[PATCH 3/4] line-log: optimize ranges by joining them when possible

From: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>
Date: Aug 4, 2018, 22:18 UTC
Message-ID: <d5d9db3c1124d29e26864596a8c36f0dc4de8a7e.1533421100.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.15.git.gitgitgadget@gmail.com>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

Technically, it is okay to have line ranges that touch (i.e. the end of the first range ends just before the next range begins). However, it is inefficient, and when the user provides such touching ranges via multiple `-L` options, we already join them.

When we traverse the history, though, we never join ranges, even they become "touchy-feely" due to added lines (which are "removed" from line-log's point of view because it traverses the commit history into the past).

Let's optimize also this case.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 line-log.c          | 4 ++++
 t/t4211-line-log.sh | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/line-log.c b/line-log.c
index d8d09b5ee..bc7ef69d6 100644
--- a/line-log.c
+++ b/line-log.c
@@ -68,6 +68,10 @@ void range_set_append_unsafe(struct range_set *rs, long a, long b)
 
 void range_set_append(struct range_set *rs, long a, long b)
 {
+	if (rs->nr > 0 && rs->ranges[rs->nr-1].end + 1 == a) {
+		rs->ranges[rs->nr-1].end = b;
+		return;
+	}
 	assert(rs->nr == 0 || rs->ranges[rs->nr-1].end <= a);
 	range_set_append_unsafe(rs, a, b);
 }
diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index 61ff37430..ebaf5ea86 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -119,7 +119,7 @@ q_to_lf () {
 	tr Q '\012'
 }
 
-test_expect_failure 'close to overlapping ranges' '
+test_expect_success 'close to overlapping ranges' '
 	test_seq 5 >a1.c &&
 	git add a1.c &&
 	git commit -m "5 lines" a1.c &&

-- 
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