get_sha1(): :path and :[0-3]:path to extract from index.

Earlier patch to say <ent>:<path> by Linus was very useful, and
this extends the same idea to the current index.  An sha1
expression :<path> extracts the object name for the named path
from the current index.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/sha1_name.c b/sha1_name.c
index 345935b..ec5cd2c 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -458,17 +458,55 @@ int get_sha1(const char *name, unsigned char *sha1)
 {
        int ret;
        unsigned unused;
+       int namelen = strlen(name);
+       const char *cp;
 
        prepare_alt_odb();
-       ret = get_sha1_1(name, strlen(name), sha1);
-       if (ret < 0) {
-               const char *cp = strchr(name, ':');
-               if (cp) {
-                       unsigned char tree_sha1[20];
-                       if (!get_sha1_1(name, cp-name, tree_sha1))
-                               return get_tree_entry(tree_sha1, cp+1, sha1,
-                                                     &unused);
+       ret = get_sha1_1(name, namelen, sha1);
+       if (!ret)
+               return ret;
+       /* sha1:path --> object name of path in ent sha1
+        * :path -> object name of path in index
+        * :[0-3]:path -> object name of path in index at stage
+        */
+       if (name[0] == ':') {
+               int stage = 0;
+               struct cache_entry *ce;
+               int pos;
+               if (namelen < 3 ||
+                   name[2] != ':' ||
+                   name[1] < '0' || '3' < name[1])
+                       cp = name + 1;
+               else {
+                       stage = name[1] - '0';
+                       cp = name + 3;
                }
+               namelen = namelen - (cp - name);
+               if (!active_cache)
+                       read_cache();
+               if (active_nr < 0)
+                       return -1;
+               pos = cache_name_pos(cp, namelen);
+               if (pos < 0)
+                       pos = -pos - 1;
+               while (pos < active_nr) {
+                       ce = active_cache[pos];
+                       if (ce_namelen(ce) != namelen ||
+                           memcmp(ce->name, cp, namelen))
+                               break;
+                       if (ce_stage(ce) == stage) {
+                               memcpy(sha1, ce->sha1, 20);
+                               return 0;
+                       }
+               }
+               return -1;
+       }
+       cp = strchr(name, ':');
+       if (cp) {
+               unsigned char tree_sha1[20];
+               if (!get_sha1_1(name, cp-name, tree_sha1))
+                       return get_tree_entry(tree_sha1, cp+1, sha1,
+                                             &unused);
        }
        return ret;
 }