@@ -758,6 +758,37 @@ with the above configuration, i.e. `j-c-diff`, with 7
parameters, just like `GIT_EXTERNAL_DIFF` program is called.
See linkgit:git[1] for details.
+Setting the internal diff algorithm
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The diff algorithm can be set through the `diff.algorithm` config key, but
+sometimes it may be helpful to set the diff algorithm per path. For example,
+one may want to use the `minimal` diff algorithm for .json files, and the
+`histogram` for .c files, and so on without having to pass in the algorithm
+through the command line each time.
+
+First, in `.gitattributes`, assign the `diff` attribute for paths.
+
+------------------------
+*.json diff=<name>
+------------------------
+
+Then, define a "diff.<name>.algorithm" configuration to specify the diff
+algorithm, choosing from `myers`, `patience`, `minimal`, or `histogram`.
+
+----------------------------------------------------------------
+[diff "<name>"]
+ algorithm = histogram
+----------------------------------------------------------------
+
+This diff algorithm applies to user facing diff output like git-diff(1),
+git-show(1) and is used for the `--stat` output as well. The merge machinery
+will not use the diff algorithm set through this method.
+
+NOTE: If `diff.<name>.command` is defined for path with the
+`diff=<name>` attribute, it is executed as an external diff driver
+(see above), and adding `diff.<name>.algorithm` has no effect, as the
+algorithm is not passed to the external diff driver.
Defining a custom hunk-header
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
@@ -4456,15 +4456,13 @@ static void run_diff_cmd(const char *pgm,
const char *xfrm_msg = NULL;
int complete_rewrite = (p->status == DIFF_STATUS_MODIFIED) && p->score;
int must_show_header = 0;
+ struct userdiff_driver *drv = NULL;
-
- if (o->flags.allow_external) {
- struct userdiff_driver *drv;
-
+ if (o->flags.allow_external || !o->ignore_driver_algorithm)
drv = userdiff_find_by_path(o->repo->index, attr_path);
- if (drv && drv->external)
- pgm = drv->external;
- }
+
+ if (o->flags.allow_external && drv && drv->external)
+ pgm = drv->external;
if (msg) {
/*
@@ -4481,12 +4479,16 @@ static void run_diff_cmd(const char *pgm,
run_external_diff(pgm, name, other, one, two, xfrm_msg, o);
return;
}
- if (one && two)
+ if (one && two) {
+ if (!o->ignore_driver_algorithm && drv && drv->algorithm)
+ set_diff_algorithm(o, drv->algorithm);
+
builtin_diff(name, other ? other : name,
one, two, xfrm_msg, must_show_header,
o, complete_rewrite);
- else
+ } else {
fprintf(o->file, "* Unmerged path %s\n", name);
+ }
}
static void diff_fill_oid_info(struct diff_filespec *one, struct index_state *istate)
@@ -4583,6 +4585,14 @@ static void run_diffstat(struct diff_filepair *p, struct diff_options *o,
const char *name;
const char *other;
+ if (!o->ignore_driver_algorithm) {
+ struct userdiff_driver *drv = userdiff_find_by_path(o->repo->index,
+ p->one->path);
+
+ if (drv && drv->algorithm)
+ set_diff_algorithm(o, drv->algorithm);
+ }
+
if (DIFF_PAIR_UNMERGED(p)) {
/* unmerged */
builtin_diffstat(p->one->path, NULL, NULL, NULL,
@@ -5130,6 +5140,8 @@ static int diff_opt_diff_algorithm(const struct option *opt,
return error(_("option diff-algorithm accepts \"myers\", "
"\"minimal\", \"patience\" and \"histogram\""));
+ options->ignore_driver_algorithm = 1;
+
return 0;
}
@@ -5145,6 +5157,8 @@ static int diff_opt_diff_algorithm_no_arg(const struct option *opt,
BUG("available diff algorithms include \"myers\", "
"\"minimal\", \"patience\" and \"histogram\"");
+ options->ignore_driver_algorithm = 1;
+
return 0;
}
@@ -5285,6 +5299,7 @@ static int diff_opt_patience(const struct option *opt,
for (i = 0; i < options->anchors_nr; i++)
free(options->anchors[i]);
options->anchors_nr = 0;
+ options->ignore_driver_algorithm = 1;
return set_diff_algorithm(options, "patience");
}
@@ -333,6 +333,7 @@ struct diff_options {
int prefix_length;
const char *stat_sep;
int xdl_opts;
+ int ignore_driver_algorithm;
/* see Documentation/diff-options.txt */
char **anchors;
@@ -105,10 +105,46 @@ index $file1..$file2 100644
}
EOF
+ cat >expect_diffstat <<EOF
+ file1 => file2 | 21 ++++++++++-----------
+ 1 file changed, 10 insertions(+), 11 deletions(-)
+EOF
+
STRATEGY=$1
+ test_expect_success "$STRATEGY diff from attributes" '
+ echo "file* diff=driver" >.gitattributes &&
+ git config diff.driver.algorithm "$STRATEGY" &&
+ test_must_fail git diff --no-index file1 file2 > output &&
+ cat expect &&
+ cat output &&
+ test_cmp expect output
+ '
+
+ test_expect_success "$STRATEGY diff from attributes has valid diffstat" '
+ echo "file* diff=driver" >.gitattributes &&
+ git config diff.driver.algorithm "$STRATEGY" &&
+ test_must_fail git diff --stat --no-index file1 file2 > output &&
+ test_cmp expect_diffstat output
+ '
+
test_expect_success "$STRATEGY diff" '
- test_must_fail git diff --no-index "--$STRATEGY" file1 file2 > output &&
+ test_must_fail git diff --no-index "--diff-algorithm=$STRATEGY" file1 file2 > output &&
+ test_cmp expect output
+ '
+
+ test_expect_success "$STRATEGY diff command line precedence before attributes" '
+ echo "file* diff=driver" >.gitattributes &&
+ git config diff.driver.algorithm myers &&
+ test_must_fail git diff --no-index "--diff-algorithm=$STRATEGY" file1 file2 > output &&
+ test_cmp expect output
+ '
+
+ test_expect_success "$STRATEGY diff attributes precedence before config" '
+ git config diff.algorithm default &&
+ echo "file* diff=driver" >.gitattributes &&
+ git config diff.driver.algorithm "$STRATEGY" &&
+ test_must_fail git diff --no-index file1 file2 > output &&
test_cmp expect output
'
@@ -293,7 +293,7 @@ PATTERNS("scheme",
"|([^][)(}{[ \t])+"),
PATTERNS("tex", "^(\\\\((sub)*section|chapter|part)\\*{0,1}\\{.*)$",
"\\\\[a-zA-Z@]+|\\\\.|[a-zA-Z0-9\x80-\xff]+"),
-{ "default", NULL, -1, { NULL, 0 } },
+{ "default", NULL, NULL, -1, { NULL, 0 } },
};
#undef PATTERNS
#undef IPATTERN
@@ -394,6 +394,8 @@ int userdiff_config(const char *k, const char *v)
return parse_bool(&drv->textconv_want_cache, k, v);
if (!strcmp(type, "wordregex"))
return git_config_string(&drv->word_regex, k, v);
+ if (!strcmp(type, "algorithm"))
+ return git_config_string(&drv->algorithm, k, v);
return 0;
}
@@ -14,6 +14,7 @@ struct userdiff_funcname {
struct userdiff_driver {
const char *name;
const char *external;
+ const char *algorithm;
int binary;
struct userdiff_funcname funcname;
const char *word_regex;