import { balanced } from 'balanced-match';
const escSlash = '\0SLASH' + Math.random() + '\0';
const escOpen = '\0OPEN' + Math.random() + '\0';
const escClose = '\0CLOSE' + Math.random() + '\0';
const escComma = '\0COMMA' + Math.random() + '\0';
const escPeriod = '\0PERIOD' + Math.random() + '\0';
const escSlashPattern = new RegExp(escSlash, 'g');
const escOpenPattern = new RegExp(escOpen, 'g');
const escClosePattern = new RegExp(escClose, 'g');
const escCommaPattern = new RegExp(escComma, 'g');
const escPeriodPattern = new RegExp(escPeriod, 'g');
const slashPattern = /\\\\/g;
const openPattern = /\\{/g;
const closePattern = /\\}/g;
const commaPattern = /\\,/g;
const periodPattern = /\\\./g;
export const EXPANSION_MAX = 100_000;
function numeric(str) {
    return !isNaN(str) ? parseInt(str, 10) : str.charCodeAt(0);
}
function escapeBraces(str) {
    return str
        .replace(slashPattern, escSlash)
        .replace(openPattern, escOpen)
        .replace(closePattern, escClose)
        .replace(commaPattern, escComma)
        .replace(periodPattern, escPeriod);
}
function unescapeBraces(str) {
    return str
        .replace(escSlashPattern, '\\')
        .replace(escOpenPattern, '{')
        .replace(escClosePattern, '}')
        .replace(escCommaPattern, ',')
        .replace(escPeriodPattern, '.');
}
/**
 * Basically just str.split(","), but handling cases
 * where we have nested braced sections, which should be
 * treated as individual members, like {a,{b,c},d}
 */
function parseCommaParts(str) {
    if (!str) {
        return [''];
    }
    const parts = [];
    const m = balanced('{', '}', str);
    if (!m) {
        return str.split(',');
    }
    const { pre, body, post } = m;
    const p = pre.split(',');
    p[p.length - 1] += '{' + body + '}';
    const postParts = parseCommaParts(post);
    if (post.length) {
        ;
        p[p.length - 1] += postParts.shift();
        p.push.apply(p, postParts);
    }
    parts.push.apply(parts, p);
    return parts;
}
export function expand(str, options = {}) {
    if (!str) {
        return [];
    }
    const { max = EXPANSION_MAX } = options;
    // I don't know why Bash 4.3 does this, but it does.
    // Anything starting with {} will have the first two bytes preserved
    // but *only* at the top level, so {},a}b will not expand to anything,
    // but a{},b}c will be expanded to [a}c,abc].
    // One could argue that this is a bug in Bash, but since the goal of
    // this module is to match Bash's rules, we escape a leading {}
    if (str.slice(0, 2) === '{}') {
        str = '\\{\\}' + str.slice(2);
    }
    return expand_(escapeBraces(str), max, true).map(unescapeBraces);
}
function embrace(str) {
    return '{' + str + '}';
}
function isPadded(el) {
    return /^-?0\d/.test(el);
}
function lte(i, y) {
    return i <= y;
}
function gte(i, y) {
    return i >= y;
}
function expand_(str, max, isTop) {
    /** @type {string[]} */
    const expansions = [];
    const m = balanced('{', '}', str);
    if (!m)
        return [str];
    // no need to expand pre, since it is guaranteed to be free of brace-sets
    const pre = m.pre;
    const post = m.post.length ? expand_(m.post, max, false) : [''];
    if (/\$$/.test(m.pre)) {
        for (let k = 0; k < post.length && k < max; k++) {
            const expansion = pre + '{' + m.body + '}' + post[k];
            expansions.push(expansion);
        }
    }
    else {
        const isNumericSequence = /^-?\d+\.\.-?\d+(?:\.\.-?\d+)?$/.test(m.body);
        const isAlphaSequence = /^[a-zA-Z]\.\.[a-zA-Z](?:\.\.-?\d+)?$/.test(m.body);
        const isSequence = isNumericSequence || isAlphaSequence;
        const isOptions = m.body.indexOf(',') >= 0;
        if (!isSequence && !isOptions) {
            // {a},b}
            if (m.post.match(/,(?!,).*\}/)) {
                str = m.pre + '{' + m.body + escClose + m.post;
                return expand_(str, max, true);
            }
            return [str];
        }
        let n;
        if (isSequence) {
            n = m.body.split(/\.\./);
        }
        else {
            n = parseCommaParts(m.body);
            if (n.length === 1 && n[0] !== undefined) {
                // x{{a,b}}y ==> x{a}y x{b}y
                n = expand_(n[0], max, false).map(embrace);
                //XXX is this necessary? Can't seem to hit it in tests.
                /* c8 ignore start */
                if (n.length === 1) {
                    return post.map(p => m.pre + n[0] + p);
                }
                /* c8 ignore stop */
            }
        }
        // at this point, n is the parts, and we know it's not a comma set
        // with a single entry.
        let N;
        if (isSequence && n[0] !== undefined && n[1] !== undefined) {
            const x = numeric(n[0]);
            const y = numeric(n[1]);
            const width = Math.max(n[0].length, n[1].length);
            let incr = n.length === 3 && n[2] !== undefined ?
                Math.max(Math.abs(numeric(n[2])), 1)
                : 1;
            let test = lte;
            const reverse = y < x;
            if (reverse) {
                incr *= -1;
                test = gte;
            }
            const pad = n.some(isPadded);
            N = [];
            for (let i = x; test(i, y) && N.length < max; i += incr) {
                let c;
                if (isAlphaSequence) {
                    c = String.fromCharCode(i);
                    if (c === '\\') {
                        c = '';
                    }
                }
                else {
                    c = String(i);
                    if (pad) {
                        const need = width - c.length;
                        if (need > 0) {
                            const z = new Array(need + 1).join('0');
                            if (i < 0) {
                                c = '-' + z + c.slice(1);
                            }
                            else {
                                c = z + c;
                            }
                        }
                    }
                }
                N.push(c);
            }
        }
        else {
            N = [];
            for (let j = 0; j < n.length; j++) {
                N.push.apply(N, expand_(n[j], max, false));
            }
        }
        for (let j = 0; j < N.length; j++) {
            for (let k = 0; k < post.length && expansions.length < max; k++) {
                const expansion = pre + N[j] + post[k];
                if (!isTop || isSequence || expansion) {
                    expansions.push(expansion);
                }
            }
        }
    }
    return expansions;
}
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