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hush: optimize #[#] and %[%] for speed. size -2 bytes.

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Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko
2010-09-04 21:21:07 +02:00
parent e298ce69ba
commit 701e127f7d
3 changed files with 89 additions and 72 deletions
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110
shell/match.c
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@@ -18,6 +18,9 @@
# include <stdlib.h>
# include <string.h>
# include <unistd.h>
# define FAST_FUNC /* nothing */
# define PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN /* nothing */
# define POP_SAVED_FUNCTION_VISIBILITY /* nothing */
#else
# include "libbb.h"
#endif
@@ -26,16 +29,48 @@
#define pmatch(a, b) !fnmatch((a), (b), 0)
char *scanleft(char *string, char *pattern, bool match_at_left)
char* FAST_FUNC scan_and_match(char *string, const char *pattern, unsigned flags)
{
char c;
char *loc = string;
char *loc;
char *end;
unsigned len = strlen(string);
int early_exit;
while (1) {
/* We can stop the scan early only if the string part
* we are matching against is shrinking, and the pattern has
* an unquoted "star" at the corresponding end. There are two cases.
* Case 1:
* "qwerty" does not match against pattern "*zy",
* no point in trying to match "werty", "erty" etc:
*/
early_exit = (flags == (SCAN_MOVE_FROM_LEFT + SCAN_MATCH_RIGHT_HALF) && pattern[0] == '*');
if (flags & SCAN_MOVE_FROM_LEFT) {
loc = string;
end = string + len + 1;
} else {
loc = string + len;
end = string - 1;
if (flags == (SCAN_MOVE_FROM_RIGHT + SCAN_MATCH_LEFT_HALF)) {
/* Case 2:
* "qwerty" does not match against pattern "qz*",
* no point in trying to match "qwert", "qwer" etc:
*/
const char *p = pattern + strlen(pattern);
if (--p >= pattern && *p == '*') {
early_exit = 1;
while (--p >= pattern && *p == '\\')
early_exit ^= 1;
}
}
}
while (loc != end) {
char c;
int match;
c = *loc;
if (match_at_left) {
if (flags & SCAN_MATCH_LEFT_HALF) {
*loc = '\0';
match = pmatch(pattern, string);
*loc = c;
@@ -44,33 +79,19 @@ char *scanleft(char *string, char *pattern, bool match_at_left)
}
if (match)
return loc;
if (!c)
return NULL;
loc++;
}
}
char *scanright(char *string, char *pattern, bool match_at_left)
{
char c;
char *loc = string + strlen(string);
while (loc >= string) {
int match;
c = *loc;
if (match_at_left) {
*loc = '\0';
match = pmatch(pattern, string);
*loc = c;
} else {
match = pmatch(pattern, loc);
if (early_exit) {
#ifdef STANDALONE
printf("(early exit) ");
#endif
break;
}
if (match)
return loc;
loc--;
}
if (flags & SCAN_MOVE_FROM_LEFT) {
loc++;
} else {
loc--;
}
}
return NULL;
}
@@ -80,12 +101,11 @@ int main(int argc, char *argv[])
char *string;
char *op;
char *pattern;
bool match_at_left;
char *loc;
int i;
setvbuf(stdout, NULL, _IONBF, 0);
if (argc == 1) {
if (!argv[1]) {
puts(
"Usage: match <test> [test...]\n\n"
"Where a <test> is the form: <string><op><match>\n"
@@ -95,36 +115,34 @@ int main(int argc, char *argv[])
return 1;
}
for (i = 1; i < argc; ++i) {
while (*++argv) {
size_t off;
scan_t scan;
unsigned scan_flags;
printf("'%s': ", argv[i]);
string = strdup(argv[i]);
string = *argv;
off = strcspn(string, "#%");
if (!off) {
printf("invalid format\n");
free(string);
continue;
}
op = string + off;
scan = pick_scan(op[0], op[1], &match_at_left);
scan_flags = pick_scan(op[0], op[1]);
printf("'%s': flags:%x, ", string, scan_flags);
pattern = op + 1;
if (op[0] == op[1])
op[1] = '\0', ++pattern;
pattern++;
op[0] = '\0';
loc = scan(string, pattern, match_at_left);
loc = scan_and_match(string, pattern, scan_flags);
if (match_at_left) {
if (scan_flags & SCAN_MATCH_LEFT_HALF) {
printf("'%s'\n", loc);
} else {
*loc = '\0';
if (loc)
*loc = '\0';
printf("'%s'\n", string);
}
free(string);
}
return 0;