Merge branch 'cc/skip-to-optional-val'

Introduce a helper to simplify code to parse a common pattern that
expects either "--key" or "--key=<something>".

* cc/skip-to-optional-val:
  t4045: reindent to make helpers readable
  diff: add tests for --relative without optional prefix value
  diff: use skip_to_optional_arg_default() in parsing --relative
  diff: use skip_to_optional_arg_default()
  diff: use skip_to_optional_arg()
  index-pack: use skip_to_optional_arg()
  git-compat-util: introduce skip_to_optional_arg()

5 files changed, 126 insertions, 90 deletions

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 8ec459f52..4c51aec81 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1660,10 +1660,7 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 				from_stdin = 1;
 			} else if (!strcmp(arg, "--fix-thin")) {
 				fix_thin_pack = 1;
-			} else if (!strcmp(arg, "--strict")) {
-				strict = 1;
-				do_fsck_object = 1;
-			} else if (skip_prefix(arg, "--strict=", &arg)) {
+			} else if (skip_to_optional_arg(arg, "--strict", &arg)) {
 				strict = 1;
 				do_fsck_object = 1;
 				fsck_set_msg_types(&fsck_options, arg);
@@ -1679,10 +1676,8 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 				verify = 1;
 				show_stat = 1;
 				stat_only = 1;
-			} else if (!strcmp(arg, "--keep")) {
-				keep_msg = "";
-			} else if (starts_with(arg, "--keep=")) {
-				keep_msg = arg + 7;
+			} else if (skip_to_optional_arg(arg, "--keep", &keep_msg)) {
+				; /* nothing to do */
 			} else if (starts_with(arg, "--threads=")) {
 				char *end;
 				nr_threads = strtoul(arg+10, &end, 0);
diff --git a/diff.c b/diff.c
index 3fb445a54..fb22b19f0 100644
--- a/diff.c
+++ b/diff.c
@@ -4512,17 +4512,12 @@ int diff_opt_parse(struct diff_options *options,
 		options->output_format |= DIFF_FORMAT_NUMSTAT;
 	else if (!strcmp(arg, "--shortstat"))
 		options->output_format |= DIFF_FORMAT_SHORTSTAT;
-	else if (!strcmp(arg, "-X") || !strcmp(arg, "--dirstat"))
-		return parse_dirstat_opt(options, "");
-	else if (skip_prefix(arg, "-X", &arg))
-		return parse_dirstat_opt(options, arg);
-	else if (skip_prefix(arg, "--dirstat=", &arg))
+	else if (skip_prefix(arg, "-X", &arg) ||
+		 skip_to_optional_arg(arg, "--dirstat", &arg))
 		return parse_dirstat_opt(options, arg);
 	else if (!strcmp(arg, "--cumulative"))
 		return parse_dirstat_opt(options, "cumulative");
-	else if (!strcmp(arg, "--dirstat-by-file"))
-		return parse_dirstat_opt(options, "files");
-	else if (skip_prefix(arg, "--dirstat-by-file=", &arg)) {
+	else if (skip_to_optional_arg(arg, "--dirstat-by-file", &arg)) {
 		parse_dirstat_opt(options, "files");
 		return parse_dirstat_opt(options, arg);
 	}
@@ -4544,13 +4539,13 @@ int diff_opt_parse(struct diff_options *options,
 		return stat_opt(options, av);
 
 	/* renames options */
-	else if (starts_with(arg, "-B") || starts_with(arg, "--break-rewrites=") ||
-		 !strcmp(arg, "--break-rewrites")) {
+	else if (starts_with(arg, "-B") ||
+		 skip_to_optional_arg(arg, "--break-rewrites", NULL)) {
 		if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
 			return error("invalid argument to -B: %s", arg+2);
 	}
-	else if (starts_with(arg, "-M") || starts_with(arg, "--find-renames=") ||
-		 !strcmp(arg, "--find-renames")) {
+	else if (starts_with(arg, "-M") ||
+		 skip_to_optional_arg(arg, "--find-renames", NULL)) {
 		if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
 			return error("invalid argument to -M: %s", arg+2);
 		options->detect_rename = DIFF_DETECT_RENAME;
@@ -4558,8 +4553,8 @@ int diff_opt_parse(struct diff_options *options,
 	else if (!strcmp(arg, "-D") || !strcmp(arg, "--irreversible-delete")) {
 		options->irreversible_delete = 1;
 	}
-	else if (starts_with(arg, "-C") || starts_with(arg, "--find-copies=") ||
-		 !strcmp(arg, "--find-copies")) {
+	else if (starts_with(arg, "-C") ||
+		 skip_to_optional_arg(arg, "--find-copies", NULL)) {
 		if (options->detect_rename == DIFF_DETECT_COPY)
 			options->flags.find_copies_harder = 1;
 		if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
@@ -4572,11 +4567,10 @@ int diff_opt_parse(struct diff_options *options,
 		options->flags.rename_empty = 1;
 	else if (!strcmp(arg, "--no-rename-empty"))
 		options->flags.rename_empty = 0;
-	else if (!strcmp(arg, "--relative"))
-		options->flags.relative_name = 1;
-	else if (skip_prefix(arg, "--relative=", &arg)) {
+	else if (skip_to_optional_arg_default(arg, "--relative", &arg, NULL)) {
 		options->flags.relative_name = 1;
-		options->prefix = arg;
+		if (arg)
+			options->prefix = arg;
 	}
 
 	/* xdiff options */
@@ -4646,9 +4640,7 @@ int diff_opt_parse(struct diff_options *options,
 	else if (!strcmp(arg, "--no-follow")) {
 		options->flags.follow_renames = 0;
 		options->flags.default_follow_renames = 0;
-	} else if (!strcmp(arg, "--color"))
-		options->use_color = 1;
-	else if (skip_prefix(arg, "--color=", &arg)) {
+	} else if (skip_to_optional_arg_default(arg, "--color", &arg, "always")) {
 		int value = git_config_colorbool(NULL, arg);
 		if (value < 0)
 			return error("option `color' expects \"always\", \"auto\", or \"never\"");
@@ -4668,14 +4660,9 @@ int diff_opt_parse(struct diff_options *options,
 		if (cm < 0)
 			die("bad --color-moved argument: %s", arg);
 		options->color_moved = cm;
-	} else if (!strcmp(arg, "--color-words")) {
-		options->use_color = 1;
-		options->word_diff = DIFF_WORDS_COLOR;
-	}
-	else if (skip_prefix(arg, "--color-words=", &arg)) {
+	} else if (skip_to_optional_arg_default(arg, "--color-words", &options->word_regex, NULL)) {
 		options->use_color = 1;
 		options->word_diff = DIFF_WORDS_COLOR;
-		options->word_regex = arg;
 	}
 	else if (!strcmp(arg, "--word-diff")) {
 		if (options->word_diff == DIFF_WORDS_NONE)
@@ -4714,15 +4701,10 @@ int diff_opt_parse(struct diff_options *options,
 		options->flags.textconv_set_via_cmdline = 1;
 	} else if (!strcmp(arg, "--no-textconv"))
 		options->flags.allow_textconv = 0;
-	else if (!strcmp(arg, "--ignore-submodules")) {
-		options->flags.override_submodule_config = 1;
-		handle_ignore_submodules_arg(options, "all");
-	} else if (skip_prefix(arg, "--ignore-submodules=", &arg)) {
+	else if (skip_to_optional_arg_default(arg, "--ignore-submodules", &arg, "all")) {
 		options->flags.override_submodule_config = 1;
 		handle_ignore_submodules_arg(options, arg);
-	} else if (!strcmp(arg, "--submodule"))
-		options->submodule_format = DIFF_SUBMODULE_LOG;
-	else if (skip_prefix(arg, "--submodule=", &arg))
+	} else if (skip_to_optional_arg_default(arg, "--submodule", &arg, "log"))
 		return parse_submodule_opt(options, arg);
 	else if (skip_prefix(arg, "--ws-error-highlight=", &arg))
 		return parse_ws_error_highlight_opt(options, arg);
diff --git a/git-compat-util.h b/git-compat-util.h
index cedad4d58..68b2ad531 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -485,6 +485,29 @@ static inline int skip_prefix(const char *str, const char *prefix,
 }
 
 /*
+ * If the string "str" is the same as the string in "prefix", then the "arg"
+ * parameter is set to the "def" parameter and 1 is returned.
+ * If the string "str" begins with the string found in "prefix" and then a
+ * "=" sign, then the "arg" parameter is set to "str + strlen(prefix) + 1"
+ * (i.e., to the point in the string right after the prefix and the "=" sign),
+ * and 1 is returned.
+ *
+ * Otherwise, return 0 and leave "arg" untouched.
+ *
+ * When we accept both a "--key" and a "--key=<val>" option, this function
+ * can be used instead of !strcmp(arg, "--key") and then
+ * skip_prefix(arg, "--key=", &arg) to parse such an option.
+ */
+int skip_to_optional_arg_default(const char *str, const char *prefix,
+				 const char **arg, const char *def);
+
+static inline int skip_to_optional_arg(const char *str, const char *prefix,
+				       const char **arg)
+{
+	return skip_to_optional_arg_default(str, prefix, arg, "");
+}
+
+/*
  * Like skip_prefix, but promises never to read past "len" bytes of the input
  * buffer, and returns the remaining number of bytes in "out" via "outlen".
  */
diff --git a/strbuf.c b/strbuf.c
index ac5a7ab62..8007be8fb 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -11,6 +11,28 @@ int starts_with(const char *str, const char *prefix)
 			return 0;
 }
 
+int skip_to_optional_arg_default(const char *str, const char *prefix,
+				 const char **arg, const char *def)
+{
+	const char *p;
+
+	if (!skip_prefix(str, prefix, &p))
+		return 0;
+
+	if (!*p) {
+		if (arg)
+			*arg = def;
+		return 1;
+	}
+
+	if (*p != '=')
+		return 0;
+
+	if (arg)
+		*arg = p + 1;
+	return 1;
+}
+
 /*
  * Used as the default ->buf value, so that people can always assume
  * buf is non NULL and ->buf is NUL terminated even for a freshly
diff --git a/t/t4045-diff-relative.sh b/t/t4045-diff-relative.sh
index 3950f5034..6471a6870 100755
--- a/t/t4045-diff-relative.sh
+++ b/t/t4045-diff-relative.sh
@@ -12,62 +12,76 @@ test_expect_success 'setup' '
 	git commit -m one
 '
 
-check_diff() {
-expect=$1; shift
-cat >expected <<EOF
-diff --git a/$expect b/$expect
-new file mode 100644
-index 0000000..25c05ef
---- /dev/null
-+++ b/$expect
-@@ -0,0 +1 @@
-+other content
-EOF
-test_expect_success "-p $*" "
-	git diff -p $* HEAD^ >actual &&
-	test_cmp expected actual
-"
+check_diff () {
+	dir=$1
+	shift
+	expect=$1
+	shift
+	cat >expected <<-EOF
+	diff --git a/$expect b/$expect
+	new file mode 100644
+	index 0000000..25c05ef
+	--- /dev/null
+	+++ b/$expect
+	@@ -0,0 +1 @@
+	+other content
+	EOF
+	test_expect_success "-p $*" "
+		git -C '$dir' diff -p $* HEAD^ >actual &&
+		test_cmp expected actual
+	"
 }
 
-check_numstat() {
-expect=$1; shift
-cat >expected <<EOF
-1	0	$expect
-EOF
-test_expect_success "--numstat $*" "
-	echo '1	0	$expect' >expected &&
-	git diff --numstat $* HEAD^ >actual &&
-	test_cmp expected actual
-"
+check_numstat () {
+	dir=$1
+	shift
+	expect=$1
+	shift
+	cat >expected <<-EOF
+	1	0	$expect
+	EOF
+	test_expect_success "--numstat $*" "
+		echo '1	0	$expect' >expected &&
+		git -C '$dir' diff --numstat $* HEAD^ >actual &&
+		test_cmp expected actual
+	"
 }
 
-check_stat() {
-expect=$1; shift
-cat >expected <<EOF
- $expect | 1 +
- 1 file changed, 1 insertion(+)
-EOF
-test_expect_success "--stat $*" "
-	git diff --stat $* HEAD^ >actual &&
-	test_i18ncmp expected actual
-"
+check_stat () {
+	dir=$1
+	shift
+	expect=$1
+	shift
+	cat >expected <<-EOF
+	 $expect | 1 +
+	 1 file changed, 1 insertion(+)
+	EOF
+	test_expect_success "--stat $*" "
+		git -C '$dir' diff --stat $* HEAD^ >actual &&
+		test_i18ncmp expected actual
+	"
 }
 
-check_raw() {
-expect=$1; shift
-cat >expected <<EOF
-:000000 100644 0000000000000000000000000000000000000000 25c05ef3639d2d270e7fe765a67668f098092bc5 A	$expect
-EOF
-test_expect_success "--raw $*" "
-	git diff --no-abbrev --raw $* HEAD^ >actual &&
-	test_cmp expected actual
-"
+check_raw () {
+	dir=$1
+	shift
+	expect=$1
+	shift
+	cat >expected <<-EOF
+	:000000 100644 0000000000000000000000000000000000000000 25c05ef3639d2d270e7fe765a67668f098092bc5 A	$expect
+	EOF
+	test_expect_success "--raw $*" "
+		git -C '$dir' diff --no-abbrev --raw $* HEAD^ >actual &&
+		test_cmp expected actual
+	"
 }
 
-for type in diff numstat stat raw; do
-	check_$type file2 --relative=subdir/
-	check_$type file2 --relative=subdir
-	check_$type dir/file2 --relative=sub
+for type in diff numstat stat raw
+do
+	check_$type . file2 --relative=subdir/
+	check_$type . file2 --relative=subdir
+	check_$type subdir file2 --relative
+	check_$type . dir/file2 --relative=sub
 done
 
 test_done