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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 | $class |
17 | ); |
18 | } |
19 | |
20 | sub next { |
21 | my ($self) = @_; |
22 | |
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23 | # peeked entry so return that |
24 | |
25 | if (exists $self->{_peeked}) { |
26 | return (delete $self->{_peeked}); |
27 | } |
28 | |
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29 | # if our main stream is already gone then we can short-circuit |
30 | # straight out - there's no way for an alternate stream to be there |
31 | |
32 | return unless $self->{_stream}; |
33 | |
34 | # if we have an alternate stream (provided by a filter call resulting |
35 | # from a match on the main stream) then we want to read from that until |
36 | # it's gone - we're still effectively "in the match" but this is the |
37 | # point at which that fact is abstracted away from downstream consumers |
38 | |
39 | if (my $alt = $self->{_alt_stream}) { |
40 | |
41 | if (my ($evt) = $alt->next) { |
42 | return $evt; |
43 | } |
44 | |
45 | # once the alternate stream is exhausted we can throw it away so future |
46 | # requests fall straight through to the main stream |
47 | |
48 | delete $self->{_alt_stream}; |
49 | } |
50 | |
51 | # if there's no alternate stream currently, process the main stream |
52 | |
53 | while (my ($evt) = $self->{_stream}->next) { |
54 | |
55 | # don't match this event? return it immediately |
56 | |
57 | return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt); |
58 | |
59 | # run our filter routine against the current event |
60 | |
61 | my ($res) = $self->{_filter}->($evt, $self->{_stream}); |
62 | |
63 | # if the result is just an event, we can return that now |
64 | |
65 | return $res if ref($res) eq 'HASH'; |
66 | |
67 | # if no result at all, jump back to the top of the loop to get the |
68 | # next event and try again - the filter has eaten this one |
69 | |
70 | next unless defined $res; |
71 | |
72 | # ARRAY means a pair of [ $evt, $new_stream ] |
73 | |
74 | if (ref($res) eq 'ARRAY') { |
75 | $self->{_alt_stream} = $res->[1]; |
76 | return $res->[0]; |
77 | } |
78 | |
79 | # the filter returned a stream - if it contains something return the |
80 | # first entry and stash it as the new alternate stream |
81 | |
82 | if (my ($new_evt) = $res->next) { |
83 | $self->{_alt_stream} = $res; |
84 | return $new_evt; |
85 | } |
86 | |
87 | # we got a new alternate stream but it turned out to be empty |
88 | # - this will happens for e.g. with an in place close (<foo />) that's |
89 | # being removed. In that case, we fall off to loop back round and try |
90 | # the next event from our main stream |
91 | } |
92 | |
93 | # main stream exhausted so throw it away so we hit the short circuit |
94 | # at the top and return nothing to indicate to our caller we're done |
95 | |
96 | delete $self->{_stream}; |
97 | return; |
98 | } |
99 | |
100 | 1; |