From b552fc05c231ca6800330a318d3a74ddd0f5a13c Mon Sep 17 00:00:00 2001 From: Mattias Engdegård Date: Wed, 15 May 2019 22:44:00 +0200 Subject: Allow zero-argument rx `or' and `seq' forms Make the rx `or' and `seq' forms accept zero arguments to produce a never-matching regexp and an empty string, respectively. * lisp/emacs-lisp/rx.el (rx-constituents, rx-or): Permit zero args. (rx): Amend doc string for `or' and `seq'. * test/lisp/emacs-lisp/rx-tests.el (rx-or, rx-seq): Test the change. * etc/NEWS (Changes in Specialized Modes and Packages): Mention the change. --- lisp/emacs-lisp/rx.el | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) (limited to 'lisp/emacs-lisp/rx.el') diff --git a/lisp/emacs-lisp/rx.el b/lisp/emacs-lisp/rx.el index 9d9028d87d5..9478bd3bbdb 100644 --- a/lisp/emacs-lisp/rx.el +++ b/lisp/emacs-lisp/rx.el @@ -110,11 +110,11 @@ ;; FIXME: support macros. (defvar rx-constituents ;Not `const' because some modes extend it. - '((and . (rx-and 1 nil)) + '((and . (rx-and 0 nil)) (seq . and) ; SRE (: . and) ; SRE (sequence . and) ; sregex - (or . (rx-or 1 nil)) + (or . (rx-or 0 nil)) (| . or) ; SRE (not-newline . ".") (nonl . not-newline) ; SRE @@ -390,9 +390,11 @@ FORM is of the form `(and FORM1 ...)'." "Parse and produce code from FORM, which is `(or FORM1 ...)'." (rx-check form) (rx-group-if - (if (memq nil (mapcar 'stringp (cdr form))) - (mapconcat (lambda (x) (rx-form x '|)) (cdr form) "\\|") + (cond + ((null (cdr form)) regexp-unmatchable) + ((cl-every #'stringp (cdr form)) (regexp-opt (cdr form) nil t)) + (t (mapconcat (lambda (x) (rx-form x '|)) (cdr form) "\\|"))) (and (memq rx-parent '(: * t)) rx-parent))) @@ -1121,6 +1123,7 @@ CHAR `(seq SEXP1 SEXP2 ...)' `(sequence SEXP1 SEXP2 ...)' matches what SEXP1 matches, followed by what SEXP2 matches, etc. + Without arguments, matches the empty string. `(submatch SEXP1 SEXP2 ...)' `(group SEXP1 SEXP2 ...)' @@ -1136,7 +1139,7 @@ CHAR `(| SEXP1 SEXP2 ...)' matches anything that matches SEXP1 or SEXP2, etc. If all args are strings, use `regexp-opt' to optimize the resulting - regular expression. + regular expression. Without arguments, never matches anything. `(minimal-match SEXP)' produce a non-greedy regexp for SEXP. Normally, regexps matching -- cgit v1.2.3