[PATCH] Support for pickaxe matching regular expressions

From: Petr Baudis <pasky@suse.cz>
Date: Mar 29, 2006, 00:16 UTC
Message-ID: <20060329001633.GF27689@pasky.or.cz>
In-Reply-To: <Pine.LNX.4.64.0603281500280.15714@g5.osdl.org>

Dear diary, on Wed, Mar 29, 2006 at 01:03:05AM CEST, I got a letter where Linus Torvalds <torvalds@osdl.org> said that...

Show 5 quoted lines

> On Tue, 28 Mar 2006, Mark Wooding wrote:
> > Urgh.  So, which regex library do people want to use? ;-)  (My vote's
> > for pcre.)
> 
> ... No regexps, ...

To toss a random feature idea around, in the recent days I've found myself thinking about regexp pickaxe several times.

And while already tossing stuff, what about a naive proof-of-concept patch? A silly example:

	git-whatchanged --pickaxe-regex -p -S' +$' | less -p '^[-+ ].* +$'

Then keep hitting 'n'. Good that most of the matches are deletions. :) (Or commit messages.)

---

git-diff-* --pickaxe-regex will change the -S pickaxe to match POSIX extended regular expressions instead of fixed strings.

The regex.h library is a rather stupid interface and I like pcre too, but with any luck it will be everywhere we will want to run Git on, it being POSIX.2 and all. I'm not sure if we can expect platforms like AIX to conform to POSIX.2 or if win32 has regex.h. We might add a flag to Makefile if there is a portability trouble potential.

Signed-off-by: Petr Baudis <pasky@suse.cz>
---

 Documentation/diff-options.txt |    4 ++
 diff.c                         |    2 +
 diff.h                         |    1 +
 diffcore-pickaxe.c             |   68 ++++++++++++++++++++++++++++++----------
 4 files changed, 58 insertions(+), 17 deletions(-)

diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt
index 2a0275e..ec6811c 100644
--- a/Documentation/diff-options.txt
+++ b/Documentation/diff-options.txt
@@ -69,6 +69,10 @@
 	changeset, not just the files that contain the change
 	in <string>.
 
+--pickaxe-regex::
+	Make the <string> not a plain string but an extended POSIX
+	regex to match.
+
 -O<orderfile>::
 	Output the patch in the order specified in the
 	<orderfile>, which has one shell glob pattern per line.
diff --git a/diff.c b/diff.c
index 8b37477..e006adb 100644
--- a/diff.c
+++ b/diff.c
@@ -883,6 +883,8 @@ int diff_opt_parse(struct diff_options *
 		options->filter = arg + 14;
 	else if (!strcmp(arg, "--pickaxe-all"))
 		options->pickaxe_opts = DIFF_PICKAXE_ALL;
+	else if (!strcmp(arg, "--pickaxe-regex"))
+		options->pickaxe_opts = DIFF_PICKAXE_REGEX;
 	else if (!strncmp(arg, "-B", 2)) {
 		if ((options->break_opt =
 		     diff_scoreopt_parse(arg)) == -1)
diff --git a/diff.h b/diff.h
index 8fac465..564c94f 100644
--- a/diff.h
+++ b/diff.h
@@ -112,6 +112,7 @@ #define DIFF_DETECT_RENAME	1
 #define DIFF_DETECT_COPY	2
 
 #define DIFF_PICKAXE_ALL	1
+#define DIFF_PICKAXE_REGEX	2
 
 extern void diffcore_std(struct diff_options *);
 
diff --git a/diffcore-pickaxe.c b/diffcore-pickaxe.c
index 50e46ab..d89f314 100644
--- a/diffcore-pickaxe.c
+++ b/diffcore-pickaxe.c
@@ -1,12 +1,15 @@
 /*
  * Copyright (C) 2005 Junio C Hamano
  */
+#include <regex.h>
+
 #include "cache.h"
 #include "diff.h"
 #include "diffcore.h"
 
 static unsigned int contains(struct diff_filespec *one,
-			     const char *needle, unsigned long len)
+			     const char *needle, unsigned long len,
+			     regex_t *regexp)
 {
 	unsigned int cnt;
 	unsigned long offset, sz;
@@ -17,15 +20,28 @@ static unsigned int contains(struct diff
 	sz = one->size;
 	data = one->data;
 	cnt = 0;
-
-	/* Yes, I've heard of strstr(), but the thing is *data may
-	 * not be NUL terminated.  Sue me.
-	 */
-	for (offset = 0; offset + len <= sz; offset++) {
-		/* we count non-overlapping occurrences of needle */
-		if (!memcmp(needle, data + offset, len)) {
-			offset += len - 1;
+
+	if (regexp) {
+		regmatch_t regmatch;
+		int flags = 0;
+
+		while (*data && !regexec(regexp, data, 1, &regmatch, flags)) {
+			flags |= REG_NOTBOL;
+			data += regmatch.rm_so;
+			if (*data) data++;
 			cnt++;
+		}
+
+	} else { /* Classic exact string match */
+		/* Yes, I've heard of strstr(), but the thing is *data may
+		 * not be NUL terminated.  Sue me.
+		 */
+		for (offset = 0; offset + len <= sz; offset++) {
+			/* we count non-overlapping occurrences of needle */
+			if (!memcmp(needle, data + offset, len)) {
+				offset += len - 1;
+				cnt++;
+			}
 		}
 	}
 	return cnt;
@@ -36,10 +52,24 @@ void diffcore_pickaxe(const char *needle
 	struct diff_queue_struct *q = &diff_queued_diff;
 	unsigned long len = strlen(needle);
 	int i, has_changes;
+	regex_t regex, *regexp = NULL;
 	struct diff_queue_struct outq;
 	outq.queue = NULL;
 	outq.nr = outq.alloc = 0;
 
+	if (opts & DIFF_PICKAXE_REGEX) {
+		int err;
+		err = regcomp(&regex, needle, REG_EXTENDED | REG_NEWLINE);
+		if (err) {
+			/* The POSIX.2 people are surely sick */
+			char errbuf[1024];
+			regerror(err, &regex, errbuf, 1024);
+			regfree(&regex);
+			die("invalid pickaxe regex: %s", errbuf);
+		}
+		regexp = &regex;
+	}
+
 	if (opts & DIFF_PICKAXE_ALL) {
 		/* Showing the whole changeset if needle exists */
 		for (i = has_changes = 0; !has_changes && i < q->nr; i++) {
@@ -48,16 +78,16 @@ void diffcore_pickaxe(const char *needle
 				if (!DIFF_FILE_VALID(p->two))
 					continue; /* ignore unmerged */
 				/* created */
-				if (contains(p->two, needle, len))
+				if (contains(p->two, needle, len, regexp))
 					has_changes++;
 			}
 			else if (!DIFF_FILE_VALID(p->two)) {
-				if (contains(p->one, needle, len))
+				if (contains(p->one, needle, len, regexp))
 					has_changes++;
 			}
 			else if (!diff_unmodified_pair(p) &&
-				 contains(p->one, needle, len) !=
-				 contains(p->two, needle, len))
+				 contains(p->one, needle, len, regexp) !=
+				 contains(p->two, needle, len, regexp))
 				has_changes++;
 		}
 		if (has_changes)
@@ -80,16 +110,16 @@ void diffcore_pickaxe(const char *needle
 				if (!DIFF_FILE_VALID(p->two))
 					; /* ignore unmerged */
 				/* created */
-				else if (contains(p->two, needle, len))
+				else if (contains(p->two, needle, len, regexp))
 					has_changes = 1;
 			}
 			else if (!DIFF_FILE_VALID(p->two)) {
-				if (contains(p->one, needle, len))
+				if (contains(p->one, needle, len, regexp))
 					has_changes = 1;
 			}
 			else if (!diff_unmodified_pair(p) &&
-				 contains(p->one, needle, len) !=
-				 contains(p->two, needle, len))
+				 contains(p->one, needle, len, regexp) !=
+				 contains(p->two, needle, len, regexp))
 				has_changes = 1;
 
 			if (has_changes)
@@ -97,6 +127,10 @@ void diffcore_pickaxe(const char *needle
 			else
 				diff_free_filepair(p);
 		}
+
+	if (opts & DIFF_PICKAXE_REGEX) {
+		regfree(&regex);
+	}
 
 	free(q->queue);
 	*q = outq;

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
Right now I am having amnesia and deja-vu at the same time.  I think
I have forgotten this before.