[PATCH 2/9] Add display_columns() to display in columnar layout

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Currently it does not do that, just provide the API. In order to
output in columns, COL_ENABLED bit must be set. A nice consequence is
mode 0 is effectively no column mode.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 Makefile |    3 ++-
 column.c |   37 +++++++++++++++++++++++++++++++++++++
 column.h |    5 +++++
 3 files changed, 44 insertions(+), 1 deletions(-)
 create mode 100644 column.c

diff --git a/Makefile b/Makefile
index 6007f68..94e1cf0 100644
--- a/Makefile
+++ b/Makefile
@@ -575,6 +575,7 @@ LIB_OBJS += branch.o
 LIB_OBJS += bundle.o
 LIB_OBJS += cache-tree.o
 LIB_OBJS += color.o
+LIB_OBJS += column.o
 LIB_OBJS += combine-diff.o
 LIB_OBJS += commit.o
 LIB_OBJS += config.o
@@ -1956,7 +1957,7 @@ builtin/prune.o builtin/reflog.o reachable.o: reachable.h
 builtin/commit.o builtin/revert.o wt-status.o: wt-status.h
 builtin/tar-tree.o archive-tar.o: tar.h
 connect.o transport.o http-backend.o: url.h
-help.o pager.o: column.h
+column.o help.o pager.o: column.h
 http-fetch.o http-walker.o remote-curl.o transport.o walker.o: walker.h
 http.o http-walker.o http-push.o http-fetch.o remote-curl.o: http.h url.h
 
diff --git a/column.c b/column.c
new file mode 100644
index 0000000..8422c89
--- /dev/null
+++ b/column.c
@@ -0,0 +1,37 @@
+#include "cache.h"
+#include "column.h"
+#include "string-list.h"
+
+#define MODE(mode) ((mode) & COL_MODE)
+
+struct string_list_item *add_to_columns(struct string_list *list, int mode,
+					const char *string)
+{
+	if (mode & COL_ENABLED)
+		return string_list_append(list, string);
+	printf("%s\n", string);
+	return NULL;
+}
+
+/* Display without layout when COL_ENABLED is not set */
+static void display_plain(const struct string_list *list, const char *indent)
+{
+	int i;
+
+	for (i = 0; i < list->nr; i++)
+		printf("%s%s\n", indent, list->items[i].string);
+}
+
+void display_columns(const struct string_list *list, int mode,
+		     int width, int padding, const char *indent)
+{
+	if (!list->nr)
+		return;
+	if (!indent)
+		indent = "";
+	if (width <= 1 || !(mode & COL_ENABLED)) {
+		display_plain(list, indent);
+		return;
+	}
+	die("BUG: invalid mode %d", MODE(mode));
+}
diff --git a/column.h b/column.h
index 55d8067..ffae87c 100644
--- a/column.h
+++ b/column.h
@@ -1,6 +1,11 @@
 #ifndef COLUMN_H
 #define COLUMN_H
 
+#define COL_MODE          0x000F
+#define COL_ENABLED      (1 << 4)
+
 extern int term_columns(void);
+extern struct string_list_item *add_to_columns(struct string_list *list, int mode, const char *string);
+extern void display_columns(const struct string_list *list, int mode, int width, int padding, const char *indent);
 
 #endif
-- 
1.7.4.74.g639db