grep: add color.grep.matchcontext and color.grep.matchselected

The config option color.grep.match can be used to specify the highlighting
color for matching strings.  Add the options matchContext and matchSelected
to allow different colors to be specified for matching strings in the
context vs. in selected lines.  This is similar to the ms and mc specifiers
in GNU grep's environment variable GREP_COLORS.

Tests are from Zoltan Klinger's earlier attempt to solve the same
issue in a different way.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -860,7 +860,11 @@ color.grep.<slot>::
 `linenumber`;;
 	line number prefix (when using `-n`)
 `match`;;
-	matching text
+	matching text (same as setting `matchContext` and `matchSelected`)
+`matchContext`;;
+	matching text in context lines
+`matchSelected`;;
+	matching text in selected lines
 `selected`;;
 	non-matching text in selected lines
 `separator`;;

grep.c

@@ -35,7 +35,8 @@ void init_grep_defaults(void)
 	strcpy(opt->color_filename, "");
 	strcpy(opt->color_function, "");
 	strcpy(opt->color_lineno, "");
-	strcpy(opt->color_match, GIT_COLOR_BOLD_RED);
+	strcpy(opt->color_match_context, GIT_COLOR_BOLD_RED);
+	strcpy(opt->color_match_selected, GIT_COLOR_BOLD_RED);
 	strcpy(opt->color_selected, "");
 	strcpy(opt->color_sep, GIT_COLOR_CYAN);
 	opt->color = -1;
@@ -96,12 +97,22 @@ int grep_config(const char *var, const char *value, void *cb)
 		color = opt->color_function;
 	else if (!strcmp(var, "color.grep.linenumber"))
 		color = opt->color_lineno;
-	else if (!strcmp(var, "color.grep.match"))
-		color = opt->color_match;
+	else if (!strcmp(var, "color.grep.matchcontext"))
+		color = opt->color_match_context;
+	else if (!strcmp(var, "color.grep.matchselected"))
+		color = opt->color_match_selected;
 	else if (!strcmp(var, "color.grep.selected"))
 		color = opt->color_selected;
 	else if (!strcmp(var, "color.grep.separator"))
 		color = opt->color_sep;
+	else if (!strcmp(var, "color.grep.match")) {
+		int rc = 0;
+		if (!value)
+			return config_error_nonbool(var);
+		color_parse(value, var, opt->color_match_context);
+		color_parse(value, var, opt->color_match_selected);
+		return rc;
+	}
 
 	if (color) {
 		if (!value)
@@ -139,7 +150,8 @@ void grep_init(struct grep_opt *opt, const char *prefix)
 	strcpy(opt->color_filename, def->color_filename);
 	strcpy(opt->color_function, def->color_function);
 	strcpy(opt->color_lineno, def->color_lineno);
-	strcpy(opt->color_match, def->color_match);
+	strcpy(opt->color_match_context, def->color_match_context);
+	strcpy(opt->color_match_selected, def->color_match_selected);
 	strcpy(opt->color_selected, def->color_selected);
 	strcpy(opt->color_sep, def->color_sep);
 }
@@ -1079,7 +1091,7 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		      const char *name, unsigned lno, char sign)
 {
 	int rest = eol - bol;
-	char *line_color = NULL;
+	const char *match_color, *line_color = NULL;
 
 	if (opt->file_break && opt->last_shown == 0) {
 		if (opt->show_hunk_mark)
@@ -1117,6 +1129,10 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		int ch = *eol;
 		int eflags = 0;
 
+		if (sign == ':')
+			match_color = opt->color_match_selected;
+		else
+			match_color = opt->color_match_context;
 		if (sign == ':')
 			line_color = opt->color_selected;
 		else if (sign == '-')
@@ -1130,8 +1146,7 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 
 			output_color(opt, bol, match.rm_so, line_color);
 			output_color(opt, bol + match.rm_so,
-				     match.rm_eo - match.rm_so,
-				     opt->color_match);
+				     match.rm_eo - match.rm_so, match_color);
 			bol += match.rm_eo;
 			rest -= match.rm_eo;
 			eflags = REG_NOTBOL;

grep.h

@@ -124,7 +124,8 @@ struct grep_opt {
 	char color_filename[COLOR_MAXLEN];
 	char color_function[COLOR_MAXLEN];
 	char color_lineno[COLOR_MAXLEN];
-	char color_match[COLOR_MAXLEN];
+	char color_match_context[COLOR_MAXLEN];
+	char color_match_selected[COLOR_MAXLEN];
 	char color_selected[COLOR_MAXLEN];
 	char color_sep[COLOR_MAXLEN];
 	int regflags;

t/t7810-grep.sh

@@ -1195,4 +1195,98 @@ test_expect_success LIBPCRE 'grep -P "^ "' '
 	test_cmp expected actual
 '
 
+cat >expected <<EOF
+space-line without leading space1
+space: line <RED>with <RESET>leading space1
+space: line <RED>with <RESET>leading <RED>space2<RESET>
+space: line <RED>with <RESET>leading space3
+space:line without leading <RED>space2<RESET>
+EOF
+
+test_expect_success 'grep --color -e A -e B with context' '
+	test_config color.grep.context		normal &&
+	test_config color.grep.filename		normal &&
+	test_config color.grep.function		normal &&
+	test_config color.grep.linenumber	normal &&
+	test_config color.grep.matchContext	normal &&
+	test_config color.grep.matchSelected	red &&
+	test_config color.grep.selected		normal &&
+	test_config color.grep.separator	normal &&
+
+	git grep --color=always -C2 -e "with " -e space2  space |
+	test_decode_color >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
+space-line without leading space1
+space- line with leading space1
+space: line <RED>with <RESET>leading <RED>space2<RESET>
+space- line with leading space3
+space-line without leading space2
+EOF
+
+test_expect_success 'grep --color -e A --and -e B with context' '
+	test_config color.grep.context		normal &&
+	test_config color.grep.filename		normal &&
+	test_config color.grep.function		normal &&
+	test_config color.grep.linenumber	normal &&
+	test_config color.grep.matchContext	normal &&
+	test_config color.grep.matchSelected	red &&
+	test_config color.grep.selected		normal &&
+	test_config color.grep.separator	normal &&
+
+	git grep --color=always -C2 -e "with " --and -e space2  space |
+	test_decode_color >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
+space-line without leading space1
+space: line <RED>with <RESET>leading space1
+space- line with leading space2
+space: line <RED>with <RESET>leading space3
+space-line without leading space2
+EOF
+
+test_expect_success 'grep --color -e A --and --not -e B with context' '
+	test_config color.grep.context		normal &&
+	test_config color.grep.filename		normal &&
+	test_config color.grep.function		normal &&
+	test_config color.grep.linenumber	normal &&
+	test_config color.grep.matchContext	normal &&
+	test_config color.grep.matchSelected	red &&
+	test_config color.grep.selected		normal &&
+	test_config color.grep.separator	normal &&
+
+	git grep --color=always -C2 -e "with " --and --not -e space2  space |
+	test_decode_color >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
+hello.c-#include <stdio.h>
+hello.c=int main(int argc, const char **argv)
+hello.c-{
+hello.c:	pr<RED>int<RESET>f("<RED>Hello<RESET> world.\n");
+hello.c-	return 0;
+hello.c-	/* char ?? */
+hello.c-}
+EOF
+
+test_expect_success 'grep --color -e A --and -e B -p with context' '
+	test_config color.grep.context		normal &&
+	test_config color.grep.filename		normal &&
+	test_config color.grep.function		normal &&
+	test_config color.grep.linenumber	normal &&
+	test_config color.grep.matchContext	normal &&
+	test_config color.grep.matchSelected	red &&
+	test_config color.grep.selected		normal &&
+	test_config color.grep.separator	normal &&
+
+	git grep --color=always -p -C3 -e int --and -e Hello --no-index hello.c |
+	test_decode_color >actual &&
+	test_cmp expected actual
+'
+
 test_done