git-clone: exit early if repo isn't specified
[gitweb.git] / show-branch.c
index fc827ee4972254661f5fc09cb7f8890b1d007646..24efb65e622d8dfe44db22e5bc23c9f8cc328109 100644 (file)
@@ -1,10 +1,15 @@
 #include <stdlib.h>
+#include <fnmatch.h>
 #include "cache.h"
 #include "commit.h"
 #include "refs.h"
 
 static const char show_branch_usage[] =
-"git-show-branch [--all] [--heads] [--tags] [--more=count] [<refs>...]";
+"git-show-branch [--current] [--all] [--heads] [--tags] [--topo-order] [--more=count | --list | --independent | --merge-base ] [--topics] [<refs>...]";
+
+static int default_num = 0;
+static int default_alloc = 0;
+static char **default_arg = NULL;
 
 #define UNINTERESTING  01
 
@@ -35,26 +40,26 @@ static struct commit *pop_one_commit(struct commit_list **list_p)
 }
 
 struct commit_name {
-       int head_rev;   /* which head's ancestor? */
-       int generation; /* how many parents away from head_rev */
+       const char *head_name; /* which head's ancestor? */
+       int generation; /* how many parents away from head_name */
 };
 
-/* Name the commit as nth generation ancestor of head_rev;
+/* Name the commit as nth generation ancestor of head_name;
  * we count only the first-parent relationship for naming purposes.
  */
-static void name_commit(struct commit *commit, int head_rev, int nth)
+static void name_commit(struct commit *commit, const char *head_name, int nth)
 {
        struct commit_name *name;
        if (!commit->object.util)
                commit->object.util = xmalloc(sizeof(struct commit_name));
        name = commit->object.util;
-       name->head_rev = head_rev;
+       name->head_name = head_name;
        name->generation = nth;
 }
 
 /* Parent is the first parent of the commit.  We may name it
- * as (n+1)th generation ancestor of the same head_rev as
- * commit is nth generation ancestore of, if that generation
+ * as (n+1)th generation ancestor of the same head_name as
+ * commit is nth generation ancestor of, if that generation
  * number is better than the name it already has.
  */
 static void name_parent(struct commit *commit, struct commit *parent)
@@ -65,10 +70,104 @@ static void name_parent(struct commit *commit, struct commit *parent)
                return;
        if (!parent_name ||
            commit_name->generation + 1 < parent_name->generation)
-               name_commit(parent, commit_name->head_rev,
+               name_commit(parent, commit_name->head_name,
                            commit_name->generation + 1);
 }
 
+static int name_first_parent_chain(struct commit *c)
+{
+       int i = 0;
+       while (c) {
+               struct commit *p;
+               if (!c->object.util)
+                       break;
+               if (!c->parents)
+                       break;
+               p = c->parents->item;
+               if (!p->object.util) {
+                       name_parent(c, p);
+                       i++;
+               }
+               c = p;
+       }
+       return i;
+}
+
+static void name_commits(struct commit_list *list,
+                        struct commit **rev,
+                        char **ref_name,
+                        int num_rev)
+{
+       struct commit_list *cl;
+       struct commit *c;
+       int i;
+
+       /* First give names to the given heads */
+       for (cl = list; cl; cl = cl->next) {
+               c = cl->item;
+               if (c->object.util)
+                       continue;
+               for (i = 0; i < num_rev; i++) {
+                       if (rev[i] == c) {
+                               name_commit(c, ref_name[i], 0);
+                               break;
+                       }
+               }
+       }
+
+       /* Then commits on the first parent ancestry chain */
+       do {
+               i = 0;
+               for (cl = list; cl; cl = cl->next) {
+                       i += name_first_parent_chain(cl->item);
+               }
+       } while (i);
+
+       /* Finally, any unnamed commits */
+       do {
+               i = 0;
+               for (cl = list; cl; cl = cl->next) {
+                       struct commit_list *parents;
+                       struct commit_name *n;
+                       int nth;
+                       c = cl->item;
+                       if (!c->object.util)
+                               continue;
+                       n = c->object.util;
+                       parents = c->parents;
+                       nth = 0;
+                       while (parents) {
+                               struct commit *p = parents->item;
+                               char newname[1000], *en;
+                               parents = parents->next;
+                               nth++;
+                               if (p->object.util)
+                                       continue;
+                               en = newname;
+                               switch (n->generation) {
+                               case 0:
+                                       en += sprintf(en, "%s", n->head_name);
+                                       break;
+                               case 1:
+                                       en += sprintf(en, "%s^", n->head_name);
+                                       break;
+                               default:
+                                       en += sprintf(en, "%s~%d",
+                                               n->head_name, n->generation);
+                                       break;
+                               }
+                               if (nth == 1)
+                                       en += sprintf(en, "^");
+                               else
+                                       en += sprintf(en, "^%d", nth);
+                               name_commit(p, strdup(newname), 0);
+                               i++;
+                               name_first_parent_chain(p);
+                       }
+               }
+       } while (i);
+}
+
 static int mark_seen(struct commit *commit, struct commit_list **seen_p)
 {
        if (!commit->object.flags) {
@@ -87,12 +186,11 @@ static void join_revs(struct commit_list **list_p,
 
        while (*list_p) {
                struct commit_list *parents;
+               int still_interesting = !!interesting(*list_p);
                struct commit *commit = pop_one_commit(list_p);
                int flags = commit->object.flags & all_mask;
-               int nth_parent = 0;
-               int still_interesting = !!interesting(*list_p);
 
-               if (!still_interesting && extra < 0)
+               if (!still_interesting && extra <= 0)
                        break;
 
                mark_seen(commit, seen_p);
@@ -104,36 +202,85 @@ static void join_revs(struct commit_list **list_p,
                        struct commit *p = parents->item;
                        int this_flag = p->object.flags;
                        parents = parents->next;
-                       nth_parent++;
-                       if (nth_parent == 1)
-                               name_parent(commit, p);
-
                        if ((this_flag & flags) == flags)
                                continue;
-                       parse_commit(p);
+                       if (!p->object.parsed)
+                               parse_commit(p);
                        if (mark_seen(p, seen_p) && !still_interesting)
                                extra--;
                        p->object.flags |= flags;
                        insert_by_date(p, list_p);
                }
        }
+
+       /*
+        * Postprocess to complete well-poisoning.
+        *
+        * At this point we have all the commits we have seen in
+        * seen_p list (which happens to be sorted chronologically but
+        * it does not really matter).  Mark anything that can be
+        * reached from uninteresting commits not interesting.
+        */
+       for (;;) {
+               int changed = 0;
+               struct commit_list *s;
+               for (s = *seen_p; s; s = s->next) {
+                       struct commit *c = s->item;
+                       struct commit_list *parents;
+
+                       if (((c->object.flags & all_revs) != all_revs) &&
+                           !(c->object.flags & UNINTERESTING))
+                               continue;
+
+                       /* The current commit is either a merge base or
+                        * already uninteresting one.  Mark its parents
+                        * as uninteresting commits _only_ if they are
+                        * already parsed.  No reason to find new ones
+                        * here.
+                        */
+                       parents = c->parents;
+                       while (parents) {
+                               struct commit *p = parents->item;
+                               parents = parents->next;
+                               if (!(p->object.flags & UNINTERESTING)) {
+                                       p->object.flags |= UNINTERESTING;
+                                       changed = 1;
+                               }
+                       }
+               }
+               if (!changed)
+                       break;
+       }
 }
 
-static void show_one_commit(struct commit *commit, char **head_name)
+static void show_one_commit(struct commit *commit, int no_name)
 {
-       char pretty[128], *cp;
+       char pretty[256], *cp;
        struct commit_name *name = commit->object.util;
-       pretty_print_commit(CMIT_FMT_ONELINE, commit->buffer, ~0,
-                           pretty, sizeof(pretty));
+       if (commit->object.parsed)
+               pretty_print_commit(CMIT_FMT_ONELINE, commit, ~0,
+                                   pretty, sizeof(pretty), 0);
+       else
+               strcpy(pretty, "(unavailable)");
        if (!strncmp(pretty, "[PATCH] ", 8))
                cp = pretty + 8;
        else
                cp = pretty;
-       if (name && head_name) {
-               printf("[%s", head_name[name->head_rev]);
-               if (name->generation)
-                       printf("~%d", name->generation);
-               printf("] ");
+
+       if (!no_name) {
+               if (name && name->head_name) {
+                       printf("[%s", name->head_name);
+                       if (name->generation) {
+                               if (name->generation == 1)
+                                       printf("^");
+                               else
+                                       printf("~%d", name->generation);
+                       }
+                       printf("] ");
+               }
+               else
+                       printf("[%s] ",
+                              find_unique_abbrev(commit->object.sha1, 7));
        }
        puts(cp);
 }
@@ -141,14 +288,77 @@ static void show_one_commit(struct commit *commit, char **head_name)
 static char *ref_name[MAX_REVS + 1];
 static int ref_name_cnt;
 
+static const char *find_digit_prefix(const char *s, int *v)
+{
+       const char *p;
+       int ver;
+       char ch;
+
+       for (p = s, ver = 0;
+            '0' <= (ch = *p) && ch <= '9';
+            p++)
+               ver = ver * 10 + ch - '0';
+       *v = ver;
+       return p;
+}
+
+
+static int version_cmp(const char *a, const char *b)
+{
+       while (1) {
+               int va, vb;
+
+               a = find_digit_prefix(a, &va);
+               b = find_digit_prefix(b, &vb);
+               if (va != vb)
+                       return va - vb;
+
+               while (1) {
+                       int ca = *a;
+                       int cb = *b;
+                       if ('0' <= ca && ca <= '9')
+                               ca = 0;
+                       if ('0' <= cb && cb <= '9')
+                               cb = 0;
+                       if (ca != cb)
+                               return ca - cb;
+                       if (!ca)
+                               break;
+                       a++;
+                       b++;
+               }
+               if (!*a && !*b)
+                       return 0;
+       }
+}
+
+static int compare_ref_name(const void *a_, const void *b_)
+{
+       const char * const*a = a_, * const*b = b_;
+       return version_cmp(*a, *b);
+}
+
+static void sort_ref_range(int bottom, int top)
+{
+       qsort(ref_name + bottom, top - bottom, sizeof(ref_name[0]),
+             compare_ref_name);
+}
+
 static int append_ref(const char *refname, const unsigned char *sha1)
 {
        struct commit *commit = lookup_commit_reference_gently(sha1, 1);
+       int i;
+
        if (!commit)
                return 0;
-       if (MAX_REVS < ref_name_cnt) {
+       /* Avoid adding the same thing twice */
+       for (i = 0; i < ref_name_cnt; i++)
+               if (!strcmp(refname, ref_name[i]))
+                       return 0;
+
+       if (MAX_REVS <= ref_name_cnt) {
                fprintf(stderr, "warning: ignoring %s; "
-                       "cannot handle more than %d refs",
+                       "cannot handle more than %d refs\n",
                        refname, MAX_REVS);
                return 0;
        }
@@ -159,9 +369,16 @@ static int append_ref(const char *refname, const unsigned char *sha1)
 
 static int append_head_ref(const char *refname, const unsigned char *sha1)
 {
-       if (strncmp(refname, "refs/heads/", 11))
+       unsigned char tmp[20];
+       int ofs = 11;
+       if (strncmp(refname, "refs/heads/", ofs))
                return 0;
-       return append_ref(refname + 5, sha1);
+       /* If both heads/foo and tags/foo exists, get_sha1 would
+        * get confused.
+        */
+       if (get_sha1(refname + ofs, tmp) || memcmp(tmp, sha1, 20))
+               ofs = 5;
+       return append_ref(refname + ofs, sha1);
 }
 
 static int append_tag_ref(const char *refname, const unsigned char *sha1)
@@ -171,20 +388,59 @@ static int append_tag_ref(const char *refname, const unsigned char *sha1)
        return append_ref(refname + 5, sha1);
 }
 
+static const char *match_ref_pattern = NULL;
+static int match_ref_slash = 0;
+static int count_slash(const char *s)
+{
+       int cnt = 0;
+       while (*s)
+               if (*s++ == '/')
+                       cnt++;
+       return cnt;
+}
+
+static int append_matching_ref(const char *refname, const unsigned char *sha1)
+{
+       /* we want to allow pattern hold/<asterisk> to show all
+        * branches under refs/heads/hold/, and v0.99.9? to show
+        * refs/tags/v0.99.9a and friends.
+        */
+       const char *tail;
+       int slash = count_slash(refname);
+       for (tail = refname; *tail && match_ref_slash < slash; )
+               if (*tail++ == '/')
+                       slash--;
+       if (!*tail)
+               return 0;
+       if (fnmatch(match_ref_pattern, tail, 0))
+               return 0;
+       if (!strncmp("refs/heads/", refname, 11))
+               return append_head_ref(refname, sha1);
+       if (!strncmp("refs/tags/", refname, 10))
+               return append_tag_ref(refname, sha1);
+       return append_ref(refname, sha1);
+}
+
 static void snarf_refs(int head, int tag)
 {
-       if (head)
+       if (head) {
+               int orig_cnt = ref_name_cnt;
                for_each_ref(append_head_ref);
-       if (tag)
+               sort_ref_range(orig_cnt, ref_name_cnt);
+       }
+       if (tag) {
+               int orig_cnt = ref_name_cnt;
                for_each_ref(append_tag_ref);
+               sort_ref_range(orig_cnt, ref_name_cnt);
+       }
 }
 
-static int rev_is_head(char *head_path, int headlen,
-                      char *name,
+static int rev_is_head(char *head_path, int headlen, char *name,
                       unsigned char *head_sha1, unsigned char *sha1)
 {
        int namelen;
-       if ((!head_path[0]) || memcmp(head_sha1, sha1, 20))
+       if ((!head_path[0]) ||
+           (head_sha1 && sha1 && memcmp(head_sha1, sha1, 20)))
                return 0;
        namelen = strlen(name);
        if ((headlen < namelen) ||
@@ -200,6 +456,7 @@ static int show_merge_base(struct commit_list *seen, int num_rev)
 {
        int all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
        int all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
+       int exit_status = 1;
 
        while (seen) {
                struct commit *commit = pop_one_commit(&seen);
@@ -207,27 +464,107 @@ static int show_merge_base(struct commit_list *seen, int num_rev)
                if (!(flags & UNINTERESTING) &&
                    ((flags & all_revs) == all_revs)) {
                        puts(sha1_to_hex(commit->object.sha1));
-                       return 0;
+                       exit_status = 0;
+                       commit->object.flags |= UNINTERESTING;
+               }
+       }
+       return exit_status;
+}
+
+static int show_independent(struct commit **rev,
+                           int num_rev,
+                           char **ref_name,
+                           unsigned int *rev_mask)
+{
+       int i;
+
+       for (i = 0; i < num_rev; i++) {
+               struct commit *commit = rev[i];
+               unsigned int flag = rev_mask[i];
+
+               if (commit->object.flags == flag)
+                       puts(sha1_to_hex(commit->object.sha1));
+               commit->object.flags |= UNINTERESTING;
+       }
+       return 0;
+}
+
+static void append_one_rev(const char *av)
+{
+       unsigned char revkey[20];
+       if (!get_sha1(av, revkey)) {
+               append_ref(av, revkey);
+               return;
+       }
+       if (strchr(av, '*') || strchr(av, '?') || strchr(av, '[')) {
+               /* glob style match */
+               int saved_matches = ref_name_cnt;
+               match_ref_pattern = av;
+               match_ref_slash = count_slash(av);
+               for_each_ref(append_matching_ref);
+               if (saved_matches == ref_name_cnt &&
+                   ref_name_cnt < MAX_REVS)
+                       error("no matching refs with %s", av);
+               if (saved_matches + 1 < ref_name_cnt)
+                       sort_ref_range(saved_matches, ref_name_cnt);
+               return;
+       }
+       die("bad sha1 reference %s", av);
+}
+
+static int git_show_branch_config(const char *var, const char *value)
+{
+       if (!strcmp(var, "showbranch.default")) {
+               if (default_alloc <= default_num + 1) {
+                       default_alloc = default_alloc * 3 / 2 + 20;
+                       default_arg = xrealloc(default_arg, sizeof *default_arg * default_alloc);
                }
+               default_arg[default_num++] = strdup(value);
+               default_arg[default_num] = NULL;
+               return 0;
        }
-       return 1;
+
+       return git_default_config(var, value);
 }
 
 int main(int ac, char **av)
 {
        struct commit *rev[MAX_REVS], *commit;
        struct commit_list *list = NULL, *seen = NULL;
+       unsigned int rev_mask[MAX_REVS];
        int num_rev, i, extra = 0;
        int all_heads = 0, all_tags = 0;
+       int all_mask, all_revs;
+       int lifo = 1;
        char head_path[128];
+       const char *head_path_p;
        int head_path_len;
        unsigned char head_sha1[20];
        int merge_base = 0;
-       char **label;
+       int independent = 0;
+       int no_name = 0;
+       int sha1_name = 0;
+       int shown_merge_point = 0;
+       int with_current_branch = 0;
+       int head_at = -1;
+       int topics = 0;
+
+       setup_git_directory();
+       git_config(git_show_branch_config);
+
+       /* If nothing is specified, try the default first */
+       if (ac == 1 && default_num) {
+               ac = default_num + 1;
+               av = default_arg - 1; /* ick; we would not address av[0] */
+       }
 
        while (1 < ac && av[1][0] == '-') {
                char *arg = av[1];
-               if (!strcmp(arg, "--all"))
+               if (!strcmp(arg, "--")) {
+                       ac--; av++;
+                       break;
+               }
+               else if (!strcmp(arg, "--all"))
                        all_heads = all_tags = 1;
                else if (!strcmp(arg, "--heads"))
                        all_heads = 1;
@@ -235,71 +572,118 @@ int main(int ac, char **av)
                        all_tags = 1;
                else if (!strcmp(arg, "--more"))
                        extra = 1;
-               else if (!strncmp(arg, "--more=", 7)) {
+               else if (!strcmp(arg, "--list"))
+                       extra = -1;
+               else if (!strcmp(arg, "--no-name"))
+                       no_name = 1;
+               else if (!strcmp(arg, "--current"))
+                       with_current_branch = 1;
+               else if (!strcmp(arg, "--sha1-name"))
+                       sha1_name = 1;
+               else if (!strncmp(arg, "--more=", 7))
                        extra = atoi(arg + 7);
-                       if (extra < 0)
-                               usage(show_branch_usage);
-               }
                else if (!strcmp(arg, "--merge-base"))
                        merge_base = 1;
+               else if (!strcmp(arg, "--independent"))
+                       independent = 1;
+               else if (!strcmp(arg, "--topo-order"))
+                       lifo = 1;
+               else if (!strcmp(arg, "--topics"))
+                       topics = 1;
+               else if (!strcmp(arg, "--date-order"))
+                       lifo = 0;
                else
                        usage(show_branch_usage);
                ac--; av++;
        }
        ac--; av++;
 
+       /* Only one of these is allowed */
+       if (1 < independent + merge_base + (extra != 0))
+               usage(show_branch_usage);
+
+       /* If nothing is specified, show all branches by default */
+       if (ac + all_heads + all_tags == 0)
+               all_heads = 1;
+
        if (all_heads + all_tags)
                snarf_refs(all_heads, all_tags);
-
        while (0 < ac) {
-               unsigned char revkey[20];
-               if (get_sha1(*av, revkey))
-                       die("bad sha1 reference %s", *av);
-               append_ref(*av, revkey);
+               append_one_rev(*av);
                ac--; av++;
        }
 
-       /* If still no revs, then add heads */
-       if (!ref_name_cnt)
-               snarf_refs(1, 0);
+       head_path_p = resolve_ref(git_path("HEAD"), head_sha1, 1);
+       if (head_path_p) {
+               head_path_len = strlen(head_path_p);
+               memcpy(head_path, head_path_p, head_path_len + 1);
+       }
+       else {
+               head_path_len = 0;
+               head_path[0] = 0;
+       }
+
+       if (with_current_branch && head_path_p) {
+               int has_head = 0;
+               for (i = 0; !has_head && i < ref_name_cnt; i++) {
+                       /* We are only interested in adding the branch
+                        * HEAD points at.
+                        */
+                       if (rev_is_head(head_path,
+                                       head_path_len,
+                                       ref_name[i],
+                                       head_sha1, NULL))
+                               has_head++;
+               }
+               if (!has_head) {
+                       int pfxlen = strlen(git_path("refs/heads/"));
+                       append_one_rev(head_path + pfxlen);
+               }
+       }
+
+       if (!ref_name_cnt) {
+               fprintf(stderr, "No revs to be shown.\n");
+               exit(0);
+       }
 
        for (num_rev = 0; ref_name[num_rev]; num_rev++) {
                unsigned char revkey[20];
+               unsigned int flag = 1u << (num_rev + REV_SHIFT);
 
                if (MAX_REVS <= num_rev)
                        die("cannot handle more than %d revs.", MAX_REVS);
                if (get_sha1(ref_name[num_rev], revkey))
-                       usage(show_branch_usage);
+                       die("'%s' is not a valid ref.", ref_name[num_rev]);
                commit = lookup_commit_reference(revkey);
                if (!commit)
                        die("cannot find commit %s (%s)",
                            ref_name[num_rev], revkey);
                parse_commit(commit);
-               if (!commit->object.util)
-                       name_commit(commit, num_rev, 0);
                mark_seen(commit, &seen);
 
                /* rev#0 uses bit REV_SHIFT, rev#1 uses bit REV_SHIFT+1,
                 * and so on.  REV_SHIFT bits from bit 0 are used for
                 * internal bookkeeping.
                 */
-               commit->object.flags |= 1u << (num_rev + REV_SHIFT);
-               insert_by_date(commit, &list);
+               commit->object.flags |= flag;
+               if (commit->object.flags == flag)
+                       insert_by_date(commit, &list);
                rev[num_rev] = commit;
        }
-       join_revs(&list, &seen, num_rev, extra);
+       for (i = 0; i < num_rev; i++)
+               rev_mask[i] = rev[i]->object.flags;
 
-       head_path_len = readlink(".git/HEAD", head_path, sizeof(head_path)-1);
-       if ((head_path_len < 0) || get_sha1("HEAD", head_sha1))
-               head_path[0] = 0;
-       else
-               head_path[head_path_len] = 0;
+       if (0 <= extra)
+               join_revs(&list, &seen, num_rev, extra);
 
        if (merge_base)
                return show_merge_base(seen, num_rev);
 
-       /* Show list */
-       if (1 < num_rev) {
+       if (independent)
+               return show_independent(rev, num_rev, ref_name, rev_mask);
+
+       /* Show list; --more=-1 means list-only */
+       if (1 < num_rev || extra < 0) {
                for (i = 0; i < num_rev; i++) {
                        int j;
                        int is_head = rev_is_head(head_path,
@@ -307,33 +691,71 @@ int main(int ac, char **av)
                                                  ref_name[i],
                                                  head_sha1,
                                                  rev[i]->object.sha1);
-                       for (j = 0; j < i; j++)
-                               putchar(' ');
-                       printf("%c [%s] ", is_head ? '*' : '!', ref_name[i]);
-                       show_one_commit(rev[i], NULL);
+                       if (extra < 0)
+                               printf("%c [%s] ",
+                                      is_head ? '*' : ' ', ref_name[i]);
+                       else {
+                               for (j = 0; j < i; j++)
+                                       putchar(' ');
+                               printf("%c [%s] ",
+                                      is_head ? '*' : '!', ref_name[i]);
+                       }
+                       /* header lines never need name */
+                       show_one_commit(rev[i], 1);
+                       if (is_head)
+                               head_at = i;
+               }
+               if (0 <= extra) {
+                       for (i = 0; i < num_rev; i++)
+                               putchar('-');
+                       putchar('\n');
                }
-               for (i = 0; i < num_rev; i++)
-                       putchar('-');
-               putchar('\n');
        }
+       if (extra < 0)
+               exit(0);
+
+       /* Sort topologically */
+       sort_in_topological_order(&seen, lifo);
+
+       /* Give names to commits */
+       if (!sha1_name && !no_name)
+               name_commits(seen, rev, ref_name, num_rev);
+
+       all_mask = ((1u << (REV_SHIFT + num_rev)) - 1);
+       all_revs = all_mask & ~((1u << REV_SHIFT) - 1);
 
-       label = ref_name;
        while (seen) {
                struct commit *commit = pop_one_commit(&seen);
                int this_flag = commit->object.flags;
-               static char *obvious[] = { "" };
+               int is_merge_point = ((this_flag & all_revs) == all_revs);
+
+               shown_merge_point |= is_merge_point;
 
-               if ((this_flag & UNINTERESTING) && (--extra < 0))
-                       break;
                if (1 < num_rev) {
-                       for (i = 0; i < num_rev; i++)
-                               putchar((this_flag & (1u << (i + REV_SHIFT)))
-                                       ? '+' : ' ');
+                       int is_merge = !!(commit->parents && commit->parents->next);
+                       if (topics &&
+                           !is_merge_point &&
+                           (this_flag & (1u << REV_SHIFT)))
+                               continue;
+
+                       for (i = 0; i < num_rev; i++) {
+                               int mark;
+                               if (!(this_flag & (1u << (i + REV_SHIFT))))
+                                       mark = ' ';
+                               else if (is_merge)
+                                       mark = '-';
+                               else if (i == head_at)
+                                       mark = '*';
+                               else
+                                       mark = '+';
+                               putchar(mark);
+                       }
                        putchar(' ');
                }
-               show_one_commit(commit, label);
-               if (num_rev == 1)
-                       label = obvious;
+               show_one_commit(commit, no_name);
+
+               if (shown_merge_point && --extra < 0)
+                       break;
        }
        return 0;
 }