hush: optimize #[#] and %[%] for speed. size -2 bytes.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com>
This commit is contained in:
Denys Vlasenko
parent
e298ce69ba
commit
701e127f7d
22
shell/hush.c
22
shell/hush.c
@ -2829,23 +2829,21 @@ static NOINLINE int expand_vars_to_list(o_string *output, int n, char *arg, char
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* Then var's value is matched to it and matching part removed.
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*/
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if (val) {
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bool match_at_left;
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char *exp_exp_word;
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char *loc;
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scan_t scan = pick_scan(exp_op, *exp_word, &match_at_left);
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unsigned scan_flags = pick_scan(exp_op, *exp_word);
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if (exp_op == *exp_word) /* ## or %% */
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exp_word++;
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val = to_be_freed = xstrdup(val);
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{
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char *exp_exp_word = expand_pseudo_dquoted(exp_word);
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if (exp_exp_word)
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exp_word = exp_exp_word;
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loc = scan(to_be_freed, exp_word, match_at_left);
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//bb_error_msg("op:%c str:'%s' pat:'%s' res:'%s'",
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// exp_op, to_be_freed, exp_word, loc);
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free(exp_exp_word);
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}
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exp_exp_word = expand_pseudo_dquoted(exp_word);
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if (exp_exp_word)
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exp_word = exp_exp_word;
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loc = scan_and_match(to_be_freed, exp_word, scan_flags);
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//bb_error_msg("op:%c str:'%s' pat:'%s' res:'%s'",
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// exp_op, to_be_freed, exp_word, loc);
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free(exp_exp_word);
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if (loc) { /* match was found */
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if (match_at_left) /* # or ## */
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if (scan_flags & SCAN_MATCH_LEFT_HALF) /* # or ## */
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val = loc;
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else /* % or %% */
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*loc = '\0';
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110
shell/match.c
110
shell/match.c
@ -18,6 +18,9 @@
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# include <stdlib.h>
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# include <string.h>
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# include <unistd.h>
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# define FAST_FUNC /* nothing */
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# define PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN /* nothing */
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# define POP_SAVED_FUNCTION_VISIBILITY /* nothing */
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#else
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# include "libbb.h"
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#endif
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@ -26,16 +29,48 @@
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#define pmatch(a, b) !fnmatch((a), (b), 0)
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char *scanleft(char *string, char *pattern, bool match_at_left)
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char* FAST_FUNC scan_and_match(char *string, const char *pattern, unsigned flags)
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{
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char c;
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char *loc = string;
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char *loc;
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char *end;
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unsigned len = strlen(string);
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int early_exit;
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while (1) {
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/* We can stop the scan early only if the string part
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* we are matching against is shrinking, and the pattern has
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* an unquoted "star" at the corresponding end. There are two cases.
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* Case 1:
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* "qwerty" does not match against pattern "*zy",
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* no point in trying to match "werty", "erty" etc:
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*/
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early_exit = (flags == (SCAN_MOVE_FROM_LEFT + SCAN_MATCH_RIGHT_HALF) && pattern[0] == '*');
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if (flags & SCAN_MOVE_FROM_LEFT) {
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loc = string;
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end = string + len + 1;
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} else {
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loc = string + len;
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end = string - 1;
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if (flags == (SCAN_MOVE_FROM_RIGHT + SCAN_MATCH_LEFT_HALF)) {
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/* Case 2:
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* "qwerty" does not match against pattern "qz*",
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* no point in trying to match "qwert", "qwer" etc:
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*/
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const char *p = pattern + strlen(pattern);
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if (--p >= pattern && *p == '*') {
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early_exit = 1;
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while (--p >= pattern && *p == '\\')
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early_exit ^= 1;
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}
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}
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}
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while (loc != end) {
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char c;
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int match;
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c = *loc;
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if (match_at_left) {
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if (flags & SCAN_MATCH_LEFT_HALF) {
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*loc = '\0';
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match = pmatch(pattern, string);
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*loc = c;
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@ -44,33 +79,19 @@ char *scanleft(char *string, char *pattern, bool match_at_left)
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}
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if (match)
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return loc;
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if (!c)
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return NULL;
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loc++;
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}
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}
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char *scanright(char *string, char *pattern, bool match_at_left)
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{
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char c;
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char *loc = string + strlen(string);
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while (loc >= string) {
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int match;
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c = *loc;
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if (match_at_left) {
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*loc = '\0';
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match = pmatch(pattern, string);
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*loc = c;
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} else {
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match = pmatch(pattern, loc);
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if (early_exit) {
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#ifdef STANDALONE
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printf("(early exit) ");
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#endif
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break;
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}
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if (match)
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return loc;
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loc--;
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}
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if (flags & SCAN_MOVE_FROM_LEFT) {
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loc++;
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} else {
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loc--;
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}
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}
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return NULL;
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}
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@ -80,12 +101,11 @@ int main(int argc, char *argv[])
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char *string;
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char *op;
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char *pattern;
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bool match_at_left;
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char *loc;
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int i;
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setvbuf(stdout, NULL, _IONBF, 0);
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if (argc == 1) {
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if (!argv[1]) {
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puts(
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"Usage: match <test> [test...]\n\n"
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"Where a <test> is the form: <string><op><match>\n"
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@ -95,36 +115,34 @@ int main(int argc, char *argv[])
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return 1;
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}
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for (i = 1; i < argc; ++i) {
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while (*++argv) {
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size_t off;
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scan_t scan;
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unsigned scan_flags;
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printf("'%s': ", argv[i]);
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string = strdup(argv[i]);
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string = *argv;
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off = strcspn(string, "#%");
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if (!off) {
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printf("invalid format\n");
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free(string);
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continue;
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}
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op = string + off;
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scan = pick_scan(op[0], op[1], &match_at_left);
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scan_flags = pick_scan(op[0], op[1]);
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printf("'%s': flags:%x, ", string, scan_flags);
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pattern = op + 1;
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if (op[0] == op[1])
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op[1] = '\0', ++pattern;
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pattern++;
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op[0] = '\0';
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loc = scan(string, pattern, match_at_left);
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loc = scan_and_match(string, pattern, scan_flags);
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if (match_at_left) {
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if (scan_flags & SCAN_MATCH_LEFT_HALF) {
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printf("'%s'\n", loc);
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} else {
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*loc = '\0';
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if (loc)
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*loc = '\0';
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printf("'%s'\n", string);
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}
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free(string);
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}
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return 0;
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@ -7,25 +7,26 @@ PUSH_AND_SET_FUNCTION_VISIBILITY_TO_HIDDEN
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//TODO! Why ash.c still uses internal version?!
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typedef char *(*scan_t)(char *string, char *match, bool match_at_left);
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enum {
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SCAN_MOVE_FROM_LEFT = (1 << 0),
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SCAN_MOVE_FROM_RIGHT = (1 << 1),
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SCAN_MATCH_LEFT_HALF = (1 << 2),
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SCAN_MATCH_RIGHT_HALF = (1 << 3),
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};
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char *scanleft(char *string, char *match, bool match_at_left);
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char *scanright(char *string, char *match, bool match_at_left);
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char* FAST_FUNC scan_and_match(char *string, const char *pattern, unsigned flags);
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static inline scan_t pick_scan(char op1, char op2, bool *match_at_left)
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static inline unsigned pick_scan(char op1, char op2)
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{
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/* # - scanleft
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* ## - scanright
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* % - scanright
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* %% - scanleft
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*/
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unsigned scan_flags;
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if (op1 == '#') {
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*match_at_left = true;
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return op1 == op2 ? scanright : scanleft;
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} else {
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*match_at_left = false;
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return op1 == op2 ? scanleft : scanright;
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scan_flags = SCAN_MATCH_LEFT_HALF +
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(op1 == op2 ? SCAN_MOVE_FROM_RIGHT : SCAN_MOVE_FROM_LEFT);
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} else { /* % */
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scan_flags = SCAN_MATCH_RIGHT_HALF +
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(op1 == op2 ? SCAN_MOVE_FROM_LEFT : SCAN_MOVE_FROM_RIGHT);
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}
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return scan_flags;
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}
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POP_SAVED_FUNCTION_VISIBILITY
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