cjke-strings/lib/firstCompleteChar.js

a set of Chinese Japanese Korean and Emoji strings helpers

import { everything, ansiRegexStarting, emojiRegexStarting, emojiSimpleRegex } from './base.js';
import { combiningCharactersRegexStarting, isCombiningCharacters } from './combiningCharacters.js';
import { isFullwidthCodePointLibrary } from './shim.lib.js';
export function readFirstCompleteChar(str, supports = everything) {
    if (!str) {
        return { data: '', width: 0, length: 0, visible: false };
    }
    const code = str.codePointAt(0);
    let ret;
    if (code <= 0xff) {
        // ansi control sequence
        const ansiMatch = str.match(ansiRegexStarting);
        if (ansiMatch) {
            return commonInvisible(ansiMatch[0]);
        }
        // ansi control characters
        if (code <= 0x1f || (code >= 0x7f && code <= 0x9f)) {
            return commonInvisible(str[0]);
        }
        // common ansi char
        ret = commonSingleChar(str, code);
    }
    else if (isCombiningCharacters(code)) {
        // handle multiple combine char
        const allChars = str.match(combiningCharactersRegexStarting);
        return {
            data: allChars[0],
            width: supports.combining ? 0 : allChars[0].length,
            length: allChars[0].length,
            visible: false,
        };
    }
    else {
        // emoji
        const emojiMatch = str.match(emojiRegexStarting);
        if (emojiMatch) {
            ret = {
                data: emojiMatch[0],
                width: 2,
                length: emojiMatch[0].length,
                visible: true,
            };
            if (!supports.emojiSequence) {
                let i = 0;
                while (emojiSimpleRegex.exec(emojiMatch[0])) {
                    i++;
                }
                ret.width = i * 2;
            }
        }
        else if (code > 0xffff) {
            // Surrogates
            ret = {
                data: str.slice(0, 2),
                width: 2,
                length: 2,
                visible: true,
            };
            if (supports.surrogates) {
                ret.width = isFullwidthCodePointLibrary(code) ? 2 : 1;
            }
        }
        else {
            // common unicode char
            ret = commonSingleChar(str, code);
        }
    }
    // look ahead for combining chars
    const nextCode = str.codePointAt(ret.length);
    if (isCombiningCharacters(nextCode)) {
        const m = str.slice(ret.length).match(combiningCharactersRegexStarting);
        ret.data += m[0];
        ret.length += m[0].length;
        if (!supports.combining) {
            ret.width += m[0].length;
        }
    }
    return ret;
}
function commonSingleChar(str, code) {
    return {
        data: str[0],
        width: isFullwidthCodePointLibrary(code) ? 2 : 1,
        length: 1,
        visible: true,
    };
}
function commonInvisible(str) {
    return {
        data: str,
        width: 0,
        length: str.length,
        visible: false,
    };
}
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