Struct SequiturModel 

pub struct SequiturModel { /* private fields */ }

Online Sequitur-based byte predictor with rollback support.

The model learns grammar structure from committed updates and exposes a normalized next-byte distribution for coding and planning.

Implementations

impl SequiturModel

pub fn new(context_bytes: usize) -> Self

Create a new Sequitur model.

context_bytes is clamped to at least 2 and controls the maximum tail context length considered by the fallback context statistics.

pub fn reserve_for_stream(&mut self, additional_symbols: usize)

Reserve internal capacity for an upcoming stream.

This only affects allocation behavior and does not change model state.

pub fn begin_stream(&mut self, total_symbols: Option<u64>)

Prepare the model for a new stream.

If total_symbols is provided, internal storage is pre-reserved. Any speculative frozen tail is cleared.

pub fn finish_stream(&mut self)

Finish a stream.

This is currently a no-op and exists for API symmetry with other predictors.

pub fn checkpoint(&mut self) -> SequiturCheckpoint

Capture a rollback point for subsequent speculative updates.

Calling this enables undo journaling until checkpoints are cleared.

pub fn restore(&mut self, checkpoint: &SequiturCheckpoint)

Restore model state to a previously created checkpoint.

pub fn clear_checkpoints(&mut self)

Drop all stored undo history and disable journaling.

pub fn reset_frozen(&mut self)

Clear speculative frozen updates without touching committed state.

pub fn fill_pdf(&mut self, out: &mut [f64; 256])

Fill out with the current normalized next-byte probability mass.

pub fn pdf(&mut self) -> &[f64; 256]

Return the current normalized next-byte probability mass.

pub fn log_prob(&mut self, symbol: u8, min_prob: f64) -> f64

Return the natural-log probability of symbol under the current model.

The symbol probability is clamped from below by min_prob.

pub fn update(&mut self, symbol: u8)

Commit one observed symbol into grammar and context statistics.

pub fn update_frozen(&mut self, symbol: u8)

Apply a speculative symbol update used for lookahead.

Frozen updates affect only the temporary raw-tail context and can be cleared with Self::reset_frozen. They do not mutate committed grammar structure or follower counts.

pub fn decode(&self) -> Vec<u8>

Decode the current start rule into the equivalent terminal byte stream.

pub fn canonical_grammar(&self) -> CanonicalGrammar

Export a deterministic canonical grammar snapshot.

Rules are emitted in preorder from the start rule, and non-terminals are rewritten to canonical rule ids.

pub fn predictive_trace( &mut self, data: &[u8], alphabet_prefix: usize, ) -> Vec<Vec<f64>>

Record a per-step predictive trace for data.

At each position this captures the current PDF prefix of length alphabet_prefix (capped at 256) and then commits the observed byte.

Trait Implementations

impl Clone for SequiturModel

fn clone(&self) -> SequiturModel

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for SequiturModel

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

Formats the value using the given formatter.