reflog-walk: clean up "flag" field of commit_reflog struct

When we prepare to walk a reflog, we parse the specification
and pull some information from it, such as which reflog to
look in (e.g., HEAD), and where to start (e.g., HEAD@{10} or
HEAD@{yesterday}). The resulting struct has a "recno" field
to show where in the reflog we are starting. It also has a
"flag" field; if true, it means the recno field came from
parsing a date like HEAD@{yesterday}.

There are two problems with this:

  1. "flag" is an absolutely terrible name, as it conveys
     nothing about the meaning

  2. you can tell "HEAD" from "HEAD@{yesterday}", but you
     can't differentiate "HEAD" from "HEAD{0}"

This patch converts the flag into a tri-state (and gives it
a better name!).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

reflog-walk.c

@@ -122,7 +122,12 @@ static void add_commit_info(struct commit *commit, void *util,
 }
 
 struct commit_reflog {
-	int flag, recno;
+	int recno;
+	enum selector_type {
+		SELECTOR_NONE,
+		SELECTOR_INDEX,
+		SELECTOR_DATE
+	} selector;
 	struct complete_reflogs *reflogs;
 };
 
@@ -146,6 +151,7 @@ int add_reflog_for_walk(struct reflog_walk_info *info,
 	struct complete_reflogs *reflogs;
 	char *branch, *at = strchr(name, '@');
 	struct commit_reflog *commit_reflog;
+	enum selector_type selector = SELECTOR_NONE;
 
 	if (commit->object.flags & UNINTERESTING)
 		die ("Cannot walk reflogs for %s", name);
@@ -158,7 +164,10 @@ int add_reflog_for_walk(struct reflog_walk_info *info,
 		if (*ep != '}') {
 			recno = -1;
 			timestamp = approxidate(at + 2);
+			selector = SELECTOR_DATE;
 		}
+		else
+			selector = SELECTOR_INDEX;
 	} else
 		recno = 0;
 
@@ -196,7 +205,6 @@ int add_reflog_for_walk(struct reflog_walk_info *info,
 
 	commit_reflog = xcalloc(sizeof(struct commit_reflog), 1);
 	if (recno < 0) {
-		commit_reflog->flag = 1;
 		commit_reflog->recno = get_reflog_recno_by_time(reflogs, timestamp);
 		if (commit_reflog->recno < 0) {
 			free(branch);
@@ -205,6 +213,7 @@ int add_reflog_for_walk(struct reflog_walk_info *info,
 		}
 	} else
 		commit_reflog->recno = reflogs->nr - recno - 1;
+	commit_reflog->selector = selector;
 	commit_reflog->reflogs = reflogs;
 
 	add_commit_info(commit, commit_reflog, &info->reflogs);
@@ -263,7 +272,7 @@ void get_reflog_selector(struct strbuf *sb,
 	}
 
 	strbuf_addf(sb, "%s@{", printed_ref);
-	if (commit_reflog->flag || dmode) {
+	if (commit_reflog->selector == SELECTOR_DATE || dmode) {
 		info = &commit_reflog->reflogs->items[commit_reflog->recno+1];
 		strbuf_addstr(sb, show_date(info->timestamp, info->tz, dmode));
 	} else {