Struct BbqRerank 

pub struct BbqRerank { /* private fields */ }

Object-safe RerankCodec wrapper around BbqCodec.

The codec starts untrained. encode and prepare_query return RerankError::NotTrained until train() has been called with a representative sample of vectors.

from_codec accepts a pre-calibrated BbqCodec (used when restoring from a snapshot).

Implementations

impl BbqRerank

pub fn new(dim: usize, oversample: u8) -> Self

Construct an untrained wrapper.

encode / distance_prepared return RerankError::NotTrained until train() is called.

pub fn from_codec(codec: BbqCodec) -> Self

Construct from a pre-calibrated codec (used when restoring from snapshot).

Trait Implementations

impl RerankCodec for BbqRerank

fn encode(&self, v: &[f32]) -> Result<Vec<u8>, RerankError>

Encode a full-precision vector to BBQ 1-bit bytes.

The serialised form is the raw UnifiedQuantizedVector buffer (as_bytes()): 32-byte QuantHeader followed by dim.div_ceil(8) sign-packed bits plus 14 bytes of corrective factors in the header.

fn prepare_query(&self, q: &[f32]) -> Result<PreparedQuery, RerankError>

Prepare the query by centering it and serialising the exact FP32 centered vector alongside the query norm.

The prepared form is PreparedQuery::Bytes with the layout: 4 bytes query_norm (f32 LE) || dim × 4 bytes centered f32 LE.

fn distance_prepared( &self, prepared: &PreparedQuery, encoded: &[u8], ) -> Result<f32, RerankError>

Compute asymmetric L2 distance from a prepared query to a BBQ-encoded candidate.

The query is the exact centered FP32 vector. The stored candidate is reconstructed from its sign bits and residual_norm (each dim ≈ ±norm/√dim). Returns L2 distance between them.

Expects PreparedQuery::Bytes produced by prepare_query.

fn train(&mut self, samples: &[&[f32]]) -> Result<(), RerankError>

Calibrate from a sample of vectors.

Validates that:

• samples is non-empty.
• Every sample has length self.dim.

On success, stores the calibrated codec; subsequent encode / distance_prepared calls will succeed.

fn name(&self) -> CodecName

Identity tag for mismatch detection.

fn to_bytes(&self) -> Result<Vec<u8>, RerankError>

Serialize trained state to bytes. Each codec uses its own magic header (NDSQ / NDBIN / NDPQ / NDRBQ / NDBBQ). The bytes are codec-specific; rerank_codec_from_bytes is used for restore, paired with name().