Enum regex_automata::nfa::thompson::backtrack::Frame

enum Frame {
    Step {
        sid: StateID,
        at: usize,
    },
    RestoreCapture {
        slot: SmallIndex,
        offset: Option<NonMaxUsize>,
    },
}

Represents a stack frame on the heap while doing backtracking.

Instead of using explicit recursion for backtracking, we use a stack on the heap to keep track of things that we want to explore if the current backtracking branch turns out to not lead to a match.

Variants

Step

Look for a match starting at sid and the given position in the haystack.

Fields

sid: StateID

at: usize

RestoreCapture

Reset the given slot to the given offset (which might be None). This effectively gives a “scope” to capturing groups, such that an offset for a particular group only gets returned if the match goes through that capturing group. If backtracking ends up going down a different branch that results in a different offset (or perhaps none at all), then this “restore capture” frame will cause the offset to get reset.

Fields

slot: SmallIndex

offset: Option<NonMaxUsize>

Trait Implementations

impl Clone for Frame

fn clone(&self) -> Frame

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Frame

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.