grep.c: extract show_line_header()

The grep code invokes show_line() to display the contents of a matched
or context line in its output. Part of this execution is to print a line
header that includes information such as the kind, the line- and
column-number and etc. of that match.

To prepare for the addition of an option to print only the matching
component(s) of a non-context line, we must prepare for the possibility
that a single line may contain multiple matching parts, and thus will
need multiple headers printed for a single line.

Extracting show_line_header allows us to do just that. In the subsequent
commit, it will be used within the colorization loop to print out only
the matching parts of a line, optionally with LFs delimiting
sub-matches.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

grep.c

@@ -1410,26 +1410,9 @@ static int next_match(struct grep_opt *opt, char *bol, char *eol,
 	return hit;
 }
 
-static void show_line(struct grep_opt *opt, char *bol, char *eol,
-		      const char *name, unsigned lno, ssize_t cno, char sign)
+static void show_line_header(struct grep_opt *opt, const char *name,
+			     unsigned lno, ssize_t cno, char sign)
 {
-	int rest = eol - bol;
-	const char *match_color, *line_color = NULL;
-
-	if (opt->file_break && opt->last_shown == 0) {
-		if (opt->show_hunk_mark)
-			opt->output(opt, "\n", 1);
-	} else if (opt->pre_context || opt->post_context || opt->funcbody) {
-		if (opt->last_shown == 0) {
-			if (opt->show_hunk_mark) {
-				output_color(opt, "--", 2, opt->color_sep);
-				opt->output(opt, "\n", 1);
-			}
-		} else if (lno > opt->last_shown + 1) {
-			output_color(opt, "--", 2, opt->color_sep);
-			opt->output(opt, "\n", 1);
-		}
-	}
 	if (opt->heading && opt->last_shown == 0) {
 		output_color(opt, name, strlen(name), opt->color_filename);
 		opt->output(opt, "\n", 1);
@@ -1457,6 +1440,29 @@ static void show_line(struct grep_opt *opt, char *bol, char *eol,
 		output_color(opt, buf, strlen(buf), opt->color_columnno);
 		output_sep(opt, sign);
 	}
+}
+
+static void show_line(struct grep_opt *opt, char *bol, char *eol,
+		      const char *name, unsigned lno, ssize_t cno, char sign)
+{
+	int rest = eol - bol;
+	const char *match_color, *line_color = NULL;
+
+	if (opt->file_break && opt->last_shown == 0) {
+		if (opt->show_hunk_mark)
+			opt->output(opt, "\n", 1);
+	} else if (opt->pre_context || opt->post_context || opt->funcbody) {
+		if (opt->last_shown == 0) {
+			if (opt->show_hunk_mark) {
+				output_color(opt, "--", 2, opt->color_sep);
+				opt->output(opt, "\n", 1);
+			}
+		} else if (lno > opt->last_shown + 1) {
+			output_color(opt, "--", 2, opt->color_sep);
+			opt->output(opt, "\n", 1);
+		}
+	}
+	show_line_header(opt, name, lno, cno, sign);
 	if (opt->color) {
 		regmatch_t match;
 		enum grep_context ctx = GREP_CONTEXT_BODY;