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1 | package DX::SearchState; |
2 | |
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3 | use Types::Standard qw(Maybe); |
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4 | use DX::Step::InvokeNextPredicate; |
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5 | use DX::Class; |
6 | |
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7 | has current_hypothesis => (is => 'ro', isa => Hypothesis, required => 1); |
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8 | |
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9 | has next_step => (is => 'ro', isa => Maybe[Step]); |
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10 | |
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11 | has propositions => (is => 'ro', isa => PropositionSequence, required => 1); |
12 | |
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13 | has alternatives => (is => 'ro', isa => AlternativeList, required => 1); |
14 | |
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15 | sub next_proposition { |
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16 | my ($self, $hyp) = @_; |
17 | $hyp ||= $self->current_hypothesis; |
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18 | $self->propositions->members->[ |
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19 | $hyp->resolved_propositions->resolved_count |
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20 | ]; |
21 | } |
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22 | |
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23 | sub new_for { |
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24 | my ($class, $hyp, $props) = @_; |
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25 | $class->new( |
26 | current_hypothesis => $hyp, |
27 | alternatives => [], |
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28 | next_step => DX::Step::InvokeNextPredicate->new( |
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29 | proposition => $props->members->[0], |
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30 | ), |
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31 | propositions => $props, |
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32 | ); |
33 | } |
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34 | |
35 | sub with_one_step { |
36 | my ($self) = @_; |
37 | my $hyp = $self->current_hypothesis; |
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38 | return undef unless my $step = $self->next_step; |
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39 | my ($new_ss) = $step->apply_to($self); |
40 | return $new_ss if $new_ss; |
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41 | my ($first_alt, @rest_alt) = @{$self->alternatives}; |
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42 | return undef unless $first_alt; |
43 | trace 'search.backtrack.rewind_to' => $first_alt->[1]; |
44 | return $self->but( |
45 | current_hypothesis => $first_alt->[0], |
46 | alternatives => \@rest_alt, |
47 | next_step => $first_alt->[1], |
48 | ); |
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49 | } |
50 | |
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51 | sub force_backtrack { |
52 | my ($self) = @_; |
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53 | my ($first_alt, @rest_alt) = @{$self->alternatives}; |
54 | return undef unless $first_alt; |
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55 | trace 'search.backtrack.forced' => $first_alt->[0]; |
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56 | return ref($self)->new( |
57 | current_hypothesis => $first_alt->[0], |
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58 | next_step => $first_alt->[1], |
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59 | alternatives => \@rest_alt, |
60 | propositions => $self->propositions, |
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61 | ); |
62 | } |
63 | |
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64 | 1; |