pretty: add %(decorate[:<options>]) format

Add %(decorate[:<options>]) format that lists ref names similarly to the
%d format, but which allows the otherwise fixed prefix, suffix and
separator strings to be customized. Omitted options default to the
strings used in %d.

Rename expand_separator() function used to expand %x literal formatting
codes to expand_string_arg(), as it is now used on strings other than
separators.

Examples:
- %(decorate) is equivalent to %d.
- %(decorate:prefix=,suffix=) is equivalent to %D.
- %(decorate:prefix=[,suffix=],separator=%x3B) produces a list enclosed
in square brackets and separated by semicolons.

Test the format in t4205-log-pretty-formats.sh and document it in
pretty-formats.txt.

Signed-off-by: Andy Koppe <andy.koppe@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 55 insertions, 4 deletions

diff --git a/pretty.c b/pretty.c
index 69b6db3340..1639efe2f8 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1252,8 +1252,8 @@ static int format_trailer_match_cb(const struct strbuf *key, void *ud)
 	return 0;
 }
 
-static struct strbuf *expand_separator(struct strbuf *sb,
-				       const char *argval, size_t arglen)
+static struct strbuf *expand_string_arg(struct strbuf *sb,
+					const char *argval, size_t arglen)
 {
 	char *fmt = xstrndup(argval, arglen);
 	const char *format = fmt;
@@ -1301,9 +1301,9 @@ int format_set_trailers_options(struct process_trailer_options *opts,
 			opts->filter_data = filter_list;
 			opts->only_trailers = 1;
 		} else if (match_placeholder_arg_value(*arg, "separator", arg, &argval, &arglen)) {
-			opts->separator = expand_separator(sepbuf, argval, arglen);
+			opts->separator = expand_string_arg(sepbuf, argval, arglen);
 		} else if (match_placeholder_arg_value(*arg, "key_value_separator", arg, &argval, &arglen)) {
-			opts->key_value_separator = expand_separator(kvsepbuf, argval, arglen);
+			opts->key_value_separator = expand_string_arg(kvsepbuf, argval, arglen);
 		} else if (!match_placeholder_bool_arg(*arg, "only", arg, &opts->only_trailers) &&
 			   !match_placeholder_bool_arg(*arg, "unfold", arg, &opts->unfold) &&
 			   !match_placeholder_bool_arg(*arg, "keyonly", arg, &opts->key_only) &&
@@ -1384,6 +1384,40 @@ static size_t parse_describe_args(const char *start, struct strvec *args)
 	return arg - start;
 }
 
+
+static int parse_decoration_option(const char **arg,
+				   const char *name,
+				   char **opt)
+{
+	const char *argval;
+	size_t arglen;
+
+	if (match_placeholder_arg_value(*arg, name, arg, &argval, &arglen)) {
+		struct strbuf sb = STRBUF_INIT;
+
+		expand_string_arg(&sb, argval, arglen);
+		*opt = strbuf_detach(&sb, NULL);
+		return 1;
+	}
+	return 0;
+}
+
+static void parse_decoration_options(const char **arg,
+				     struct decoration_options *opts)
+{
+	while (parse_decoration_option(arg, "prefix", &opts->prefix) ||
+	       parse_decoration_option(arg, "suffix", &opts->suffix) ||
+	       parse_decoration_option(arg, "separator", &opts->separator))
+		;
+}
+
+static void free_decoration_options(const struct decoration_options *opts)
+{
+	free(opts->prefix);
+	free(opts->suffix);
+	free(opts->separator);
+}
+
 static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 				const char *placeholder,
 				void *context)
@@ -1645,6 +1679,23 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		return 2;
 	}
 
+	if (skip_prefix(placeholder, "(decorate", &arg)) {
+		struct decoration_options opts = { NULL };
+		size_t ret = 0;
+
+		if (*arg == ':') {
+			arg++;
+			parse_decoration_options(&arg, &opts);
+		}
+		if (*arg == ')') {
+			format_decorations(sb, commit, c->auto_color, &opts);
+			ret = arg - placeholder + 1;
+		}
+
+		free_decoration_options(&opts);
+		return ret;
+	}
+
 	/* For the rest we have to parse the commit header. */
 	if (!c->commit_header_parsed) {
 		msg = c->message =