iregex/ir/
alternation.rs

1use std::{hash::Hash, ops::Deref};
2
3use iregex_automata::{
4	nfa::{BuildNFA, StateBuilder, Tags},
5	Class, Map, Token, NFA,
6};
7
8use crate::{Atom, Boundary, CaptureTag, Concatenation};
9
10/// Regular expression sequence disjunction.
11#[derive(Debug, Clone)]
12pub struct Alternation<T = char, B = ()>(Vec<Concatenation<T, B>>);
13
14impl<T, B> Default for Alternation<T, B> {
15	fn default() -> Self {
16		Self(Vec::new())
17	}
18}
19
20impl<T, B> Alternation<T, B> {
21	pub fn new() -> Self {
22		Self::default()
23	}
24}
25
26impl<T, B> From<Concatenation<T, B>> for Alternation<T, B> {
27	fn from(value: Concatenation<T, B>) -> Self {
28		Self(vec![value])
29	}
30}
31
32impl<T, B> From<Atom<T, B>> for Alternation<T, B> {
33	fn from(value: Atom<T, B>) -> Self {
34		Self(vec![value.into()])
35	}
36}
37
38impl<T, B> Deref for Alternation<T, B> {
39	type Target = [Concatenation<T, B>];
40
41	fn deref(&self) -> &Self::Target {
42		self.0.as_slice()
43	}
44}
45
46impl<'a, T, B> IntoIterator for &'a Alternation<T, B> {
47	type IntoIter = std::slice::Iter<'a, Concatenation<T, B>>;
48	type Item = &'a Concatenation<T, B>;
49
50	fn into_iter(self) -> Self::IntoIter {
51		self.0.iter()
52	}
53}
54
55impl<T, B> IntoIterator for Alternation<T, B> {
56	type IntoIter = std::vec::IntoIter<Concatenation<T, B>>;
57	type Item = Concatenation<T, B>;
58
59	fn into_iter(self) -> Self::IntoIter {
60		self.0.into_iter()
61	}
62}
63
64impl<T, B> FromIterator<Concatenation<T, B>> for Alternation<T, B> {
65	fn from_iter<I: IntoIterator<Item = Concatenation<T, B>>>(iter: I) -> Self {
66		Self(Vec::from_iter(iter))
67	}
68}
69
70impl<T, B, Q, C> BuildNFA<T, Q, C, CaptureTag> for Alternation<T, B>
71where
72	T: Token,
73	B: Boundary<T, Class = C>,
74	Q: Copy + Ord,
75	C: Clone + Eq + Hash + Class<T>,
76{
77	fn build_nfa_from<S: StateBuilder<T, Q, C>>(
78		&self,
79		state_builder: &mut S,
80		nfa: &mut NFA<Q, T>,
81		tags: &mut Tags<Q, CaptureTag>,
82		class: &C,
83	) -> Result<(Q, C::Map<Q>), S::Error> {
84		match self.0.as_slice() {
85			[] => {
86				let a = state_builder.next_state(nfa, class.clone())?;
87				Ok((a, Default::default()))
88			}
89			[concat] => concat.build_nfa_from(state_builder, nfa, tags, class),
90			list => {
91				let a = state_builder.next_state(nfa, class.clone())?;
92				let mut output: C::Map<Q> = Default::default();
93
94				for concat in list {
95					let (concat_a, concat_b_map) =
96						concat.build_nfa_from(state_builder, nfa, tags, class)?;
97					nfa.add(a, None, concat_a);
98
99					for (b_class, concat_b) in concat_b_map.into_entries() {
100						let b = *output.get_or_try_insert_with(&b_class, || {
101							state_builder.next_state(nfa, b_class.clone())
102						})?;
103
104						nfa.add(concat_b, None, b);
105					}
106				}
107
108				Ok((a, output))
109			}
110		}
111	}
112}
iregex/ir/alternation.rs

iregex/ir/
alternation.rs
