grep: Colorize selected, context, and function lines

Colorize non-matching text of selected lines, context lines, and
function name lines.  The default for all three is no color, but they
can be configured using color.grep.<slot>.  The first two are similar
to the corresponding options in GNU grep, except that GNU grep applies
the color to the entire line, not just non-matching text.

Signed-off-by: Mark Lodato <lodatom@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -688,12 +688,18 @@ color.grep.<slot>::
 	part of the line to use the specified color, and is one of
 +
 --
+`context`;;
+	non-matching text in context lines (when using `-A`, `-B`, or `-C`)
 `filename`;;
 	filename prefix (when not using `-h`)
+`function`;;
+	function name lines (when using `-p`)
 `linenumber`;;
 	line number prefix (when using `-n`)
 `match`;;
 	matching text
+`selected`;;
+	non-matching text in selected lines
 `separator`;;
 	separators between fields on a line (`:`, `-`, and `=`)
 	and between hunks (`--`)

builtin-grep.c

@@ -299,12 +299,18 @@ static int grep_config(const char *var, const char *value, void *cb)
 
 	if (!strcmp(var, "color.grep"))
 		opt->color = git_config_colorbool(var, value, -1);
+	else if (!strcmp(var, "color.grep.context"))
+		color = opt->color_context;
 	else if (!strcmp(var, "color.grep.filename"))
 		color = opt->color_filename;
+	else if (!strcmp(var, "color.grep.function"))
+		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.selected"))
+		color = opt->color_selected;
 	else if (!strcmp(var, "color.grep.separator"))
 		color = opt->color_sep;
 	else
@@ -879,9 +885,12 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 	opt.regflags = REG_NEWLINE;
 	opt.max_depth = -1;
 
+	strcpy(opt.color_context, "");
 	strcpy(opt.color_filename, "");
+	strcpy(opt.color_function, "");
 	strcpy(opt.color_lineno, "");
 	strcpy(opt.color_match, GIT_COLOR_BOLD_RED);
+	strcpy(opt.color_selected, "");
 	strcpy(opt.color_sep, GIT_COLOR_CYAN);
 	opt.color = -1;
 	git_config(grep_config, &opt);

grep.c

@@ -529,6 +529,7 @@ 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;
 
 	if (opt->pre_context || opt->post_context) {
 		if (opt->last_shown == 0) {
@@ -560,12 +561,18 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		int ch = *eol;
 		int eflags = 0;
 
+		if (sign == ':')
+			line_color = opt->color_selected;
+		else if (sign == '-')
+			line_color = opt->color_context;
+		else if (sign == '=')
+			line_color = opt->color_function;
 		*eol = '\0';
 		while (next_match(opt, bol, eol, ctx, &match, eflags)) {
 			if (match.rm_so == match.rm_eo)
 				break;
 
-			opt->output(opt, bol, match.rm_so);
+			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);
@@ -575,7 +582,7 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		}
 		*eol = ch;
 	}
-	opt->output(opt, bol, rest);
+	output_color(opt, bol, rest, line_color);
 	opt->output(opt, "\n", 1);
 }
 

grep.h

@@ -84,9 +84,12 @@ struct grep_opt {
 	int color;
 	int max_depth;
 	int funcname;
+	char color_context[COLOR_MAXLEN];
 	char color_filename[COLOR_MAXLEN];
+	char color_function[COLOR_MAXLEN];
 	char color_lineno[COLOR_MAXLEN];
 	char color_match[COLOR_MAXLEN];
+	char color_selected[COLOR_MAXLEN];
 	char color_sep[COLOR_MAXLEN];
 	int regflags;
 	unsigned pre_context;