Merge branch 're/color-default-reset'

"default" and "reset" colors have been added to our palette.

* re/color-default-reset:
  color: allow colors to be prefixed with "reset"
  color: support "default" to restore fg/bg color
  color: add missing GIT_COLOR_* white/black constants

Documentation/config.txt

@@ -262,11 +262,19 @@ color::
        colors (at most two, one for foreground and one for background)
        and attributes (as many as you want), separated by spaces.
 +
-The basic colors accepted are `normal`, `black`, `red`, `green`, `yellow`,
+The basic colors accepted are `normal`, `black`, `red`, `green`,
-`blue`, `magenta`, `cyan` and `white`.  The first color given is the
+`yellow`, `blue`, `magenta`, `cyan`, `white` and `default`.  The first
-foreground; the second is the background.  All the basic colors except
+color given is the foreground; the second is the background.  All the
-`normal` have a bright variant that can be specified by prefixing the
+basic colors except `normal` and `default` have a bright variant that can
-color with `bright`, like `brightred`.
+be specified by prefixing the color with `bright`, like `brightred`.
++
+The color `normal` makes no change to the color. It is the same as an
+empty string, but can be used as the foreground color when specifying a
+background color alone (for example, "normal red").
++
+The color `default` explicitly resets the color to the terminal default,
+for example to specify a cleared background. Although it varies between
+terminals, this is usually not the same as setting to "white black".
 +
 Colors may also be given as numbers between 0 and 255; these use ANSI
 256-color mode (but note that not all terminals may support this).  If
@@ -280,6 +288,11 @@ The position of any attributes with respect to the colors
 be turned off by prefixing them with `no` or `no-` (e.g., `noreverse`,
 `no-ul`, etc).
 +
+The pseudo-attribute `reset` resets all colors and attributes before
+applying the specified coloring. For example, `reset green` will result
+in a green foreground and default background without any active
+attributes.
++
 An empty color string produces no color effect at all. This can be used
 to avoid coloring specific elements without disabling color entirely.
 +

color.c

@@ -40,7 +40,7 @@ struct color {
 	enum {
 		COLOR_UNSPECIFIED = 0,
 		COLOR_NORMAL,
-		COLOR_ANSI, /* basic 0-7 ANSI colors */
+		COLOR_ANSI, /* basic 0-7 ANSI colors + "default" (value = 9) */
 		COLOR_256,
 		COLOR_RGB
 	} type;
@@ -83,6 +83,27 @@ static int parse_ansi_color(struct color *out, const char *name, int len)
 	int i;
 	int color_offset = COLOR_FOREGROUND_ANSI;
 
+	if (match_word(name, len, "default")) {
+		/*
+		 * Restores to the terminal's default color, which may not be
+		 * the same as explicitly setting "white" or "black".
+		 *
+		 * ECMA-48 - Control Functions \
+		 *  for Coded Character Sets, 5th edition (June 1991):
+		 * > 39 default display colour (implementation-defined)
+		 * > 49 default background colour (implementation-defined)
+		 *
+		 * Although not supported /everywhere/--according to terminfo,
+		 * some terminals define "op" (original pair) as a blunt
+		 * "set to white on black", or even "send full SGR reset"--
+		 * it's standard and well-supported enough that if a user
+		 * asks for it in their config this will do the right thing.
+		 */
+		out->type = COLOR_ANSI;
+		out->value = 9 + color_offset;
+		return 0;
+	}
+
 	if (strncasecmp(name, "bright", 6) == 0) {
 		color_offset = COLOR_FOREGROUND_BRIGHT_ANSI;
 		name += 6;
@@ -234,6 +255,7 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 	const char *ptr = value;
 	int len = value_len;
 	char *end = dst + COLOR_MAXLEN;
+	unsigned int has_reset = 0;
 	unsigned int attr = 0;
 	struct color fg = { COLOR_UNSPECIFIED };
 	struct color bg = { COLOR_UNSPECIFIED };
@@ -248,12 +270,7 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 		return 0;
 	}
 
-	if (!strncasecmp(ptr, "reset", len)) {
+	/* [reset] [fg [bg]] [attr]... */
-		xsnprintf(dst, end - dst, GIT_COLOR_RESET);
-		return 0;
-	}
-
-	/* [fg [bg]] [attr]... */
 	while (len > 0) {
 		const char *word = ptr;
 		struct color c = { COLOR_UNSPECIFIED };
@@ -270,6 +287,11 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 			len--;
 		}
 
+		if (match_word(word, wordlen, "reset")) {
+			has_reset = 1;
+			continue;
+		}
+
 		if (!parse_color(&c, word, wordlen)) {
 			if (fg.type == COLOR_UNSPECIFIED) {
 				fg = c;
@@ -295,13 +317,16 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 	*dst++ = (x); \
 } while(0)
 
-	if (attr || !color_empty(&fg) || !color_empty(&bg)) {
+	if (has_reset || attr || !color_empty(&fg) || !color_empty(&bg)) {
 		int sep = 0;
 		int i;
 
 		OUT('\033');
 		OUT('[');
 
+		if (has_reset)
+			sep++;
+
 		for (i = 0; attr; i++) {
 			unsigned bit = (1 << i);
 			if (!(attr & bit))

color.h

@@ -6,6 +6,7 @@ struct strbuf;
 /*
  * The maximum length of ANSI color sequence we would generate:
  * - leading ESC '['            2
+ * - reset ';' .................1
  * - attr + ';'                 2 * num_attr (e.g. "1;")
  * - no-attr + ';'              3 * num_attr (e.g. "22;")
  * - fg color + ';'             17 (e.g. "38;2;255;255;255;")
@@ -24,30 +25,42 @@ struct strbuf;
 #define GIT_COLOR_NORMAL	""
 #define GIT_COLOR_RESET		"\033[m"
 #define GIT_COLOR_BOLD		"\033[1m"
+#define GIT_COLOR_BLACK		"\033[30m"
 #define GIT_COLOR_RED		"\033[31m"
 #define GIT_COLOR_GREEN		"\033[32m"
 #define GIT_COLOR_YELLOW	"\033[33m"
 #define GIT_COLOR_BLUE		"\033[34m"
 #define GIT_COLOR_MAGENTA	"\033[35m"
 #define GIT_COLOR_CYAN		"\033[36m"
+#define GIT_COLOR_WHITE		"\033[37m"
+#define GIT_COLOR_DEFAULT	"\033[39m"
+#define GIT_COLOR_BOLD_BLACK	"\033[1;30m"
 #define GIT_COLOR_BOLD_RED	"\033[1;31m"
 #define GIT_COLOR_BOLD_GREEN	"\033[1;32m"
 #define GIT_COLOR_BOLD_YELLOW	"\033[1;33m"
 #define GIT_COLOR_BOLD_BLUE	"\033[1;34m"
 #define GIT_COLOR_BOLD_MAGENTA	"\033[1;35m"
 #define GIT_COLOR_BOLD_CYAN	"\033[1;36m"
+#define GIT_COLOR_BOLD_WHITE	"\033[1;37m"
+#define GIT_COLOR_BOLD_DEFAULT	"\033[1;39m"
+#define GIT_COLOR_FAINT_BLACK	"\033[2;30m"
 #define GIT_COLOR_FAINT_RED	"\033[2;31m"
 #define GIT_COLOR_FAINT_GREEN	"\033[2;32m"
 #define GIT_COLOR_FAINT_YELLOW	"\033[2;33m"
 #define GIT_COLOR_FAINT_BLUE	"\033[2;34m"
 #define GIT_COLOR_FAINT_MAGENTA	"\033[2;35m"
 #define GIT_COLOR_FAINT_CYAN	"\033[2;36m"
+#define GIT_COLOR_FAINT_WHITE	"\033[2;37m"
+#define GIT_COLOR_FAINT_DEFAULT	"\033[2;39m"
+#define GIT_COLOR_BG_BLACK	"\033[40m"
 #define GIT_COLOR_BG_RED	"\033[41m"
 #define GIT_COLOR_BG_GREEN	"\033[42m"
 #define GIT_COLOR_BG_YELLOW	"\033[43m"
 #define GIT_COLOR_BG_BLUE	"\033[44m"
 #define GIT_COLOR_BG_MAGENTA	"\033[45m"
 #define GIT_COLOR_BG_CYAN	"\033[46m"
+#define GIT_COLOR_BG_WHITE	"\033[47m"
+#define GIT_COLOR_BG_DEFAULT	"\033[49m"
 #define GIT_COLOR_FAINT		"\033[2m"
 #define GIT_COLOR_FAINT_ITALIC	"\033[2;3m"
 #define GIT_COLOR_REVERSE	"\033[7m"

t/t4026-color.sh

@@ -60,6 +60,10 @@ test_expect_success 'fg bg attr...' '
 	color "blue bold dim ul blink reverse" "[1;2;4;5;7;34m"
 '
 
+test_expect_success 'reset fg bg attr...' '
+	color "reset blue bold dim ul blink reverse" "[;1;2;4;5;7;34m"
+'
+
 # note that nobold and nodim are the same code (22)
 test_expect_success 'attr negation' '
 	color "nobold nodim noul noblink noreverse" "[22;24;25;27m"
@@ -96,6 +100,18 @@ test_expect_success '24-bit colors' '
 	color "#ff00ff black" "[38;2;255;0;255;40m"
 '
 
+test_expect_success '"default" foreground' '
+	color "default" "[39m"
+'
+
+test_expect_success '"normal default" to clear background' '
+	color "normal default" "[49m"
+'
+
+test_expect_success '"default" can be combined with attributes' '
+	color "default default no-reverse bold" "[1;27;39;49m"
+'
+
 test_expect_success '"normal" yields no color at all"' '
 	color "normal black" "[40m"
 '