Module seq_feature 

Configurable feature templates for sequence labeling models.

Provides SeqFeatureTemplate for specifying what observations and labels each model sees, plus extraction functions used by both averaged perceptron and HMM models.

Structs

FeatureBuffer

A reusable buffer for building feature strings.

SeqFeatureConfig

Validated collection of feature templates with pre-computed metadata.

SeqFeatureTemplate

A single feature template for sequence labeling.

Enums

SeqTransform

Transform applied to observation strings.

Constants

END

Sentinel strings for positions after the end of a sequence.

START

Sentinel strings for positions before the start of a sequence.

Functions

default_segmenter_ap_features

Default features for the wordseg averaged perceptron.

default_segmenter_hmm_features

Default features for the wordseg HMM.

default_tagger_ap_features

Default features for the tagging averaged perceptron.

default_tagger_hmm_features

Default features for the tagging HMM.

extract_features

Extract AP features into buf for position i.

extract_observation

Extract a single observation string for an HMM feature template at position i.

extract_observation_cow

Like extract_observation, but returns Cow::Borrowed when possible (single-position templates) to avoid heap allocation.

final_char

Get the final character of a string, or an empty string if empty.

first_char

Get the first character of a string, or an empty string if empty.

validate_templates

Validate a list of feature templates.