Full Unicode case folding

Use /unicode for Unicode 17 common/full folding, including expansions such as ß → ss (v3.2.0+).

Match folded text

import UnicodeAhoCorasick from 'modern-ahocorasick/unicode'

const matcher = new UnicodeAhoCorasick(['STRASSE', 'ss', 's'])
matcher.replace('😀Straße', 'X') // '😀X'
matcher.search('ß').map(match => match.pattern) // ['ss']

Folding contract

Folding uses Unicode 17.0 CaseFolding.txt common/full mappings with the bundled Unicode License v3. It does not normalize text or apply Turkic tailoring. Thus é and e\u0301 remain distinct; Σ, σ and ς fold together. İ folds to i\u0307. Matches must cover whole original graphemes: ss matches ß, but s does not match half of that expansion. Patterns and metadata are preserved; ranges and replacement callback text refer to the unmodified input. The folding table is fixed, while grapheme segmentation still follows the host ICU version.

Choose the right entry

/unicode supports whole-text queries and the /stream adapters. /unicode-fast adds the optional double-array backend. Neither normalizes text or applies Turkic tailoring. Use /text when those transformations are required; it accepts complete strings and has no stream or persistence API.

See Incremental sessions.