send-email: reduce dependencies impact on parse_address_line

parse_address_line had not the same behavior whether the user had
Mail::Address or not. Teach parse_address_line to behave like
Mail::Address.

When the user input is correct, this implementation behaves
exactly like Mail::Address except when there are quotes
inside the name:

  "Jane Do"e <jdoe@example.com>

In this case the result of parse_address_line is:

  With M::A : "Jane Do" e <jdoe@example.com>
  Without   : "Jane Do e" <jdoe@example.com>

When the user input is not correct, the behavior is also mostly
the same.

Unlike Mail::Address, this doesn't parse groups and recursive
commentaries.

Signed-off-by: Remi Lespinet <remi.lespinet@ensimag.grenoble-inp.fr>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/perl/Git.pm b/perl/Git.pm
index 9026a7b..19ef081 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -864,6 +864,73 @@
 	return "$ident[0] <$ident[1]>";
 }
 
+=item parse_mailboxes
+
+Return an array of mailboxes extracted from a string.
+
+=cut
+
+sub parse_mailboxes {
+	my $re_comment = qr/\((?:[^)]*)\)/;
+	my $re_quote = qr/"(?:[^\"\\]|\\.)*"/;
+	my $re_word = qr/(?:[^]["\s()<>:;@\\,.]|\\.)+/;
+
+	# divide the string in tokens of the above form
+	my $re_token = qr/(?:$re_quote|$re_word|$re_comment|\S)/;
+	my @tokens = map { $_ =~ /\s*($re_token)\s*/g } @_;
+
+	# add a delimiter to simplify treatment for the last mailbox
+	push @tokens, ",";
+
+	my (@addr_list, @phrase, @address, @comment, @buffer) = ();
+	foreach my $token (@tokens) {
+		if ($token =~ /^[,;]$/) {
+			# if buffer still contains undeterminated strings
+			# append it at the end of @address or @phrase
+			if (@address) {
+				push @address, @buffer;
+			} else {
+				push @phrase, @buffer;
+			}
+
+			my $str_phrase = join ' ', @phrase;
+			my $str_address = join '', @address;
+			my $str_comment = join ' ', @comment;
+
+			# quote are necessary if phrase contains
+			# special characters
+			if ($str_phrase =~ /[][()<>:;@\\,.\000-\037\177]/) {
+				$str_phrase =~ s/(^|[^\\])"/$1/g;
+				$str_phrase = qq["$str_phrase"];
+			}
+
+			# add "<>" around the address if necessary
+			if ($str_address ne "" && $str_phrase ne "") {
+				$str_address = qq[<$str_address>];
+			}
+
+			my $str_mailbox = "$str_phrase $str_address $str_comment";
+			$str_mailbox =~ s/^\s*|\s*$//g;
+			push @addr_list, $str_mailbox if ($str_mailbox);
+
+			@phrase = @address = @comment = @buffer = ();
+		} elsif ($token =~ /^\(/) {
+			push @comment, $token;
+		} elsif ($token eq "<") {
+			push @phrase, (splice @address), (splice @buffer);
+		} elsif ($token eq ">") {
+			push @address, (splice @buffer);
+		} elsif ($token eq "@") {
+			push @address, (splice @buffer), "@";
+		} elsif ($token eq ".") {
+			push @address, (splice @buffer), ".";
+		} else {
+			push @buffer, $token;
+		}
+	}
+
+	return @addr_list;
+}
 
 =item hash_object ( TYPE, FILENAME )