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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]
}
}
impl DFA {
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
}
}