[RFC PATCH, WAS: "weird diff output?" v2 0/2] implement empty line diff chunk heuristic
- From
Jacob Keller <jacob.e.keller@intel.com>
- Date
- Apr 15, 2016, 21:56 UTC
- Message-ID
- <20160415215622.6040-1-jacob.e.keller@intel.com>
From: Jacob Keller <jacob.keller@gmail.com>
Second version of my series with a few more minor fixups. I left the diff command line and configuration option alone for now, suspecting that long term we either (a) remove it or (b) use a gitattribute, so there is no reason to bikeshed the name or its contents right now.
TODO: * add some tests * think about whether we need a git attribute or not (I did some thinking, and if we do need to configure this at all, this is where I would put it) * figure out how to make is_emptyline CRLF aware
Changes since my v1: * rename xdl_hash_and_recmatch to recs_match * remove counting empty lines in the first section of the looping
Changes since Stefan's v1: * Added a patch to implement xdl_hash_and_recmatch as Junio suggested. * Fixed a segfault in Stefan's patch * Added XDL flag to configure the behavior * Used an int and counted empty lines via += instead of |= * Renamed starts_with_emptyline to is_emptyline * Added diff command line and config options
For reviewer convenience, the interdiff between v1 and v2:
diff --git a/Documentation/diff-config.txt b/Documentation/diff-config.txt index cebf82702d2a..9265d60d9571 100644 --- a/Documentation/diff-config.txt +++ b/Documentation/diff-config.txt @@ -173,8 +173,8 @@ include::mergetools-diff.txt[] diff.emptyLineHeuristic:: Set this option to true to enable the empty line chunk heuristic when producing diff output. This heuristic will attempt to shift hunks such - that a common empty line occurs below the hunk with the rest of the - context above it. + that the last common empty line occurs below the hunk with the rest of + the context above it. diff.algorithm:: Choose a diff algorithm. The variants are as follows: diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c index 83984b90f82f..9436ad735243 100644 --- a/xdiff/xdiffi.c +++ b/xdiff/xdiffi.c @@ -405,7 +405,7 @@ static int is_emptyline(const char *recs) return recs[0] == '\n'; /* CRLF not covered here */ } -static int xdl_hash_and_recmatch(xrecord_t **recs, long ixs, long ix, long flags) +static int recs_match(xrecord_t **recs, long ixs, long ix, long flags) { return (recs[ixs]->ha == recs[ix]->ha && xdl_recmatch(recs[ixs]->ptr, recs[ixs]->size, @@ -457,9 +457,7 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { * the last line of the current change group, shift backward * the group. */ - while (ixs > 0 && xdl_hash_and_recmatch(recs, ixs - 1, ix - 1, flags)) { - emptylines += is_emptyline(recs[ix - 1]->ptr); - + while (ixs > 0 && recs_match(recs, ixs - 1, ix - 1, flags)) { rchg[--ixs] = 1; rchg[--ix] = 0; @@ -486,7 +484,7 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { * the line next of the current change group, shift forward * the group. */ - while (ix < nrec && xdl_hash_and_recmatch(recs, ixs, ix, flags)) { + while (ix < nrec && recs_match(recs, ixs, ix, flags)) { emptylines += is_emptyline(recs[ix]->ptr); rchg[ixs++] = 0; @@ -527,7 +525,7 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { if ((flags & XDF_EMPTY_LINE_HEURISTIC) && emptylines) { while (ixs > 0 && !is_emptyline(recs[ix - 1]->ptr) && - xdl_hash_and_recmatch(recs, ixs - 1, ix - 1, flags)) { + recs_match(recs, ixs - 1, ix - 1, flags)) { rchg[--ixs] = 1; rchg[--ix] = 0; } Jacob Keller (1): xdiff: add recs_match helper function Stefan Beller (1): xdiff: implement empty line chunk heuristic Documentation/diff-config.txt | 6 ++++++ Documentation/diff-options.txt | 6 ++++++ diff.c | 11 +++++++++++ xdiff/xdiff.h | 2 ++ xdiff/xdiffi.c | 40 ++++++++++++++++++++++++++++++++++++---- 5 files changed, 61 insertions(+), 4 deletions(-)
-- 2.8.1.369.geae769a