Add git-name-rev

git-name-rev tries to find nice symbolic names for commits. It does so by
walking the commits from the refs. When the symbolic name is ambiguous, the
following heuristic is applied: Try to avoid too many ~'s, and if two ambiguous
names have the same count of ~'s, take the one whose last number is smaller.

With "--tags", the names are derived only from tags.

With "--stdin", the stdin is parsed, and after every sha1 for which a name
could be found, the name is appended. (Try "git log | git name-rev --stdin".)

Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Documentation/git-name-rev.txt b/Documentation/git-name-rev.txt
new file mode 100644 (file)
index 0000000..e37b0b8
--- /dev/null
+++ b/Documentation/git-name-rev.txt
@@ -0,0 +1,66 @@
+git-name-rev(1)
+===============
+
+NAME
+----
+git-name-rev - Find symbolic names for given revs.
+
+
+SYNOPSIS
+--------
+'git-name-rev' [--tags] ( --all | --stdin | <commitish>... )
+
+DESCRIPTION
+-----------
+Finds symbolic names suitable for human digestion for revisions given in any
+format parsable by git-rev-parse.
+
+
+OPTIONS
+-------
+
+--tags::
+       Do not use branch names, but only tags to name the commits
+
+--all::
+       List all commits reachable from all refs
+
+--stdin::
+       Read from stdin, append "(<rev_name>)" to all sha1's of name'able
+       commits, and pass to stdout
+
+EXAMPLE
+-------
+
+Given a commit, find out where it is relative to the local refs. Say somebody
+wrote you about that phantastic commit 33db5f4d9027a10e477ccf054b2c1ab94f74c85a.
+Of course, you look into the commit, but that only tells you what happened, but
+not the context.
+
+Enter git-name-rev:
+
+------------
+% git name-rev 33db5f4d9027a10e477ccf054b2c1ab94f74c85a
+------------
+
+Now you are wiser, because you know that it happened 940 revisions before v0.99.
+
+Another nice thing you can do is:
+
+------------
+% git log | git name-rev --stdin
+------------
+
+
+Author
+------
+Written by Johannes Schindelin <Johannes.Schindelin@gmx.de>
+
+Documentation
+--------------
+Documentation by Johannes Schindelin.
+
+GIT
+---
+Part of the gitlink:git[7] suite
+

diff --git a/Makefile b/Makefile
index 701067d..e76e6c4 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -122,7 +122,7 @@ PROGRAMS = \
        git-unpack-objects$X git-update-index$X git-update-server-info$X \
        git-upload-pack$X git-verify-pack$X git-write-tree$X \
        git-update-ref$X git-symbolic-ref$X git-check-ref-format$X \
-       $(SIMPLE_PROGRAMS)
+       git-name-rev$X $(SIMPLE_PROGRAMS)
 
 # Backward compatibility -- to be removed after 1.0
 PROGRAMS += git-ssh-pull$X git-ssh-push$X

diff --git a/name-rev.c b/name-rev.c
new file mode 100644 (file)
index 0000000..21fecdf
--- /dev/null
+++ b/name-rev.c
@@ -0,0 +1,246 @@
+#include <stdlib.h>
+#include "cache.h"
+#include "commit.h"
+#include "tag.h"
+#include "refs.h"
+
+static const char name_rev_usage[] =
+       "git-name-rev [--tags] ( --all | --stdin | commitish [commitish...] )\n";
+
+typedef struct rev_name {
+       const char *tip_name;
+       int merge_traversals;
+       int generation;
+} rev_name;
+
+static long cutoff = LONG_MAX;
+
+static void name_rev(struct commit *commit,
+               const char *tip_name, int merge_traversals, int generation,
+               int deref)
+{
+       struct rev_name *name = (struct rev_name *)commit->object.util;
+       struct commit_list *parents;
+       int parent_number = 0;
+
+       if (!commit->object.parsed)
+               parse_commit(commit);
+
+       if (commit->date < cutoff)
+               return;
+
+       if (deref) {
+               char *new_name = xmalloc(strlen(tip_name)+3);
+               strcpy(new_name, tip_name);
+               strcat(new_name, "^0");
+               tip_name = new_name;
+
+               if (generation)
+                       die("generation: %d, but deref?", generation);
+       }
+
+       if (name == NULL) {
+               name = xmalloc(sizeof(rev_name));
+               commit->object.util = name;
+               goto copy_data;
+       } else if (name->merge_traversals > merge_traversals ||
+                       (name->merge_traversals == merge_traversals &&
+                        name->generation > generation)) {
+copy_data:
+               name->tip_name = tip_name;
+               name->merge_traversals = merge_traversals;
+               name->generation = generation;
+       } else
+               return;
+
+       for (parents = commit->parents;
+                       parents;
+                       parents = parents->next, parent_number++) {
+               if (parent_number > 0) {
+                       char *new_name = xmalloc(strlen(tip_name)+8);
+
+                       if (generation > 0)
+                               sprintf(new_name, "%s~%d^%d", tip_name,
+                                               generation, parent_number);
+                       else
+                               sprintf(new_name, "%s^%d", tip_name, parent_number);
+
+                       name_rev(parents->item, new_name,
+                               merge_traversals + 1 , 0, 0);
+               } else {
+                       name_rev(parents->item, tip_name, merge_traversals,
+                               generation + 1, 0);
+               }
+       }
+}
+
+static int tags_only = 0;
+
+static int name_ref(const char *path, const unsigned char *sha1)
+{
+       struct object *o = parse_object(sha1);
+       int deref = 0;
+
+       if (tags_only && strncmp(path, "refs/tags/", 10))
+               return 0;
+
+       while (o && o->type == tag_type) {
+               struct tag *t = (struct tag *) o;
+               if (!t->tagged)
+                       break; /* broken repository */
+               o = parse_object(t->tagged->sha1);
+               deref = 1;
+       }
+       if (o && o->type == commit_type) {
+               struct commit *commit = (struct commit *)o;
+               const char *p;
+
+               while ((p = strchr(path, '/')))
+                       path = p+1;
+
+               name_rev(commit, strdup(path), 0, 0, deref);
+       }
+       return 0;
+}
+
+/* returns a static buffer */
+static const char* get_rev_name(struct object *o)
+{
+       static char buffer[1024];
+       struct rev_name *n = (struct rev_name *)o->util;
+       if (!n)
+               return "undefined";
+
+       if (!n->generation)
+               return n->tip_name;
+
+       snprintf(buffer, sizeof(buffer), "%s~%d", n->tip_name, n->generation);
+
+       return buffer;
+}
+       
+int main(int argc, char **argv)
+{
+       struct object_list *revs = NULL;
+       struct object_list **walker = &revs;
+       int as_is = 0, all = 0, transform_stdin = 0;
+
+       setup_git_directory();
+
+       if (argc < 2)
+               usage(name_rev_usage);
+
+       for (--argc, ++argv; argc; --argc, ++argv) {
+               unsigned char sha1[20];
+               struct object *o;
+               struct commit *commit;
+
+               if (!as_is && (*argv)[0] == '-') {
+                       if (!strcmp(*argv, "--")) {
+                               as_is = 1;
+                               continue;
+                       } else if (!strcmp(*argv, "--tags")) {
+                               tags_only = 1;
+                               continue;
+                       } else if (!strcmp(*argv, "--all")) {
+                               if (argc > 1)
+                                       die("Specify either a list, or --all, not both!");
+                               all = 1;
+                               cutoff = 0;
+                               continue;
+                       } else if (!strcmp(*argv, "--stdin")) {
+                               if (argc > 1)
+                                       die("Specify either a list, or --stdin, not both!");
+                               transform_stdin = 1;
+                               cutoff = 0;
+                               continue;
+                       }
+                       usage(name_rev_usage);
+               }
+
+               if (get_sha1(*argv, sha1)) {
+                       fprintf(stderr, "Could not get sha1 for %s. Skipping.\n",
+                                       *argv);
+                       continue;
+               }
+
+               o = deref_tag(parse_object(sha1));
+               if (!o || o->type != commit_type) {
+                       fprintf(stderr, "Could not get commit for %s. Skipping.\n",
+                                       *argv);
+                       continue;
+               }
+
+               commit = (struct commit *)o;
+
+               if (cutoff > commit->date)
+                       cutoff = commit->date;
+
+               object_list_append((struct object *)commit, walker);
+               (*walker)->name = *argv;
+               walker = &((*walker)->next);
+       }
+
+       for_each_ref(name_ref);
+
+       if (transform_stdin) {
+               char buffer[2048];
+               char *p, *p_start;
+
+               while (!feof(stdin)) {
+                       int forty = 0;
+                       p = fgets(buffer, sizeof(buffer), stdin);
+                       if (!p)
+                               break;
+
+                       for (p_start = p; *p; p++) {
+#define ishex(x) (isdigit((x)) || ((x) >= 'a' && (x) <= 'f'))
+                               if (!ishex(*p))
+                                       forty = 0;
+                               else if (++forty == 40 &&
+                                               !ishex(*(p+1))) {
+                                       unsigned char sha1[40];
+                                       const char *name = "undefined";
+                                       char c = *(p+1);
+
+                                       forty = 0;
+
+                                       *(p+1) = 0;
+                                       if (!get_sha1(p - 39, sha1)) {
+                                               struct object *o =
+                                                       lookup_object(sha1);
+                                               if (o)
+                                                       name = get_rev_name(o);
+                                       }
+                                       *(p+1) = c;
+
+                                       if (!strcmp(name, "undefined"))
+                                               continue;
+
+                                       fwrite(p_start, p - p_start, 1, stdout);
+                                       fputc('(', stdout);
+                                       fputs(name, stdout);
+                                       fputc(')', stdout);
+                                       p_start = p + 1;
+                               }
+                       }
+
+                       /* flush */
+                       if (p_start != p)
+                               fwrite(p_start, p - p_start, 1, stdout);
+               }
+       } else if (all) {
+               extern struct object **objs;
+               extern int nr_objs;
+               int i;
+
+               for (i = 0; i < nr_objs; i++)
+                       printf("%s %s\n", sha1_to_hex(objs[i]->sha1),
+                                       get_rev_name(objs[i]));
+       } else
+               for ( ; revs; revs = revs->next)
+                       printf("%s %s\n", revs->name, get_rev_name(revs->item));
+
+       return 0;
+}
+