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Introduce notation "ref^{type}".

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Existing "tagname^0" notation means "dereference tag zero or more
times until you cannot dereference it anymore, and make sure it is a
commit -- otherwise barf".  But tags do not necessarily reference
commit objects.

This commit introduces a bit more generalized notation, "ref^{type}".
Existing "ref^0" is a shorthand for "ref^{commit}".  If the type
is empty, it just dereferences tags until it hits a non-tag object.

With this, "git-rev-parse --verify 'junio-gpg-pub^{}'" shows the blob
object name -- there is no need to manually read the tag object and
find out the object name anymore.

"git-rev-parse --verify 'HEAD^{tree}'" can be used to find out the
tree object name of the HEAD commit.

Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Junio C Hamano 2005-10-13 18:57:40 -07:00
parent 1a7141ff28
commit 5385f52da8
1 changed files with 83 additions and 0 deletions
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83
sha1_name.c
View File

@ -1,5 +1,8 @@
#include "cache.h"
#include "tag.h"
#include "commit.h"
#include "tree.h"
#include "blob.h"
static int find_short_object_filename(int len, const char *name, unsigned char *sha1)
{
@ -274,6 +277,82 @@ static int get_nth_ancestor(const char *name, int len,
return 0;
}
static int peel_onion(const char *name, int len, unsigned char *sha1)
{
unsigned char outer[20];
const char *sp;
const char *type_string = NULL;
struct object *o;
/*
* "ref^{type}" dereferences ref repeatedly until you cannot
* dereference anymore, or you get an object of given type,
* whichever comes first. "ref^{}" means just dereference
* tags until you get a non-tag. "ref^0" is a shorthand for
* "ref^{commit}". "commit^{tree}" could be used to find the
* top-level tree of the given commit.
*/
if (len < 4 || name[len-1] != '}')
return -1;
for (sp = name + len - 1; name <= sp; sp--) {
int ch = *sp;
if (ch == '{' && name < sp && sp[-1] == '^')
break;
}
if (sp <= name)
return -1;
sp++; /* beginning of type name, or closing brace for empty */
if (!strncmp(commit_type, sp, 6) && sp[6] == '}')
type_string = commit_type;
else if (!strncmp(tree_type, sp, 4) && sp[4] == '}')
type_string = tree_type;
else if (!strncmp(blob_type, sp, 4) && sp[4] == '}')
type_string = blob_type;
else if (sp[0] == '}')
type_string = NULL;
else
return -1;
if (get_sha1_1(name, sp - name - 2, outer))
return -1;
o = parse_object(outer);
if (!o)
return -1;
if (!type_string) {
o = deref_tag(o);
memcpy(sha1, o->sha1, 20);
}
else {
/* At this point, the syntax look correct, so
* if we do not get the needed object, we should
* barf.
*/
while (1) {
if (!o)
return -1;
if (o->type == type_string) {
memcpy(sha1, o->sha1, 20);
return 0;
}
if (o->type == tag_type)
o = ((struct tag*) o)->tagged;
else if (o->type == commit_type)
o = &(((struct commit *) o)->tree->object);
else
return error("%.*s: expected %s type, but the object dereferences to %s type",
len, name, type_string,
o->type);
if (!o->parsed)
parse_object(o->sha1);
}
}
return 0;
}
static int get_sha1_1(const char *name, int len, unsigned char *sha1)
{
int parent, ret;
@ -315,6 +394,10 @@ static int get_sha1_1(const char *name, int len, unsigned char *sha1)
return get_nth_ancestor(name, len1, sha1, parent);
}
ret = peel_onion(name, len, sha1);
if (!ret)
return 0;
ret = get_sha1_basic(name, len, sha1);
if (!ret)
return 0;