Allow custom "comment char"

Some users do want to write a line that begin with a pound sign, #,
in their commit log message.  Many tracking system recognise
a token of #<bugid> form, for example.

The support we offer these use cases is not very friendly to the end
users.  They have a choice between

 - Don't do it.  Avoid such a line by rewrapping or indenting; and

 - Use --cleanup=whitespace but remove all the hint lines we add.

Give them a way to set a custom comment char, e.g.

    $ git -c core.commentchar="%" commit

so that they do not have to do either of the two workarounds.

[jc: although I started the topic, all the tests and documentation
updates, many of the call sites of the new strbuf_add_commented_*()
functions, and the change to git-submodule.sh scripted Porcelain are
from Ralf.]

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Ralf Thielow <ralf.thielow@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 41 insertions, 8 deletions

diff --git a/builtin/stripspace.c b/builtin/stripspace.c
index f16986c0a..e981dfb9f 100644
--- a/builtin/stripspace.c
+++ b/builtin/stripspace.c
@@ -30,7 +30,8 @@ static size_t cleanup(char *line, size_t len)
  *
  * If last line does not have a newline at the end, one is added.
  *
- * Enable skip_comments to skip every line starting with "#".
+ * Enable skip_comments to skip every line starting with comment
+ * character.
  */
 void stripspace(struct strbuf *sb, int skip_comments)
 {
@@ -45,7 +46,7 @@ void stripspace(struct strbuf *sb, int skip_comments)
 		eol = memchr(sb->buf + i, '\n', sb->len - i);
 		len = eol ? eol - (sb->buf + i) + 1 : sb->len - i;
 
-		if (skip_comments && len && sb->buf[i] == '#') {
+		if (skip_comments && len && sb->buf[i] == comment_line_char) {
 			newlen = 0;
 			continue;
 		}
@@ -66,21 +67,53 @@ void stripspace(struct strbuf *sb, int skip_comments)
 	strbuf_setlen(sb, j);
 }
 
+static void comment_lines(struct strbuf *buf)
+{
+	char *msg;
+	size_t len;
+
+	msg = strbuf_detach(buf, &len);
+	strbuf_add_commented_lines(buf, msg, len);
+	free(msg);
+}
+
+static const char *usage_msg = "\n"
+"  git stripspace [-s | --strip-comments] < input\n"
+"  git stripspace [-c | --comment-lines] < input";
+
 int cmd_stripspace(int argc, const char **argv, const char *prefix)
 {
 	struct strbuf buf = STRBUF_INIT;
 	int strip_comments = 0;
+	enum { INVAL = 0, STRIP_SPACE = 1, COMMENT_LINES = 2 } mode = STRIP_SPACE;
+
+	if (argc == 2) {
+		if (!strcmp(argv[1], "-s") ||
+			!strcmp(argv[1], "--strip-comments")) {
+			 strip_comments = 1;
+		} else if (!strcmp(argv[1], "-c") ||
+					 !strcmp(argv[1], "--comment-lines")) {
+			 mode = COMMENT_LINES;
+		} else {
+			mode = INVAL;
+		}
+	} else if (argc > 1) {
+		mode = INVAL;
+	}
+
+	if (mode == INVAL)
+		usage(usage_msg);
 
-	if (argc == 2 && (!strcmp(argv[1], "-s") ||
-				!strcmp(argv[1], "--strip-comments")))
-		strip_comments = 1;
-	else if (argc > 1)
-		usage("git stripspace [-s | --strip-comments] < input");
+	if (strip_comments || mode == COMMENT_LINES)
+		git_config(git_default_config, NULL);
 
 	if (strbuf_read(&buf, 0, 1024) < 0)
 		die_errno("could not read the input");
 
-	stripspace(&buf, strip_comments);
+	if (mode == STRIP_SPACE)
+		stripspace(&buf, strip_comments);
+	else
+		comment_lines(&buf);
 
 	write_or_die(1, buf.buf, buf.len);
 	strbuf_release(&buf);