column: support piping stdout to external git-column process

For too complicated output handling, it'd be easier to just spawn
git-column and redirect stdout to it. This patch provides helpers
to do that.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/column.h b/column.h
index 4f178d84a8..0a61917fa7 100644
--- a/column.h
+++ b/column.h
@@ -39,4 +39,7 @@ static inline int column_active(unsigned int colopts)
 extern void print_columns(const struct string_list *list, unsigned int colopts,
 			  const struct column_options *opts);
 
+extern int run_column_filter(int colopts, const struct column_options *);
+extern int stop_column_filter(void);
+
 #endif