1 package HTML::Zoom::FilterStream;
4 use base qw(HTML::Zoom::StreamBase);
7 my ($class, $args) = @_;
8 if ($args->{filters}) {
9 die "Single filter please (XXX FIXME)"
10 unless @{$args->{filters}} == 1;
11 $args->{filter} = $args->{filters}[0];
15 _stream => $args->{stream},
16 _match => $args->{match},
17 _filter => $args->{filter},
18 _zconfig => $args->{zconfig},
25 my ($self, $am_peek) = @_;
27 # if our main stream is already gone then we can short-circuit
28 # straight out - there's no way for an alternate stream to be there
30 return unless $self->{_stream};
32 # if we have an alternate stream (provided by a filter call resulting
33 # from a match on the main stream) then we want to read from that until
34 # it's gone - we're still effectively "in the match" but this is the
35 # point at which that fact is abstracted away from downstream consumers
37 my $_next = $am_peek ? 'peek' : 'next';
39 if (my $alt = $self->{_alt_stream}) {
41 if (my ($evt) = $alt->$_next) {
42 $self->{_peeked_from} = $alt if $am_peek;
46 # once the alternate stream is exhausted we can throw it away so future
47 # requests fall straight through to the main stream
49 delete $self->{_alt_stream};
52 # if there's no alternate stream currently, process the main stream
54 while (my ($evt) = $self->{_stream}->$_next) {
56 $self->{_peeked_from} = $self->{_stream} if $am_peek;
58 # don't match this event? return it immediately
60 return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt);
62 # run our filter routine against the current event
64 my ($res) = $self->{_filter}->($evt, $self->{_stream});
66 # if the result is just an event, we can return that now
68 return $res if ref($res) eq 'HASH';
70 # if no result at all, jump back to the top of the loop to get the
71 # next event and try again - the filter has eaten this one
73 next unless defined $res;
75 # ARRAY means a pair of [ $evt, $new_stream ]
77 if (ref($res) eq 'ARRAY') {
78 $self->{_alt_stream} = $res->[1];
82 # the filter returned a stream - if it contains something return the
83 # first entry and stash it as the new alternate stream
85 if (my ($new_evt) = $res->$_next) {
86 $self->{_alt_stream} = $res;
87 $self->{_peeked_from} = $res if $am_peek;
91 # we got a new alternate stream but it turned out to be empty
92 # - this will happens for e.g. with an in place close (<foo />) that's
93 # being removed. In that case, we fall off to loop back round and try
94 # the next event from our main stream
97 # if we fell off the bottom (empty new alternate stream or filter ate
98 # the event) then we need to advance our internal stream one so that the
99 # top of the while loop gets the right thing; also, we need to clear the
100 # _peeked_from in case our source stream is exhausted (it'll be
101 # re-assigned if the while condition gets a new event)
104 $self->{_stream}->next;
105 delete $self->{_peeked_from};
109 # main stream exhausted so throw it away so we hit the short circuit
110 # at the top and return nothing to indicate to our caller we're done
112 delete $self->{_stream};