[PATCH v3 6/6] fetch: reduce duplicate in ref update status lines with placeholder

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

In the "remote -> local" line, if either ref is a substring of the
other, the common part in the other string is replaced with "$". For
example

    abc                -> origin/abc
    refs/pull/123/head -> pull/123

become

    abc         -> origin/$
    refs/$/head -> pull/123

Activated with fetch.format=dollar.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/fetch.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/builtin/fetch.c b/builtin/fetch.c
index e2ca6bc..c63f913 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -488,11 +488,13 @@ static void prepare_format_display(struct ref *ref_map)
 		compact_format = 0;
 	else if (!strcasecmp(format, "compact"))
 		compact_format = 1;
+	else if (!strcasecmp(format, "dollar"))
+		compact_format = 2;
 	else
 		die(_("configuration fetch.output contains invalid value %s"),
 		    format);
 
-	if (compact_format)
+	if (compact_format == 1)
 		return;
 
 	for (rm = ref_map; rm; rm = rm->next) {
@@ -549,6 +551,48 @@ static void print_compact(struct strbuf *display,
 	print_remote_to_local(display, remote, local);
 }
 
+static int dollarize(struct strbuf *haystack, const char *needle)
+{
+	const char *p = strstr(haystack->buf, needle);
+	int plen, nlen;
+
+	if (!p)
+		return 0;
+
+	if (p > haystack->buf && p[-1] != '/')
+		return 0;
+
+	plen = strlen(p);
+	nlen = strlen(needle);
+	if (plen > nlen && p[nlen] != '/')
+		return 0;
+
+	strbuf_splice(haystack, p - haystack->buf, nlen, "$", 1);
+	return 1;
+}
+
+static void print_dollar(struct strbuf *display,
+			 const char *remote, const char *local)
+{
+	struct strbuf r = STRBUF_INIT;
+	struct strbuf l = STRBUF_INIT;
+
+	if (!strcmp(remote, local)) {
+		strbuf_addf(display, "%s -> $", remote);
+		return;
+	}
+
+	strbuf_addstr(&r, remote);
+	strbuf_addstr(&l, local);
+
+	if (!dollarize(&r, local))
+		dollarize(&l, remote);
+	print_remote_to_local(display, r.buf, l.buf);
+
+	strbuf_release(&r);
+	strbuf_release(&l);
+}
+
 static void format_display(struct strbuf *display, char code,
 			   const char *summary, const char *error,
 			   const char *remote, const char *local)
@@ -561,6 +605,9 @@ static void format_display(struct strbuf *display, char code,
 	case 1:
 		print_compact(display, remote, local);
 		break;
+	case 2:
+		print_dollar(display, remote, local);
+		break;
 	}
 	if (error)
 		strbuf_addf(display, "  (%s)", error);
-- 
2.8.2.524.g6ff3d78