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40 lines
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JavaScript

"use strict"
// Based on: https://github.com/lodash/lodash/blob/6018350ac10d5ce6a5b7db625140b82aeab804df/.internal/unicodeSize.js
module.exports = () => {
// Used to compose unicode character classes.
const astralRange = "\\ud800-\\udfff"
const comboMarksRange = "\\u0300-\\u036f"
const comboHalfMarksRange = "\\ufe20-\\ufe2f"
const comboSymbolsRange = "\\u20d0-\\u20ff"
const comboMarksExtendedRange = "\\u1ab0-\\u1aff"
const comboMarksSupplementRange = "\\u1dc0-\\u1dff"
const comboRange = comboMarksRange + comboHalfMarksRange + comboSymbolsRange + comboMarksExtendedRange + comboMarksSupplementRange
const varRange = "\\ufe0e\\ufe0f"
const familyRange = "\\uD83D\\uDC69\\uD83C\\uDFFB\\u200D\\uD83C\\uDF93"
// Used to compose unicode capture groups.
const astral = `[${astralRange}]`
const combo = `[${comboRange}]`
const fitz = "\\ud83c[\\udffb-\\udfff]"
const modifier = `(?:${combo}|${fitz})`
const nonAstral = `[^${astralRange}]`
const regional = "(?:\\uD83C[\\uDDE6-\\uDDFF]){2}"
const surrogatePair = "[\\ud800-\\udbff][\\udc00-\\udfff]"
const zwj = "\\u200d"
const blackFlag = "(?:\\ud83c\\udff4\\udb40\\udc67\\udb40\\udc62\\udb40(?:\\udc65|\\udc73|\\udc77)\\udb40(?:\\udc6e|\\udc63|\\udc6c)\\udb40(?:\\udc67|\\udc74|\\udc73)\\udb40\\udc7f)"
const family = `[${familyRange}]`
// Used to compose unicode regexes.
const optModifier = `${modifier}?`
const optVar = `[${varRange}]?`
const optJoin = `(?:${zwj}(?:${[nonAstral, regional, surrogatePair].join("|")})${optVar + optModifier})*`
const seq = optVar + optModifier + optJoin
const nonAstralCombo = `${nonAstral}${combo}?`
const symbol = `(?:${[nonAstralCombo, combo, regional, surrogatePair, astral, family].join("|")})`
// Used to match [String symbols](https://mathiasbynens.be/notes/javascript-unicode).
return new RegExp(`${blackFlag}|${fitz}(?=${fitz})|${symbol + seq}`, "g")
}