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[PATCH] Add a new extended SHA1 syntax <name>~<num> 

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>
This commit is contained in:
Junio C Hamano 2005-08-21 02:43:54 -07:00
parent 792fe559d0
commit 4f7599ac25
1 changed files with 41 additions and 0 deletions
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41
sha1_name.c
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@ -191,9 +191,29 @@ static int get_parent(const char *name, int len,
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, int len, unsigned char *sha1)
if (parent >= 0)
return get_parent(name, len, sha1, parent);
/* "name~3" is "name^^^",
* "name~12" is "name^^^^^^^^^^^^", and
* "name~" and "name~0" are name -- not "name^0"!
*/
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;