1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152

use std::marker::PhantomData;
use std::sync::Arc;

use anyhow::Result;

use crate::algorithms::compose::compose_filters::{ComposeFilter, ComposeFilterBuilder};
use crate::algorithms::compose::filter_states::{FilterState, IntegerFilterState};
use crate::algorithms::compose::matchers::{MatchType, Matcher};
use crate::fst_properties::FstProperties;
use crate::fst_traits::CoreFst;
use crate::semirings::Semiring;
use crate::{StateId, Tr, EPS_LABEL, NO_LABEL, NO_STATE_ID};

#[derive(Debug, Clone)]
/// This filter requires epsilons on FST1 to be read before epsilons on FST2.
pub struct SequenceComposeFilter<W: Semiring, M1: Matcher<W>, M2: Matcher<W>> {
    matcher1: Arc<M1>,
    matcher2: Arc<M2>,
    /// Current fst1 state
    s1: StateId,
    /// Current fst2 state
    s2: StateId,
    /// Current filter state
    fs: IntegerFilterState,
    /// Only epsilons (and non-final) leaving s1 ?
    alleps1: bool,
    /// No epsilons leaving s1 ?
    noeps1: bool,
    w: PhantomData<W>,
}

#[derive(Debug, Clone)]
pub struct SequenceComposeFilterBuilder<W: Semiring, M1: Matcher<W>, M2: Matcher<W>> {
    matcher1: Arc<M1>,
    matcher2: Arc<M2>,
    w: PhantomData<W>,
}

impl<W: Semiring, M1: Matcher<W>, M2: Matcher<W>> ComposeFilterBuilder<W>
    for SequenceComposeFilterBuilder<W, M1, M2>
{
    type CF = SequenceComposeFilter<W, M1, M2>;
    type M1 = M1;
    type M2 = M2;

    fn new(
        fst1: Arc<M1::F>,
        fst2: Arc<M2::F>,
        matcher1: Option<M1>,
        matcher2: Option<M2>,
    ) -> Result<Self> {
        let matcher1 =
            matcher1.unwrap_or_else(|| M1::new(Arc::clone(&fst1), MatchType::MatchOutput).unwrap());
        let matcher2 =
            matcher2.unwrap_or_else(|| M2::new(Arc::clone(&fst2), MatchType::MatchInput).unwrap());
        Ok(Self {
            matcher1: Arc::new(matcher1),
            matcher2: Arc::new(matcher2),
            w: PhantomData,
        })
    }

    fn build(&self) -> Result<Self::CF> {
        Ok(SequenceComposeFilter::<W, M1, M2> {
            matcher1: Arc::clone(&self.matcher1),
            matcher2: Arc::clone(&self.matcher2),
            s1: NO_STATE_ID,
            s2: NO_STATE_ID,
            fs: <Self::CF as ComposeFilter<W>>::FS::new(NO_STATE_ID),
            alleps1: false,
            noeps1: false,
            w: PhantomData,
        })
    }
}

impl<W: Semiring, M1: Matcher<W>, M2: Matcher<W>> ComposeFilter<W>
    for SequenceComposeFilter<W, M1, M2>
{
    type M1 = M1;
    type M2 = M2;
    type FS = IntegerFilterState;

    fn start(&self) -> Self::FS {
        Self::FS::new(0)
    }

    fn set_state(&mut self, s1: usize, s2: usize, filter_state: &Self::FS) -> Result<()> {
        if !(self.s1 == s1 && self.s2 == s2 && &self.fs == filter_state) {
            self.s1 = s1;
            self.s2 = s2;
            self.fs = filter_state.clone();
            // TODO: Could probably use unchecked here as the state should exist.
            let fst1 = self.fst1();
            let na1 = fst1.num_trs(self.s1)?;
            let ne1 = fst1.num_output_epsilons(self.s1)?;
            let fin1 = fst1.is_final(self.s1)?;
            self.alleps1 = na1 == ne1 && !fin1;
            self.noeps1 = ne1 == 0;
        }
        Ok(())
    }

    fn filter_tr(&mut self, arc1: &mut Tr<W>, arc2: &mut Tr<W>) -> Result<Self::FS> {
        let res = if arc1.olabel == NO_LABEL {
            if self.alleps1 {
                Self::FS::new_no_state()
            } else if self.noeps1 {
                Self::FS::new(0)
            } else {
                Self::FS::new(1)
            }
        } else if arc2.ilabel == NO_LABEL {
            if self.fs != Self::FS::new(0) {
                Self::FS::new_no_state()
            } else {
                Self::FS::new(0)
            }
        } else {
            if arc1.olabel == EPS_LABEL {
                Self::FS::new_no_state()
            } else {
                Self::FS::new(0)
            }
        };
        Ok(res)
    }

    fn filter_final(&self, _w1: &mut W, _w2: &mut W) -> Result<()> {
        Ok(())
    }

    fn matcher1(&self) -> &Self::M1 {
        &self.matcher1
    }

    fn matcher2(&self) -> &Self::M2 {
        &self.matcher2
    }

    fn matcher1_shared(&self) -> &Arc<Self::M1> {
        &self.matcher1
    }

    fn matcher2_shared(&self) -> &Arc<Self::M2> {
        &self.matcher2
    }

    fn properties(&self, inprops: FstProperties) -> FstProperties {
        inprops
    }
}