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2018-03-21diff-highlight: detect --graph by indentJeff King
This patch fixes a corner case where diff-highlight may scramble some diffs when combined with --graph. Commit 7e4ffb4c17 (diff-highlight: add support for --graph output, 2016-08-29) taught diff-highlight to skip past the graph characters at the start of each line with this regex: ($COLOR?\|$COLOR?\s+)* I.e., any series of pipes separated by and followed by arbitrary whitespace. We need to match more than just a single space because the commit in question may be indented to accommodate other parts of the graph drawing. E.g.: * commit 1234abcd | ... | diff --git ... has only a single space, but for the last commit before a fork: | | | | * | commit 1234abcd | |/ ... | | diff --git the diff lines have more spaces between the pipes and the start of the diff. However, when we soak up all of those spaces with the $GRAPH regex, we may accidentally include the leading space for a context line. That means we may consider the actual contents of a context line as part of the diff syntax. In other words, something like this: normal context line -old line +new line -this is a context line with a leading dash would cause us to see that final context line as a removal line, and we'd end up showing the hunk in the wrong order: normal context line -old line -this is a context line with a leading dash +new line Instead, let's a be a little more clever about parsing the graph. We'll look for the actual "*" line that marks the start of a commit, and record the indentation we see there. Then we can skip past that indentation when checking whether the line is a hunk header, removal, addition, etc. There is one tricky thing: the indentation in bytes may be different for various lines of the graph due to coloring. E.g., the "*" on a commit line is generally shown without color, but on the actual diff lines, it will be replaced with a colorized "|" character, adding several bytes. We work around this here by counting "visible" bytes. This is unfortunately a bit more expensive, making us about twice as slow to handle --graph output. But since this is meant to be used interactively anyway, it's tolerably fast (and the non-graph case is unaffected). One alternative would be to search for hunk header lines and use their indentation (since they'd have the same colors as the diff lines which follow). But that just opens up different corner cases. If we see: | | @@ 1,2 1,3 @@ we cannot know if this is a real diff that has been indented due to the graph, or if it's a context line that happens to look like a diff header. We can only be sure of the indent on the "*" lines, since we know those don't contain arbitrary data (technically the user could include a bunch of extra indentation via --format, but that's rare enough to disregard). Reported-by: Phillip Wood <phillip.wood@dunelm.org.uk> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-21diff-highlight: test graphs with --colorJeff King
Our tests send git's output directly to files or pipes, so there will never be any color. Let's do at least one --color test to make sure that we can handle this case (which we currently can, but will be an easy thing to mess up when we touch the graph code in a future patch). We'll just cover the --graph case, since this is much more complex than the earlier cases (i.e., if it manages to highlight, then the non-graph case definitely would). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-21diff-highlight: test interleaved parallel lines of historyJeff King
The graph test in t9400 covers the case of two simultaneous branches, but all of the commits during this time are on the right-hand branch. So we test a graph structure like: | | | * commit ... | | but we never see the reverse, a commit on the left-hand branch: | | * | commit ... | | Since this is an easy thing to get wrong when touching the graph-matching code, let's cover it by adding one more commit with its timestamp interleaved with the other branch. Note that we need to pass --date-order to convince Git to show it this way (since --topo-order tries to keep lines of history separate). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-21diff-highlight: prefer "echo" to "cat" in testsJeff King
We generate a bunch of one-line files whose contents match their names, and then generate our commits by cat-ing those files. Let's just echo the contents directly, which saves some processes. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-21diff-highlight: use test_tick in graph testJeff King
The exact ordering output by Git may depend on the commit timestamps, so let's make sure they're actually monotonically increasing, and not all the same (or worse, subject to how long the test script takes to run). Let's use test_tick to make sure this is stable. Note that we actually have to rearrange the order of the branches to match the expected graph structure (which means that previously we might racily have been testing a slightly different output, though the test is written in such a way that we'd still pass). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-03-21diff-highlight: correct test graph diagramJeff King
We actually branch "A" off of "D". The sample "--graph" output is right, but the left-to-right diagram is misleading. Let's fix it. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-31diff-highlight: avoid highlighting combined diffsJeff King
The algorithm in diff-highlight only understands how to look at two sides of a diff; it cannot correctly handle combined diffs with multiple preimages. Often highlighting does not trigger at all for these diffs because the line counts do not match up. E.g., if we see: - ours -theirs ++resolved we would not bother highlighting; it naively looks like a single line went away, and then a separate hunk added another single line. But of course there are exceptions. E.g., if the other side deleted the line, we might see: - ours ++resolved which looks like we dropped " ours" and added "+resolved". This is only a small highlighting glitch (we highlight the space and the "+" along with the content), but it's also the tip of the iceberg. Even if we learned to find the true content here (by noticing we are in a 3-way combined diff and marking _two_ characters from the front of the line as uninteresting), there are other more complicated cases where we really do need to handle a 3-way hunk. Let's just punt for now; we can recognize combined diffs by the presence of extra "@" symbols in the hunk header, and treat them as non-diff content. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-31diff-highlight: add multi-byte testsJeff King
Now that we have a test suite for diff highlight, we can show off the improvements from 8d00662 (diff-highlight: do not split multibyte characters, 2015-04-03). While we're at it, we can also add another case that _doesn't_ work: combining code points are treated as their own unit, which means that we may stick colors between them and the character they are modifying (with the result that the color is not shown in an xterm, though it's possible that other terminals err the other way, and show the color but not the accent). There's no fix here, but let's document it as a failure. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-31diff-highlight: ignore test cruftJeff King
These are the same as in the normal t/.gitignore, with the exception of ".prove", as our Makefile does not support it. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-29diff-highlight: add support for --graph outputBrian Henderson
Signed-off-by: Brian Henderson <henderson.bj@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-29diff-highlight: add failing test for handling --graph outputBrian Henderson
Signed-off-by: Brian Henderson <henderson.bj@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
2016-08-29diff-highlight: add some testsBrian Henderson
Signed-off-by: Brian Henderson <henderson.bj@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>