end
 574                (let ((i start))
 575                  (while (<= i end)
 576                    (aset chars i t)
 577                    (setq i (1+ i))))))))
 578     ;; now chars is a map of the characters in the class
 579     (let ((caret (aref chars ?^))
 580           (dash (aref chars ?-))
 581           (class (if (aref chars ?\]) "]" "")))
 582       (aset chars ?^ nil)
 583       (aset chars ?- nil)
 584       (aset chars ?\] nil)
 585
 586       (let (start end)
 587         (dotimes (i 256)
 588           (if (aref chars i)
 589               (progn
 590                 (unless start (setq start i))
 591                 (setq end i)
 592                 (aset chars i nil))
 593             (when start
 594               (setq class (concat class (sregex--char-range start end)))
 595               (setq start nil))))
 596         (if start
 597             (setq class (concat class (sregex--char-range start end)))))
 598
 599       (if (> (length class) 0)
 600           (setq class (concat class (if caret "^") (if dash "-")))
 601         (setq class (concat class (if dash "-") (if caret "^"))))
 602       (if (and (not complement) (= (length class) 1))
 603           (regexp-quote class)
 604         (concat "[" (if complement "^") class "]")))))
 605
 606 (provide 'sregex)
 607
 608 ;;; sregex.el ends here