[RFC PATCH] line-log: clarify [a,b) notation for ranges

[Andrei Rybak <rybak.a.v@gmail.com>]

line-log.[ch] use left-closed, right-open interval logic. Change comment
and debug output to square brackets+parentheses notation to help
developers avoid off-by-one errors.
---

Original idea for this change in recent thread about line-log changes:

  https://public-inbox.org/git/9776862d-18b2-43ec-cfeb-829418d4d967@gmail.com/

line-log.c also uses ASCII graphics |---| in some comments, like:

	/*
	 * a:         |-------
	 * b: ------|
	 */

But I'm not sure if replacing them with

	/*
	 * a:         [-------
	 * b: ------)
	 */

will be helpful.  Another possibility is to update comment for
range_set_append_unsafe to read

  /* tack on a _new_ range [a,b) _at the end_ */
  void range_set_append_unsafe(struct range_set *rs, long a, long b)

 line-log.c | 4 ++--
 line-log.h | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/line-log.c b/line-log.c
index fa9cfd5bd..60f3174ac 100644
--- a/line-log.c
+++ b/line-log.c
@@ -353,7 +353,7 @@ static void dump_range_set(struct range_set *rs, const char *desc)
 	int i;
 	printf("range set %s (%d items):\n", desc, rs->nr);
 	for (i = 0; i < rs->nr; i++)
-		printf("\t[%ld,%ld]\n", rs->ranges[i].start, rs->ranges[i].end);
+		printf("\t[%ld,%ld)\n", rs->ranges[i].start, rs->ranges[i].end);
 }
 
 static void dump_line_log_data(struct line_log_data *r)
@@ -373,7 +373,7 @@ static void dump_diff_ranges(struct diff_ranges *diff, const char *desc)
 	printf("diff ranges %s (%d items):\n", desc, diff->parent.nr);
 	printf("\tparent\ttarget\n");
 	for (i = 0; i < diff->parent.nr; i++) {
-		printf("\t[%ld,%ld]\t[%ld,%ld]\n",
+		printf("\t[%ld,%ld)\t[%ld,%ld)\n",
 		       diff->parent.ranges[i].start,
 		       diff->parent.ranges[i].end,
 		       diff->target.ranges[i].start,
diff --git a/line-log.h b/line-log.h
index e2a5ee7c6..488c86409 100644
--- a/line-log.h
+++ b/line-log.h
@@ -6,7 +6,7 @@
 struct rev_info;
 struct commit;
 
-/* A range [start,end].  Lines are numbered starting at 0, and the
+/* A range [start,end).  Lines are numbered starting at 0, and the
  * ranges include start but exclude end. */
 struct range {
 	long start, end;
-- 
2.18.0