[PATCH 1/2] grep -w: forward to next possible position after rejected match
From: René Scharfe <hidden>
Date: 2016-06-15 22:45:55
Subsystem:
the rest · Maintainer:
Linus Torvalds
grep -w accepts matches between non-word characters, only. If a match from regexec() doesn't meet this criteria, grep continues its search after the first character of that match. We can be a bit smarter here and skip all positions that follow a word character first, as they can't match our criteria. This way we can consume characters quite cheaply and don't need to special-case the handling of the beginning of a line. Here's a contrived example command on msysgit (best of five runs): $ time git grep -w ...... v1.6.1 >/dev/null real 0m1.611s user 0m0.000s sys 0m0.015s With the patch it's quite a bit faster: $ time git grep -w ...... v1.6.1 >/dev/null real 0m1.179s user 0m0.000s sys 0m0.015s More common search patterns will gain a lot less, but it's a nice clean up anyway. Signed-off-by: Rene Scharfe <redacted> --- grep.c | 11 +++++++---- 1 files changed, 7 insertions(+), 4 deletions(-)
diff --git a/grep.c b/grep.c
index 49e9319..394703b 100644
--- a/grep.c
+++ b/grep.c@@ -294,7 +294,6 @@ static struct { static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol, char *eol, enum grep_context ctx) { int hit = 0; - int at_true_bol = 1; int saved_ch = 0; regmatch_t pmatch[10];
@@ -337,7 +336,7 @@ static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol * either end of the line, or at word boundary * (i.e. the next char must not be a word char). */ - if ( ((pmatch[0].rm_so == 0 && at_true_bol) || + if ( ((pmatch[0].rm_so == 0) || !word_char(bol[pmatch[0].rm_so-1])) && ((pmatch[0].rm_eo == (eol-bol)) || !word_char(bol[pmatch[0].rm_eo])) )
@@ -349,10 +348,14 @@ static int match_one_pattern(struct grep_opt *opt, struct grep_pat *p, char *bol /* There could be more than one match on the * line, and the first match might not be * strict word match. But later ones could be! + * Forward to the next possible start, i.e. the + * next position following a non-word char. */ bol = pmatch[0].rm_so + bol + 1; - at_true_bol = 0; - goto again; + while (word_char(bol[-1]) && bol < eol) + bol++; + if (bol < eol) + goto again; } } if (p->token == GREP_PATTERN_HEAD && saved_ch)
--
1.6.1