Merge branch 'jk/colors'

"diff-highlight" filter (in contrib/) allows its color output
to be customized via configuration variables.

* jk/colors:
  parse_color: drop COLOR_BACKGROUND macro
  diff-highlight: allow configurable colors
  parse_color: recognize "no$foo" to clear the $foo attribute
  parse_color: support 24-bit RGB values
  parse_color: refactor color storage

6 files changed, 250 insertions, 54 deletions

diff --git a/Documentation/config.txt b/Documentation/config.txt
index ac781a44d7..6862e3e301 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -849,11 +849,13 @@ accepted are `normal`, `black`, `red`, `green`, `yellow`, `blue`,
 `magenta`, `cyan` and `white`; the attributes are `bold`, `dim`, `ul`,
 `blink` and `reverse`.  The first color given is the foreground; the
 second is the background.  The position of the attribute, if any,
-doesn't matter.
+doesn't matter. Attributes may be turned off specifically by prefixing
+them with `no` (e.g., `noreverse`, `noul`, etc).
 +
 Colors (foreground and background) 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).
+terminals may support this).  If your terminal supports it, you may also
+specify 24-bit RGB values as hex, like `#ff0ab3`.
 
 color.diff::
 	Whether to use ANSI escape sequences to add color to patches.
diff --git a/color.c b/color.c
index 7941e932d2..809b359a42 100644
--- a/color.c
+++ b/color.c
@@ -26,30 +26,109 @@ const char *column_colors_ansi[] = {
 /* Ignore the RESET at the end when giving the size */
 const int column_colors_ansi_max = ARRAY_SIZE(column_colors_ansi) - 1;
 
-static int parse_color(const char *name, int len)
+/* An individual foreground or background color. */
+struct color {
+	enum {
+		COLOR_UNSPECIFIED = 0,
+		COLOR_NORMAL,
+		COLOR_ANSI, /* basic 0-7 ANSI colors */
+		COLOR_256,
+		COLOR_RGB
+	} type;
+	/* The numeric value for ANSI and 256-color modes */
+	unsigned char value;
+	/* 24-bit RGB color values */
+	unsigned char red, green, blue;
+};
+
+/*
+ * "word" is a buffer of length "len"; does it match the NUL-terminated
+ * "match" exactly?
+ */
+static int match_word(const char *word, int len, const char *match)
 {
+	return !strncasecmp(word, match, len) && !match[len];
+}
+
+static int get_hex_color(const char *in, unsigned char *out)
+{
+	unsigned int val;
+	val = (hexval(in[0]) << 4) | hexval(in[1]);
+	if (val & ~0xff)
+		return -1;
+	*out = val;
+	return 0;
+}
+
+static int parse_color(struct color *out, const char *name, int len)
+{
+	/* Positions in array must match ANSI color codes */
 	static const char * const color_names[] = {
-		"normal", "black", "red", "green", "yellow",
+		"black", "red", "green", "yellow",
 		"blue", "magenta", "cyan", "white"
 	};
 	char *end;
 	int i;
+	long val;
+
+	/* First try the special word "normal"... */
+	if (match_word(name, len, "normal")) {
+		out->type = COLOR_NORMAL;
+		return 0;
+	}
+
+	/* Try a 24-bit RGB value */
+	if (len == 7 && name[0] == '#') {
+		if (!get_hex_color(name + 1, &out->red) &&
+		    !get_hex_color(name + 3, &out->green) &&
+		    !get_hex_color(name + 5, &out->blue)) {
+			out->type = COLOR_RGB;
+			return 0;
+		}
+	}
+
+	/* Then pick from our human-readable color names... */
 	for (i = 0; i < ARRAY_SIZE(color_names); i++) {
-		const char *str = color_names[i];
-		if (!strncasecmp(name, str, len) && !str[len])
-			return i - 1;
+		if (match_word(name, len, color_names[i])) {
+			out->type = COLOR_ANSI;
+			out->value = i;
+			return 0;
+		}
+	}
+
+	/* And finally try a literal 256-color-mode number */
+	val = strtol(name, &end, 10);
+	if (end - name == len) {
+		/*
+		 * Allow "-1" as an alias for "normal", but other negative
+		 * numbers are bogus.
+		 */
+		if (val < -1)
+			; /* fall through to error */
+		else if (val < 0) {
+			out->type = COLOR_NORMAL;
+			return 0;
+		/* Rewrite low numbers as more-portable standard colors. */
+		} else if (val < 8) {
+			out->type = COLOR_ANSI;
+			out->value = val;
+		} else if (val < 256) {
+			out->type = COLOR_256;
+			out->value = val;
+			return 0;
+		}
 	}
-	i = strtol(name, &end, 10);
-	if (end - name == len && i >= -1 && i <= 255)
-		return i;
-	return -2;
+
+	return -1;
 }
 
 static int parse_attr(const char *name, int len)
 {
-	static const int attr_values[] = { 1, 2, 4, 5, 7 };
+	static const int attr_values[] = { 1, 2, 4, 5, 7,
+					   22, 22, 24, 25, 27 };
 	static const char * const attr_names[] = {
-		"bold", "dim", "ul", "blink", "reverse"
+		"bold", "dim", "ul", "blink", "reverse",
+		"nobold", "nodim", "noul", "noblink", "noreverse"
 	};
 	int i;
 	for (i = 0; i < ARRAY_SIZE(attr_names); i++) {
@@ -65,13 +144,44 @@ int color_parse(const char *value, char *dst)
 	return color_parse_mem(value, strlen(value), dst);
 }
 
+/*
+ * Write the ANSI color codes for "c" to "out"; the string should
+ * already have the ANSI escape code in it. "out" should have enough
+ * space in it to fit any color.
+ */
+static char *color_output(char *out, const struct color *c, char type)
+{
+	switch (c->type) {
+	case COLOR_UNSPECIFIED:
+	case COLOR_NORMAL:
+		break;
+	case COLOR_ANSI:
+		*out++ = type;
+		*out++ = '0' + c->value;
+		break;
+	case COLOR_256:
+		out += sprintf(out, "%c8;5;%d", type, c->value);
+		break;
+	case COLOR_RGB:
+		out += sprintf(out, "%c8;2;%d;%d;%d", type,
+			       c->red, c->green, c->blue);
+		break;
+	}
+	return out;
+}
+
+static int color_empty(const struct color *c)
+{
+	return c->type <= COLOR_NORMAL;
+}
+
 int color_parse_mem(const char *value, int value_len, char *dst)
 {
 	const char *ptr = value;
 	int len = value_len;
 	unsigned int attr = 0;
-	int fg = -2;
-	int bg = -2;
+	struct color fg = { COLOR_UNSPECIFIED };
+	struct color bg = { COLOR_UNSPECIFIED };
 
 	if (!strncasecmp(value, "reset", len)) {
 		strcpy(dst, GIT_COLOR_RESET);
@@ -81,6 +191,7 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 	/* [fg [bg]] [attr]... */
 	while (len > 0) {
 		const char *word = ptr;
+		struct color c;
 		int val, wordlen = 0;
 
 		while (len > 0 && !isspace(word[wordlen])) {
@@ -94,14 +205,13 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 			len--;
 		}
 
-		val = parse_color(word, wordlen);
-		if (val >= -1) {
-			if (fg == -2) {
-				fg = val;
+		if (!parse_color(&c, word, wordlen)) {
+			if (fg.type == COLOR_UNSPECIFIED) {
+				fg = c;
 				continue;
 			}
-			if (bg == -2) {
-				bg = val;
+			if (bg.type == COLOR_UNSPECIFIED) {
+				bg = c;
 				continue;
 			}
 			goto bad;
@@ -113,7 +223,7 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 			goto bad;
 	}
 
-	if (attr || fg >= 0 || bg >= 0) {
+	if (attr || !color_empty(&fg) || !color_empty(&bg)) {
 		int sep = 0;
 		int i;
 
@@ -127,27 +237,19 @@ int color_parse_mem(const char *value, int value_len, char *dst)
 			attr &= ~bit;
 			if (sep++)
 				*dst++ = ';';
-			*dst++ = '0' + i;
+			dst += sprintf(dst, "%d", i);
 		}
-		if (fg >= 0) {
+		if (!color_empty(&fg)) {
 			if (sep++)
 				*dst++ = ';';
-			if (fg < 8) {
-				*dst++ = '3';
-				*dst++ = '0' + fg;
-			} else {
-				dst += sprintf(dst, "38;5;%d", fg);
-			}
+			/* foreground colors are all in the 3x range */
+			dst = color_output(dst, &fg, '3');
 		}
-		if (bg >= 0) {
+		if (!color_empty(&bg)) {
 			if (sep++)
 				*dst++ = ';';
-			if (bg < 8) {
-				*dst++ = '4';
-				*dst++ = '0' + bg;
-			} else {
-				dst += sprintf(dst, "48;5;%d", bg);
-			}
+			/* background colors are all in the 4x range */
+			dst = color_output(dst, &bg, '4');
 		}
 		*dst++ = 'm';
 	}
diff --git a/color.h b/color.h
index f5beab1ed7..7fe77fb55e 100644
--- a/color.h
+++ b/color.h
@@ -8,15 +8,15 @@ struct strbuf;
 /*
  * The maximum length of ANSI color sequence we would generate:
  * - leading ESC '['            2
- * - attr + ';'                 2 * 8 (e.g. "1;")
- * - fg color + ';'             9 (e.g. "38;5;2xx;")
- * - fg color + ';'             9 (e.g. "48;5;2xx;")
+ * - attr + ';'                 3 * 10 (e.g. "1;")
+ * - fg color + ';'             17 (e.g. "38;2;255;255;255;")
+ * - bg color + ';'             17 (e.g. "48;2;255;255;255;")
  * - terminating 'm' NUL        2
  *
  * The above overcounts attr (we only use 5 not 8) and one semicolon
  * but it is close enough.
  */
-#define COLOR_MAXLEN 40
+#define COLOR_MAXLEN 70
 
 /*
  * IMPORTANT: Due to the way these color codes are emulated on Windows,
diff --git a/contrib/diff-highlight/README b/contrib/diff-highlight/README
index 502e03b305..836b97a730 100644
--- a/contrib/diff-highlight/README
+++ b/contrib/diff-highlight/README
@@ -58,6 +58,47 @@ following in your git configuration:
 	diff = diff-highlight | less
 ---------------------------------------------
 
+
+Color Config
+------------
+
+You can configure the highlight colors and attributes using git's
+config. The colors for "old" and "new" lines can be specified
+independently. There are two "modes" of configuration:
+
+  1. You can specify a "highlight" color and a matching "reset" color.
+     This will retain any existing colors in the diff, and apply the
+     "highlight" and "reset" colors before and after the highlighted
+     portion.
+
+  2. You can specify a "normal" color and a "highlight" color. In this
+     case, existing colors are dropped from that line. The non-highlighted
+     bits of the line get the "normal" color, and the highlights get the
+     "highlight" color.
+
+If no "new" colors are specified, they default to the "old" colors. If
+no "old" colors are specified, the default is to reverse the foreground
+and background for highlighted portions.
+
+Examples:
+
+---------------------------------------------
+# Underline highlighted portions
+[color "diff-highlight"]
+oldHighlight = ul
+oldReset = noul
+---------------------------------------------
+
+---------------------------------------------
+# Varying background intensities
+[color "diff-highlight"]
+oldNormal = "black #f8cbcb"
+oldHighlight = "black #ffaaaa"
+newNormal = "black #cbeecb"
+newHighlight = "black #aaffaa"
+---------------------------------------------
+
+
 Bugs
 ----
 
diff --git a/contrib/diff-highlight/diff-highlight b/contrib/diff-highlight/diff-highlight
index 69a652e7b2..08c88bbc87 100755
--- a/contrib/diff-highlight/diff-highlight
+++ b/contrib/diff-highlight/diff-highlight
@@ -5,8 +5,18 @@ use strict;
 
 # Highlight by reversing foreground and background. You could do
 # other things like bold or underline if you prefer.
-my $HIGHLIGHT   = "\x1b[7m";
-my $UNHIGHLIGHT = "\x1b[27m";
+my @OLD_HIGHLIGHT = (
+	color_config('color.diff-highlight.oldnormal'),
+	color_config('color.diff-highlight.oldhighlight', "\x1b[7m"),
+	color_config('color.diff-highlight.oldreset', "\x1b[27m")
+);
+my @NEW_HIGHLIGHT = (
+	color_config('color.diff-highlight.newnormal', $OLD_HIGHLIGHT[0]),
+	color_config('color.diff-highlight.newhighlight', $OLD_HIGHLIGHT[1]),
+	color_config('color.diff-highlight.newreset', $OLD_HIGHLIGHT[2])
+);
+
+my $RESET = "\x1b[m";
 my $COLOR = qr/\x1b\[[0-9;]*m/;
 my $BORING = qr/$COLOR|\s/;
 
@@ -57,6 +67,17 @@ show_hunk(\@removed, \@added);
 
 exit 0;
 
+# Ideally we would feed the default as a human-readable color to
+# git-config as the fallback value. But diff-highlight does
+# not otherwise depend on git at all, and there are reports
+# of it being used in other settings. Let's handle our own
+# fallback, which means we will work even if git can't be run.
+sub color_config {
+	my ($key, $default) = @_;
+	my $s = `git config --get-color $key 2>/dev/null`;
+	return length($s) ? $s : $default;
+}
+
 sub show_hunk {
 	my ($a, $b) = @_;
 
@@ -132,8 +153,8 @@ sub highlight_pair {
 	}
 
 	if (is_pair_interesting(\@a, $pa, $sa, \@b, $pb, $sb)) {
-		return highlight_line(\@a, $pa, $sa),
-		       highlight_line(\@b, $pb, $sb);
+		return highlight_line(\@a, $pa, $sa, \@OLD_HIGHLIGHT),
+		       highlight_line(\@b, $pb, $sb, \@NEW_HIGHLIGHT);
 	}
 	else {
 		return join('', @a),
@@ -148,15 +169,30 @@ sub split_line {
 }
 
 sub highlight_line {
-	my ($line, $prefix, $suffix) = @_;
-
-	return join('',
-		@{$line}[0..($prefix-1)],
-		$HIGHLIGHT,
-		@{$line}[$prefix..$suffix],
-		$UNHIGHLIGHT,
-		@{$line}[($suffix+1)..$#$line]
-	);
+	my ($line, $prefix, $suffix, $theme) = @_;
+
+	my $start = join('', @{$line}[0..($prefix-1)]);
+	my $mid = join('', @{$line}[$prefix..$suffix]);
+	my $end = join('', @{$line}[($suffix+1)..$#$line]);
+
+	# If we have a "normal" color specified, then take over the whole line.
+	# Otherwise, we try to just manipulate the highlighted bits.
+	if (defined $theme->[0]) {
+		s/$COLOR//g for ($start, $mid, $end);
+		chomp $end;
+		return join('',
+			$theme->[0], $start, $RESET,
+			$theme->[1], $mid, $RESET,
+			$theme->[0], $end, $RESET,
+			"\n"
+		);
+	} else {
+		return join('',
+			$start,
+			$theme->[1], $mid, $theme->[2],
+			$end
+		);
+	}
 }
 
 # Pairs are interesting to highlight only if we are going to end up
diff --git a/t/t4026-color.sh b/t/t4026-color.sh
index 63e423838f..267c43bd95 100755
--- a/t/t4026-color.sh
+++ b/t/t4026-color.sh
@@ -45,14 +45,29 @@ test_expect_success 'fg bg attr...' '
 	color "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"
+'
+
 test_expect_success 'long color specification' '
 	color "254 255 bold dim ul blink reverse" "[1;2;4;5;7;38;5;254;48;5;255m"
 '
 
+test_expect_success 'absurdly long color specification' '
+	color \
+	  "#ffffff #ffffff bold nobold dim nodim ul noul blink noblink reverse noreverse" \
+	  "[1;2;4;5;7;22;24;25;27;38;2;255;255;255;48;2;255;255;255m"
+'
+
 test_expect_success '256 colors' '
 	color "254 bold 255" "[1;38;5;254;48;5;255m"
 '
 
+test_expect_success '24-bit colors' '
+	color "#ff00ff black" "[38;2;255;0;255;40m"
+'
+
 test_expect_success '"normal" yields no color at all"' '
 	color "normal black" "[40m"
 '