Merge branch 'jt/diff-anchored-patience'

"git diff" learned a variant of the "--patience" algorithm, to
which the user can specify which 'unique' line to be used as
anchoring points.

* jt/diff-anchored-patience:
  diff: support anchoring line(s)
This commit is contained in:
Junio C Hamano 2017-12-19 11:33:56 -08:00
Родитель 6d2c4619a5 2477ab2ea8
Коммит d7c6c2369a
6 изменённых файлов: 169 добавлений и 7 удалений

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@ -80,6 +80,16 @@ endif::git-format-patch[]
--histogram::
Generate a diff using the "histogram diff" algorithm.
--anchored=<text>::
Generate a diff using the "anchored diff" algorithm.
+
This option may be specified more than once.
+
If a line exists in both the source and destination, exists only once,
and starts with this text, this algorithm attempts to prevent it from
appearing as a deletion or addition in the output. It uses the "patience
diff" algorithm internally.
--diff-algorithm={patience|minimal|histogram|myers}::
Choose a diff algorithm. The variants are as follows:
+

22
diff.c
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@ -3210,6 +3210,8 @@ static void builtin_diff(const char *name_a,
ecbdata.opt = o;
ecbdata.header = header.len ? &header : NULL;
xpp.flags = o->xdl_opts;
xpp.anchors = o->anchors;
xpp.anchors_nr = o->anchors_nr;
xecfg.ctxlen = o->context;
xecfg.interhunkctxlen = o->interhunkcontext;
xecfg.flags = XDL_EMIT_FUNCNAMES;
@ -3302,6 +3304,8 @@ static void builtin_diffstat(const char *name_a, const char *name_b,
memset(&xpp, 0, sizeof(xpp));
memset(&xecfg, 0, sizeof(xecfg));
xpp.flags = o->xdl_opts;
xpp.anchors = o->anchors;
xpp.anchors_nr = o->anchors_nr;
xecfg.ctxlen = o->context;
xecfg.interhunkctxlen = o->interhunkcontext;
if (xdi_diff_outf(&mf1, &mf2, diffstat_consume, diffstat,
@ -4594,9 +4598,18 @@ int diff_opt_parse(struct diff_options *options,
DIFF_XDL_SET(options, INDENT_HEURISTIC);
else if (!strcmp(arg, "--no-indent-heuristic"))
DIFF_XDL_CLR(options, INDENT_HEURISTIC);
else if (!strcmp(arg, "--patience"))
else if (!strcmp(arg, "--patience")) {
int i;
options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
else if (!strcmp(arg, "--histogram"))
/*
* Both --patience and --anchored use PATIENCE_DIFF
* internally, so remove any anchors previously
* specified.
*/
for (i = 0; i < options->anchors_nr; i++)
free(options->anchors[i]);
options->anchors_nr = 0;
} else if (!strcmp(arg, "--histogram"))
options->xdl_opts = DIFF_WITH_ALG(options, HISTOGRAM_DIFF);
else if ((argcount = parse_long_opt("diff-algorithm", av, &optarg))) {
long value = parse_algorithm_value(optarg);
@ -4608,6 +4621,11 @@ int diff_opt_parse(struct diff_options *options,
options->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
options->xdl_opts |= value;
return argcount;
} else if (skip_prefix(arg, "--anchored=", &arg)) {
options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
ALLOC_GROW(options->anchors, options->anchors_nr + 1,
options->anchors_alloc);
options->anchors[options->anchors_nr++] = xstrdup(arg);
}
/* flags options */

4
diff.h
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@ -166,6 +166,10 @@ struct diff_options {
const char *stat_sep;
long xdl_opts;
/* see Documentation/diff-options.txt */
char **anchors;
size_t anchors_nr, anchors_alloc;
int stat_width;
int stat_name_width;
int stat_graph_width;

94
t/t4065-diff-anchored.sh Executable file
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@ -0,0 +1,94 @@
#!/bin/sh
test_description='anchored diff algorithm'
. ./test-lib.sh
test_expect_success '--anchored' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
# normally, c is moved to produce the smallest diff
test_expect_code 1 git diff --no-index pre post >diff &&
grep "^+c" diff &&
# with anchor, a is moved
test_expect_code 1 git diff --no-index --anchored=c pre post >diff &&
grep "^+a" diff
'
test_expect_success '--anchored multiple' '
printf "a\nb\nc\nd\ne\nf\n" >pre &&
printf "c\na\nb\nf\nd\ne\n" >post &&
# with 1 anchor, c is not moved, but f is moved
test_expect_code 1 git diff --no-index --anchored=c pre post >diff &&
grep "^+a" diff && # a is moved instead of c
grep "^+f" diff &&
# with 2 anchors, c and f are not moved
test_expect_code 1 git diff --no-index --anchored=c --anchored=f pre post >diff &&
grep "^+a" diff &&
grep "^+d" diff # d is moved instead of f
'
test_expect_success '--anchored with nonexistent line has no effect' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
test_expect_code 1 git diff --no-index --anchored=x pre post >diff &&
grep "^+c" diff
'
test_expect_success '--anchored with non-unique line has no effect' '
printf "a\nb\nc\nd\ne\nc\n" >pre &&
printf "c\na\nb\nc\nd\ne\n" >post &&
test_expect_code 1 git diff --no-index --anchored=c pre post >diff &&
grep "^+c" diff
'
test_expect_success 'diff still produced with impossible multiple --anchored' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
test_expect_code 1 git diff --no-index --anchored=a --anchored=c pre post >diff &&
mv post expected_post &&
# Ensure that the diff is correct by applying it and then
# comparing the result with the original
git apply diff &&
diff expected_post post
'
test_expect_success 'later algorithm arguments override earlier ones' '
printf "a\nb\nc\n" >pre &&
printf "c\na\nb\n" >post &&
test_expect_code 1 git diff --no-index --patience --anchored=c pre post >diff &&
grep "^+a" diff &&
test_expect_code 1 git diff --no-index --anchored=c --patience pre post >diff &&
grep "^+c" diff &&
test_expect_code 1 git diff --no-index --histogram --anchored=c pre post >diff &&
grep "^+a" diff &&
test_expect_code 1 git diff --no-index --anchored=c --histogram pre post >diff &&
grep "^+c" diff
'
test_expect_success '--anchored works with other commands like "git show"' '
printf "a\nb\nc\n" >file &&
git add file &&
git commit -m foo &&
printf "c\na\nb\n" >file &&
git add file &&
git commit -m foo &&
# with anchor, a is moved
git show --patience --anchored=c >diff &&
grep "^+a" diff
'
test_done

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@ -86,6 +86,10 @@ typedef struct s_mmbuffer {
typedef struct s_xpparam {
unsigned long flags;
/* See Documentation/diff-options.txt. */
char **anchors;
size_t anchors_nr;
} xpparam_t;
typedef struct s_xdemitcb {

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@ -62,6 +62,12 @@ struct hashmap {
* initially, "next" reflects only the order in file1.
*/
struct entry *next, *previous;
/*
* If 1, this entry can serve as an anchor. See
* Documentation/diff-options.txt for more information.
*/
unsigned anchor : 1;
} *entries, *first, *last;
/* were common records found? */
unsigned long has_matches;
@ -70,8 +76,19 @@ struct hashmap {
xpparam_t const *xpp;
};
static int is_anchor(xpparam_t const *xpp, const char *line)
{
int i;
for (i = 0; i < xpp->anchors_nr; i++) {
if (!strncmp(line, xpp->anchors[i], strlen(xpp->anchors[i])))
return 1;
}
return 0;
}
/* The argument "pass" is 1 for the first file, 2 for the second. */
static void insert_record(int line, struct hashmap *map, int pass)
static void insert_record(xpparam_t const *xpp, int line, struct hashmap *map,
int pass)
{
xrecord_t **records = pass == 1 ?
map->env->xdf1.recs : map->env->xdf2.recs;
@ -110,6 +127,7 @@ static void insert_record(int line, struct hashmap *map, int pass)
return;
map->entries[index].line1 = line;
map->entries[index].hash = record->ha;
map->entries[index].anchor = is_anchor(xpp, map->env->xdf1.recs[line - 1]->ptr);
if (!map->first)
map->first = map->entries + index;
if (map->last) {
@ -147,11 +165,11 @@ static int fill_hashmap(mmfile_t *file1, mmfile_t *file2,
/* First, fill with entries from the first file */
while (count1--)
insert_record(line1++, result, 1);
insert_record(xpp, line1++, result, 1);
/* Then search for matches in the second file */
while (count2--)
insert_record(line2++, result, 2);
insert_record(xpp, line2++, result, 2);
return 0;
}
@ -192,14 +210,28 @@ static struct entry *find_longest_common_sequence(struct hashmap *map)
int longest = 0, i;
struct entry *entry;
/*
* If not -1, this entry in sequence must never be overridden.
* Therefore, overriding entries before this has no effect, so
* do not do that either.
*/
int anchor_i = -1;
for (entry = map->first; entry; entry = entry->next) {
if (!entry->line2 || entry->line2 == NON_UNIQUE)
continue;
i = binary_search(sequence, longest, entry);
entry->previous = i < 0 ? NULL : sequence[i];
sequence[++i] = entry;
if (i == longest)
++i;
if (i <= anchor_i)
continue;
sequence[i] = entry;
if (entry->anchor) {
anchor_i = i;
longest = anchor_i + 1;
} else if (i == longest) {
longest++;
}
}
/* No common unique lines were found */