--- /dev/null
+# Copyright (C) 2016 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+#
+package PublicInbox::MsgIter;
+use strict;
+use warnings;
+use base qw(Exporter);
+our @EXPORT = qw(msg_iter);
+
+# Like Email::MIME::walk_parts, but this is:
+# * non-recursive
+# * passes depth and indices to the iterator callback
+sub msg_iter ($$) {
+ my ($mime, $cb) = @_;
+ my @parts = $mime->subparts;
+ if (@parts) {
+ my $i = 0;
+ @parts = map { [ $_, 1, ++$i ] } @parts;
+ while (my $p = shift @parts) {
+ my ($part, $depth, @idx) = @$p;
+ my @sub = $part->subparts;
+ if (@sub) {
+ $depth++;
+ $i = 0;
+ @sub = map { [ $_, $depth, @idx, ++$i ] } @sub;
+ @parts = (@sub, @parts);
+ } else {
+ $cb->($p);
+ }
+ }
+ } else {
+ $cb->([$mime, 0, 0]);
+ }
+}
+
+1;
--- /dev/null
+# Copyright (C) 2016 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use strict;
+use warnings;
+use Test::More;
+use Email::MIME;
+use_ok('PublicInbox::MsgIter');
+
+{
+ my $parts = [ Email::MIME->create(body => 'a'),
+ Email::MIME->create(body => 'b') ];
+ my $mime = Email::MIME->create(parts => $parts,
+ header_str => [ From => 'root@localhost' ]);
+ my @parts;
+ msg_iter($mime, sub {
+ my ($part, $level, @ex) = @{$_[0]};
+ push @parts, [ $part->body_str, $level, @ex ];
+ });
+ is_deeply(\@parts, [ [ qw(a 1 1) ], [ qw(b 1 2) ] ], 'order is fine');
+}
+
+{
+ my $parts = [ Email::MIME->create(body => 'a'),
+ Email::MIME->create(body => 'b') ];
+ $parts = [ Email::MIME->create(parts => $parts,
+ header_str => [ From => 'sub@localhost' ]),
+ Email::MIME->create(body => 'sig') ];
+ my $mime = Email::MIME->create(parts => $parts,
+ header_str => [ From => 'root@localhost' ]);
+ my @parts;
+ msg_iter($mime, sub {
+ my ($part, $level, @ex) = @{$_[0]};
+ push @parts, [ $part->body_str, $level, @ex ];
+ });
+ is_deeply(\@parts, [ [ qw(a 2 1 1)], [qw(b 2 1 2)], [qw(sig 1 2)] ],
+ 'nested part shows up properly');
+}
+
+done_testing();
+1;