@ckeditor/ckeditor5-utils/src/unicode.js

Miscellaneous utilities used by CKEditor 5.

/**
 * @license Copyright (c) 2003-2025, CKSource Holding sp. z o.o. All rights reserved.
 * For licensing, see LICENSE.md or https://ckeditor.com/legal/ckeditor-licensing-options
 */
/**
 * Set of utils to handle unicode characters.
 *
 * @module utils/unicode
 */
/**
 * Checks whether given `character` is a combining mark.
 *
 * @param character Character to check.
 */
export function isCombiningMark(character) {
    // eslint-disable-next-line no-misleading-character-class
    return !!character && character.length == 1 && /[\u0300-\u036f\u1ab0-\u1aff\u1dc0-\u1dff\u20d0-\u20ff\ufe20-\ufe2f]/.test(character);
}
/**
 * Checks whether given `character` is a high half of surrogate pair.
 *
 * Using UTF-16 terminology, a surrogate pair denotes UTF-16 character using two UTF-8 characters. The surrogate pair
 * consist of high surrogate pair character followed by low surrogate pair character.
 *
 * @param character Character to check.
 */
export function isHighSurrogateHalf(character) {
    return !!character && character.length == 1 && /[\ud800-\udbff]/.test(character);
}
/**
 * Checks whether given `character` is a low half of surrogate pair.
 *
 * Using UTF-16 terminology, a surrogate pair denotes UTF-16 character using two UTF-8 characters. The surrogate pair
 * consist of high surrogate pair character followed by low surrogate pair character.
 *
 * @param character Character to check.
 */
export function isLowSurrogateHalf(character) {
    return !!character && character.length == 1 && /[\udc00-\udfff]/.test(character);
}
/**
 * Checks whether given offset in a string is inside a surrogate pair (between two surrogate halves).
 *
 * @param string String to check.
 * @param offset Offset to check.
 */
export function isInsideSurrogatePair(string, offset) {
    return isHighSurrogateHalf(string.charAt(offset - 1)) && isLowSurrogateHalf(string.charAt(offset));
}
/**
 * Checks whether given offset in a string is between base character and combining mark or between two combining marks.
 *
 * @param string String to check.
 * @param offset Offset to check.
 */
export function isInsideCombinedSymbol(string, offset) {
    return isCombiningMark(string.charAt(offset));
}
const EMOJI_PATTERN = /* #__PURE__ */ buildEmojiRegexp();
/**
 * Checks whether given offset in a string is inside multi-character emoji sequence.
 *
 * @param string String to check.
 * @param offset Offset to check.
 */
export function isInsideEmojiSequence(string, offset) {
    const matches = String(string).matchAll(EMOJI_PATTERN);
    return Array.from(matches).some(match => match.index < offset && offset < match.index + match[0].length);
}
function buildEmojiRegexp() {
    const parts = [
        // Emoji Tag Sequence (ETS)
        /\p{Emoji}[\u{E0020}-\u{E007E}]+\u{E007F}/u,
        // Emoji Keycap Sequence
        /\p{Emoji}\u{FE0F}?\u{20E3}/u,
        // Emoji Presentation Sequence
        /\p{Emoji}\u{FE0F}/u,
        // Single-Character Emoji / Emoji Modifier Sequence
        /(?=\p{General_Category=Other_Symbol})\p{Emoji}\p{Emoji_Modifier}*/u
    ];
    const flagSequence = /\p{Regional_Indicator}{2}/u.source;
    const emoji = '(?:' + parts.map(part => part.source).join('|') + ')';
    const sequence = `${flagSequence}|${emoji}(?:\u{200D}${emoji})*`;
    return new RegExp(sequence, 'ug');
}