Struct PromptLookupIndex 

pub struct PromptLookupIndex { /* private fields */ }

2026-10-02: Per-sequence n-gram index over a token history.

Implementations

impl PromptLookupIndex

pub fn new(n: usize) -> Self

2026-10-02: An empty index matching n-grams of length n (n >= 1).

pub fn ngram_len(&self) -> usize

2026-10-02: The n-gram length this index matches.

pub fn observe(&mut self, history: &[u32])

2026-10-02: Indexes every n-gram of history that has a following token and is not indexed yet. Amortised O(n) per new token. A history shorter than the indexed length (a rewind) moves the mark back; the entries past it are left in place and rejected on use.

pub fn propose<'h>( &self, history: &'h [u32], max_len: usize, ) -> Option<&'h [u32]>

2026-10-02: The continuation of the latest earlier occurrence of history’s final n-gram, at most max_len tokens; None when there is no earlier occurrence, max_len is 0, or the history is too short. Call observe with the same history first.

pub fn continuation_start(&self, history: &[u32]) -> Option<usize>

2026-10-02: Where the continuation propose copies from starts: the position after the latest earlier occurrence of the history’s final n-gram, re-checked token by token.

pub fn match_len(history: &[u32], start: usize, cap: usize) -> usize

2026-10-02: How many tokens before start equal the tokens before the history’s end, counted back from both, up to cap: the length of the match a copy starting at start rests on. At least n for a start propose returned.

Trait Implementations

impl Clone for PromptLookupIndex

fn clone(&self) -> PromptLookupIndex

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PromptLookupIndex

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

Formats the value using the given formatter.