Struct FtsIndex 

pub struct FtsIndex<B>
where
    B: FtsBackend,
{ /* private fields */ }

Full-text search index generic over storage backend.

Provides identical indexing, search, and highlighting logic for Origin (redb), Lite (in-memory), and WASM deployments.

Writes accumulate in an in-memory Memtable. When the memtable exceeds its threshold, it is flushed to an immutable segment stored via the backend. Queries merge the active memtable with all persisted segments.

Implementations

impl<B> FtsIndex<B>

where B: FtsBackend,

pub fn highlight( &self, text: &str, query: &str, prefix: &str, suffix: &str, ) -> String

Generate highlighted text with matched query terms wrapped in tags.

Returns the original text with each occurrence of a matched query term surrounded by prefix and suffix (e.g., <b> and </b>).

pub fn offsets(&self, text: &str, query: &str) -> Vec<MatchOffset>

Return byte offsets of matched query terms in the original text.

impl<B> FtsIndex<B>

where B: FtsBackend,

pub fn set_collection_analyzer( &self, collection: &str, analyzer_name: &str, ) -> Result<(), <B as FtsBackend>::Error>

Set the analyzer for a collection. Persists to backend metadata.

pub fn set_collection_language( &self, collection: &str, lang_code: &str, ) -> Result<(), <B as FtsBackend>::Error>

Set the language for a collection. Persists to backend metadata.

pub fn get_collection_analyzer( &self, collection: &str, ) -> Result<Option<String>, <B as FtsBackend>::Error>

Get the configured analyzer name for a collection.

pub fn get_collection_language( &self, collection: &str, ) -> Result<Option<String>, <B as FtsBackend>::Error>

Get the configured language for a collection.

pub fn analyze_for_collection( &self, collection: &str, text: &str, ) -> Result<Vec<String>, <B as FtsBackend>::Error>

Analyze text using the collection’s configured analyzer.

Falls back to the standard English analyzer if no analyzer is configured.

pub fn tokenize_raw_for_collection( &self, collection: &str, text: &str, ) -> Result<Vec<String>, <B as FtsBackend>::Error>

Tokenize text WITHOUT stemming for fuzzy matching.

Returns raw (unstemmed but normalized) tokens so that fuzzy edit distance is computed on original word forms, not stemmed forms.

impl<B> FtsIndex<B>

where B: FtsBackend,

pub fn read_fieldnorm( &self, collection: &str, doc_id: u32, ) -> Result<Option<u32>, <B as FtsBackend>::Error>

Get the fieldnorm (SmallFloat-encoded doc length) for a doc.

Returns the decoded approximate u32 length, or None if not stored.

pub fn write_fieldnorm( &self, collection: &str, doc_id: u32, doc_length: u32, ) -> Result<(), <B as FtsBackend>::Error>

Write a fieldnorm byte for a doc_id. Grows the array if needed.

impl<B> FtsIndex<B>

where B: FtsBackend,

pub fn index_stats( &self, collection: &str, ) -> Result<(u32, f32), <B as FtsBackend>::Error>

Get total document count and average document length for a collection.

Returns (total_docs, avg_doc_len). If the collection is empty, returns (0, 1.0) to avoid division by zero.

impl<B> FtsIndex<B>

where B: FtsBackend,

pub fn new(backend: B) -> FtsIndex<B>

Create a new FTS index with the given backend and default BM25 params.

pub fn with_params(backend: B, params: Bm25Params) -> FtsIndex<B>

Create a new FTS index with custom BM25 parameters.

pub fn backend(&self) -> &B

Access the underlying backend.

pub fn backend_mut(&mut self) -> &mut B

Mutable access to the underlying backend.

pub fn memtable(&self) -> &Memtable

Access the active memtable (for LSM query merging).

pub fn load_doc_id_map( &self, collection: &str, ) -> Result<DocIdMap, <B as FtsBackend>::Error>

Load the DocIdMap for a collection from backend metadata.

pub fn index_document( &self, collection: &str, doc_id: &str, text: &str, ) -> Result<(), <B as FtsBackend>::Error>

Index a document’s text content.

Analyzes text into tokens, writes postings to the LSM memtable, and flushes to an immutable segment when the threshold is reached.

pub fn remove_document( &self, collection: &str, doc_id: &str, ) -> Result<(), <B as FtsBackend>::Error>

Remove a document from the index.

Tombstones the document in the DocIdMap, removes from the LSM memtable, and decrements backend stats. Segment postings are filtered at query time via the DocIdMap tombstone.

pub fn purge_collection( &self, collection: &str, ) -> Result<usize, <B as FtsBackend>::Error>

Purge all entries for a collection. Returns count of removed entries.

impl<B> FtsIndex<B>

where B: FtsBackend,

pub fn search( &self, collection: &str, query: &str, top_k: usize, fuzzy_enabled: bool, ) -> Result<Vec<TextSearchResult>, <B as FtsBackend>::Error>

Search the index using BM25 scoring.

Uses AND-first with automatic OR-fallback: if AND yields zero results for a multi-term query, retries with OR and applies a coverage penalty of matched_terms / total_terms to each document’s score.

pub fn search_with_mode( &self, collection: &str, query: &str, top_k: usize, fuzzy_enabled: bool, mode: QueryMode, ) -> Result<Vec<TextSearchResult>, <B as FtsBackend>::Error>

Search with explicit boolean mode (AND or OR).

When mode is AND and a multi-term query returns zero results, automatically falls back to OR with a coverage penalty.

Dispatches to Block-Max WAND (BMW) for OR-mode queries when a DocIdMap is available. Falls back to exhaustive BM25 scoring otherwise.