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Allow characters and single-char strings in rx charsets

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The `not' and `intersection' forms, and `or' inside these forms,
now accept characters and single-character strings as arguments.
Previously, they had to be wrapped in `any' forms.
This does not add expressive power but is a convenience and is easily
understood.

* doc/lispref/searching.texi (Rx Constructs): Amend the documentation.
* etc/NEWS: Announce the change.
* lisp/emacs-lisp/rx.el (rx--charset-p, rx--translate-not)
(rx--charset-intervals, rx): Accept characters and 1-char strings in
more places.
* test/lisp/emacs-lisp/rx-tests.el (rx-not, rx-charset-or)
(rx-def-in-charset-or, rx-intersection): Test the change.
This commit is contained in:
Mattias Engdegård 2019-12-13 13:10:58 +01:00
parent b04086adf6
commit 82b4e48c59
4 changed files with 43 additions and 17 deletions
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26
lisp/emacs-lisp/rx.el
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@ -309,6 +309,8 @@ and set operations."
(rx--every (lambda (x) (not (symbolp x))) (cdr form)))
(and (memq (car form) '(not or | intersection))
(rx--every #'rx--charset-p (cdr form)))))
(characterp form)
(and (stringp form) (= (length form) 1))
(and (or (symbolp form) (consp form))
(let ((expanded (rx--expand-def form)))
(and expanded
@ -521,6 +523,11 @@ If NEGATED, negate the sense (thus making it positive)."
((eq arg 'word-boundary)
(rx--translate-symbol
(if negated 'word-boundary 'not-word-boundary)))
((characterp arg)
(rx--generate-alt (not negated) (list (cons arg arg)) nil))
((and (stringp arg) (= (length arg) 1))
(let ((char (string-to-char arg)))
(rx--generate-alt (not negated) (list (cons char char)) nil)))
((let ((expanded (rx--expand-def arg)))
(and expanded
(rx--translate-not negated (list expanded)))))
@ -571,8 +578,8 @@ If NEGATED, negate the sense (thus making it positive)."
(defun rx--charset-intervals (charset)
"Return a sorted list of non-adjacent disjoint intervals from CHARSET.
CHARSET is any expression allowed in a character set expression:
either `any' (no classes permitted), or `not', `or' or `intersection'
forms whose arguments are charsets."
characters, single-char strings, `any' forms (no classes permitted),
or `not', `or' or `intersection' forms whose arguments are charsets."
(pcase charset
(`(,(or 'any 'in 'char) . ,body)
(let ((parsed (rx--parse-any body)))
@ -584,6 +591,11 @@ forms whose arguments are charsets."
(`(not ,x) (rx--complement-intervals (rx--charset-intervals x)))
(`(,(or 'or '|) . ,body) (rx--charset-union body))
(`(intersection . ,body) (rx--charset-intersection body))
((pred characterp)
(list (cons charset charset)))
((guard (and (stringp charset) (= (length charset) 1)))
(let ((char (string-to-char charset)))
(list (cons char char))))
(_ (let ((expanded (rx--expand-def charset)))
(if expanded
(rx--charset-intervals expanded)
@ -1161,10 +1173,12 @@ CHAR Match a literal character.
character, a string, a range as string \"A-Z\" or cons
(?A . ?Z), or a character class (see below). Alias: in, char.
(not CHARSPEC) Match one character not matched by CHARSPEC. CHARSPEC
can be (any ...), (or ...), (intersection ...),
(syntax ...), (category ...), or a character class.
(intersection CHARSET...) Intersection of CHARSETs.
CHARSET is (any...), (not...), (or...) or (intersection...).
can be a character, single-char string, (any ...), (or ...),
(intersection ...), (syntax ...), (category ...),
or a character class.
(intersection CHARSET...) Match all CHARSETs.
CHARSET is (any...), (not...), (or...) or (intersection...),
a character or a single-char string.
not-newline Match any character except a newline. Alias: nonl.
anychar Match any character. Alias: anything.
unmatchable Never match anything at all.