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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, $args) = @_; |
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9 | if ($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 | $class |
22 | ); |
23 | } |
24 | |
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25 | sub _next { |
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26 | my ($self, $am_peek) = @_; |
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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 | |
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38 | my $_next = $am_peek ? 'peek' : 'next'; |
39 | |
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40 | if (my $alt = $self->{_alt_stream}) { |
41 | |
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42 | if (my ($evt) = $alt->$_next) { |
43 | $self->{_peeked_from} = $alt if $am_peek; |
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44 | return $evt; |
45 | } |
46 | |
47 | # once the alternate stream is exhausted we can throw it away so future |
48 | # requests fall straight through to the main stream |
49 | |
50 | delete $self->{_alt_stream}; |
51 | } |
52 | |
53 | # if there's no alternate stream currently, process the main stream |
54 | |
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55 | while (my ($evt) = $self->{_stream}->$_next) { |
56 | |
57 | $self->{_peeked_from} = $self->{_stream} if $am_peek; |
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58 | |
59 | # don't match this event? return it immediately |
60 | |
61 | return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt); |
62 | |
63 | # run our filter routine against the current event |
64 | |
65 | my ($res) = $self->{_filter}->($evt, $self->{_stream}); |
66 | |
67 | # if the result is just an event, we can return that now |
68 | |
69 | return $res if ref($res) eq 'HASH'; |
70 | |
71 | # if no result at all, jump back to the top of the loop to get the |
72 | # next event and try again - the filter has eaten this one |
73 | |
74 | next unless defined $res; |
75 | |
76 | # ARRAY means a pair of [ $evt, $new_stream ] |
77 | |
78 | if (ref($res) eq 'ARRAY') { |
79 | $self->{_alt_stream} = $res->[1]; |
80 | return $res->[0]; |
81 | } |
82 | |
83 | # the filter returned a stream - if it contains something return the |
84 | # first entry and stash it as the new alternate stream |
85 | |
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86 | if (my ($new_evt) = $res->$_next) { |
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87 | $self->{_alt_stream} = $res; |
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88 | $self->{_peeked_from} = $res if $am_peek; |
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89 | return $new_evt; |
90 | } |
91 | |
92 | # we got a new alternate stream but it turned out to be empty |
93 | # - this will happens for e.g. with an in place close (<foo />) that's |
94 | # being removed. In that case, we fall off to loop back round and try |
95 | # the next event from our main stream |
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96 | } continue { |
97 | |
98 | # if we fell off the bottom (empty new alternate stream or filter ate |
99 | # the event) then we need to advance our internal stream one so that the |
100 | # top of the while loop gets the right thing; also, we need to clear the |
101 | # _peeked_from in case our source stream is exhausted (it'll be |
102 | # re-assigned if the while condition gets a new event) |
103 | |
104 | if ($am_peek) { |
105 | $self->{_stream}->next; |
106 | delete $self->{_peeked_from}; |
107 | } |
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108 | } |
109 | |
110 | # main stream exhausted so throw it away so we hit the short circuit |
111 | # at the top and return nothing to indicate to our caller we're done |
112 | |
113 | delete $self->{_stream}; |
114 | return; |
115 | } |
116 | |
117 | 1; |