Refactor "tracking statistics" code used by "git checkout"

People seem to like "Your branch is ahead by N commit" report made by
"git checkout", but the interface into the statistics function was a bit
clunky.  This splits the function into three parts:

 * The core "commit counting" function that takes "struct branch" and
   returns number of commits to show if we are ahead, behind or forked;

 * Convenience "stat formating" function that takes "struct branch" and
   formats the report into a given strbuf, using the above function;

 * "checkout" specific function that takes "branch_info" (type that is
   internal to checkout implementation), calls the above function and
   print the formatted result.

in the hope that the former two can be more easily reusable.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-checkout.c b/builtin-checkout.c
index 93ea69bfaa083f49a6e808c7317ea1910b29c847..d6641c2c562c6b35bfed1cd3053945b460472581 100644 (file)
--- a/builtin-checkout.c
+++ b/builtin-checkout.c
@@ -305,97 +305,15 @@ static int merge_working_tree(struct checkout_opts *opts,
        return 0;
 }
 
-static void report_tracking(struct branch_info *new, struct checkout_opts *opts)
+static void report_tracking(struct branch_info *new)
 {
-       /*
-        * We have switched to a new branch; is it building on
-        * top of another branch, and if so does that other branch
-        * have changes we do not have yet?
-        */
-       char *base;
-       unsigned char sha1[20];
-       struct commit *ours, *theirs;
-       char symmetric[84];
-       struct rev_info revs;
-       const char *rev_argv[10];
-       int rev_argc;
-       int num_ours, num_theirs;
-       const char *remote_msg;
+       struct strbuf sb = STRBUF_INIT;
        struct branch *branch = branch_get(new->name);
 
-       /*
-        * Nothing to report unless we are marked to build on top of
-        * somebody else.
-        */
-       if (!branch || !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
-               return;
-
-       /*
-        * If what we used to build on no longer exists, there is
-        * nothing to report.
-        */
-       base = branch->merge[0]->dst;
-       if (!resolve_ref(base, sha1, 1, NULL))
+       if (!format_tracking_info(branch, &sb))
                return;
-
-       theirs = lookup_commit(sha1);
-       ours = new->commit;
-       if (!hashcmp(sha1, ours->object.sha1))
-               return; /* we are the same */
-
-       /* Run "rev-list --left-right ours...theirs" internally... */
-       rev_argc = 0;
-       rev_argv[rev_argc++] = NULL;
-       rev_argv[rev_argc++] = "--left-right";
-       rev_argv[rev_argc++] = symmetric;
-       rev_argv[rev_argc++] = "--";
-       rev_argv[rev_argc] = NULL;
-
-       strcpy(symmetric, sha1_to_hex(ours->object.sha1));
-       strcpy(symmetric + 40, "...");
-       strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
-
-       init_revisions(&revs, NULL);
-       setup_revisions(rev_argc, rev_argv, &revs, NULL);
-       prepare_revision_walk(&revs);
-
-       /* ... and count the commits on each side. */
-       num_ours = 0;
-       num_theirs = 0;
-       while (1) {
-               struct commit *c = get_revision(&revs);
-               if (!c)
-                       break;
-               if (c->object.flags & SYMMETRIC_LEFT)
-                       num_ours++;
-               else
-                       num_theirs++;
-       }
-
-       if (!prefixcmp(base, "refs/remotes/")) {
-               remote_msg = " remote";
-               base += strlen("refs/remotes/");
-       } else {
-               remote_msg = "";
-       }
-
-       if (!num_theirs)
-               printf("Your branch is ahead of the tracked%s branch '%s' "
-                      "by %d commit%s.\n",
-                      remote_msg, base,
-                      num_ours, (num_ours == 1) ? "" : "s");
-       else if (!num_ours)
-               printf("Your branch is behind the tracked%s branch '%s' "
-                      "by %d commit%s,\n"
-                      "and can be fast-forwarded.\n",
-                      remote_msg, base,
-                      num_theirs, (num_theirs == 1) ? "" : "s");
-       else
-               printf("Your branch and the tracked%s branch '%s' "
-                      "have diverged,\nand respectively "
-                      "have %d and %d different commit(s) each.\n",
-                      remote_msg, base,
-                      num_ours, num_theirs);
+       fputs(sb.buf, stdout);
+       strbuf_release(&sb);
 }
 
 static void update_refs_for_switch(struct checkout_opts *opts,
@@ -441,7 +359,7 @@ static void update_refs_for_switch(struct checkout_opts *opts,
        remove_branch_state();
        strbuf_release(&msg);
        if (!opts->quiet && (new->path || !strcmp(new->name, "HEAD")))
-               report_tracking(new, opts);
+               report_tracking(new);
 }
 
 static int switch_branches(struct checkout_opts *opts, struct branch_info *new)

diff --git a/remote.c b/remote.c
index ff2c8021678fee5ef12060d35c6eb1960e8792c7..bd5c3be3ecda20cf9724152bd54a66fd904326e7 100644 (file)
--- a/remote.c
+++ b/remote.c
@@ -1,6 +1,9 @@
 #include "cache.h"
 #include "remote.h"
 #include "refs.h"
+#include "commit.h"
+#include "diff.h"
+#include "revision.h"
 
 static struct refspec s_tag_refspec = {
        0,
@@ -1222,3 +1225,113 @@ int resolve_remote_symref(struct ref *ref, struct ref *list)
                }
        return 1;
 }
+
+/*
+ * Return true if there is anything to report, otherwise false.
+ */
+int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs)
+{
+       unsigned char sha1[20];
+       struct commit *ours, *theirs;
+       char symmetric[84];
+       struct rev_info revs;
+       const char *rev_argv[10], *base;
+       int rev_argc;
+
+       /*
+        * Nothing to report unless we are marked to build on top of
+        * somebody else.
+        */
+       if (!branch ||
+           !branch->merge || !branch->merge[0] || !branch->merge[0]->dst)
+               return 0;
+
+       /*
+        * If what we used to build on no longer exists, there is
+        * nothing to report.
+        */
+       base = branch->merge[0]->dst;
+       if (!resolve_ref(base, sha1, 1, NULL))
+               return 0;
+       theirs = lookup_commit(sha1);
+       if (!theirs)
+               return 0;
+
+       if (!resolve_ref(branch->refname, sha1, 1, NULL))
+               return 0;
+       ours = lookup_commit(sha1);
+       if (!ours)
+               return 0;
+
+       /* are we the same? */
+       if (theirs == ours)
+               return 0;
+
+       /* Run "rev-list --left-right ours...theirs" internally... */
+       rev_argc = 0;
+       rev_argv[rev_argc++] = NULL;
+       rev_argv[rev_argc++] = "--left-right";
+       rev_argv[rev_argc++] = symmetric;
+       rev_argv[rev_argc++] = "--";
+       rev_argv[rev_argc] = NULL;
+
+       strcpy(symmetric, sha1_to_hex(ours->object.sha1));
+       strcpy(symmetric + 40, "...");
+       strcpy(symmetric + 43, sha1_to_hex(theirs->object.sha1));
+
+       init_revisions(&revs, NULL);
+       setup_revisions(rev_argc, rev_argv, &revs, NULL);
+       prepare_revision_walk(&revs);
+
+       /* ... and count the commits on each side. */
+       *num_ours = 0;
+       *num_theirs = 0;
+       while (1) {
+               struct commit *c = get_revision(&revs);
+               if (!c)
+                       break;
+               if (c->object.flags & SYMMETRIC_LEFT)
+                       (*num_ours)++;
+               else
+                       (*num_theirs)++;
+       }
+       return 1;
+}
+
+/*
+ * Return true when there is anything to report, otherwise false.
+ */
+int format_tracking_info(struct branch *branch, struct strbuf *sb)
+{
+       int num_ours, num_theirs;
+       const char *base, *remote_msg;
+
+       if (!stat_tracking_info(branch, &num_ours, &num_theirs))
+               return 0;
+
+       base = branch->merge[0]->dst;
+       if (!prefixcmp(base, "refs/remotes/")) {
+               remote_msg = " remote";
+               base += strlen("refs/remotes/");
+       } else {
+               remote_msg = "";
+       }
+       if (!num_theirs)
+               strbuf_addf(sb, "Your branch is ahead of the tracked%s branch '%s' "
+                           "by %d commit%s.\n",
+                           remote_msg, base,
+                           num_ours, (num_ours == 1) ? "" : "s");
+       else if (!num_ours)
+               strbuf_addf(sb, "Your branch is behind the tracked%s branch '%s' "
+                           "by %d commit%s,\n"
+                           "and can be fast-forwarded.\n",
+                           remote_msg, base,
+                           num_theirs, (num_theirs == 1) ? "" : "s");
+       else
+               strbuf_addf(sb, "Your branch and the tracked%s branch '%s' "
+                           "have diverged,\nand respectively "
+                           "have %d and %d different commit(s) each.\n",
+                           remote_msg, base,
+                           num_ours, num_theirs);
+       return 1;
+}

diff --git a/remote.h b/remote.h
index 8eed87ba5ab78eb4635632c21843590467d0d864..091b1d041f8a4d255f59bfc001e098e692dbc15c 100644 (file)
--- a/remote.h
+++ b/remote.h
@@ -129,4 +129,8 @@ enum match_refs_flags {
        MATCH_REFS_MIRROR       = (1 << 1),
 };
 
+/* Reporting of tracking info */
+int stat_tracking_info(struct branch *branch, int *num_ours, int *num_theirs);
+int format_tracking_info(struct branch *branch, struct strbuf *sb);
+
 #endif