Git.pm: add subroutines for commenting lines

Add subroutines prefix_lines and comment_lines.

Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/perl/Git.pm b/perl/Git.pm
index ce7e4e8..f699fee 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -1421,6 +1421,44 @@
 
 } # %TEMP_* Lexical Context
 
+=item prefix_lines ( PREFIX, STRING [, STRING... ])
+
+Prefixes lines in C<STRING> with C<PREFIX>.
+
+=cut
+
+sub prefix_lines {
+	my $prefix = shift;
+	my $string = join("\n", @_);
+	$string =~ s/^/$prefix/mg;
+	return $string;
+}
+
+=item get_comment_line_char ( )
+
+Gets the core.commentchar configuration value.
+The value falls-back to '#' if core.commentchar is set to 'auto'.
+
+=cut
+
+sub get_comment_line_char {
+	my $comment_line_char = config("core.commentchar") || '#';
+	$comment_line_char = '#' if ($comment_line_char eq 'auto');
+	$comment_line_char = '#' if (length($comment_line_char) != 1);
+	return $comment_line_char;
+}
+
+=item comment_lines ( STRING [, STRING... ])
+
+Comments lines following core.commentchar configuration.
+
+=cut
+
+sub comment_lines {
+	my $comment_line_char = get_comment_line_char;
+	return prefix_lines("$comment_line_char ", @_);
+}
+
 =back
 
 =head1 ERROR HANDLING