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456a815d |
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, $args) = @_; |
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9 | if ($args->{filters}) { |
10 | die "Single filter please (XXX FIXME)" |
11 | unless @{$args->{filters}} == 1; |
12 | $args->{filter} = $args->{filters}[0]; |
13 | } |
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14 | bless( |
15 | { |
16 | _stream => $args->{stream}, |
17 | _match => $args->{match}, |
18 | _filter => $args->{filter}, |
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19 | _zconfig => $args->{zconfig}, |
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20 | }, |
21 | $class |
22 | ); |
23 | } |
24 | |
b5a48c47 |
25 | sub _next { |
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26 | my ($self) = @_; |
27 | |
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 |
30 | |
31 | return unless $self->{_stream}; |
32 | |
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 |
37 | |
38 | if (my $alt = $self->{_alt_stream}) { |
39 | |
40 | if (my ($evt) = $alt->next) { |
41 | return $evt; |
42 | } |
43 | |
44 | # once the alternate stream is exhausted we can throw it away so future |
45 | # requests fall straight through to the main stream |
46 | |
47 | delete $self->{_alt_stream}; |
48 | } |
49 | |
50 | # if there's no alternate stream currently, process the main stream |
51 | |
52 | while (my ($evt) = $self->{_stream}->next) { |
53 | |
54 | # don't match this event? return it immediately |
55 | |
56 | return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt); |
57 | |
58 | # run our filter routine against the current event |
59 | |
60 | my ($res) = $self->{_filter}->($evt, $self->{_stream}); |
61 | |
62 | # if the result is just an event, we can return that now |
63 | |
64 | return $res if ref($res) eq 'HASH'; |
65 | |
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 |
68 | |
69 | next unless defined $res; |
70 | |
71 | # ARRAY means a pair of [ $evt, $new_stream ] |
72 | |
73 | if (ref($res) eq 'ARRAY') { |
74 | $self->{_alt_stream} = $res->[1]; |
75 | return $res->[0]; |
76 | } |
77 | |
78 | # the filter returned a stream - if it contains something return the |
79 | # first entry and stash it as the new alternate stream |
80 | |
81 | if (my ($new_evt) = $res->next) { |
82 | $self->{_alt_stream} = $res; |
83 | return $new_evt; |
84 | } |
85 | |
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 |
90 | } |
91 | |
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 |
94 | |
95 | delete $self->{_stream}; |
96 | return; |
97 | } |
98 | |
99 | 1; |