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2019-11-13t4215: use helper function to check outputLibravatar Denton Liu1-111/+97
When git commands are placed in the upstream of a pipe, their return codes are lost. In this particular case, it is especially bad since we are testing the intricacies of `git log --graph` behavior and if we hit an unexpected failure or segfault, we want to know this. Extract the common output checking logic into check_graph() where we redirect the output of git commands upstream of pipe into a file and have sed read from that file so that git failures are detected. This patch is best viewed with `--color-moved`. Signed-off-by: Denton Liu <liu.denton@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-16graph: flatten edges that fuse with their right neighborLibravatar James Coglan1-9/+47
When a merge commit is printed and its final parent is the same commit that occupies the column to the right of the merge, this results in a kink in the displayed edges: * | |\ \ | |/ | * Graphs containing these shapes can be hard to read, as the expansion to the right followed immediately by collapsing back to the left creates a lot of zig-zagging edges, especially when many columns are present. We can improve this by eliminating the zig-zag and having the merge's final parent edge fuse immediately with its neighbor: * | |\| | * This reduces the horizontal width for the current commit by 2, and requires one less row, making the graph display more compact. Taken in combination with other graph-smoothing enhancements, it greatly compresses the space needed to display certain histories: * |\ | * * | |\ |\ | | * | * | | | | |\ | | \ | | * | *-. \ | * | | |\ \ \ => |/|\| |/ / / / | | * | | | / | * | | | |/ | |/ | | * * / | * | |/ | |/ * * | |/ * One of the test cases here cannot be correctly rendered in Git v2.23.0; it produces this output following commit E: | | *-. \ 5_E | | |\ \ \ | |/ / / / | | | / _ | |_|/ |/| | The new implementation makes sure that the rightmost edge in this history is not left dangling as above. Signed-off-by: James Coglan <jcoglan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-16graph: smooth appearance of collapsing edges on commit linesLibravatar James Coglan1-2/+2
When a graph contains edges that are in the process of collapsing to the left, but those edges cross a commit line, the effect is that the edges have a jagged appearance: * |\ | * | \ *-. \ |\ \ \ | | * | | * | | | |/ / * | | |/ / * | |/ * We already takes steps to smooth edges like this when they're expanding; when an edge appears to the right of a merge commit marker on a GRAPH_COMMIT line immediately following a GRAPH_POST_MERGE line, we render it as a `\`: * \ |\ \ | * \ | |\ \ We can make a similar improvement to collapsing edges, making them easier to follow and giving the overall graph a feeling of increased symmetry: * |\ | * | \ *-. \ |\ \ \ | | * | | * | | | |/ / * / / |/ / * / |/ * To do this, we introduce a new special case for edges on GRAPH_COMMIT lines that immediately follow a GRAPH_COLLAPSING line. By retaining a copy of the `mapping` array used to render the GRAPH_COLLAPSING line in the `old_mapping` array, we can determine that an edge is collapsing through the GRAPH_COMMIT line and should be smoothed. Signed-off-by: James Coglan <jcoglan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-16graph: commit and post-merge lines for left-skewed mergesLibravatar James Coglan1-2/+145
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>
2019-10-16graph: tidy up display of left-skewed mergesLibravatar James Coglan1-6/+39
Currently, when we display a merge whose first parent is already present in a column to the left of the merge commit, we display the first parent as a vertical pipe `|` in the GRAPH_POST_MERGE line and then immediately enter the GRAPH_COLLAPSING state. The first-parent line tracks to the left and all the other parent lines follow it; this creates a "kink" in those lines: | *---. | |\ \ \ |/ / / / | | | * This change tidies the display of such commits such that if the first parent appears to the left of the merge, we render it as a `/` and the second parent as a `|`. This reduces the horizontal and vertical space needed to render the merge, and makes the resulting lines easier to read. | *-. |/|\ \ | | | * If the first parent is separated from the merge by several columns, a horizontal line is drawn in a similar manner to how the GRAPH_COLLAPSING state displays the line. | | | *-. | |_|/|\ \ |/| | | | * This effect is applied to both "normal" two-parent merges, and to octopus merges. It also reduces the vertical space needed for pre-commit lines, as the merge occupies one less column than usual. Before: After: | * | * | |\ | |\ | | \ | * \ | | \ |/|\ \ | *-. \ | |\ \ \ Signed-off-by: James Coglan <jcoglan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2019-10-16graph: example of graph output that can be simplifiedLibravatar James Coglan1-0/+43
The commits following this one introduce a series of improvements to the layout of graphs, tidying up a few edge cases, namely: - merge whose first parent fuses with an existing column to the left - merge whose last parent fuses with its immediate neighbor on the right - edges that collapse to the left above and below a commit line This test case exemplifies these cases and provides a motivating example of the kind of history I'm aiming to clear up. The first parent of merge E is the same as the parent of H, so those edges fuse together. * H | | *-. E | |\ \ |/ / / | * B We can "skew" the display of this merge so that it doesn't introduce additional columns that immediately collapse: * H | | * E |/|\ | * B The last parent of E is D, the same as the parent of F which is the edge to the right of the merge. * F | \ *-. \ E |\ \ \ / / / / | / |/ * D The two edges leading to D could be fused sooner: rather than expanding the F edge around the merge and then letting the edges collapse, the F edge could fuse with the E edge in the post-merge line: * F | \ *-. | E |\ \| / / / | * D If this is combined with the "skew" effect above, we get a much cleaner graph display for these edges: * F | * | E /|\| | * D Finally, the edge leading from C to A appears jagged as it passes through the commit line for B: | * | C | |/ * | B |/ * A This can be smoothed out so that such edges are easier to read: | * | C | |/ * / B |/ * A Signed-off-by: James Coglan <jcoglan@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>