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hush: tweak ${var/pattern/repl} optimization

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function                                             old     new   delta
expand_one_var                                      2507    2502      -5

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2021-07-27 18:13:11 +02:00
parent 49cc3cac30
commit 37460f5daf
1 changed files with 4 additions and 5 deletions
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9
shell/hush.c
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@ -6466,17 +6466,16 @@ static arith_t expand_and_evaluate_arith(const char *arg, const char **errmsg_p)
/* ${var/[/]pattern[/repl]} helpers */ /* ${var/[/]pattern[/repl]} helpers */
static char *strstr_pattern(char *val, const char *pattern, int *size) static char *strstr_pattern(char *val, const char *pattern, int *size)
{ {
if (!strpbrk(pattern, "*?[\\")) { int sz = strcspn(pattern, "*?[\\");
if (pattern[sz] == '\0') {
/* Optimization for trivial patterns. /* Optimization for trivial patterns.
* Testcase for very slow replace (performs about 22k replaces): * Testcase for very slow replace (performs about 22k replaces):
* x=:::::::::::::::::::::: * x=::::::::::::::::::::::
* x=$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$x;echo ${#x} * x=$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//:/|}" * echo "${x//:/|}"
*/ */
char *found = strstr(val, pattern); *size = sz;
if (found) return strstr(val, pattern);
*size = strlen(pattern);
return found;
} }
while (1) { while (1) {