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9 commits

Author SHA1 Message Date
Eric Sunshine 73a834e9e2 range-diff: relieve callers of low-level configuration burden
There are a number of very low-level configuration details which need to
be managed precisely to generate a proper range-diff. In particular,
'diff_options' output format, header suppression, indentation, and
dual-color mode must all be set appropriately to ensure proper behavior.

Handle these details locally in the libified range-diff back-end rather
than forcing each caller to have specialized knowledge of these
implementation details, and to avoid duplication as new callers are
added.

While at it, localize these tweaks to be active only while generating
the range-diff, so they don't clobber the caller-provided
'diff_options', which might be used beyond range-diff generation.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-14 14:27:04 -07:00
Eric Sunshine 25668659bf range-diff: publish default creation factor
The range-diff back-end allows its heuristic to be tweaked via the
"creation factor". git-range-diff, the only client of the back-end,
defaults the factor to 60% (hard-coded in builtin/range-diff.c), but
allows the user to override it with the --creation-factor option.

Publish the default range factor to allow new callers of the range-diff
back-end to default to the same value without duplicating the hard-coded
constant, and to avoid worrying about various callers becoming
out-of-sync if the default ever needs to change.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-14 14:24:56 -07:00
Johannes Schindelin 275267937b range-diff: make --dual-color the default mode
After using this command extensively for the last two months, this
developer came to the conclusion that even if the dual color mode still
leaves a lot of room for confusion about what was actually changed, the
non-dual color mode is substantially worse in that regard.

Therefore, we really want to make the dual color mode the default.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:52 -07:00
Johannes Schindelin 31cf61a080 range-diff: offer to dual-color the diffs
When showing what changed between old and new commits, we show a diff of
the patches. This diff is a diff between diffs, therefore there are
nested +/- signs, and it can be relatively hard to understand what is
going on.

With the --dual-color option, the preimage and the postimage are colored
like the diffs they are, and the *outer* +/- sign is inverted for
clarity.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:51 -07:00
Johannes Schindelin 1cdde296a5 range-diff: suppress the diff headers
When showing the diff between corresponding patches of the two branch
versions, we have to make up a fake filename to run the diff machinery.

That filename does not carry any meaningful information, hence tbdiff
suppresses it. So we should, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:51 -07:00
Johannes Schindelin 5e242e63d0 range-diff: indent the diffs just like tbdiff
The main information in the `range-diff` view comes from the list of
matching and non-matching commits, the diffs are additional information.
Indenting them helps with the reading flow.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:51 -07:00
Johannes Schindelin c8c5e43ac3 range-diff: also show the diff between patches
Just like tbdiff, we now show the diff between matching patches. This is
a "diff of two diffs", so it can be a bit daunting to read for the
beginner.

An alternative would be to display an interdiff, i.e. the hypothetical
diff which is the result of first reverting the old diff and then
applying the new diff.

Especially when rebasing frequently, an interdiff is often not feasible,
though: if the old diff cannot be applied in reverse (due to a moving
upstream), an interdiff can simply not be inferred.

This commit brings `range-diff` closer to feature parity with regard
to tbdiff.

To make `git range-diff` respect e.g. color.diff.* settings, we have
to adjust git_branch_config() accordingly.

Note: while we now parse diff options such as --color, the effect is not
yet the same as in tbdiff, where also the commit pairs would be colored.
This is left for a later commit.

Note also: while tbdiff accepts the `--no-patches` option to suppress
these diffs between patches, we prefer the `-s` (or `--no-patch`) option
that is automatically supported via our use of diff_opt_parse().

And finally note: to support diff options, we have to call
`parse_options()` such that it keeps unknown options, and then loop over
those and let `diff_opt_parse()` handle them. After that loop, we have
to call `parse_options()` again, to make sure that no unknown options
are left.

Helped-by: Thomas Gummerer <t.gummerer@gmail.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:50 -07:00
Johannes Schindelin d9c66f0b5b range-diff: first rudimentary implementation
At this stage, `git range-diff` can determine corresponding commits
of two related commit ranges. This makes use of the recently introduced
implementation of the linear assignment algorithm.

The core of this patch is a straight port of the ideas of tbdiff, the
apparently dormant project at https://github.com/trast/tbdiff.

The output does not at all match `tbdiff`'s output yet, as this patch
really concentrates on getting the patch matching part right.

Note: due to differences in the diff algorithm (`tbdiff` uses the Python
module `difflib`, Git uses its xdiff fork), the cost matrix calculated
by `range-diff` is different (but very similar) to the one calculated
by `tbdiff`. Therefore, it is possible that they find different matching
commits in corner cases (e.g. when a patch was split into two patches of
roughly equal length).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:50 -07:00
Johannes Schindelin 348ae56cb2 Introduce range-diff to compare iterations of a topic branch
This command does not do a whole lot so far, apart from showing a usage
that is oddly similar to that of `git tbdiff`. And for a good reason:
the next commits will turn `range-branch` into a full-blown replacement
for `tbdiff`.

At this point, we ignore tbdiff's color options, as they will all be
implemented later using diff_options.

Since f318d73915 (generate-cmds.sh: export all commands to
command-list.h, 2018-05-10), every new command *requires* a man page to
build right away, so let's also add a blank man page, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2018-08-13 10:44:50 -07:00