diff.c: emit_diff_symbol learns DIFF_SYMBOL_REWRITE_DIFF

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -561,6 +561,7 @@ static void emit_line(struct diff_options *o, const char *set, const char *reset
 }
 
 enum diff_symbol {
+	DIFF_SYMBOL_REWRITE_DIFF,
 	DIFF_SYMBOL_BINARY_FILES,
 	DIFF_SYMBOL_HEADER,
 	DIFF_SYMBOL_FILEPAIR_PLUS,
@@ -615,7 +616,7 @@ static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
 			     const char *line, int len, unsigned flags)
 {
 	static const char *nneof = " No newline at end of file\n";
-	const char *context, *reset, *set, *meta;
+	const char *context, *reset, *set, *meta, *fraginfo;
 	switch (s) {
 	case DIFF_SYMBOL_NO_LF_EOF:
 		context = diff_get_color_opt(o, DIFF_CONTEXT);
@@ -695,6 +696,11 @@ static void emit_diff_symbol(struct diff_options *o, enum diff_symbol s,
 	case DIFF_SYMBOL_HEADER:
 		fprintf(o->file, "%s", line);
 		break;
+	case DIFF_SYMBOL_REWRITE_DIFF:
+		fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
+		reset = diff_get_color_opt(o, DIFF_RESET);
+		emit_line(o, fraginfo, reset, line, len);
+		break;
 	default:
 		die("BUG: unknown diff symbol");
 	}
@@ -817,17 +823,17 @@ static void remove_tempfile(void)
 	}
 }
 
-static void print_line_count(FILE *file, int count)
+static void add_line_count(struct strbuf *out, int count)
 {
 	switch (count) {
 	case 0:
-		fprintf(file, "0,0");
+		strbuf_addstr(out, "0,0");
 		break;
 	case 1:
-		fprintf(file, "1");
+		strbuf_addstr(out, "1");
 		break;
 	default:
-		fprintf(file, "1,%d", count);
+		strbuf_addf(out, "1,%d", count);
 		break;
 	}
 }
@@ -866,14 +872,12 @@ static void emit_rewrite_diff(const char *name_a,
 			      struct diff_options *o)
 {
 	int lc_a, lc_b;
-	const char *fraginfo = diff_get_color(o->use_color, DIFF_FRAGINFO);
-	const char *reset = diff_get_color(o->use_color, DIFF_RESET);
 	static struct strbuf a_name = STRBUF_INIT, b_name = STRBUF_INIT;
 	const char *a_prefix, *b_prefix;
 	char *data_one, *data_two;
 	size_t size_one, size_two;
 	struct emit_callback ecbdata;
-	const char *line_prefix = diff_line_prefix(o);
+	struct strbuf out = STRBUF_INIT;
 
 	if (diff_mnemonic_prefix && DIFF_OPT_TST(o, REVERSE_DIFF)) {
 		a_prefix = o->b_prefix;
@@ -917,14 +921,17 @@ static void emit_rewrite_diff(const char *name_a,
 	emit_diff_symbol(o, DIFF_SYMBOL_FILEPAIR_PLUS,
 			 b_name.buf, b_name.len, 0);
 
-	fprintf(o->file, "%s%s@@ -", line_prefix, fraginfo);
+	strbuf_addstr(&out, "@@ -");
 	if (!o->irreversible_delete)
-		print_line_count(o->file, lc_a);
+		add_line_count(&out, lc_a);
 	else
-		fprintf(o->file, "?,?");
-	fprintf(o->file, " +");
-	print_line_count(o->file, lc_b);
-	fprintf(o->file, " @@%s\n", reset);
+		strbuf_addstr(&out, "?,?");
+	strbuf_addstr(&out, " +");
+	add_line_count(&out, lc_b);
+	strbuf_addstr(&out, " @@\n");
+	emit_diff_symbol(o, DIFF_SYMBOL_REWRITE_DIFF, out.buf, out.len, 0);
+	strbuf_release(&out);
+
 	if (lc_a && !o->irreversible_delete)
 		emit_rewrite_lines(&ecbdata, '-', data_one, size_one);
 	if (lc_b)