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authorJunio C Hamano <gitster@pobox.com>2010-01-12 00:56:15 -0800
committerJunio C Hamano <gitster@pobox.com>2010-01-12 00:58:13 -0800
commite2d2e383d87dcbcd296ca9f21f3c8b7ef853c928 (patch)
tree1cd0fcf96fe378a0c27a2b3b06ca4af9463fac78 /grep.c
parent902f235378cb2b2f6dd5dd664b9630c95321f0ae (diff)
parenta26345b6085340ebd61e156aa8154a80196bee0f (diff)
downloadgit-e2d2e383d87dcbcd296ca9f21f3c8b7ef853c928.tar.gz
Merge branch 'jc/maint-1.6.4-grep-lookahead' into jc/maint-grep-lookahead
* jc/maint-1.6.4-grep-lookahead: grep: optimize built-in grep by skipping lines that do not hit This needs to be an evil merge as fixmatch() changed signature since 5183bf6 (grep: Allow case insensitive search of fixed-strings, 2009-11-06). Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'grep.c')
-rw-r--r--grep.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/grep.c b/grep.c
index bdadf2c0cc..62723da134 100644
--- a/grep.c
+++ b/grep.c
@@ -615,6 +615,65 @@ static void show_pre_context(struct grep_opt *opt, const char *name, char *buf,
}
}
+static int should_lookahead(struct grep_opt *opt)
+{
+ struct grep_pat *p;
+
+ if (opt->extended)
+ return 0; /* punt for too complex stuff */
+ if (opt->invert)
+ return 0;
+ for (p = opt->pattern_list; p; p = p->next) {
+ if (p->token != GREP_PATTERN)
+ return 0; /* punt for "header only" and stuff */
+ }
+ return 1;
+}
+
+static int look_ahead(struct grep_opt *opt,
+ unsigned long *left_p,
+ unsigned *lno_p,
+ char **bol_p)
+{
+ unsigned lno = *lno_p;
+ char *bol = *bol_p;
+ struct grep_pat *p;
+ char *sp, *last_bol;
+ regoff_t earliest = -1;
+
+ for (p = opt->pattern_list; p; p = p->next) {
+ int hit;
+ regmatch_t m;
+
+ if (p->fixed)
+ hit = !fixmatch(p->pattern, bol, p->ignore_case, &m);
+ else
+ hit = !regexec(&p->regexp, bol, 1, &m, 0);
+ if (!hit || m.rm_so < 0 || m.rm_eo < 0)
+ continue;
+ if (earliest < 0 || m.rm_so < earliest)
+ earliest = m.rm_so;
+ }
+
+ if (earliest < 0) {
+ *bol_p = bol + *left_p;
+ *left_p = 0;
+ return 1;
+ }
+ for (sp = bol + earliest; bol < sp && sp[-1] != '\n'; sp--)
+ ; /* find the beginning of the line */
+ last_bol = sp;
+
+ for (sp = bol; sp < last_bol; sp++) {
+ if (*sp == '\n')
+ lno++;
+ }
+ *left_p -= last_bol - bol;
+ *bol_p = last_bol;
+ *lno_p = lno;
+ return 0;
+}
+
static int grep_buffer_1(struct grep_opt *opt, const char *name,
char *buf, unsigned long size, int collect_hits)
{
@@ -624,6 +683,7 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
unsigned last_hit = 0;
int binary_match_only = 0;
unsigned count = 0;
+ int try_lookahead = 0;
enum grep_context ctx = GREP_CONTEXT_HEAD;
xdemitconf_t xecfg;
@@ -652,11 +712,26 @@ static int grep_buffer_1(struct grep_opt *opt, const char *name,
opt->priv = &xecfg;
}
}
+ try_lookahead = should_lookahead(opt);
while (left) {
char *eol, ch;
int hit;
+ /*
+ * look_ahead() skips quicly to the line that possibly
+ * has the next hit; don't call it if we need to do
+ * something more than just skipping the current line
+ * in response to an unmatch for the current line. E.g.
+ * inside a post-context window, we will show the current
+ * line as a context around the previous hit when it
+ * doesn't hit.
+ */
+ if (try_lookahead
+ && !(last_hit
+ && lno <= last_hit + opt->post_context)
+ && look_ahead(opt, &left, &lno, &bol))
+ break;
eol = end_of_line(bol, &left);
ch = *eol;
*eol = 0;