src/xdiff


Log

Author Commit Date CI Message
Patrick Steinhardt f347a441 2018-06-25T11:55:13 treewide: avoid use of `inline` attribute ISO C90 does not specify the `inline` attribute, and as such we cannot use it in our code. While we already use `__inline` when building in Microsoft Visual Studio, we should also be using the `__inline__` attribute from GCC/Clang. Otherwise, if we're using neither MSVC nor GCC/Clang, we should simply avoid using `inline` at all and just define functions as static. This commit adjusts our own `GIT_INLINE` macro as well as the inline macros specified by khash and xdiff. This allows us to enable strict C90 mode in a later commit.
Edward Thomson 7f52bc5a 2018-01-20T18:19:26 xdiff: upgrade to git's included xdiff Upgrade xdiff to git's most recent version, which includes changes to CR/LF handling. Now CR/LF included in the input files will be detected and conflict markers will be emitted with CR/LF when appropriate.
Michael Haggerty 5efe9d12 2017-10-14T08:58:14 Introduce a new `XDL_INLINE` macro and use it instead of `inline` `inline` is not portable enough, and the `xdiff` code doesn't import the `GIT_INLINE` macro. So introduce a new `XDL_INLINE` macro (with the same definition as `GIT_INLINE`). Use the new macro to inline two functions in `xdiffi.c`.
Jeff King b28825a1 2016-09-27T00:37:33 xdiff: rename "struct group" to "struct xdlgroup" Commit a49895b593 (xdl_change_compact(): introduce the concept of a change group, 2016-08-22) added a "struct group" type to xdiff/xdiffi.c. But the POSIX system header "grp.h" already defines "struct group" (it is part of the getgrnam interface). Let's resolve by giving the xdiff variant a scoped name, which is closer to other xdiff types anyway (e.g., xdlfile_t, though note that xdiff is fond if typedefs when Git usually is not).
Michael Haggerty 19f1a8e6 2016-09-05T11:44:51 diff: improve positioning of add/delete blocks in diffs 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]. [1] https://github.com/mhagger/diff-slider-tools Original Git commit: 433860f3d0beb0c6f205290bd16cda413148f098
Michael Haggerty a49895b5 2016-08-22T13:22:44 xdl_change_compact(): introduce the concept of a change group The idea of xdl_change_compact() is fairly simple: * Proceed through groups of changed lines in the file to be compacted, keeping track of the corresponding location in the "other" file. * If possible, slide the group up and down to try to give the most aesthetically pleasing diff. Whenever it is slid, the current location in the other file needs to be adjusted. But these simple concepts are obfuscated by a lot of index handling that is written in terse, subtle, and varied patterns. I found it very hard to convince myself that the function was correct. So introduce a "struct group" that represents a group of changed lines in a file. Add some functions that perform elementary operations on groups: * Initialize a group to the first group in a file * Move to the next or previous group in a file * Slide a group up or down Even though the resulting code is longer, I think it is easier to understand and review. Its performance is not changed appreciably (though it would be if `group_next()` and `group_previous()` were not inlined). ...and in fact, the rewriting helped me discover another bug in the --compaction-heuristic code: The update of blank_lines was never done for the highest possible position of the group. This means that it could fail to slide the group to its highest possible position, even if that position had a blank line as its last line. So for example, it yielded the following diff: $ git diff --no-index --compaction-heuristic a.txt b.txt diff --git a/a.txt b/b.txt index e53969f..0d60c5fe 100644 --- a/a.txt +++ b/b.txt @@ -1,3 +1,7 @@ 1 A + +B + +A 2 when in fact the following diff is better (according to the rules of --compaction-heuristic): $ git diff --no-index --compaction-heuristic a.txt b.txt diff --git a/a.txt b/b.txt index e53969f..0d60c5fe 100644 --- a/a.txt +++ b/b.txt @@ -1,3 +1,7 @@ 1 +A + +B + A 2 The new code gives the bottom answer. Original Git commit: e8adf23d1ee97b57c8aea32ee8365203b77c0e42
Michael Haggerty 09fb5b2a 2016-08-22T13:22:43 recs_match(): take two xrecord_t pointers as arguments There is no reason for it to take an array and two indexes as argument, as it only accesses two elements of the array. Original Git commit: 152598cbb667471c8f5be16e199922a41452b2d5
Jacob Keller 506bf09d 2016-04-15T16:01:45 xdiff: add recs_match helper function It is a common pattern in xdl_change_compact to check that hashes and strings match. The resulting code to perform this change causes very long lines and makes it hard to follow the intention. Introduce a helper function recs_match which performs both checks to increase code readability. Original Git commit: 92e5b62fec0e9b647429e8d3736c571c434dd375
Edward Thomson c4aa5c04 2016-03-31T10:43:57 leaks: call `xdl_free_classifier`
Patrick Steinhardt 6045afd3 2016-03-31T11:32:36 xdiff/xprepare: fix a memory leak The xdl_prepare_env() function may initialise an xdlclassifier_t data structure via xdl_init_classifier(), which allocates memory to several fields, for example 'rchash', 'rcrecs' and 'ncha'. If this function later exits due to the failure of xdl_optimize_ctxs(), then this xdlclassifier_t structure, and the memory allocated to it, is not cleaned up. In order to fix the memory leak, insert a call to xdl_free_classifier() before returning. This patch was originally written by Ramsay Jones (see commit 87f16258367a3b9a62663b11f898a4a6f3c19d31 in git.git).
Patrick Steinhardt 1bce1487 2016-03-31T11:30:31 xdiff/xprepare: use the XDF_DIFF_ALG() macro to access flag bits Commit 307ab20b3 ("xdiff: PATIENCE/HISTOGRAM are not independent option bits", 19-02-2012) introduced the XDF_DIFF_ALG() macro to access the flag bits used to represent the diff algorithm requested. In addition, code which had used explicit manipulation of the flag bits was changed to use the macros. However, one example of direct manipulation remains. Update this code to use the XDF_DIFF_ALG() macro. This patch was originally written by Ramsay Jones (see commit 5cd6978a9cfef58de061a9525f3678ade479564d in git.git).
Patrick Steinhardt a4ea7faa 2016-03-01T08:54:00 xdiff: fix memleak on error case Commit 3d1abc5afce fixes a memory leak in the xdiff code. In the process of upstreaming the fix it was pointed out by Johannes Schindelin that there is another memory leak present (see [1]). Fix the second memory leak by applying the upstream fix to our code base. [1]: http://thread.gmane.org/gmane.comp.version-control.git/287034
Patrick Steinhardt 3d1abc5a 2016-02-22T17:13:23 xmerge: fix memory leak on error path
Edward Thomson c7b336b0 2015-10-22T10:29:51 xdiff: reference util.h in parent directory Although CMake will correctly configure include directories for us, some people may use their own build system, and we should reference `util.h` based on where it actually lives.
Edward Thomson e4352066 2015-09-28T18:25:24 merge_file: treat large files as binary xdiff craps the bed on large files. Treat very large files as binary, so that it doesn't even have to try. Refactor our merge binary handling to better match git.git, which looks for a NUL in the first 8000 bytes.
Edward Thomson 46c0e6e3 2015-09-28T16:34:29 xdiff: convert size variables to size_t
Edward Thomson a3c00cd8 2015-07-10T09:21:59 xdiff: cleanup some warnings
Edward Thomson 234ca40a 2015-07-07T16:46:48 xdiff: upgrade to core git 2.4.5 Upgrade xdiff to version used in core git 2.4.5 (0df0541). Corrects an issue where an LF is added at EOF while applying an unrelated change (ba31180), cleans up some unused code (be89977 and e5b0662), and provides an improved callback to avoid leaking internal (to xdiff) structures (467d348). This also adds some additional functionality that we do not yet take advantage of, namely the ability to ignore changes whose lines are all blank (36617af).
Will Stamper b874629b 2014-12-04T21:06:59 Spelling fixes
Vicent Martí 40879fac 2012-05-02T15:59:02 Merge branch 'new-error-handling' into development Conflicts: .travis.yml include/git2/diff.h src/config_file.c src/diff.c src/diff_output.c src/mwindow.c src/path.c tests-clar/clar_helpers.c tests-clar/object/tree/frompath.c tests/t00-core.c tests/t03-objwrite.c tests/t08-tag.c tests/t10-refs.c tests/t12-repo.c tests/t18-status.c tests/test_helpers.c tests/test_main.c
Sven Strickroth 8c327228 2012-04-21T18:45:32 Check for _WIN32 instead of GIT_WIN32 or WIN32 to detect windows build environments This fixes a possible compilation issue (when GIT_WIN32 was not set) which was introduced in revision 69a4bc1988fc242bd0d310781c865cce5481a0e6. Signed-off-by: Sven Strickroth <email@cs-ware.de>
Sven Strickroth b333fbf9 2012-04-20T18:51:10 WIN32 is not always defined, use GIT_WIN32 instead Signed-off-by: Sven Strickroth <email@cs-ware.de>
Russell Belfer 44ef8b1b 2012-04-13T13:00:10 Fix warnings on 64-bit windows builds This fixes all the warnings on win64 except those in deps, which come from the regex code.
Russell Belfer 74fa4bfa 2012-02-28T16:14:47 Update diff to use iterators This is a major reorganization of the diff code. This changes the diff functions to use the iterators for traversing the content. This allowed a lot of code to be simplified. Also, this moved the functions relating to outputting a diff into a new file (diff_output.c). This includes a number of other changes - adding utility functions, extending iterators, etc. plus more tests for the diff code. This also takes the example diff.c program much further in terms of emulating git-diff command line options.
Russell Belfer cd33323b 2012-01-27T11:29:25 Initial implementation of git_diff_blob This gets the basic plumbing in place for git_diff_blob. There is a known issue where additional parameters like the number of lines of context to display on the diff are not working correctly (which leads one of the new unit tests to fail).
Russell Belfer 3a5ad90a 2012-01-24T12:23:20 Import xdiff library from git This is the initial import of the xdiff code (LGPL) from core git as of rev f349b562086e2b7595d8a977d2734ab2ef9e71ef
Russell Belfer 8b75f7f3 2012-01-24T14:08:20 Eliminate xdiff compiler warnings This cleans up the various GCC compiler warnings with the xdiff code that was copied in.