diff: vary default prefix depending on what are compared
With a new configuration "diff.mnemonicprefix", "git diff" shows the
differences between various combinations of preimage and postimage trees
with prefixes different from the standard "a/" and "b/". Hopefully this
will make the distinction stand out for some people.
"git diff" compares the (i)ndex and the (w)ork tree;
"git diff HEAD" compares a (c)ommit and the (w)ork tree;
"git diff --cached" compares a (c)ommit and the (i)ndex;
"git-diff HEAD:file1 file2" compares an (o)bject and a (w)ork tree entity;
"git diff --no-index a b" compares two non-git things (1) and (2).
Because these mnemonics now have meanings, they are swapped when reverse
diff is in effect and this feature is enabled.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/diff.c b/diff.c
index 7b4300a..c1804ef 100644
--- a/diff.c
+++ b/diff.c
@@ -23,6 +23,7 @@
int diff_use_color_default = -1;
static const char *external_diff_cmd_cfg;
int diff_auto_refresh_index = 1;
+static int diff_mnemonic_prefix;
static char diff_colors[][COLOR_MAXLEN] = {
"\033[m", /* reset */
@@ -149,6 +150,10 @@
diff_auto_refresh_index = git_config_bool(var, value);
return 0;
}
+ if (!strcmp(var, "diff.mnemonicprefix")) {
+ diff_mnemonic_prefix = git_config_bool(var, value);
+ return 0;
+ }
if (!strcmp(var, "diff.external"))
return git_config_string(&external_diff_cmd_cfg, var, value);
if (!prefixcmp(var, "diff.")) {
@@ -305,6 +310,15 @@
const char *new = diff_get_color(color_diff, DIFF_FILE_NEW);
const char *reset = diff_get_color(color_diff, DIFF_RESET);
static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
+ const char *a_prefix, *b_prefix;
+
+ if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
+ a_prefix = o->b_prefix;
+ b_prefix = o->a_prefix;
+ } else {
+ a_prefix = o->a_prefix;
+ b_prefix = o->b_prefix;
+ }
name_a += (*name_a == '/');
name_b += (*name_b == '/');
@@ -313,8 +327,8 @@
strbuf_reset(&a_name);
strbuf_reset(&b_name);
- quote_two_c_style(&a_name, o->a_prefix, name_a, 0);
- quote_two_c_style(&b_name, o->b_prefix, name_b, 0);
+ quote_two_c_style(&a_name, a_prefix, name_a, 0);
+ quote_two_c_style(&b_name, b_prefix, name_b, 0);
diff_populate_filespec(one, 0);
diff_populate_filespec(two, 0);
@@ -1432,6 +1446,14 @@
return NULL;
}
+void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b)
+{
+ if (!options->a_prefix)
+ options->a_prefix = a;
+ if (!options->b_prefix)
+ options->b_prefix = b;
+}
+
static void builtin_diff(const char *name_a,
const char *name_b,
struct diff_filespec *one,
@@ -1445,9 +1467,19 @@
char *a_one, *b_two;
const char *set = diff_get_color_opt(o, DIFF_METAINFO);
const char *reset = diff_get_color_opt(o, DIFF_RESET);
+ const char *a_prefix, *b_prefix;
- a_one = quote_two(o->a_prefix, name_a + (*name_a == '/'));
- b_two = quote_two(o->b_prefix, name_b + (*name_b == '/'));
+ diff_set_mnemonic_prefix(o, "a/", "b/");
+ if (DIFF_OPT_TST(o, REVERSE_DIFF)) {
+ a_prefix = o->b_prefix;
+ b_prefix = o->a_prefix;
+ } else {
+ a_prefix = o->a_prefix;
+ b_prefix = o->b_prefix;
+ }
+
+ a_one = quote_two(a_prefix, name_a + (*name_a == '/'));
+ b_two = quote_two(b_prefix, name_b + (*name_b == '/'));
lbl[0] = DIFF_FILE_VALID(one) ? a_one : "/dev/null";
lbl[1] = DIFF_FILE_VALID(two) ? b_two : "/dev/null";
fprintf(o->file, "%sdiff --git %s %s%s\n", set, a_one, b_two, reset);
@@ -2308,8 +2340,10 @@
DIFF_OPT_CLR(options, COLOR_DIFF);
options->detect_rename = diff_detect_rename_default;
- options->a_prefix = "a/";
- options->b_prefix = "b/";
+ if (!diff_mnemonic_prefix) {
+ options->a_prefix = "a/";
+ options->b_prefix = "b/";
+ }
}
int diff_setup_done(struct diff_options *options)
