[PATCH 4/5] pretty: support %G to show the generation number of a commit

[Jeff King <peff@peff.net>]

This might be useful for external programs doing topological
sorting or other graph analysis. It's also handy for testing
the generation calculation code.

Signed-off-by: Jeff King <peff@peff.net>
---
 Documentation/pretty-formats.txt |    1 +
 pretty.c                         |    3 +++
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 561cc9f..c58ab52 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -133,6 +133,7 @@ The placeholders are:
 - '%gD': reflog selector, e.g., `refs/stash@\{1\}`
 - '%gd': shortened reflog selector, e.g., `stash@\{1\}`
 - '%gs': reflog subject
+- '%G': generation number (i.e., distance of path to farthest root ancestor)
 - '%Cred': switch color to red
 - '%Cgreen': switch color to green
 - '%Cblue': switch color to blue
diff --git a/pretty.c b/pretty.c
index f45eb54..8f1b321 100644
--- a/pretty.c
+++ b/pretty.c
@@ -965,6 +965,9 @@ static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
 			return 2;
 		}
 		return 0;	/* unknown %g placeholder */
+	case 'G':
+		strbuf_addf(sb, "%lu", commit_generation(commit));
+		return 1;
 	case 'N':
 		if (c->pretty_ctx->show_notes) {
 			format_display_notes(commit->object.sha1, sb,
-- 
1.7.6.37.g989c6