column: add columnar layout

COL_COLUMN and COL_ROW fill column by column (or row by row
respectively), given the terminal width and how many space between
columns. All cells have equal width.

Strings are supposed to be in UTF-8. Valid ANSI escape strings are OK.

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

1 files changed, 114 insertions, 0 deletions

diff --git a/column.c b/column.c
index 3349f5855b..05fa3e361c 100644
--- a/column.c
+++ b/column.c
@@ -2,6 +2,59 @@
 #include "column.h"
 #include "string-list.h"
 #include "parse-options.h"
+#include "utf8.h"
+
+#define XY2LINEAR(d, x, y) (COL_LAYOUT((d)->colopts) == COL_COLUMN ? \
+			    (x) * (d)->rows + (y) : \
+			    (y) * (d)->cols + (x))
+
+struct column_data {
+	const struct string_list *list;
+	unsigned int colopts;
+	struct column_options opts;
+
+	int rows, cols;
+	int *len;		/* cell length */
+};
+
+/* return length of 's' in letters, ANSI escapes stripped */
+static int item_length(unsigned int colopts, const char *s)
+{
+	int len, i = 0;
+	struct strbuf str = STRBUF_INIT;
+
+	strbuf_addstr(&str, s);
+	while ((s = strstr(str.buf + i, "\033[")) != NULL) {
+		int len = strspn(s + 2, "0123456789;");
+		i = s - str.buf;
+		strbuf_remove(&str, i, len + 3); /* \033[<len><func char> */
+	}
+	len = utf8_strwidth(str.buf);
+	strbuf_release(&str);
+	return len;
+}
+
+/*
+ * Calculate cell width, rows and cols for a table of equal cells, given
+ * table width and how many spaces between cells.
+ */
+static void layout(struct column_data *data, int *width)
+{
+	int i;
+
+	*width = 0;
+	for (i = 0; i < data->list->nr; i++)
+		if (*width < data->len[i])
+			*width = data->len[i];
+
+	*width += data->opts.padding;
+
+	data->cols = (data->opts.width - strlen(data->opts.indent)) / *width;
+	if (data->cols == 0)
+		data->cols = 1;
+
+	data->rows = DIV_ROUND_UP(data->list->nr, data->cols);
+}
 
 /* Display without layout when not enabled */
 static void display_plain(const struct string_list *list,
@@ -13,6 +66,61 @@ static void display_plain(const struct string_list *list,
 		printf("%s%s%s", indent, list->items[i].string, nl);
 }
 
+/* Print a cell to stdout with all necessary leading/traling space */
+static int display_cell(struct column_data *data, int initial_width,
+			const char *empty_cell, int x, int y)
+{
+	int i, len, newline;
+
+	i = XY2LINEAR(data, x, y);
+	if (i >= data->list->nr)
+		return -1;
+	len = data->len[i];
+	if (COL_LAYOUT(data->colopts) == COL_COLUMN)
+		newline = i + data->rows >= data->list->nr;
+	else
+		newline = x == data->cols - 1 || i == data->list->nr - 1;
+
+	printf("%s%s%s",
+	       x == 0 ? data->opts.indent : "",
+	       data->list->items[i].string,
+	       newline ? data->opts.nl : empty_cell + len);
+	return 0;
+}
+
+/* Display COL_COLUMN or COL_ROW */
+static void display_table(const struct string_list *list,
+			  unsigned int colopts,
+			  const struct column_options *opts)
+{
+	struct column_data data;
+	int x, y, i, initial_width;
+	char *empty_cell;
+
+	memset(&data, 0, sizeof(data));
+	data.list = list;
+	data.colopts = colopts;
+	data.opts = *opts;
+
+	data.len = xmalloc(sizeof(*data.len) * list->nr);
+	for (i = 0; i < list->nr; i++)
+		data.len[i] = item_length(colopts, list->items[i].string);
+
+	layout(&data, &initial_width);
+
+	empty_cell = xmalloc(initial_width + 1);
+	memset(empty_cell, ' ', initial_width);
+	empty_cell[initial_width] = '\0';
+	for (y = 0; y < data.rows; y++) {
+		for (x = 0; x < data.cols; x++)
+			if (display_cell(&data, initial_width, empty_cell, x, y))
+				break;
+	}
+
+	free(data.len);
+	free(empty_cell);
+}
+
 void print_columns(const struct string_list *list, unsigned int colopts,
 		   const struct column_options *opts)
 {
@@ -35,6 +143,10 @@ void print_columns(const struct string_list *list, unsigned int colopts,
 	case COL_PLAIN:
 		display_plain(list, nopts.indent, nopts.nl);
 		break;
+	case COL_ROW:
+	case COL_COLUMN:
+		display_table(list, colopts, &nopts);
+		break;
 	default:
 		die("BUG: invalid layout mode %d", COL_LAYOUT(colopts));
 	}
@@ -69,6 +181,8 @@ static int parse_option(const char *arg, int len, unsigned int *colopts,
 		{ "never",  COL_DISABLED, COL_ENABLE_MASK },
 		{ "auto",   COL_AUTO,     COL_ENABLE_MASK },
 		{ "plain",  COL_PLAIN,    COL_LAYOUT_MASK },
+		{ "column", COL_COLUMN,   COL_LAYOUT_MASK },
+		{ "row",    COL_ROW,      COL_LAYOUT_MASK },
 	};
 	int i;