Re: [PATCH 3/3] Add "%w" to pretty formats, which rewraps the commit message

[Junio C Hamano <gitster@pobox.com>]

Junio C Hamano <gitster@pobox.com> writes:

> One issue %w() sidesteps is handing of single liner commit log messages
> (this is not a new issue your %B(n) introduces).  "%s%n%b" will give us
> the original message only when the log has some contents in addition to
> the single-line summary.  Otherwise we will get an extra blank line.
>
> Perhaps we could extend the pretty-printer so that it understands %+x
> notation, which expands to %n%x when %x expands to a non-empty result, and
> otherwise it expands to empty, as a generic extension applicable to any
> format specifier 'x'.  If we have such a notation, "%s%+b", would be a
> reasonable way to say "give us the original commit log message here", and
> we won't need %w(i,j,w) -- we can instead say %S(i,j,w)%+B(i,j,w), or
> %s%+B(i,j,w) depending on what you want.

This teaches the machinery to add a separator LF before any non-empty
expansion of '%x' if you ask '%+x', and also removes LF if '%x' expands to
an empty string if you ask '%-x', for any supported expansion placeholder
'x' it supports.

With the first two patches Dscho posted (and then polished in his tree),
it shouldn't be too hard to update your %B(n) to %B(i,j,w) and also add
%S(i,j,w) in a similar way, to allow people to say %S(i,j,w)%+B(i,j,w)
instead of (or in addition to) his %w(i,j,w).



 pretty.c                   |   42 ++++++++++++++++++++++++++++++++++++++++--
 t/t6006-rev-list-format.sh |   22 ++++++++++++++++++++++
 2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/pretty.c b/pretty.c
index f5983f8..081feb6 100644
--- a/pretty.c
+++ b/pretty.c
@@ -595,8 +595,8 @@ static void format_decoration(struct strbuf *sb, const struct commit *commit)
 		strbuf_addch(sb, ')');
 }
 
-static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
-                               void *context)
+static size_t format_commit_one(struct strbuf *sb, const char *placeholder,
+				void *context)
 {
 	struct format_commit_context *c = context;
 	const struct commit *commit = c->commit;
@@ -739,6 +739,44 @@ static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
 	return 0;	/* unknown placeholder */
 }
 
+static size_t format_commit_item(struct strbuf *sb, const char *placeholder,
+				 void *context)
+{
+	int consumed;
+	size_t orig_len;
+	enum {
+		NO_MAGIC,
+		ADD_LF_BEFORE_NON_EMPTY,
+		DEL_LF_BEFORE_EMPTY,
+	} magic = NO_MAGIC;
+
+	switch (placeholder[0]) {
+	case '-':
+		magic = DEL_LF_BEFORE_EMPTY;
+		break;
+	case '+':
+		magic = ADD_LF_BEFORE_NON_EMPTY;
+		break;
+	default:
+		break;
+	}
+	if (magic != NO_MAGIC)
+		placeholder++;
+
+	orig_len = sb->len;
+	consumed = format_commit_one(sb, placeholder, context);
+	if (magic == NO_MAGIC)
+		return consumed;
+
+	if ((orig_len == sb->len) && magic == DEL_LF_BEFORE_EMPTY) {
+		while (sb->len && sb->buf[sb->len - 1] == '\n')
+			strbuf_setlen(sb, sb->len - 1);
+	} else if ((orig_len != sb->len) && magic == ADD_LF_BEFORE_NON_EMPTY) {
+		strbuf_insert(sb, orig_len, "\n", 1);
+	}
+	return consumed + 1;
+}
+
 void format_commit_message(const struct commit *commit,
 			   const void *format, struct strbuf *sb,
 			   enum date_mode dmode)
diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index 59d1f62..18a77a7 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -162,4 +162,26 @@ test_expect_success 'empty email' '
 	}
 '
 
+test_expect_success 'del LF before empty (1)' '
+	git show -s --pretty=format:"%s%n%-b%nThanks%n" HEAD^^ >actual &&
+	test $(wc -l <actual) = 2
+'
+
+test_expect_success 'del LF before empty (2)' '
+	git show -s --pretty=format:"%s%n%-b%nThanks%n" HEAD >actual &&
+	test $(wc -l <actual) = 6 &&
+	grep "^$" actual
+'
+
+test_expect_success 'add LF before non-empty (1)' '
+	git show -s --pretty=format:"%s%+b%nThanks%n" HEAD^^ >actual &&
+	test $(wc -l <actual) = 2
+'
+
+test_expect_success 'add LF before non-empty (2)' '
+	git show -s --pretty=format:"%s%+b%nThanks%n" HEAD >actual &&
+	test $(wc -l <actual) = 6 &&
+	grep "^$" actual
+'
+
 test_done
.