aho_corasick/util/
special.rs

1use crate::util::primitives::StateID;
2
3/// A collection of sentinel state IDs for Aho-Corasick automata.
4///
5/// This specifically enables the technique by which we determine which states
6/// are dead, matches or start states. Namely, by arranging states in a
7/// particular order, we can determine the type of a state simply by looking at
8/// its ID.
9#[derive(Clone, Debug)]
10pub(crate) struct Special {
11    /// The maximum ID of all the "special" states. This corresponds either to
12    /// start_anchored_id when a prefilter is active and max_match_id when a
13    /// prefilter is not active. The idea here is that if there is no prefilter,
14    /// then there is no point in treating start states as special.
15    pub(crate) max_special_id: StateID,
16    /// The maximum ID of all the match states. Any state ID bigger than this
17    /// is guaranteed to be a non-match ID.
18    ///
19    /// It is possible and legal for max_match_id to be equal to
20    /// start_anchored_id, which occurs precisely in the case where the empty
21    /// string is a pattern that was added to the underlying automaton.
22    pub(crate) max_match_id: StateID,
23    /// The state ID of the start state used for unanchored searches.
24    pub(crate) start_unanchored_id: StateID,
25    /// The state ID of the start state used for anchored searches. This is
26    /// always start_unanchored_id+1.
27    pub(crate) start_anchored_id: StateID,
28}
29
30impl Special {
31    /// Create a new set of "special" state IDs with all IDs initialized to
32    /// zero. The general idea here is that they will be updated and set to
33    /// correct values later.
34    pub(crate) fn zero() -> Special {
35        Special {
36            max_special_id: StateID::ZERO,
37            max_match_id: StateID::ZERO,
38            start_unanchored_id: StateID::ZERO,
39            start_anchored_id: StateID::ZERO,
40        }
41    }
42}
aho_corasick/util/special.rs

aho_corasick/util/
special.rs
