mirror/emacs
1
0
Fork 0
mirror of https://git.savannah.gnu.org/git/emacs.git synced 2024-12-16 09:50:25 +00:00
Code Issues Releases Activity

More string-search optimisations

Browse Source 
All-ASCII strings cannot have substrings with non-ASCII characters in
them; use this fact to avoid searching entirely.

* src/fns.c (Fstring_search): For multibyte non-ASCII needle and
unibyte haystack, don't check if the haystack is all-ASCII; it's a
waste of time. For multibyte non-ASCII needle and multibyte
all-ASCII haystack, fail immediately.
* test/src/fns-tests.el (string-search): Add more test cases.
This commit is contained in:
Mattias Engdegård 2020-11-19 14:24:24 +01:00
parent 74a35d16e2
commit 90aab73f8d
2 changed files with 22 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

23
src/fns.c
View File

@ -5502,25 +5502,32 @@ Case is always significant and text properties are ignored. */)
haybytes = SBYTES (haystack) - start_byte;
/* We can do a direct byte-string search if both strings have the
same multibyteness, or if at least one of them consists of ASCII
characters only. */
same multibyteness, or if the needle consists of ASCII characters only. */
if (STRING_MULTIBYTE (haystack)
? (STRING_MULTIBYTE (needle)
|| SCHARS (haystack) == SBYTES (haystack) || string_ascii_p (needle))
: (!STRING_MULTIBYTE (needle)
|| SCHARS (needle) == SBYTES (needle) || string_ascii_p (haystack)))
res = memmem (haystart, haybytes,
SSDATA (needle), SBYTES (needle));
else if (STRING_MULTIBYTE (haystack)) /* unibyte needle */
|| SCHARS (needle) == SBYTES (needle)))
{
if (STRING_MULTIBYTE (haystack) && STRING_MULTIBYTE (needle)
&& SCHARS (haystack) == SBYTES (haystack)
&& SCHARS (needle) != SBYTES (needle))
/* Multibyte non-ASCII needle, multibyte ASCII haystack: impossible. */
return Qnil;
else
res = memmem (haystart, haybytes,
SSDATA (needle), SBYTES (needle));
}
else if (STRING_MULTIBYTE (haystack)) /* unibyte non-ASCII needle */
{
Lisp_Object multi_needle = string_to_multibyte (needle);
res = memmem (haystart, haybytes,
SSDATA (multi_needle), SBYTES (multi_needle));
}
else /* unibyte haystack, multibyte needle */
else /* unibyte haystack, multibyte non-ASCII needle */
{
/* The only possible way we can find the multibyte needle in the
unibyte stack (since we know that neither are pure-ASCII) is
unibyte stack (since we know that the needle is non-ASCII) is
if they contain "raw bytes" (and no other non-ASCII chars.) */
ptrdiff_t nbytes = SBYTES (needle);
for (ptrdiff_t i = 0; i < nbytes; i++)

7
test/src/fns-tests.el
View File

@ -938,6 +938,13 @@
(should (equal (string-search "\303" "aøb") nil))
(should (equal (string-search "\270" "aøb") nil))
(should (equal (string-search "ø" "\303\270") nil))
(should (equal (string-search "ø" (make-string 32 ?a)) nil))
(should (equal (string-search "ø" (string-to-multibyte (make-string 32 ?a)))
nil))
(should (equal (string-search "o" (string-to-multibyte
(apply #'string
(number-sequence ?a ?z))))
14))
(should (equal (string-search "a\U00010f98z" "a\U00010f98a\U00010f98z") 2))