Jacob KellerFrom: Jacob Keller <jacob.keller@gmail.com>
I took up Stefan's patch, and modified it to resolve a couple issues. I also tried to implement the suggestions from Junio's review, as well as the suggestions I had. It appears to produce equivalent output as Jeff's script. This version is still missing a few things, and it is possible Stefan is working on a v2 of his own, but I thought I'd submit this.
There's still several TODOs: * Add some tests * better name for the heuristic(?) * better patch description plus documentation * is_emptyline should be more generic and handle CRLF
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 this and Stefan's version:
Show changes to 5 files +34 −21
Documentation/diff-config.txt, Documentation/diff-options.txt, diff.c, xdiff/xdiff.h, xdiff/xdiffi.c
diff --git a/Documentation/diff-config.txt b/Documentation/diff-config.txt index edba56522bce..cebf82702d2a 100644 --- a/Documentation/diff-config.txt +++ b/Documentation/diff-config.txt @@ -170,6 +170,12 @@ diff.tool:: 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. + diff.algorithm:: Choose a diff algorithm. The variants are as follows: + diff --git a/Documentation/diff-options.txt b/Documentation/diff-options.txt index 4b0318e2ac15..6c1cd8b35584 100644 --- a/Documentation/diff-options.txt +++ b/Documentation/diff-options.txt @@ -63,6 +63,12 @@ ifndef::git-format-patch[] Synonym for `-p --raw`. endif::git-format-patch[] +--empty-line-heuristic:: +--no-empty-line-heuristic:: + When possible, shift common empty lines in diff hunks below the hunk + such that the last common empty line for each hunk is below, with the + rest of the context above the hunk. + --minimal:: Spend extra time to make sure the smallest possible diff is produced. diff --git a/diff.c b/diff.c index 4dfe6609d059..8ab9a492928d 100644 --- a/diff.c +++ b/diff.c @@ -26,6 +26,7 @@ #endif static int diff_detect_rename_default; +static int diff_empty_line_heuristic = 0; static int diff_rename_limit_default = 400; static int diff_suppress_blank_empty; static int diff_use_color_default = -1; @@ -189,6 +190,10 @@ int git_diff_ui_config(const char *var, const char *value, void *cb) diff_detect_rename_default = git_config_rename(var, value); return 0; } + if (!strcmp(var, "diff.emptylineheuristic")) { + diff_empty_line_heuristic = git_config_bool(var, value); + return 0; + } if (!strcmp(var, "diff.autorefreshindex")) { diff_auto_refresh_index = git_config_bool(var, value); return 0; @@ -3278,6 +3283,8 @@ void diff_setup(struct diff_options *options) options->use_color = diff_use_color_default; options->detect_rename = diff_detect_rename_default; options->xdl_opts |= diff_algorithm; + if (diff_empty_line_heuristic) + DIFF_XDL_SET(options, EMPTY_LINE_HEURISTIC); options->orderfile = diff_order_file_cfg; @@ -3798,6 +3805,10 @@ int diff_opt_parse(struct diff_options *options, DIFF_XDL_SET(options, IGNORE_WHITESPACE_AT_EOL); else if (!strcmp(arg, "--ignore-blank-lines")) DIFF_XDL_SET(options, IGNORE_BLANK_LINES); + else if (!strcmp(arg, "--empty-line-heuristic")) + DIFF_XDL_SET(options, EMPTY_LINE_HEURISTIC); + else if (!strcmp(arg, "--no-empty-line-heuristic")) + DIFF_XDL_CLR(options, EMPTY_LINE_HEURISTIC); else if (!strcmp(arg, "--patience")) options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF); else if (!strcmp(arg, "--histogram")) diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h index 4fb7e79410c2..9195a5c0e958 100644 --- a/xdiff/xdiff.h +++ b/xdiff/xdiff.h @@ -41,6 +41,8 @@ extern "C" { #define XDF_IGNORE_BLANK_LINES (1 << 7) +#define XDF_EMPTY_LINE_HEURISTIC (1 << 8) + #define XDL_EMIT_FUNCNAMES (1 << 0) #define XDL_EMIT_FUNCCONTEXT (1 << 2) diff --git a/xdiff/xdiffi.c b/xdiff/xdiffi.c index 5f14beb98049..83984b90f82f 100644 --- a/xdiff/xdiffi.c +++ b/xdiff/xdiffi.c @@ -400,7 +400,7 @@ static xdchange_t *xdl_add_change(xdchange_t *xscr, long i1, long i2, long chg1, } -static int starts_with_emptyline(const char *recs) +static int is_emptyline(const char *recs) { return recs[0] == '\n'; /* CRLF not covered here */ } @@ -416,7 +416,7 @@ static int xdl_hash_and_recmatch(xrecord_t **recs, long ixs, long ix, long flags int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { long ix, ixo, ixs, ixref, grpsiz, nrec = xdf->nrec; char *rchg = xdf->rchg, *rchgo = xdfo->rchg; - unsigned char has_emptyline; + unsigned int emptylines; xrecord_t **recs = xdf->recs; /* @@ -450,7 +450,7 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { do { grpsiz = ix - ixs; - has_emptyline = 0; + emptylines = 0; /* * If the line before the current change group, is equal to @@ -458,11 +458,11 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { * the group. */ while (ixs > 0 && xdl_hash_and_recmatch(recs, ixs - 1, ix - 1, flags)) { + emptylines += is_emptyline(recs[ix - 1]->ptr); + rchg[--ixs] = 1; rchg[--ix] = 0; - has_emptyline |= - starts_with_emptyline(recs[ix]->ptr); /* * This change might have joined two change groups, * so we try to take this scenario in account by moving @@ -492,9 +492,6 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { rchg[ixs++] = 0; rchg[ix++] = 1; - has_emptyline |= - starts_with_emptyline(recs[ix]->ptr); - /* * This change might have joined two change groups, * so we try to take this scenario in account by moving @@ -527,21 +524,12 @@ int xdl_change_compact(xdfile_t *xdf, xdfile_t *xdfo, long flags) { * As we shifted the group forward as far as possible, we only * need to shift it back if at all. */ - if (has_emptyline) { - while (ixs > 0 && recs[ixs - 1]->ha == recs[ix - 1]->ha && - xdl_recmatch(recs[ixs - 1]->ptr, recs[ixs - 1]->size, recs[ix - 1]->ptr, recs[ix - 1]->size, flags) && - !starts_with_emptyline(recs[ix - 1]->ptr)) { + 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)) { rchg[--ixs] = 1; rchg[--ix] = 0; - - /* - * This change did not join two change groups, - * as we did that before already, so there is no - * need to adapt the other-file, i.e. - * running - * for (; rchg[ixs - 1]; ixs--); - * while (rchgo[--ixo]); - */ } } } Jacob Keller (1): xdiff: add xdl_hash_and_recmatch 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 | 42 ++++++++++++++++++++++++++++++++++++++---- 5 files changed, 63 insertions(+), 4 deletions(-)
-- 2.8.1.369.geae769a
