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[PATCH v2] diff: vary default prefix depending on what are compared

From
Junio C Hamano <gitster@pobox.com>
Date
Aug 20, 2008, 08:00 UTC
Message-ID
<7vljysru9b.fsf_-_@gitster.siamese.dyndns.org>
In-Reply-To
<7viqtxh4gt.fsf@gitster.siamese.dyndns.org>

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 --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>
---
 * This is much low impact mainly because it only affects "git diff" and
   Porcelains that use diff_ui_config().  As an added bonus, tests do not
   have to get fixed ;-)  I did have to fix --cc codepath, by the way.
   I'll run my git life with this enabled for two weeks to see if the "gut
   feeling" we discussed earlier changes in some way.
   Another thing we may want to do is to explicitly disable this for
   format-patch, as we may want to change the default for this
   configuration to true in some future.
 Documentation/config.txt |   14 ++++++++++++++
 builtin-diff.c           |    2 ++
 combine-diff.c           |    8 ++++++--
 diff-lib.c               |    3 +++
 diff-no-index.c          |    1 +
 diff.c                   |   46 ++++++++++++++++++++++++++++++++++++++++------
 diff.h                   |    2 ++
 7 files changed, 68 insertions(+), 8 deletions(-)
diff --git a/Documentation/config.txt b/Documentation/config.txt
index 676c39b..b125bf5 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -576,6 +576,20 @@ diff.external::
 	you want to use an external diff program only on a subset of
 	your files, you	might want to use linkgit:gitattributes[5] instead.
 
+diff.mnemonicprefix::
+	If set, 'git-diff' uses a prefix pair that is different from the
+	standard "a/" and "b/" depending on what is being compared.  When
+	this configuration is in effect, reverse diff output also swaps
+	the order of the prefixes:
+'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 --no-index a b';;
+	compares two non-git things (1) and (2).
+
 diff.renameLimit::
 	The number of files to consider when performing the copy/rename
 	detection; equivalent to the 'git-diff' option '-l'.
diff --git a/builtin-diff.c b/builtin-diff.c
index 7ffea97..266337b 100644
--- a/builtin-diff.c
+++ b/builtin-diff.c
@@ -74,6 +74,8 @@ static int builtin_diff_b_f(struct rev_info *revs,
 	if (!(S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)))
 		die("'%s': not a regular file or symlink", path);
 
+	diff_set_mnemonic_prefix(&revs->diffopt, "o/", "w/");
+
 	if (blob[0].mode == S_IFINVALID)
 		blob[0].mode = canon_mode(st.st_mode);
 
diff --git a/combine-diff.c b/combine-diff.c
index 9f80a1c..fe1970e 100644
--- a/combine-diff.c
+++ b/combine-diff.c
@@ -675,9 +675,13 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 	int i, show_hunks;
 	int working_tree_file = is_null_sha1(elem->sha1);
 	int abbrev = DIFF_OPT_TST(opt, FULL_INDEX) ? 40 : DEFAULT_ABBREV;
+	const char *a_prefix, *b_prefix;
 	mmfile_t result_file;
 
 	context = opt->context;
+	a_prefix = opt->a_prefix ? opt->a_prefix : "a/";
+	b_prefix = opt->b_prefix ? opt->b_prefix : "b/";
+
 	/* Read the result of merge first */
 	if (!working_tree_file)
 		result = grab_blob(elem->sha1, &result_size);
@@ -841,13 +845,13 @@ static void show_patch_diff(struct combine_diff_path *elem, int num_parent,
 			dump_quoted_path("--- ", "", "/dev/null",
 					 c_meta, c_reset);
 		else
-			dump_quoted_path("--- ", opt->a_prefix, elem->path,
+			dump_quoted_path("--- ", a_prefix, elem->path,
 					 c_meta, c_reset);
 		if (deleted)
 			dump_quoted_path("+++ ", "", "/dev/null",
 					 c_meta, c_reset);
 		else
-			dump_quoted_path("+++ ", opt->b_prefix, elem->path,
+			dump_quoted_path("+++ ", b_prefix, elem->path,
 					 c_meta, c_reset);
 		dump_sline(sline, cnt, num_parent,
 			   DIFF_OPT_TST(opt, COLOR_DIFF));
diff --git a/diff-lib.c b/diff-lib.c
index e7eaff9..ae96c64 100644
--- a/diff-lib.c
+++ b/diff-lib.c
@@ -63,6 +63,8 @@ int run_diff_files(struct rev_info *revs, unsigned int option)
 			      ? CE_MATCH_RACY_IS_DIRTY : 0);
 	char symcache[PATH_MAX];
 
+	diff_set_mnemonic_prefix(&revs->diffopt, "i/", "w/");
+
 	if (diff_unmerged_stage < 0)
 		diff_unmerged_stage = 2;
 	entries = active_nr;
@@ -469,6 +471,7 @@ int run_diff_index(struct rev_info *revs, int cached)
 	if (unpack_trees(1, &t, &opts))
 		exit(128);
 
+	diff_set_mnemonic_prefix(&revs->diffopt, "c/", cached ? "i/" : "w/");
 	diffcore_std(&revs->diffopt);
 	diff_flush(&revs->diffopt);
 	return 0;
diff --git a/diff-no-index.c b/diff-no-index.c
index 7d68b7f..b60d345 100644
--- a/diff-no-index.c
+++ b/diff-no-index.c
@@ -252,6 +252,7 @@ void diff_no_index(struct rev_info *revs,
 	if (queue_diff(&revs->diffopt, revs->diffopt.paths[0],
 		       revs->diffopt.paths[1]))
 		exit(1);
+	diff_set_mnemonic_prefix(&revs->diffopt, "1/", "2/");
 	diffcore_std(&revs->diffopt);
 	diff_flush(&revs->diffopt);
 
diff --git a/diff.c b/diff.c
index bf5d5f1..2768bbb 100644
--- a/diff.c
+++ b/diff.c
@@ -23,6 +23,7 @@ static int diff_rename_limit_default = 200;
 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 @@ int git_diff_ui_config(const char *var, const char *value, void *cb)
 		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 @@ static void emit_rewrite_diff(const char *name_a,
 	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 @@ static void emit_rewrite_diff(const char *name_a,
 
 	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);
@@ -1424,6 +1438,14 @@ static const char *diff_funcname_pattern(struct diff_filespec *one)
 	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,
@@ -1437,9 +1459,19 @@ static void builtin_diff(const char *name_a,
 	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;
+
+	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(o->a_prefix, name_a + (*name_a == '/'));
-	b_two = quote_two(o->b_prefix, name_b + (*name_b == '/'));
+	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);
@@ -2299,8 +2331,10 @@ void diff_setup(struct diff_options *options)
 		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)
diff --git a/diff.h b/diff.h
index 50fb5dd..9a679f5 100644
--- a/diff.h
+++ b/diff.h
@@ -160,6 +160,8 @@ extern void diff_tree_combined(const unsigned char *sha1, const unsigned char pa
 
 extern void diff_tree_combined_merge(const unsigned char *sha1, int, struct rev_info *);
 
+void diff_set_mnemonic_prefix(struct diff_options *options, const char *a, const char *b);
+
 extern void diff_addremove(struct diff_options *,
 			   int addremove,
 			   unsigned mode,

-- 
1.6.0.38.g002c7
Previous: Junio C HamanoNext: Jakub Narebski
Message 16 of 67 in “Call Me Gitless”
  1. TransAug 18, 2008
  2. Benjamin SergeantAug 18, 2008
  3. Martin LanghoffAug 18, 2008
  4. Pascal ObryAug 18, 2008
  5. Jon LoeligerAug 18, 2008
  6. Daniel BarkalowAug 18, 2008
  7. Marcus GriepAug 18, 2008
  8. Junio C HamanoAug 18, 2008
  9. Daniel BarkalowAug 18, 2008
  10. Junio C HamanoAug 18, 2008
  11. Daniel BarkalowAug 18, 2008
  12. Junio C HamanoAug 19, 2008
  13. Marcus GriepAug 19, 2008
  14. Junio C HamanoAug 19, 2008
  15. Junio C HamanoAug 19, 2008
  16. diff: vary default prefix depending on what are comparedJunio C Hamano, Aug 20, 2008
  17. Jakub NarebskiAug 20, 2008
  18. Stephen R. van den BergAug 19, 2008
  19. Jakub NarebskiAug 19, 2008
  20. Junio C HamanoAug 19, 2008
  21. Jeff KingAug 19, 2008
  22. Daniel BarkalowAug 19, 2008
  23. Jeff KingAug 19, 2008
  24. Daniel BarkalowAug 19, 2008
  25. Jeff KingAug 19, 2008
  26. Daniel BarkalowAug 19, 2008
  27. Petr BaudisAug 19, 2008
  28. Daniel BarkalowAug 19, 2008
  29. Junio C HamanoAug 19, 2008
  30. Junio C HamanoAug 19, 2008
  31. Daniel BarkalowAug 19, 2008
  32. Sverre Hvammen JohansenAug 21, 2008
  33. Junio C HamanoAug 21, 2008
  34. 1/3 sha1_object_info(): pay attention to cached objectsJunio C Hamano, Aug 21, 2008
  35. 2/3 cached_object: learn empty blobJunio C Hamano, Aug 21, 2008
  36. 3/3 git-add --intent-to-add (-N)Junio C Hamano, Aug 21, 2008
  37. Paolo BonziniAug 21, 2008
  38. Jonathan NiederAug 21, 2008
  39. Jonathan NiederAug 22, 2008
  40. Daniel BarkalowAug 22, 2008
  41. Junio C HamanoAug 22, 2008
  42. Jonathan NiederAug 22, 2008
  43. Junio C HamanoAug 22, 2008
  44. Jonathan NiederAug 22, 2008
  45. Jonathan NiederAug 22, 2008
  46. Daniel BarkalowAug 21, 2008
  47. TarmiganAug 18, 2008
  48. Daniel BarkalowAug 19, 2008
  49. TarmiganAug 19, 2008
  50. Peter Valdemar Mørch (Lists)Aug 19, 2008
  51. Junio C HamanoAug 19, 2008
  52. Imran M YousufAug 19, 2008
  53. Peter Valdemar Mørch (Lists)Aug 19, 2008
  54. Imran M YousufAug 19, 2008
  55. Alexander E GenaudAug 19, 2008
  56. Matthieu MoyAug 19, 2008
  57. Mike HommeyAug 19, 2008
  58. Alexander E GenaudAug 19, 2008
  59. Pascal ObryAug 19, 2008
  60. Paolo BonziniAug 21, 2008
  61. Elijah NewrenAug 22, 2008
  62. Peter Valdemar Mørch (Lists)Aug 19, 2008
  63. Mark StrubergAug 19, 2008
  64. Alexander E GenaudAug 19, 2008
  65. Junio C HamanoAug 19, 2008
  66. Teemu LikonenAug 19, 2008
  67. Jakub NarebskiAug 19, 2008

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