Struct RateBackendBitSession 

pub struct RateBackendBitSession { /* private fields */ }

Stateful bit-level session over a rate backend.

Byte-packed sessions keep the underlying backend byte-native and expose it through a lazy prefix-mass view. They therefore require whole-byte stream boundaries: total_bits, when provided, must be a multiple of 8, and finish must not leave a dangling partial byte. Within one buffered byte, callers must also stay within either adaptive updates or conditioning-only updates; switching modes mid-byte is rejected because the backend only commits whole-byte symbols. Binary-token sessions model each bit either through the backend’s native binary-token application or, for byte-native backends, by adapting the predictor to the literal byte symbols 0 and 1 and renormalizing those two choices.

The complete checkpoint/restore contract is available in both Rust and Python (infotheory_rs.RateBackendBitSession with RateBackendBitSessionCheckpoint).

Implementations

impl RateBackendBitSession

pub fn from_backend( backend: CompiledRateBackend, total_bits: Option<u64>, semantics: BitStreamSemantics, ) -> InfotheoryResult<Self>

Create a bit session from an explicit compiled backend.

For BitStreamSemantics::BytePacked, total_bits must be None or a multiple of 8.

pub fn from_spec( backend: RateBackend, total_bits: Option<u64>, semantics: BitStreamSemantics, ) -> InfotheoryResult<Self>

Create a bit session from a wrapper backend spec.

For BitStreamSemantics::BytePacked, total_bits must be None or a multiple of 8.

pub fn predict_bit(&mut self) -> BinaryPrediction

Predict the next bit without updating state.

pub fn predict_one(&mut self) -> f64

Convenience prediction for P(bit = 1).

pub fn checkpoint(&mut self) -> RateBackendBitSessionCheckpoint

Capture a reversible checkpoint for later restoration.

Backends that store full snapshots restore bit-identical floating-point predictions. Backends that use compact reversible journals may differ by a few ULP after restore because floating-point accumulators are replayed instead of cloned byte-for-byte.

pub fn restore_checkpoint( &mut self, checkpoint: &RateBackendBitSessionCheckpoint, ) -> InfotheoryResult<()>

Restore the session to a previously captured checkpoint.

Snapshot-backed predictors restore bit-identical predictions. Compact journaled predictors restore the same discrete predictor state and stream position, with predictions equal up to floating-point round-off.

A checkpoint is tied to the backend and bit-stream semantics it was created from. Restoring a checkpoint into a different bit session is a programmer error and returns an explicit runtime error.

pub fn clear_checkpoints_if_supported(&mut self)

Clear compact checkpoint journals when no stored checkpoints remain.

This is an optimization hint for backends with journaled checkpoints. Calling it while a checkpoint may still be restored violates the checkpoint contract. Byte-packed sessions preserve the invariant between buffered prefix state and predictor-native prefix state before clearing.

pub fn try_step_bit(&mut self, bit: bool) -> InfotheoryResult<BinaryPrediction>

Predict and then observe one adaptive/fitting bit.

pub fn step_bit(&mut self, bit: bool) -> BinaryPrediction

Predict and then observe one adaptive/fitting bit.

pub fn try_observe_bit(&mut self, bit: bool) -> InfotheoryResult<()>

Observe one adaptive/fitting bit.

pub fn observe_bit(&mut self, bit: bool)

Observe one adaptive/fitting bit.

pub fn try_condition_bit(&mut self, bit: bool) -> InfotheoryResult<()>

Advance conditioning state with one bit without fitting/adapting.

pub fn condition_bit(&mut self, bit: bool)

Advance conditioning state with one bit without fitting/adapting.

pub fn reset_frozen(&mut self, total_bits: Option<u64>) -> InfotheoryResult<()>

Reset dynamic conditioning state while preserving fitted parameters/statistics.

pub fn finish(&mut self) -> InfotheoryResult<()>

Finalize the underlying stream if the backend needs it.

Trait Implementations

impl Clone for RateBackendBitSession

fn clone(&self) -> RateBackendBitSession

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl OnlineBitPredictor for RateBackendBitSession

fn begin_bit_stream( &mut self, total_bits: Option<u64>, semantics: BitStreamSemantics, ) -> Result<(), String>

Optional stream-start hook.

fn finish_bit_stream(&mut self) -> Result<(), String>

Optional stream-finalization hook.

fn bit_prediction(&mut self) -> BinaryPrediction

Predict the next bit without updating state.

fn update_bit(&mut self, bit: bool)

Observe a bit while fitting/adapting.

fn update_bit_frozen(&mut self, bit: bool)

Observe a bit as conditioning only.