@heypano/greek-search

@heypano/greek-search

Ένα JS package για node ή browser (με TypeScript types) με μεθόδους που διευκολύνουν την αναζήτηση ελληνικού κειμένου.

A JS package for node or the browser (TypeScript types included) for searching Greek text: ignores accents, final sigma, decomposed input, look-alike characters, and optionally matches greeklish.

import { greekSearch } from "@heypano/greek-search";

greekSearch("Κάποιος ΆλΛοΣ", "αλλος");                    // true
greekSearch("Ο γιατρός", "giatros", { greeklish: true }); // true

Installation

npm i @heypano/greek-search

Ships CommonJS and ESM builds with TypeScript declarations for both, and has no runtime dependencies.

Quick reference

function	what it does
greekSearch(text, match, options?)	boolean predicate
greekMatches(text, match, options?)	match offsets, for highlighting
greekNormalize(text, options?) / foldGreek	fold to the canonical search form
foldGreekWithMap(text, options?)	fold plus a map back to the original offsets
greekKey(folded) / greeklishKeys(folded)	the greeklish primitives
trimAround(text, regex, numWords?, addEllipses?)	snippets with context
greekCompare / greekCollator(options?)	sorting Greek correctly

greekSearch(text, match[, options])

Επιστρέφει εαν το text περιέχει το match, ασχέτως τόνων και τελικών ς.

Returns whether text contains match, independent of accents and final ς.

greekSearch("Κάποιος ΆλΛοΣ", "ΆλλοΣ");  // true
greekSearch("Κάποιος ΆλΛοΣ", "αΛλΌσ");  // true
greekSearch("Κάποιος ΆλΛοΣ", "αλος");   // false

It also handles, by default, several things a character class cannot:

// Decomposed (NFD) text, found on roughly 2% of Greek web pages
greekSearch("Κάποιος άλλος".normalize("NFD"), "αλλος");  // true

// Look-alike characters: a Latin capital opening a Greek word
greekSearch("Oδύσσεια", "Οδύσσεια");                     // true  (Latin O)
greekSearch("στo σπίτι", "στο");                         // true  (Latin o)

// Lunate sigma, symbol letterforms, maths Greek
greekSearch("ΟΔΟϹ", "οδός");                             // true

Options

interface SearchOptions {
  caseSensitive?: boolean;    // default false
  accentSensitive?: boolean;  // default false
  greeklish?: boolean;        // default false
  homoglyphs?: boolean;       // default true
  letterforms?: boolean;      // default true
  wholeWord?: boolean;        // default false
  synonyms?: string[][];
  maxKeys?: number;           // greeklish fan-out cap, default 64
}

caseSensitive and accentSensitive are independent. The old positional form, greekSearch(text, match, caseSensitive, extraConversions), still works.

greekMatches(text, match[, options])

Returns Array<{ start, end }> of offsets into the original text, so you can highlight without re-deriving anything. Offsets survive folding, decomposition and greeklish.

const text = "Ο γιατρός και ο γιατρός";
greekMatches(text, "ΓΙΑΤΡΟΣ");
// [ { start: 2, end: 9 }, { start: 16, end: 23 } ]
text.slice(2, 9); // "γιατρός"

Greeklish

Off by default, so a Greek query against Greek text stays exact. Turn it on and all three transliteration conventions work, in both directions:

const opts = { greeklish: true };
greekSearch("Θεσσαλονίκη", "thessaloniki", opts);  // true  (phonetic)
greekSearch("Θεσσαλονίκη", "8essalonikh", opts);   // true  (visual)
greekSearch("Θεσσαλονίκη", "uessalonikh", opts);   // true  (keyboard)
greekSearch("to 3enodoxeio", "ξενοδοχείο", opts);  // true  (the other direction)

Both sides fold to a lossy key. Greek to key is deterministic, greeklish to key fans out into a bounded candidate set, and the text itself resolves the ambiguity. Highlighting still works, because a greeklish query returns offsets into the original Greek.

Known collisions. The key is lossy on purpose, so some distinct words merge. Most are genuine homophones and users are not surprised by them:

τείχος / τοίχος     κάλος / καλός     ώρα / όρα     ναι / νε
χέρι / ξέρει        δύνω / ντύνω      ύλη / ήλη / ίλη

χέρι/ξέρει and δύνω/ντύνω are not homophones; they merge because χ and ξ both say x, and δ and ντ both say d. This is a deliberate recall-over-precision trade.

αυ and αφ are kept apart (αυτό and αφτό get different keys), while a query of afto, auto or ayto still finds either. Recall without the merge.

Synonyms

Plain data, no regex, no escaping:

greekSearch("Άλλος ιατρός", "γιατρός", {
  synonyms: [["γιατρός", "ιατρός"], ["ξενοδοχείο", "hotel"]],
});  // true

Every term is folded, so accent and case variants collapse on their own.

trimAround(text, regex[, numWords, addEllipses])

Returns up to numWords words of context around each match, one per line.

trimAround("one two three needle four five six", /needle/g, 2);
// "...two three needle four five..."

Sorting

["Ω", "Α", "Ζ", "ά", "Β"].sort(greekCompare);  // Α, ά, Β, Ζ, Ω
["Ω", "Α", "Ζ", "ά", "Β"].sort();              // Α, Β, Ζ, Ω, ά  (wrong)

Performance

greekNormalize is exposed so a corpus can be folded once instead of on every query:

const index = docs.map((d) => ({ doc: d, key: greekNormalize(d.body) }));
const q = greekNormalize(query);
index.filter(({ key }) => key.includes(q));

Stemming

Out of scope here, but it composes. Greek declension (γιατρός / γιατρού / γιατροί) is the biggest remaining recall gap, and a stemmer wants exactly the accent-stripped uppercase input that greekNormalize produces:

import stemmer from "greek-stemmer";
stemmer(greekNormalize("γιατροί").toUpperCase());  // "ΓΙΑΤΡ"

Note that greek-stemmer is lightly maintained and pulls in lodash@3, so weigh it before taking the dependency.

Deprecated

getRegExp, getRegExpContent, conversions and the extraConversions option remain exported and working, but are superseded.

A character class cannot express ου to u, cannot be validated under the u flag, and never sees decomposed input. extraConversions additionally asks callers to write a regex fragment that also matches its own literal alternatives, and splices it into the pattern unescaped. Use synonyms instead.

getRegExp returns an expression carrying the g flag, which is stateful: test and exec advance lastIndex, so repeated checks on one instance alternate between true and false. Use greekSearch for a predicate and greekMatches for offsets.

Notes

Modern Greek only. Polytonic is explicitly out of scope; the only Greek Extended codepoints handled are the oxia forms, which NFC folds onto ordinary tonos for free.

Greek ordinals such as ΦΕΚ Α΄ 251 and Μακάριος Γ΄ are preserved. This is why the library normalizes with NFC and an explicit letterform table rather than NFKC, which decomposes U+0384 into a space plus a combining acute and splits ordinals in two.