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|
#|
~*~ sregex ~*~
Maxima interface to pregexp.lisp (a portable regex parser by Dorai Sitaram)
Copyright : 2008 - 2016 Volker van Nek
--------------------------------------------------------------------------------
This program 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 2 of the License, or
(at your option) any later version.
This program 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, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
--------------------------------------------------------------------------------
Functions:
regex_compile - returns a Lisp structure containing a compiled regex.
regex_match_pos, regex_match, regex_split, regex_subst_first, regex_subst -
the regular expression used as an argument may be a string or
compiled by regex_compile.
string_to_regex - masking special characters.
Examples:
str : "his hay needle stack -- my hay needle stack -- her hay needle stack"$
regex : regex_compile("ne{2}dle")$
regex_match_pos(regex, str);
[[9, 15]]
regex_match_pos("ne{2}dle", str);
[[9, 15]]
regex_match_pos("ne{2}dle", str, 25, 44);
[[32, 38]]
regex_match("ne{2}dle", "hay needle stack");
["needle"]
regex_match("ne{2}dle", "hay needle stack", 10);
false
regex_split("[,;]+", "split,pea;;;soup");
["split", "pea", "soup"]
regex_subst_first("ty", "t.", "liberte egalite fraternite");
"liberty egalite fraternite"
regex_subst("ty", "t.\\b", "liberte egalite fraternite");
"liberty egality fraternity"
string_to_regex(". :");
"\. :"
--------------------------------------------------------------------------------
The pregexp manual by Dorai Sitaram is at
http://ds26gte.github.io/pregexp/index.html.
--------------------------------------------------------------------------------
Like in stringproc.lisp we use 1-indexed position specifications.
When the external format is not utf-8 (unicode) positions are counted in
octets at Lisp level and in Maxima characters at Maxima level.
See remarks in stringproc.lisp.
Without unicode support non-us-ascii Maxima characters are not recognized
by regular expressions, e.g. the regex "." doesn't match to an umlaut.
|#
(in-package :maxima)
(declare-top (special *parse-utf-8-input*))
(defstruct (compiled-regex (:print-function compiled-regex-print))
parse-tree )
(defun compiled-regex-print (struct stream i)
(declare (ignore struct i))
(format stream "Structure [COMPILED-REGEX]") ) ;; wxMaxima prints this
;; terminal should print this too
(defun $regex_compile (regex)
(make-compiled-regex
:parse-tree (pregexp regex) ))
(defun regex-check-and-maybe-coerce (name regex &rest args)
(cond
((compiled-regex-p regex)
(setq regex (compiled-regex-parse-tree regex)) )
((not (stringp regex))
(gf-merror (intl:gettext "`~m': first arg must be a compiled regex or a string.") name) ))
(unless (every #'stringp args)
(gf-merror (intl:gettext "Unsuitable arguments to `~m'.") name) )
regex )
(defun regex-index-error (name)
(gf-merror (intl:gettext "`~m': improper start or end index.") name) )
;; When the external format is not utf-8 (unicode) positions are counted in octets.
;; We want them in numbers of characters to find the right position in a string.
;; utf-8-pos-dec returns the decrement we need to adjust.
;; (string position = octet position - decrement)
(defun regex-utf-8-pos-dec (ov off pos) ;; begin to count at a given offset
(do ((i off (1+ i))
(n 0))
((= i pos) n)
(when (= (logand (aref ov i) 192.) 128.)
(incf n) )))
(defun $regex_match_pos (regex str &optional (start 1) (end nil)) ;; 1-based indexing!
(setq regex (regex-check-and-maybe-coerce "regex_match_pos" regex str))
(decf start)
(when end (decf end))
(let (ov)
(or (ignore-errors
(when *parse-utf-8-input*
(setq ov (string-to-raw-bytes str))
(let ((args (utf-8-fix-start-end ov (list nil start end))))
(setq start (cadr args)
end (caddr args) )))
(let ((pos-list (pregexp-match-positions regex str start end))
(pos-mlist nil) )
(if pos-list
(dolist (pos pos-list (cons '(mlist simp) (nreverse pos-mlist)))
(when *parse-utf-8-input*
(let ((dec (regex-utf-8-pos-dec ov 0 (car pos))))
(decf (cdr pos) (+ dec (regex-utf-8-pos-dec ov (car pos) (cdr pos))))
(decf (car pos) dec) ))
(push `((mlist simp) ,(1+ (car pos)) ,(1+ (cdr pos))) pos-mlist) )
(return-from $regex_match_pos nil) )))
(regex-index-error "regex_match_pos") )))
(defun $regex_match (regex str &optional (start 1) (end nil))
(setq regex (regex-check-and-maybe-coerce "regex_match" regex str))
(or (ignore-errors
(when *parse-utf-8-input*
(let* ((ov (string-to-raw-bytes str))
(args (utf-8-fix-start-end ov (list nil start end))) )
(setq start (cadr args)
end (caddr args) )))
(let ((match
(pregexp-match regex str (1- start) (if end (1- end) nil)) ))
(if match
(cons '(mlist simp) match)
(return-from $regex_match nil) )))
(regex-index-error "regex_match") ))
(defun $regex_split (regex str)
(setq regex (regex-check-and-maybe-coerce "regex_split" regex str))
(cons '(mlist simp) (pregexp-split regex str)) )
(defun $regex_subst_first (replacement regex str)
(setq regex (regex-check-and-maybe-coerce "regex_subst_first" regex str replacement))
(pregexp-replace regex str replacement) )
;;
;; Argument order different to the order of pregexp-replace.
;; Use order like in $ssubst or substitute: new, old, str.
;;
(defun $regex_subst (replacement regex str)
(setq regex (regex-check-and-maybe-coerce "regex_subst" regex str replacement))
(pregexp-replace* regex str replacement) )
(defun $string_to_regex (str)
(unless (stringp str)
(gf-merror (intl:gettext "`string_to_regex': Argument must be a string.")) )
(pregexp-quote str) )
|
