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1 | package HTML::Zoom::FilterStream; |
2 | |
3 | use strict; |
4 | use warnings FATAL => 'all'; |
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5 | use base qw(HTML::Zoom::StreamBase); |
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6 | |
7 | sub new { |
8 | my ($class, $args) = @_; |
9 | bless( |
10 | { |
11 | _stream => $args->{stream}, |
12 | _match => $args->{match}, |
13 | _filter => $args->{filter}, |
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14 | _zconfig => $args->{zconfig}, |
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15 | }, |
16 | $class |
17 | ); |
18 | } |
19 | |
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20 | sub _next { |
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21 | my ($self) = @_; |
22 | |
23 | # if our main stream is already gone then we can short-circuit |
24 | # straight out - there's no way for an alternate stream to be there |
25 | |
26 | return unless $self->{_stream}; |
27 | |
28 | # if we have an alternate stream (provided by a filter call resulting |
29 | # from a match on the main stream) then we want to read from that until |
30 | # it's gone - we're still effectively "in the match" but this is the |
31 | # point at which that fact is abstracted away from downstream consumers |
32 | |
33 | if (my $alt = $self->{_alt_stream}) { |
34 | |
35 | if (my ($evt) = $alt->next) { |
36 | return $evt; |
37 | } |
38 | |
39 | # once the alternate stream is exhausted we can throw it away so future |
40 | # requests fall straight through to the main stream |
41 | |
42 | delete $self->{_alt_stream}; |
43 | } |
44 | |
45 | # if there's no alternate stream currently, process the main stream |
46 | |
47 | while (my ($evt) = $self->{_stream}->next) { |
48 | |
49 | # don't match this event? return it immediately |
50 | |
51 | return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt); |
52 | |
53 | # run our filter routine against the current event |
54 | |
55 | my ($res) = $self->{_filter}->($evt, $self->{_stream}); |
56 | |
57 | # if the result is just an event, we can return that now |
58 | |
59 | return $res if ref($res) eq 'HASH'; |
60 | |
61 | # if no result at all, jump back to the top of the loop to get the |
62 | # next event and try again - the filter has eaten this one |
63 | |
64 | next unless defined $res; |
65 | |
66 | # ARRAY means a pair of [ $evt, $new_stream ] |
67 | |
68 | if (ref($res) eq 'ARRAY') { |
69 | $self->{_alt_stream} = $res->[1]; |
70 | return $res->[0]; |
71 | } |
72 | |
73 | # the filter returned a stream - if it contains something return the |
74 | # first entry and stash it as the new alternate stream |
75 | |
76 | if (my ($new_evt) = $res->next) { |
77 | $self->{_alt_stream} = $res; |
78 | return $new_evt; |
79 | } |
80 | |
81 | # we got a new alternate stream but it turned out to be empty |
82 | # - this will happens for e.g. with an in place close (<foo />) that's |
83 | # being removed. In that case, we fall off to loop back round and try |
84 | # the next event from our main stream |
85 | } |
86 | |
87 | # main stream exhausted so throw it away so we hit the short circuit |
88 | # at the top and return nothing to indicate to our caller we're done |
89 | |
90 | delete $self->{_stream}; |
91 | return; |
92 | } |
93 | |
94 | 1; |