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
pub struct DFA {
pub states: Vec<bool>,
pub transitions: std::collections::HashMap<(u64,char),u64>,
}
impl DFA {
pub fn accepts(self: &DFA, s: &str) -> bool {
let d = self;
let mut at:u64 = 0;
for c in s.chars() {
if d.transitions.contains_key(&(at,c)) {
at = d.transitions.get(&(at,c)).unwrap().clone();
} else {
return false;
}
};
d.states[at as usize]
}
pub fn intersect(self: &DFA, right: &DFA) -> DFA {
let left = self;
let mut p = DFA {
states: vec![false; left.states.len() * right.states.len()],
transitions: std::collections::HashMap::new(),
};
for pi in 0..p.states.len() {
let li = pi / right.states.len();
let ri = pi % right.states.len();
if left.states[li] && right.states[ri] {
p.states[pi] = true;
}
}
for ((ls,lc),lt) in left.transitions.iter() {
for ((rs,rc),rt) in right.transitions.iter() {
if lc == rc {
let ps = ls * (right.states.len() as u64) + rs;
let pt = lt * (right.states.len() as u64) + rt;
p.transitions.insert((ps,*lc),pt);
}}}
p
}
pub fn complement(self: &DFA) -> DFA {
let d = self;
DFA {
states: d.states.iter().map(|c| !c).collect::<Vec<bool>>(),
transitions: self.transitions.clone(),
}
}
pub fn is_empty(self: &DFA) -> bool {
let mut reached = 0;
let mut reach = std::collections::HashSet::new();
reach.insert(0);
while reach.len() > reached {
reached = reach.len();
for ((ls,_lc),lt) in self.transitions.iter() {
if reach.contains(ls) {
reach.insert(*lt);
}}
}
for ri in reach.iter() {
if self.states[*ri as usize] {
return false;
}}
true
}
}