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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); |
456a815d |
6 | |
7 | sub new { |
8 | my ($class, $args) = @_; |
9 | bless( |
10 | { |
11 | _stream => $args->{stream}, |
12 | _match => $args->{match}, |
13 | _filter => $args->{filter}, |
14 | }, |
15 | $class |
16 | ); |
17 | } |
18 | |
8f962884 |
19 | sub peek { |
20 | my ($self) = @_; |
21 | if (exists $self->{_peeked}) { |
22 | return ($self->{_peeked}); |
23 | } |
24 | if (my ($peeked) = $self->next) { |
25 | return ($self->{_peeked} = $peeked); |
26 | } |
27 | return; |
28 | } |
29 | |
456a815d |
30 | sub next { |
31 | my ($self) = @_; |
32 | |
8f962884 |
33 | # peeked entry so return that |
34 | |
35 | if (exists $self->{_peeked}) { |
36 | return (delete $self->{_peeked}); |
37 | } |
38 | |
456a815d |
39 | # if our main stream is already gone then we can short-circuit |
40 | # straight out - there's no way for an alternate stream to be there |
41 | |
42 | return unless $self->{_stream}; |
43 | |
44 | # if we have an alternate stream (provided by a filter call resulting |
45 | # from a match on the main stream) then we want to read from that until |
46 | # it's gone - we're still effectively "in the match" but this is the |
47 | # point at which that fact is abstracted away from downstream consumers |
48 | |
49 | if (my $alt = $self->{_alt_stream}) { |
50 | |
51 | if (my ($evt) = $alt->next) { |
52 | return $evt; |
53 | } |
54 | |
55 | # once the alternate stream is exhausted we can throw it away so future |
56 | # requests fall straight through to the main stream |
57 | |
58 | delete $self->{_alt_stream}; |
59 | } |
60 | |
61 | # if there's no alternate stream currently, process the main stream |
62 | |
63 | while (my ($evt) = $self->{_stream}->next) { |
64 | |
65 | # don't match this event? return it immediately |
66 | |
67 | return $evt unless $evt->{type} eq 'OPEN' and $self->{_match}->($evt); |
68 | |
69 | # run our filter routine against the current event |
70 | |
71 | my ($res) = $self->{_filter}->($evt, $self->{_stream}); |
72 | |
73 | # if the result is just an event, we can return that now |
74 | |
75 | return $res if ref($res) eq 'HASH'; |
76 | |
77 | # if no result at all, jump back to the top of the loop to get the |
78 | # next event and try again - the filter has eaten this one |
79 | |
80 | next unless defined $res; |
81 | |
82 | # ARRAY means a pair of [ $evt, $new_stream ] |
83 | |
84 | if (ref($res) eq 'ARRAY') { |
85 | $self->{_alt_stream} = $res->[1]; |
86 | return $res->[0]; |
87 | } |
88 | |
89 | # the filter returned a stream - if it contains something return the |
90 | # first entry and stash it as the new alternate stream |
91 | |
92 | if (my ($new_evt) = $res->next) { |
93 | $self->{_alt_stream} = $res; |
94 | return $new_evt; |
95 | } |
96 | |
97 | # we got a new alternate stream but it turned out to be empty |
98 | # - this will happens for e.g. with an in place close (<foo />) that's |
99 | # being removed. In that case, we fall off to loop back round and try |
100 | # the next event from our main stream |
101 | } |
102 | |
103 | # main stream exhausted so throw it away so we hit the short circuit |
104 | # at the top and return nothing to indicate to our caller we're done |
105 | |
106 | delete $self->{_stream}; |
107 | return; |
108 | } |
109 | |
110 | 1; |