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I think Linus did a cut & paste from an early JIT code while
developing the current extended SHA1 notation, and left it there as a
courtesy, but the directory does not deserve to be treated any more
specially than, say, .git/refs/bisect.
If the subdirectories under .git/refs proliferate, we may want to
switch to scanning that hierarchy at runtime, instead of the current
hard-coded set, although I think that would be overkill.
Signed-off-by: Junio C Hamano <junkio@cox.net>
From nobody Mon Sep 17 00:00:00 2001
Subject: [PATCH] Add a new extended SHA1 syntax <name>:<num>
From: Junio C Hamano <junkio@cox.net>
Date: 1124617434 -0700
The new notation is a short-hand for <name> followed by <num>
caret ('^') characters. E.g. "master:4" is the fourth
generation ancestor of the current "master" branch head,
following the first parents; same as "master^^^^" but a bit more
readable.
This will be used in the updated "git show-branch" command.
Signed-off-by: Junio C Hamano <junkio@cox.net>
---
sha1_name.c | 41 +++++++++++++++++++++++++++++++++++++++++
1 files changed, 41 insertions(+), 0 deletions(-)
d5098ce769da46df6d45dc8f41b06dd758fdaea7
diff --git a/sha1_name.c b/sha1_name.c
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -191,9 +191,29 @@ static int get_parent(const char *name,
return -1;
}
+static int get_nth_ancestor(const char *name, int len,
+ unsigned char *result, int generation)
+{
+ unsigned char sha1[20];
+ int ret = get_sha1_1(name, len, sha1);
+ if (ret)
+ return ret;
+
+ while (generation--) {
+ struct commit *commit = lookup_commit_reference(sha1);
+
+ if (!commit || parse_commit(commit) || !commit->parents)
+ return -1;
+ memcpy(sha1, commit->parents->item->object.sha1, 20);
+ }
+ memcpy(result, sha1, 20);
+ return 0;
+}
+
static int get_sha1_1(const char *name, int len, unsigned char *sha1)
{
int parent, ret;
+ const char *cp;
/* foo^[0-9] or foo^ (== foo^1); we do not do more than 9 parents. */
if (len > 2 && name[len-2] == '^' &&
@@ -210,6 +230,27 @@ static int get_sha1_1(const char *name,
if (parent >= 0)
return get_parent(name, len, sha1, parent);
+ /* name:3 is name^^^,
+ * name:12 is name^^^^^^^^^^^^, and
+ * name: is name
+ */
+ parent = 0;
+ for (cp = name + len - 1; name <= cp; cp--) {
+ int ch = *cp;
+ if ('0' <= ch && ch <= '9')
+ continue;
+ if (ch != ':')
+ parent = -1;
+ break;
+ }
+ if (!parent && *cp == ':') {
+ int len1 = cp - name;
+ cp++;
+ while (cp < name + len)
+ parent = parent * 10 + *cp++ - '0';
+ return get_nth_ancestor(name, len1, sha1, parent);
+ }
+
ret = get_sha1_basic(name, len, sha1);
if (!ret)
return 0;
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git-rev-parse HEAD^1 would fail, because of an off-by-one bug (but HEAD^
would yield the expected result). Also, when the parent does not exist, do
not silently return an incorrect SHA1. Of course, this no longer applies
to git-rev-parse alone, but every user of get_sha1().
While at it, add a test.
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>
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Junio C Hamano
Linus Torvalds
Johannes Schindelin