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hush: speed up ${x//\*/|} too

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function                                             old     new   delta
expand_one_var                                      2502    2544     +42

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-10-09 03:52:04 +02:00
parent 5aaeb550b7
commit 49bcf9f40c
1 changed files with 9 additions and 4 deletions
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13
shell/hush.c
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@ -6472,16 +6472,21 @@ static arith_t expand_and_evaluate_arith(const char *arg, const char **errmsg_p)
/* ${var/[/]pattern[/repl]} helpers */
static char *strstr_pattern(char *val, const char *pattern, int *size)
{
int sz = strcspn(pattern, "*?[\\");
if (pattern[sz] == '\0') {
int first_escaped = (pattern[0] == '\\' && pattern[1]);
/* "first_escaped" trick allows to treat e.g. "\*no_glob_chars"
* as literal too (as it is semi-common, and easy to accomodate
* by just using str + 1).
*/
int sz = strcspn(pattern + first_escaped * 2, "*?[\\");
if ((pattern + first_escaped * 2)[sz] == '\0') {
/* Optimization for trivial patterns.
* Testcase for very slow replace (performs about 22k replaces):
* x=::::::::::::::::::::::
* x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;x=$x$x;echo ${#x}
* echo "${x//:/|}"
*/
*size = sz;
return strstr(val, pattern);
*size = sz + first_escaped;
return strstr(val, pattern + first_escaped);
}
while (1) {