kernel/git - git - PowerEL Git System

Commit Graph

Author	SHA1	Message	Date
Jeff King	611e42a598	xdiff: provide a separate emit callback for hunks The xdiff library always emits hunk header lines to our callbacks as formatted strings like "@@ -a,b +c,d @@\n". This is convenient if we're going to output a diff, but less so if we actually need to compute using those numbers, which requires re-parsing the line. In preparation for moving away from this, let's teach xdiff a new callback function which gets the broken-out hunk information. To help callers that don't want to use this new callback, if it's NULL we'll continue to format the hunk header into a string. Note that this function renames the "outf" callback to "out_line", as well. This isn't strictly necessary, but helps in two ways: 1. Now that there are two callbacks, it's nice to use more descriptive names. 2. Many callers did not zero the emit_callback_data struct, and needed to be modified to set ecb.out_hunk to NULL. By changing the name of the existing struct member, that guarantees that any new callers from in-flight topics will break the build and be examined manually. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	6 years ago
Stefan Beller	301ef85401	xdiff: reduce indent heuristic overhead Skip searching for better indentation heuristics if we'd slide a hunk more than its size. This is the easiest fix proposed in the analysis[1] in response to a patch that mercurial took for xdiff to limit searching by a constant. Using a performance test as: #!python open('a', 'w').write(" \n" * 1000000) open('b', 'w').write(" \n" * 1000001) This patch reduces the execution of "git diff --no-index a b" from 0.70s to 0.31s. However limiting the sliding to the size of the diff hunk, which was proposed as a solution (that I found easiest to implement for now) is not optimal for cases like open('a', 'w').write(" \n" * 1000000) open('b', 'w').write(" \n" * 2000000) as then we'd still slide 1000000 times. In addition to limiting the sliding to size of the hunk, also limit by a constant. Choose 100 lines as the constant as that fits more than a screen, which really means that the diff sliding is probably not providing a lot of benefit anyway. [1] https://public-inbox.org/git/72ac1ac2-f567-f241-41d6-d0f83072e0b3@alum.mit.edu/ Reported-by: Jun Wu <quark@fb.com> Analysis-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	79cb2ebb92	xdiff/histogram: remove tail recursion When running the same reproduction script as the previous patch, it turns out the stack is too small, which can be easily avoided. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	64c4e8bccd	xdiff/xhistogram: move index allocation into find_lcs This fixes a memory issue when recursing a lot, which can be reproduced as seq 1 100000 >one seq 1 4 100000 >two git diff --no-index --histogram one two Before this patch, histogram_diff would call itself recursively before calling free_index, which would mean a lot of memory is allocated during the recursion and only freed afterwards. By moving the memory allocation (and its free call) into find_lcs, the memory is free'd before we recurse, such that memory is reused in the next step of the recursion instead of using new memory. This addresses only the memory pressure, not the run time complexity, that is also awful for the corner case outlined above. Helpful in understanding the code (in addition to the sparse history of this file), was https://stackoverflow.com/a/32367597 which reproduces most of the code comments of the JGit implementation. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	c671d4b599	xdiff/xhistogram: factor out memory cleanup into free_index() This will be useful in the next patch as we'll introduce multiple callers. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	282098506f	xdiff/xhistogram: pass arguments directly to fall_back_to_classic_diff By passing the 'xpp' and 'env' argument directly to the function 'fall_back_to_classic_diff', we eliminate an occurrence of the 'index' in histogram_diff, which will prove useful in a bit. While at it, move it up in the file. This will make the diff of one of the next patches more legible. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	21c770b63e	xdiff/xdiffi.c: remove unneeded function declarations There is no need to forward-declare these functions, as they are used after their implementation only. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Stefan Beller	25790be634	xdiff/xdiff.h: remove unused flags These flags were there since the beginning (`3443546f6e` (Use a real built-in diff generator, 2006-03-24), but were never used. Remove them. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Jonathan Tan	2477ab2ea8	diff: support anchoring line(s) Teach diff a new algorithm, one that attempts to prevent user-specified lines from appearing as a deletion or addition in the end result. The end user can use this by specifying "--anchored=<text>" one or more times when using Git commands like "diff" and "show". Signed-off-by: Jonathan Tan <jonathantanmy@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
René Scharfe	5c3ed90f3f	xdiff: show non-empty lines before functions with -W Non-empty lines before a function definition are most likely comments for that function and thus relevant. Include them in function context. Such a non-empty line might also belong to the preceeding function if there is no separating blank line. Stop extending the context upwards also at the next function line to make sure only one extra function body is shown at most. Original-patch-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
René Scharfe	cde32bf62f	xdiff: factor out is_func_rec() Add a helper for checking if a given record is a function line. It frees callers from having to deal with the buffer arguments of match_func_rec(). Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Todd Zullinger	484257925f	Replace Free Software Foundation address in license notices The mailing address for the FSF has changed over the years. Rather than updating the address across all files, refer readers to gnu.org, as the GNU GPL documentation now suggests for license notices. The mailing address is retained in the full license files (COPYING and LGPL-2.1). The old address is still present in t/diff-lib/COPYING. This is intentional, as the file is used in tests and the contents are not expected to change. Signed-off-by: Todd Zullinger <tmz@pobox.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Junio C Hamano	e9282f02b2	diff: --ignore-cr-at-eol A new option --ignore-cr-at-eol tells the diff machinery to treat a carriage-return at the end of a (complete) line as if it does not exist. Just like other "--ignore-*" options to ignore various kinds of whitespace differences, this will help reviewing the real changes you made without getting distracted by spurious CRLF<->LF conversion made by your editor program. Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> [jch: squashed in command line completion by Dscho] Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Junio C Hamano	446d12cb3f	xdiff: reassign xpparm_t.flags bits We have packed the bits too tightly in such a way that it is not easy to add a new type of whitespace ignoring option, a new type of LCS algorithm, or a new type of post-cleanup heuristics. Reorder bits a bit to give room for these three classes of options to grow. Also make use of XDF_WHITESPACE_FLAGS macro where we check any of these bits are on, instead of using DIFF_XDL_TST() macro on individual possibilities. That way, the "is any of the bits on?" code does not have to change when we add more ways to ignore whitespaces. While at it, add a comment in front of the bit definitions to clarify in which structure these defined bits may appear. Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Derrick Stolee	19716b21a4	cleanup: fix possible overflow errors in binary search A common mistake when writing binary search is to allow possible integer overflow by using the simple average: mid = (min + max) / 2; Instead, use the overflow-safe version: mid = min + (max - min) / 2; This translation is safe since the operation occurs inside a loop conditioned on "min < max". The included changes were found using the following git grep: git grep '/ 2;' '.c' Making this cleanup will prevent future review friction when a new binary search is contructed based on existing code. Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Reviewed-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	7 years ago
Vegard Nossum	540d3eb0eb	xdiff -W: relax end-of-file function detection When adding a new function to the end of a file, it's enough to know that 1) the addition is at the end of the file; and 2) there is a function _somewhere_ in there. If we had simply been changing the end of an existing function, then we would also be deleting something from the old version. This fixes the case where we add e.g. // Begin of dummy static int dummy(void) { } to the end of the file. Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: René Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Junio C Hamano	3cde4e02ee	diff: retire "compaction" heuristics When a patch inserts a block of lines, whose last lines are the same as the existing lines that appear before the inserted block, "git diff" can choose any place between these existing lines as the boundary between the pre-context and the added lines (adjusting the end of the inserted block as appropriate) to come up with variants of the same patch, and some variants are easier to read than others. We have been trying to improve the choice of this boundary, and Git 2.11 shipped with an experimental "compaction-heuristic". Since then another attempt to improve the logic further resulted in a new "indent-heuristic" logic. It is agreed that the latter gives better result overall, and the former outlived its usefulness. Retire "compaction", and keep "indent" as an experimental feature. The latter hopefully will be turned on by default in a future release, but that should be done as a separate step. Suggested-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff King	1f7c926132	xdiff: drop XDL_FAST_HASH The xdiff code hashes every line of both sides of a diff, and then compares those hashes to find duplicates. The overall performance depends both on how fast we can compute the hashes, but also on how many hash collisions we see. The idea of XDL_FAST_HASH is to speed up the hash computation. But the generated hashes have worse collision behavior. This means that in some cases it speeds diffs up (running "git log -p" on git.git improves by ~8% with it), but in others it can slow things down. One pathological case saw over a 100x slowdown[1]. There may be a better hash function that covers both properties, but in the meantime we are better off with the original hash. It's slightly slower in the common case, but it has fewer surprising pathological cases. [1] http://public-inbox.org/git/20141222041944.GA441@peff.net/ Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Jeff King	134e40d744	xdiff: rename "struct group" to "struct xdlgroup" Commit `e8adf23` (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). This happens to work because the new type is local to xdiffi.c, and the xdiff code includes a relatively small set of system headers. But it will break compilation if xdiff ever switches to using git-compat-util.h. It can also probably cause confusion with tools that look at the whole code base, like coccinelle or ctags. 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). Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	433860f3d0	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]. 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 <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
René Scharfe	45d2f75f91	xdiff: fix merging of hunks with -W context and -u context If the function context for a hunk (with -W) reaches the beginning of the next hunk then we need to merge these two -- otherwise we'd show some lines twice, which looks strange and even confuses git apply. We already do this checking and merging in xdl_emit_diff(), but forget to consider regular context (with -u or -U). Fix that by merging hunks already if function context of the first one touches or overlaps regular context of the second one. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Stefan Beller	5e4e5bb539	xdiff: remove unneeded declarations Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	e8adf23d1e	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. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	152598cbb6	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. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	c06c0b6343	is_blank_line(): take a single xrecord_t as argument There is no reason for it to take an array and index as argument, as it only accesses a single element of the array. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	cb0eded863	xdl_change_compact(): only use heuristic if group can't be matched If the changed group of lines can be matched to a group in the other file, then that positioning should take precedence over the compaction heuristic. The old code tried the heuristic unconditionally, which cost redundant effort and also was broken if the matching code had already shifted the group higher than the blank line. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Michael Haggerty	a8fd78cc53	xdl_change_compact(): fix compaction heuristic to adjust ixo The code branch used for the compaction heuristic forgot to keep ixo in sync while the group was shifted. This is certainly wrong, as it causes the two counters to get out of sync. I think that this bug could also have caused the function to read past the end of the rchgo array, though I haven't done the work to prove it for sure. Here is my reasoning: If ixo is not decremented correctly during one iteration of the outer while loop, then it will loose sync with the ix counter. In particular, ixo will be too large. Suppose that the next iterations of the outer while loop (i.e., processing the next block of add/delete lines) don't have any sliders. Then the ixo counter would be incremented by the number of non-changed lines in xdf, which is the same as the number of non-changed lines in xdfo that should have followed the group that experienced the malfunction. But since ixo was too large at the end of that iteration, it will be incremented past the end of the xdfo->rchg array, and will try to read that memory illegally. Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Junio C Hamano <gitster@pobox.com>	8 years ago
Johannes Schindelin	044fb190f7	diff: fix a double off-by-one with --ignore-space-at-eol When comparing two lines, ignoring any whitespace at the end, we first try to match as many bytes as possible and break out of the loop only upon mismatch, to let the remainder be handled by the code shared with the other whitespace-ignoring code paths. When comparing the bytes, however, we incremented the counters always, even if the bytes did not match. And because we fall through to the space-at-eol handling at that point, it is as if that mismatch never happened. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
René Scharfe	6f8d9bccb2	xdiff: fix merging of appended hunk with -W When -W is given we search the lines between the end of the current context and the next change for a function line. If there is none then we merge those two hunks as they must be part of the same function. If the next change is an appended chunk we abort the search early in get_func_line(), however, because its line number is out of range. Fix that by searching from the end of the pre-image in that case instead. Reported-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
René Scharfe	9e6a4cfc38	xdiff: -W: don't include common trailing empty lines in context Empty lines between functions are shown by diff -W, as it considers them to be part of the function preceding them. They are not interesting in most languages. The previous patch stopped showing them in the special case of a function added at the end of a file. Stop extending context to those empty lines by skipping back over them from the start of the next function. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
René Scharfe	392f6d3166	xdiff: ignore empty lines before added functions with -W If a new function and a preceding empty line is appended, diff -W shows the previous function in full in order to provide context for that empty line. In most languages empty lines between sections are not interesting in and off themselves and showing a whole extra function for them is not what we want. Skip empty lines when checking of the appended chunk starts with a function line, thereby avoiding to extend the context just for them. Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
René Scharfe	6d5badb238	xdiff: handle appended chunks better with -W If lines are added at the end of a file, diff -W shows the whole file. That's because get_func_line() only considers the pre-image and gives up if it sees a record index beyond its end. Consider the post-image as well to see if the added lines already make up a full function. If it doesn't then search for the previous function line by starting from the bottom of the pre-image, thereby avoiding to confuse get_func_line(). Reuse the existing label called "again", as it's exactly where we need to jump to when we're done handling the pre-context, but rename it to "post_context_calculation" in order to document its new purpose better. Reported-by: Junio C Hamano <gitster@pobox.com> Initial-patch-by: Junio C Hamano <gitster@pobox.com> Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
René Scharfe	ff2981f724	xdiff: factor out match_func_rec() Add match_func_rec(), a helper that wraps accessing a record and calling the appropriate function for checking if it contains a function line. Signed-off-by: Rene Scharfe <l.s.r@web.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Stefan Beller	d634d61ed6	xdiff: implement empty line chunk heuristic In order to produce the smallest possible diff and combine several diff hunks together, we implement a heuristic from GNU Diff which moves diff hunks forward as far as possible when we find common context above and below a diff hunk. This sometimes produces less readable diffs when writing C, Shell, or other programming languages, ie: ... /* + * + * + / + +/ ... instead of the more readable equivalent of ... +/* + * + * + / + / ... Implement the following heuristic to (optionally) produce the desired output. If there are diff chunks which can be shifted around, shift each hunk such that the last common empty line is below the chunk with the rest of the context above. This heuristic appears to resolve the above example and several other common issues without producing significantly weird results. However, as with any heuristic it is not really known whether this will always be more optimal. Thus, it can be disabled via diff.compactionHeuristic. Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Jacob Keller	92e5b62fec	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. Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Stefan Beller <sbeller@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Ramsay Jones	87f1625836	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. Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Ramsay Jones	5cd6978a9c	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. Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Patrick Steinhardt	4867f1184c	xdiff/xmerge: fix memory leak in xdl_merge When building the script for the second file that is to be merged we have already allocated memory for data structures related to the first file. When we encounter an error in building the second script we only free allocated memory related to the second file before erroring out. Fix this memory leak by also releasing allocated memory related to the first file. Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de> Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Jeff King	907681e940	xdiff: drop XDL_EMIT_COMMON There are no more callers that use this mode, and none likely to be added (as our xdl_merge() eliminates the common use of it for generating 3-way merge bases). This is effectively a revert of `a9ed376` (xdiff: generate "anti-diffs" aka what is common to two files, 2006-06-28), though of course trying to revert that ancient commit directly produces many textual conflicts. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Johannes Schindelin	15980deab9	merge-file: ensure that conflict sections match eol style In the previous patch, we made sure that the conflict markers themselves match the end-of-line style of the input files. However, this still left out the conflicting text itself: if it lacks a trailing newline, we add one, and should add a carriage return when appropriate, too. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Johannes Schindelin	86efa21527	merge-file: let conflict markers match end-of-line style of the context When merging files with CR/LF line endings, the conflict markers should match those, lest the output file has mixed line endings. This is particularly of interest on Windows, where some editors get really confused by mixed line endings. The original version of this patch by Beat Bolli respected core.eol, and a subsequent improvement by this developer also respected gitattributes. This approach was suboptimal, though: `git merge-file` was invented as a drop-in replacement for GNU merge and as such has no problem operating outside of any repository at all! Another problem with the original approach was pointed out by Junio Hamano: legacy repositories might have their text files committed using CR/LF line endings (and core.eol and the gitattributes would give us a false impression there). Therefore, the much superior approach is to simply match the context's line endings, if any. We actually do not have to look at the entire context at all: if the files are all LF-only, or if they all have CR/LF line endings, it is sufficient to look at just a single line to match that style. And if the line endings are mixed anyway, it is still okay to imitate just a single line's eol: we will just add to the pile of mixed line endings, and there is nothing we can do about that. So what we do is: we look at the line preceding the conflict, falling back to the line preceding that in case it was the last line and had no line ending, falling back to the first line, first in the first post-image, then the second post-image, and finally the pre-image. If we find consistent CR/LF (or undecided) end-of-line style, we match that, otherwise we use LF-only line endings for the conflict markers. Note that while it is true that there have to be at least two lines we can look at (otherwise there would be no conflict), the same is not true for line endings: the three files in question could all consist of a single line without any line ending, each. In this case we fall back to using LF-only. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	9 years ago
Max Kirillov	ba311807f8	git-merge-file: do not add LF at EOF while applying unrelated change If 'current-file' does not contain LF at EOF, and change between 'base-file' and 'other-file' does not change any line close to EOF, the 3-way merge should not add LF to EOF. This is what 'diff3 -m' does, and seems to be a reasonable expectation. The change which introduced the behavior is `cd1d61c44f`. It always calls function xdl_recs_copy() for sides with add_nl == 1. In fact, it looks like the only case when this is needed is when 2 files are being union-merged, and they do not have LF at EOF (strictly speaking, the first of them). Add tests: * "merge without conflict (missing LF at EOF, away from change in the other file)" and "merge does not add LF away of change", to demonstrate the changed behavior. * "conflict at EOF without LF resolved by --union", to verify that the union-merge at the end inerts newline between versions. * some more tests which I felt like not covering the functionality well Signed-off-by: Max Kirillov <max@max630.net> Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Junio C Hamano	c01499ef69	C: have space around && and \|\| operators Correct all hits from git grep -e '$&&\\|\|\|$[^ ]' -e '[^ ]$&&\\|\|\|$' -- '*.c' i.e. && or \|\| operators that are followed by anything but a SP, or that follow something other than a SP or a HT, so that these operators have a SP around it when necessary. We usually refrain from making this kind of a tree-wide change in order to avoid unnecessary conflicts with other "real work" patches, but in this case, the end result does not have a potentially cumbersome tree-wide impact, while this is a tree-wide cleanup. Fixes to compat/regex/regcomp.c and xdiff/xemit.c are to replace a HT immediately after && with a SP. This is based on Felipe's patch to bultin/symbolic-ref.c; I did all the finding out what other files in the whole tree need to be fixed and did the fix and also the log message while reviewing that single liner, so any screw-ups in this version are mine. Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	11 years ago
Antoine Pelisse	36617af7ed	diff: add --ignore-blank-lines option The goal of the patch is to introduce the GNU diff -B/--ignore-blank-lines as closely as possible. The short option is not available because it's already used for "break-rewrites". When this option is used, git-diff will not create hunks that simply add or remove empty lines, but will still show empty lines addition/suppression if they are close enough to "valuable" changes. There are two differences between this option and GNU diff -B option: - GNU diff doesn't have "--inter-hunk-context", so this must be handled - The following sequence looks like a bug (context is displayed twice): $ seq 5 >file1 $ cat <<EOF >file2 change 1 2 3 4 5 change EOF $ diff -u -B file1 file2 --- file1 2013-06-08 22:13:04.471517834 +0200 +++ file2 2013-06-08 22:13:23.275517855 +0200 @@ -1,5 +1,7 @@ +change 1 2 + 3 4 5 @@ -3,3 +5,4 @@ 3 4 5 +change So here is a more thorough description of the option: - real changes are interesting - blank lines that are close enough (less than context size) to interesting changes are considered interesting (recursive definition) - "context" lines are used around each hunk of interesting changes - If two hunks are separated by less than "inter-hunk-context", they will be merged into one. The implementation does the "interesting changes selection" in a single pass. Signed-off-by: Antoine Pelisse <apelisse@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
Stefano Lattarini	41ccfdd9c9	Correct common spelling mistakes in comments and tests Most of these were found using Lucas De Marchi's codespell tool. Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Acked-by: Matthieu Moy <Matthieu.Moy@imag.fr> Signed-off-by: Junio C Hamano <gitster@pobox.com>	12 years ago
René Scharfe	8072766cc6	xdiff: import new 32-bit version of count_masked_bytes() Import the latest 32-bit implementation of count_masked_bytes() from Linux (arch/x86/include/asm/word-at-a-time.h). It's shorter and avoids overflows and negative numbers. This fixes test failures on 32-bit, where negative partial results had been shifted right using the "wrong" method (logical shift right instead of arithmetic short right). The compiler is free to chose the method, so it was only wrong in the sense that it didn't work as intended by us. Reported-by: Øyvind A. Holm <sunny@sunbase.org> Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>	13 years ago
René Scharfe	7e356a9794	xdiff: avoid more compiler warnings with XDL_FAST_HASH on 32-bit machines Hide literals that can cause compiler warnings for 32-bit architectures in expressions that evaluate to small numbers there. Some compilers warn that 0x0001020304050608 won't fit into a 32-bit long, others that shifting right by 56 bits clears a 32-bit value completely. The correct values are calculated in the 64-bit case, which is all that matters in this if-branch. Reported-by: Øyvind A. Holm <sunny@sunbase.org> Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Acked-by: Thomas Rast <trast@student.ethz.ch> Signed-off-by: Junio C Hamano <gitster@pobox.com>	13 years ago
René Scharfe	9322ce21ee	xdiff: avoid compiler warnings with XDL_FAST_HASH on 32-bit machines Import macro REPEAT_BYTE from Linux (arch/x86/include/asm/word-at-a-time.h) to avoid 64-bit integer literals, which cause some 32-bit compilers to print warnings. Reported-by: Øyvind A. Holm <sunny@sunbase.org> Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>	13 years ago
René Scharfe	be89977543	xdiff: remove unused functions The functions xdl_cha_first(), xdl_cha_next() and xdl_atol() are not used by us. While removing them increases the difference to the upstream version of libxdiff, it only adds a bit to the more than 600 differing lines in xutils.c (mmfile_t management was simplified significantly when the library was imported initially). Besides, if upstream modifies these functions in the future, we won't need to think about importing those changes, so in that sense it makes tracking modifications easier. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>	13 years ago
René Scharfe	3319e60633	xdiff: remove emit_func() and xdi_diff_hunks() The functions are unused now, remove them. Signed-off-by: Rene Scharfe <rene.scharfe@lsrfire.ath.cx> Signed-off-by: Junio C Hamano <gitster@pobox.com>	13 years ago

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166 Commits (4c8b882ada9e2a4cfa8c97087ed91601c8b0286e)