git/git-add--interactive.perl, branch v2.11.2

diff: improve positioning of add/delete blocks in diffs

2016-09-19T17:25:11Z

Some groups of added/deleted lines in diffs can be slid up or down, because lines at the edges of the group are not unique. Picking good shifts for such groups is not a matter of correctness but definitely has a big effect on aesthetics. For example, consider the following two diffs. The first is what standard Git emits: --- a/9c572b21dd090a1e5c5bb397053bf8043ffe7fb4:git-send-email.perl +++ b/6dcfa306f2b67b733a7eb2d7ded1bc9987809edb:git-send-email.perl @@ -231,6 +231,9 @@ if (!defined $initial_reply_to && $prompting) { } if (!$smtp_server) { + $smtp_server = $repo->config('sendemail.smtpserver'); +} +if (!$smtp_server) { foreach (qw( /usr/sbin/sendmail /usr/lib/sendmail )) { if (-x $_) { $smtp_server = $_; The following diff is equivalent, but is obviously preferable from an aesthetic point of view: --- a/9c572b21dd090a1e5c5bb397053bf8043ffe7fb4:git-send-email.perl +++ b/6dcfa306f2b67b733a7eb2d7ded1bc9987809edb:git-send-email.perl @@ -230,6 +230,9 @@ if (!defined $initial_reply_to && $prompting) { $initial_reply_to =~ s/(^\s+|\s+$)//g; } +if (!$smtp_server) { + $smtp_server = $repo->config('sendemail.smtpserver'); +} if (!$smtp_server) { foreach (qw( /usr/sbin/sendmail /usr/lib/sendmail )) { if (-x $_) { This patch teaches Git to pick better positions for such "diff sliders" using heuristics that take the positions of nearby blank lines and the indentation of nearby lines into account. The existing Git code basically always shifts such "sliders" as far down in the file as possible. The only exception is when the slider can be aligned with a group of changed lines in the other file, in which case Git favors depicting the change as one add+delete block rather than one add and a slightly offset delete block. This naive algorithm often yields ugly diffs. Commit d634d61ed6 improved the situation somewhat by preferring to position add/delete groups to make their last line a blank line, when that is possible. This heuristic does more good than harm, but (1) it can only help if there are blank lines in the right places, and (2) always picks the last blank line, even if there are others that might be better. The end result is that it makes perhaps 1/3 as many errors as the default Git algorithm, but that still leaves a lot of ugly diffs. This commit implements a new and much better heuristic for picking optimal "slider" positions using the following approach: First observe that each hypothetical positioning of a diff slider introduces two splits: one between the context lines preceding the group and the first added/deleted line, and the other between the last added/deleted line and the first line of context following it. It tries to find the positioning that creates the least bad splits. Splits are evaluated based only on the presence and locations of nearby blank lines, and the indentation of lines near the split. Basically, it prefers to introduce splits adjacent to blank lines, between lines that are indented less, and between lines with the same level of indentation. In more detail: 1. It measures the following characteristics of a proposed splitting position in a `struct split_measurement`: * the number of blank lines above the proposed split * whether the line directly after the split is blank * the number of blank lines following that line * the indentation of the nearest non-blank line above the split * the indentation of the line directly below the split * the indentation of the nearest non-blank line after that line 2. It combines the measured attributes using a bunch of empirically-optimized weighting factors to derive a `struct split_score` that measures the "badness" of splitting the text at that position. 3. It combines the `split_score` for the top and the bottom of the slider at each of its possible positions, and selects the position that has the best `split_score`. I determined the initial set of weighting factors by collecting a corpus of Git histories from 29 open-source software projects in various programming languages. I generated many diffs from this corpus, and determined the best positioning "by eye" for about 6600 diff sliders. I used about half of the repositories in the corpus (corresponding to about 2/3 of the sliders) as a training set, and optimized the weights against this corpus using a crude automated search of the parameter space to get the best agreement with the manually-determined values. Then I tested the resulting heuristic against the full corpus. The results are summarized in the following table, in column `indent-1`: | repository | count | Git 2.9.0 | compaction | compaction-fixed | indent-1 | indent-2 | | --------------------- | ----- | -------------- | -------------- | ---------------- | -------------- | -------------- | | afnetworking | 109 | 89 (81.7%) | 37 (33.9%) | 37 (33.9%) | 2 (1.8%) | 2 (1.8%) | | alamofire | 30 | 18 (60.0%) | 14 (46.7%) | 15 (50.0%) | 0 (0.0%) | 0 (0.0%) | | angular | 184 | 127 (69.0%) | 39 (21.2%) | 23 (12.5%) | 5 (2.7%) | 5 (2.7%) | | animate | 313 | 2 (0.6%) | 2 (0.6%) | 2 (0.6%) | 2 (0.6%) | 2 (0.6%) | | ant | 380 | 356 (93.7%) | 152 (40.0%) | 148 (38.9%) | 15 (3.9%) | 15 (3.9%) | * | bugzilla | 306 | 263 (85.9%) | 109 (35.6%) | 99 (32.4%) | 14 (4.6%) | 15 (4.9%) | * | corefx | 126 | 91 (72.2%) | 22 (17.5%) | 21 (16.7%) | 6 (4.8%) | 6 (4.8%) | | couchdb | 78 | 44 (56.4%) | 26 (33.3%) | 28 (35.9%) | 6 (7.7%) | 6 (7.7%) | * | cpython | 937 | 158 (16.9%) | 50 (5.3%) | 49 (5.2%) | 5 (0.5%) | 5 (0.5%) | * | discourse | 160 | 95 (59.4%) | 42 (26.2%) | 36 (22.5%) | 18 (11.2%) | 13 (8.1%) | | docker | 307 | 194 (63.2%) | 198 (64.5%) | 253 (82.4%) | 8 (2.6%) | 8 (2.6%) | * | electron | 163 | 132 (81.0%) | 38 (23.3%) | 39 (23.9%) | 6 (3.7%) | 6 (3.7%) | | git | 536 | 470 (87.7%) | 73 (13.6%) | 78 (14.6%) | 16 (3.0%) | 16 (3.0%) | * | gitflow | 127 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | | ionic | 133 | 89 (66.9%) | 29 (21.8%) | 38 (28.6%) | 1 (0.8%) | 1 (0.8%) | | ipython | 482 | 362 (75.1%) | 167 (34.6%) | 169 (35.1%) | 11 (2.3%) | 11 (2.3%) | * | junit | 161 | 147 (91.3%) | 67 (41.6%) | 66 (41.0%) | 1 (0.6%) | 1 (0.6%) | * | lighttable | 15 | 5 (33.3%) | 0 (0.0%) | 2 (13.3%) | 0 (0.0%) | 0 (0.0%) | | magit | 88 | 75 (85.2%) | 11 (12.5%) | 9 (10.2%) | 1 (1.1%) | 0 (0.0%) | | neural-style | 28 | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | 0 (0.0%) | | nodejs | 781 | 649 (83.1%) | 118 (15.1%) | 111 (14.2%) | 4 (0.5%) | 5 (0.6%) | * | phpmyadmin | 491 | 481 (98.0%) | 75 (15.3%) | 48 (9.8%) | 2 (0.4%) | 2 (0.4%) | * | react-native | 168 | 130 (77.4%) | 79 (47.0%) | 81 (48.2%) | 0 (0.0%) | 0 (0.0%) | | rust | 171 | 128 (74.9%) | 30 (17.5%) | 27 (15.8%) | 16 (9.4%) | 14 (8.2%) | | spark | 186 | 149 (80.1%) | 52 (28.0%) | 52 (28.0%) | 2 (1.1%) | 2 (1.1%) | | tensorflow | 115 | 66 (57.4%) | 48 (41.7%) | 48 (41.7%) | 5 (4.3%) | 5 (4.3%) | | test-more | 19 | 15 (78.9%) | 2 (10.5%) | 2 (10.5%) | 1 (5.3%) | 1 (5.3%) | * | test-unit | 51 | 34 (66.7%) | 14 (27.5%) | 8 (15.7%) | 2 (3.9%) | 2 (3.9%) | * | xmonad | 23 | 22 (95.7%) | 2 (8.7%) | 2 (8.7%) | 1 (4.3%) | 1 (4.3%) | * | --------------------- | ----- | -------------- | -------------- | ---------------- | -------------- | -------------- | | totals | 6668 | 4391 (65.9%) | 1496 (22.4%) | 1491 (22.4%) | 150 (2.2%) | 144 (2.2%) | | totals (training set) | 4552 | 3195 (70.2%) | 1053 (23.1%) | 1061 (23.3%) | 86 (1.9%) | 88 (1.9%) | | totals (test set) | 2116 | 1196 (56.5%) | 443 (20.9%) | 430 (20.3%) | 64 (3.0%) | 56 (2.6%) | In this table, the numbers are the count and percentage of human-rated sliders that the corresponding algorithm got *wrong*. The columns are * "repository" - the name of the repository used. I used the diffs between successive non-merge commits on the HEAD branch of the corresponding repository. * "count" - the number of sliders that were human-rated. I chose most, but not all, sliders to rate from those among which the various algorithms gave different answers. * "Git 2.9.0" - the default algorithm used by `git diff` in Git 2.9.0. * "compaction" - the heuristic used by `git diff --compaction-heuristic` in Git 2.9.0. * "compaction-fixed" - the heuristic used by `git diff --compaction-heuristic` after the fixes from earlier in this patch series. Note that the results are not dramatically different than those for "compaction". Both produce non-ideal diffs only about 1/3 as often as the default `git diff`. * "indent-1" - the new `--indent-heuristic` algorithm, using the first set of weighting factors, determined as described above. * "indent-2" - the new `--indent-heuristic` algorithm, using the final set of weighting factors, determined as described below. * `*` - indicates that repo was part of training set used to determine the first set of weighting factors. The fact that the heuristic performed nearly as well on the test set as on the training set in column "indent-1" is a good indication that the heuristic was not over-trained. Given that fact, I ran a second round of optimization, using the entire corpus as the training set. The resulting set of weights gave the results in column "indent-2". These are the weights included in this patch. The final result gives consistently and significantly better results across the whole corpus than either `git diff` or `git diff --compaction-heuristic`. It makes only about 1/30 as many errors as the former and about 1/10 as many errors as the latter. (And a good fraction of the remaining errors are for diffs that involve weirdly-formatted code, sometimes apparently machine-generated.) The tools that were used to do this optimization and analysis, along with the human-generated data values, are recorded in a separate project [1]. This patch adds a new command-line option `--indent-heuristic`, and a new configuration setting `diff.indentHeuristic`, that activate this heuristic. This interface is only meant for testing purposes, and should be finalized before including this change in any release. [1] https://github.com/mhagger/diff-slider-tools Signed-off-by: Michael Haggerty Signed-off-by: Junio C Hamano

add--interactive: respect diff.compactionHeuristic

2016-06-16T18:38:58Z

We use plumbing to generate the diff, so it doesn't automatically pick up UI config like compactionHeuristic. Let's forward it on, since interactive adding is porcelain. Note that we only need to handle the "true" case. There's no point in passing --no-compaction-heuristic when the variable is false, since nothing else could have turned it on. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

add--interactive: allow custom diff highlighting programs

2016-02-28T18:53:54Z

The patch hunk selector of add--interactive knows how ask git for colorized diffs, and correlate them with the uncolored diffs we apply. But there's not any way for somebody who uses a diff-filter tool like contrib's diff-highlight to see their normal highlighting. This patch lets users define an arbitrary shell command to pipe the colorized diff through. The exact output shouldn't matter (since we just show the result to humans) as long as it is line-compatible with the original diff (so that hunk-splitting can split the colorized version, too). I left two minor issues with the new system that I don't think are worth fixing right now, but could be done later: 1. We only filter colorized diffs. Theoretically a user could want to filter a non-colorized diff, but I find it unlikely in practice. Users who are doing things like diff-highlighting are likely to want color, too. 2. add--interactive will re-colorize a diff which has been hand-edited, but it won't have run through the filter. Fixing this is conceptually easy (just pipe the diff through the filter), but practically hard to do without using tempfiles (it would need to feed data to and read the result from the filter without deadlocking; this raises portability questions with respect to Windows). I've punted on both issues for now, and if somebody really cares later, they can do a patch on top. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'ak/add-i-empty-candidates'

2015-02-17T18:15:20Z

The interactive "show a list and let the user choose from it" interface "add -i" used showed and prompted to the user even when the candidate list was empty, against which the only "choice" the user could have made was to choose nothing. * ak/add-i-empty-candidates: add -i: return from list_and_choose if there is no candidate

add -i: return from list_and_choose if there is no candidate

2015-01-22T22:44:36Z

The list_and_choose() helper is given a prompt and a list, asks the user to make selection from the list, and then returns a list of items chosen. Even when it is given an empty list as the original candidate set to choose from, it gave a prompt to the user, who can only say "I am done choosing". Return an empty result when the input is an empty list without bothering the user. The existing caller must already have a logic to say "Nothing to do" or an equivalent when the returned list is empty (i.e. the user chose to select nothing) if it is necessary, so no change to the callers is necessary. This fixes the case where "add untracked" is asked in "git add -i" and there is no untracked files in the working tree. We used to give an empty list of files to choose from with a prompt, but with this change, we no longer do. Signed-off-by: Alexander Kuleshov Signed-off-by: Junio C Hamano

add--interactive: leave main loop on read error

2014-12-15T18:12:20Z

The main hunk loop for add--interactive will loop if it does not get a known input. This is a good thing if the user typed some invalid input. However, if we have an uncorrectable read error, we'll end up looping infinitely. We can fix this by noticing read errors (i.e., returns undef) and breaking out of the loop. One easy way to trigger this is if you have an editor that does not take over the terminal (e.g., one that spawns a window in an existing process and waits), start the editor with the hunk-edit command, and hit ^C to send SIGINT. The editor process dies due to SIGINT, but the perl add--interactive process does not (perl suspends SIGINT for the duration of our system() call). We return to the main loop, but further reads from stdin don't work. The SIGINT _also_ killed our parent git process, which orphans our process group, meaning that further reads from the terminal will always fail. We loop infinitely, getting EIO on each read. Note that there are several other spots where we read from stdin, too. However, in each of those cases, we do something sane when the read returns undef (breaking out of the loop, taking the input as "no", etc). They don't need similar treatment. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

Merge branch 'jl/nor-or-nand-and'

2014-04-08T19:00:28Z

Eradicate mistaken use of "nor" (that is, essentially "nor" used not in "neither A nor B" ;-)) from in-code comments, command output strings, and documentations. * jl/nor-or-nand-and: code and test: fix misuses of "nor" comments: fix misuses of "nor" contrib: fix misuses of "nor" Documentation: fix misuses of "nor"

code and test: fix misuses of "nor"

2014-03-31T22:29:33Z

Signed-off-by: Justin Lebar Signed-off-by: Junio C Hamano

git-add--interactive: warn if module for interactive.singlekey is missing

2014-03-03T22:11:18Z

Suggested-by: Junio C Hamano Signed-off-by: Simon Ruderich Signed-off-by: Junio C Hamano

add-interactive: handle unborn branch in patch mode

2013-10-25T21:54:17Z

The list_modified function already knows how to handle an unborn branch by diffing against the empty tree. However, the diff we perform to get the actual hunks does not. Let's use the same logic for both diffs. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano