Struct RankHead 

pub struct RankHead { /* private fields */ }

The classification head a reranker checkpoint carries on top of the encoder.

Implementations

impl RankHead

pub fn n_cls_out(&self) -> usize

How many floats Self::apply returns.

pub fn labels(&self) -> &[String]

{arch}.classifier.output_labels, in output order. Empty for a single-output head that named none.

pub fn apply(&self, pooled: &[f32]) -> Vec<f32>

Every output of the head, for pooled — which must already be the CLS row, not the whole hidden-state matrix.

pub fn score(&self, pooled: &[f32]) -> f32

The single relevance score /v1/rerank reports: output 0, which is what upstream’s send_rerank sends (res->score = embd[0]).

pub fn has_pooler(&self) -> bool

Whether cls — HuggingFace’s bert.pooler.dense — is in this checkpoint, and therefore in every score this head produces.

The one bit that decides which of the two score scales in the module docs a caller is reading. Everything else that reports the regime is derived from it, so nothing can disagree with the weights that are actually loaded.

pub fn graph(&self) -> String

The composition Self::apply runs, as a formula over the CLS row: classifier(tanh(pooler(cls))) for a head with its pooler, classifier(cls) for one without.

Built from the same three Options Self::apply branches on, in the same order, rather than restated as a table of the four shapes — two structures that must agree about one thing is this repo’s dominant bug shape, and a description that has drifted from the graph is worse than none. The test the_graph_names_a_tanh_exactly_when_a_tanh_is_applied closes the loop by checking the label against the arithmetic.