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author | James Coglan <jcoglan@gmail.com> | 2019-10-15 23:47:55 (GMT) |
---|---|---|
committer | Junio C Hamano <gitster@pobox.com> | 2019-10-16 02:11:25 (GMT) |
commit | d62893ecc125767d44a194279bcaffa0d02d2572 (patch) | |
tree | 663e39919b1460afe1c0ecfecf47e9efc59e8271 /column.h | |
parent | 0f0f389f12029b1c3745f8ed7aacfe6b2fc7a6cc (diff) | |
download | git-d62893ecc125767d44a194279bcaffa0d02d2572.zip git-d62893ecc125767d44a194279bcaffa0d02d2572.tar.gz git-d62893ecc125767d44a194279bcaffa0d02d2572.tar.bz2 |
graph: commit and post-merge lines for left-skewed merges
Following the introduction of "left-skewed" merges, which are merges
whose first parent fuses with another edge to its left, we have some
more edge cases to deal with in the display of commit and post-merge
lines.
The current graph code handles the following cases for edges appearing
to the right of the commit (*) on commit lines. A 2-way merge is usually
followed by vertical lines:
| | |
| * |
| |\ \
An octopus merge (more than two parents) is always followed by edges
sloping to the right:
| | \ | | \
| *-. \ | *---. \
| |\ \ \ | |\ \ \ \
A 2-way merge is followed by a right-sloping edge if the commit line
immediately follows a post-merge line for a commit that appears in the
same column as the current commit, or any column to the left of that:
| * | * |
| |\ | |\ \
| * \ | | * \
| |\ \ | | |\ \
This commit introduces the following new cases for commit lines. If a
2-way merge skews to the left, then the edges to its right are always
vertical lines, even if the commit follows a post-merge line:
| | | | |\
| * | | * |
|/| | |/| |
A commit with 3 parents that skews left is followed by vertical edges:
| | |
| * |
|/|\ \
If a 3-way left-skewed merge commit appears immediately after a
post-merge line, then it may be followed the right-sloping edges, just
like a 2-way merge that is not skewed.
| |\
| * \
|/|\ \
Octopus merges with 4 or more parents that skew to the left will always
be followed by right-sloping edges, because the existing columns need to
expand around the merge.
| | \
| *-. \
|/|\ \ \
On post-merge lines, usually all edges following the current commit
slope to the right:
| * | |
| |\ \ \
However, if the commit is a left-skewed 2-way merge, the edges to its
right remain vertical. We also need to display a space after the
vertical line descending from the commit marker, whereas this line would
normally be followed by a backslash.
| * | |
|/| | |
If a left-skewed merge has more than 2 parents, then the edges to its
right are still sloped as they bend around the edges introduced by the
merge.
| * | |
|/|\ \ \
To handle these new cases, we need to know not just how many parents
each commit has, but how many new columns it adds to the display; this
quantity is recorded in the `edges_added` field for the current commit,
and `prev_edges_added` field for the previous commit.
Here, "column" refers to visual columns, not the logical columns of the
`columns` array. This is because even if all the commit's parents end up
fusing with existing edges, they initially introduce distinct edges in
the commit and post-merge lines before those edges collapse. For
example, a 3-way merge whose 2nd and 3rd parents fuse with existing
edges still introduces 2 visual columns that affect the display of edges
to their right.
| | | \
| | *-. \
| | |\ \ \
| |_|/ / /
|/| | / /
| | |/ /
| |/| |
| | | |
This merge does not introduce any *logical* columns; there are 4 edges
before and after this commit once all edges have collapsed. But it does
initially introduce 2 new edges that need to be accommodated by the
edges to their right.
Signed-off-by: James Coglan <jcoglan@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'column.h')
0 files changed, 0 insertions, 0 deletions