rustfst 1.3.0

Library for constructing, combining, optimizing, and searching weighted finite-state transducers (FSTs).
Documentation 
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

use std::collections::HashMap;
use std::sync::Mutex;

use bimap::BiHashMap;

use crate::algorithms::factor_weight::Element;
use crate::semirings::Semiring;
use crate::StateId;

#[derive(Debug)]
struct InnerStateTable<W: Semiring> {
    bimap: BiHashMap<StateId, Element<W>>,
    unfactored: HashMap<StateId, StateId>,
}

impl<W: Semiring> InnerStateTable<W> {
    fn new() -> Self {
        Self {
            bimap: BiHashMap::new(),
            unfactored: HashMap::new(),
        }
    }

    fn find_tuple_bimap(&self, tuple_id: StateId) -> Element<W> {
        self.bimap.get_by_left(&tuple_id).unwrap().clone()
    }

    fn find_id_or_insert_bimap(&mut self, elt: &Element<W>) -> StateId {
        if !self.bimap.contains_right(elt) {
            let n = self.bimap.len() as StateId;
            self.bimap.insert(n, elt.clone());
            return n;
        }
        *self.bimap.get_by_right(elt).unwrap()
    }
}

#[derive(Debug)]
pub struct FactorWeightStateTable<W: Semiring> {
    inner_state_table: Mutex<InnerStateTable<W>>,
    factor_tr_weights: bool,
}

impl<W: Semiring> FactorWeightStateTable<W> {
    pub fn new(factor_tr_weights: bool) -> Self {
        Self {
            factor_tr_weights,
            inner_state_table: Mutex::new(InnerStateTable::new()),
        }
    }

    pub fn find_tuple(&self, tuple_id: StateId) -> Element<W> {
        let inner_state_table = self.inner_state_table.lock().unwrap();
        inner_state_table.find_tuple_bimap(tuple_id)
    }

    pub fn find_state(&self, elt: &Element<W>) -> StateId {
        let mut inner_state_table = self.inner_state_table.lock().unwrap();
        if let Some(old_state) = elt
            .state
            .filter(|_| !self.factor_tr_weights && elt.weight.is_one())
        {
            let InnerStateTable { bimap, unfactored } = &mut *inner_state_table;
            *unfactored.entry(old_state).or_insert_with(|| {
                let n = bimap.len() as StateId;
                bimap.insert(n, elt.clone());
                n
            })
        } else {
            inner_state_table.find_id_or_insert_bimap(elt)
        }
    }
}