[PATCH 3/9] column: add functions to parse column settings

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

A column option string consists of many token separated by either
space of commas. A token belongs to one of three groups:

 - enabling: always, never and auto
 - layout mode: to be implemented
 - other tuning, which could be negated be prefix 'no'

A command line option without argument (e.g. --column) will enable
column output and reuse existing settings (layout mode and options..).
--no-column disables columnar output.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 .gitignore        |    1 +
 Makefile          |    1 +
 column.c          |  125 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 column.h          |    4 ++
 parse-options.h   |    2 +
 t/t9002-column.sh |   27 +++++++++++
 test-column.c     |   39 ++++++++++++++++
 7 files changed, 199 insertions(+), 0 deletions(-)
 create mode 100755 t/t9002-column.sh
 create mode 100644 test-column.c

diff --git a/.gitignore b/.gitignore
index 3dd6ef7..a1a1202 100644
--- a/.gitignore
+++ b/.gitignore
@@ -162,6 +162,7 @@
 /gitweb/gitweb.cgi
 /gitweb/static/gitweb.min.*
 /test-chmtime
+/test-column
 /test-ctype
 /test-date
 /test-delta
diff --git a/Makefile b/Makefile
index 94e1cf0..ba9944b 100644
--- a/Makefile
+++ b/Makefile
@@ -417,6 +417,7 @@ PROGRAM_OBJS += http-backend.o
 PROGRAMS += $(patsubst %.o,git-%$X,$(PROGRAM_OBJS))
 
 TEST_PROGRAMS_NEED_X += test-chmtime
+TEST_PROGRAMS_NEED_X += test-column
 TEST_PROGRAMS_NEED_X += test-ctype
 TEST_PROGRAMS_NEED_X += test-date
 TEST_PROGRAMS_NEED_X += test-delta
diff --git a/column.c b/column.c
index 8422c89..b32b9f9 100644
--- a/column.c
+++ b/column.c
@@ -1,6 +1,7 @@
 #include "cache.h"
 #include "column.h"
 #include "string-list.h"
+#include "parse-options.h"
 
 #define MODE(mode) ((mode) & COL_MODE)
 
@@ -35,3 +36,127 @@ void display_columns(const struct string_list *list, int mode,
 	}
 	die("BUG: invalid mode %d", MODE(mode));
 }
+
+struct colopt {
+	enum {
+		ENABLE,
+		MODE,
+		OPTION
+	} type;
+	const char *name;
+	int value;
+};
+
+/*
+ * Set COL_ENABLED and COL_ENABLED_SET. If 'set' is -1, check if
+ * stdout is tty.
+ */
+static int set_enable_bit(int *mode, int set, int stdout_is_tty)
+{
+	if (set < 0) {	/* auto */
+		if (stdout_is_tty < 0)
+			stdout_is_tty = isatty(1);
+		set = stdout_is_tty || (pager_in_use() && pager_use_color);
+	}
+	if (set)
+		*mode = *mode | COL_ENABLED | COL_ENABLED_SET;
+	else
+		*mode = (*mode & ~COL_ENABLED) | COL_ENABLED_SET;
+	return 0;
+}
+
+/*
+ * Set COL_MODE_*. mode is intially copied from column.ui. If
+ * COL_ENABLED_SET is not set, then neither 'always', 'never' nor
+ * 'auto' has been used. Default to 'always'.
+ */
+static int set_mode(int *mode, int value)
+{
+	*mode = (*mode & ~COL_MODE) | value;
+	if (!(*mode & COL_ENABLED_SET))
+		*mode |= COL_ENABLED | COL_ENABLED_SET;
+
+	return 0;
+}
+
+/* Set or unset other COL_* */
+static int set_option(int *mode, int opt, int set)
+{
+	if (set)
+		*mode |= opt;
+	else
+		*mode &= ~opt;
+	return 0;
+}
+
+static int parse_option(const char *arg, int len,
+			int *mode, int stdout_is_tty)
+{
+	struct colopt opts[] = {
+		{ ENABLE, "always",  1 },
+		{ ENABLE, "never",   0 },
+		{ ENABLE, "auto",   -1 },
+	};
+	int i, set, name_len;
+
+	for (i = 0; i < ARRAY_SIZE(opts); i++) {
+		if (opts[i].type == OPTION) {
+			if (len > 2 && !strncmp(arg, "no", 2)) {
+				arg += 2;
+				len -= 2;
+				set = 0;
+			}
+			else
+				set = 1;
+		}
+
+		name_len = strlen(opts[i].name);
+		if (len != name_len ||
+		    strncmp(arg, opts[i].name, name_len))
+			continue;
+
+		switch (opts[i].type) {
+		case ENABLE: return set_enable_bit(mode, opts[i].value,
+						   stdout_is_tty);
+		case MODE: return set_mode(mode, opts[i].value);
+		case OPTION: return set_option(mode, opts[i].value, set);
+		default: die("BUG: Unknown option type %d", opts[i].type);
+		}
+	}
+
+	return error("unsupported style '%s'", arg);
+}
+
+static int parse_string(int *mode, const char *value,
+			int stdout_is_tty)
+{
+	const char *sep = " ,";
+
+	while (*value) {
+		int len = strcspn(value, sep);
+		if (len) {
+			if (parse_option(value, len, mode, stdout_is_tty))
+				return -1;
+
+			value += len;
+		}
+		value += strspn(value, sep);
+	}
+	return 0;
+}
+
+int parseopt_column_callback(const struct option *opt,
+			     const char *arg, int unset)
+{
+	int *mode = opt->value;
+	if (unset) {
+		*mode = (*mode & ~COL_ENABLED) | COL_ENABLED_SET;
+		return 0;
+	}
+	if (arg)
+		return parse_string(mode, arg, -1);
+
+	/* no arg, turn it on */
+	*mode |= COL_ENABLED | COL_ENABLED_SET;
+	return 0;
+}
diff --git a/column.h b/column.h
index ffae87c..a8b24e8 100644
--- a/column.h
+++ b/column.h
@@ -3,9 +3,13 @@
 
 #define COL_MODE          0x000F
 #define COL_ENABLED      (1 << 4)
+#define COL_ENABLED_SET  (1 << 5)  /* Has COL_ENABLED been set? */
 
 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);
 
+struct option;
+extern int parseopt_column_callback(const struct option *opt, const char *arg, int unset);
+
 #endif
diff --git a/parse-options.h b/parse-options.h
index 31ec5d2..14816b6 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -220,5 +220,7 @@ extern int parse_opt_tertiary(const struct option *, const char *, int);
 	  PARSE_OPT_OPTARG, &parse_opt_abbrev_cb, 0 }
 #define OPT__COLOR(var, h) \
 	OPT_COLOR_FLAG(0, "color", (var), (h))
+#define OPT_COLUMN(s, l, v, h) \
+	{ OPTION_CALLBACK, (s), (l), (v), "style", (h), PARSE_OPT_OPTARG, parseopt_column_callback }
 
 #endif
diff --git a/t/t9002-column.sh b/t/t9002-column.sh
new file mode 100755
index 0000000..099a29f
--- /dev/null
+++ b/t/t9002-column.sh
@@ -0,0 +1,27 @@
+#!/bin/sh
+
+test_description='git column'
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	cat >lista <<\EOF
+one
+two
+three
+four
+five
+six
+seven
+eight
+nine
+ten
+eleven
+EOF
+'
+
+test_expect_success 'never' '
+	test-column --mode=never <lista >actual &&
+	test_cmp lista actual
+'
+
+test_done
diff --git a/test-column.c b/test-column.c
new file mode 100644
index 0000000..d6321a4
--- /dev/null
+++ b/test-column.c
@@ -0,0 +1,39 @@
+#include "cache.h"
+#include "strbuf.h"
+#include "parse-options.h"
+#include "string-list.h"
+#include "column.h"
+
+static const char * const builtin_column_usage[] = {
+	"git column [--mode=<mode>] [--width=<width>] [--left-space=<N>] [--right-space=<N>]",
+	NULL
+};
+
+int main(int argc, const char **argv)
+{
+	struct string_list list = STRING_LIST_INIT_DUP;
+	int mode = 0;
+	struct strbuf sb = STRBUF_INIT;
+	int left_space = 0, right_space = 0, padding = 1;
+	int term_width = term_columns();
+	struct option options[] = {
+		OPT_INTEGER(0, "width", &term_width, "Maximum width"),
+		OPT_INTEGER(0, "left", &left_space, "Padding space on left border"),
+		OPT_INTEGER(0, "right", &right_space, "Padding space on right border"),
+		OPT_INTEGER(0, "padding", &padding, "Padding space between columns"),
+		OPT_COLUMN(0, "mode", &mode, "layout to use"),
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, "", options, builtin_column_usage, 0);
+
+	while (!strbuf_getline(&sb, stdin, '\n'))
+		string_list_append(&list, sb.buf);
+
+	strbuf_setlen(&sb, left_space);
+	memset(sb.buf, ' ', left_space);
+	display_columns(&list, mode,
+			term_width - right_space - left_space,
+			padding, sb.buf);
+	return 0;
+}
-- 
1.7.4.74.g639db