1 package HTML::Zoom::FilterStream;
4 use warnings FATAL => 'all';
5 use base qw(HTML::Zoom::StreamBase);
8 my ($class, $args) = @_;
11 _stream => $args->{stream},
12 _match => $args->{match},
13 _filter => $args->{filter},
22 # peeked entry so return that
24 if (exists $self->{_peeked}) {
25 return (delete $self->{_peeked});
28 # if our main stream is already gone then we can short-circuit
29 # straight out - there's no way for an alternate stream to be there
31 return unless $self->{_stream};
33 # if we have an alternate stream (provided by a filter call resulting
34 # from a match on the main stream) then we want to read from that until
35 # it's gone - we're still effectively "in the match" but this is the
36 # point at which that fact is abstracted away from downstream consumers
38 if (my $alt = $self->{_alt_stream}) {
40 if (my ($evt) = $alt->next) {
44 # once the alternate stream is exhausted we can throw it away so future
45 # requests fall straight through to the main stream
47 delete $self->{_alt_stream};
50 # if there's no alternate stream currently, process the main stream
52 while (my ($evt) = $self->{_stream}->next) {
54 # don't match this event? return it immediately
56 return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt);
58 # run our filter routine against the current event
60 my ($res) = $self->{_filter}->($evt, $self->{_stream});
62 # if the result is just an event, we can return that now
64 return $res if ref($res) eq 'HASH';
66 # if no result at all, jump back to the top of the loop to get the
67 # next event and try again - the filter has eaten this one
69 next unless defined $res;
71 # ARRAY means a pair of [ $evt, $new_stream ]
73 if (ref($res) eq 'ARRAY') {
74 $self->{_alt_stream} = $res->[1];
78 # the filter returned a stream - if it contains something return the
79 # first entry and stash it as the new alternate stream
81 if (my ($new_evt) = $res->next) {
82 $self->{_alt_stream} = $res;
86 # we got a new alternate stream but it turned out to be empty
87 # - this will happens for e.g. with an in place close (<foo />) that's
88 # being removed. In that case, we fall off to loop back round and try
89 # the next event from our main stream
92 # main stream exhausted so throw it away so we hit the short circuit
93 # at the top and return nothing to indicate to our caller we're done
95 delete $self->{_stream};