bug#37659: rx additions: anychar, unmatchable, unordered-or

["Mattias Engdegård" <mattiase@acm.org>]

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Also consider changing the rendition of anychar/anything from ".\\|\n" to "[^z-a]", which is faster and does not allocate stack space. Previously, (* anything) wouldn't match large strings.


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From c72633774b375eaadd6117eb0b26fb9792fed1bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Wed, 9 Oct 2019 10:22:10 +0200
Subject: [PATCH 4/4] Use [^z-a] for matching any character (anychar/anything)
 in rx
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

* lisp/emacs-lisp/rx.el (rx--translate-symbol):
* test/lisp/emacs-lisp/rx-tests.el (rx-any, rx-atoms):
Use [^z-a] instead of ".\\|\n" for anychar.

The new expression is faster (about 2×) and does not allocate regexp
stack space.  For example, (0+ anychar) now matches strings of any
size.
---
 lisp/emacs-lisp/rx.el            | 2 +-
 test/lisp/emacs-lisp/rx-tests.el | 6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/lisp/emacs-lisp/rx.el b/lisp/emacs-lisp/rx.el
index 0b14144698..2f58033ffd 100644
--- a/lisp/emacs-lisp/rx.el
+++ b/lisp/emacs-lisp/rx.el
@@ -131,7 +131,7 @@ rx--translate-symbol
     ;; Use `list' instead of a quoted list to wrap the strings here,
     ;; since the return value may be mutated.
     ((or 'nonl 'not-newline 'any) (cons (list ".") t))
-    ((or 'anychar 'anything)      (rx--translate-form '(or nonl "\n")))
+    ((or 'anychar 'anything)      (cons (list "[^z-a]") t))
     ('unmatchable                 (rx--empty))
     ((or 'bol 'line-start)        (cons (list "^") 'lseq))
     ((or 'eol 'line-end)          (cons (list "$") 'rseq))
diff --git a/test/lisp/emacs-lisp/rx-tests.el b/test/lisp/emacs-lisp/rx-tests.el
index bced74569f..a098784a85 100644
--- a/test/lisp/emacs-lisp/rx-tests.el
+++ b/test/lisp/emacs-lisp/rx-tests.el
@@ -134,9 +134,9 @@ rx-any
   (should (equal (rx (not (any "!a" "0-8" digit nonascii)))
                  "[^!0-8a[:digit:][:nonascii:]]"))
   (should (equal (rx (any) (not (any)))
-                 "\\`a\\`\\(?:.\\|\n\\)"))
+                 "\\`a\\`[^z-a]"))
   (should (equal (rx (any "") (not (any "")))
-                 "\\`a\\`\\(?:.\\|\n\\)")))
+                 "\\`a\\`[^z-a]")))
 
 (ert-deftest rx-pcase ()
   (should (equal (pcase "a 1 2 3 1 1 b"
@@ -193,7 +193,7 @@ rx-repeat
 
 (ert-deftest rx-atoms ()
   (should (equal (rx anychar anything)
-                 "\\(?:.\\|\n\\)\\(?:.\\|\n\\)"))
+                 "[^z-a][^z-a]"))
   (should (equal (rx unmatchable)
                  "\\`a\\`"))
   (should (equal (rx line-start not-newline nonl any line-end)
-- 
2.21.0 (Apple Git-122)