messageformat-number-skeleton/lib/parse-pattern.js

A parser & formatter for ICU NumberFormat skeleton strings & patterns

import { parseTokens } from './pattern-parser/parse-tokens.js';
import { parseNumberAsSkeleton } from './pattern-parser/number-as-skeleton.js';
import { PatternError } from './errors.js';
function handleAffix(affixTokens, res, currency, onError, isPrefix) {
    let inFmt = false;
    let str = '';
    for (const token of affixTokens) {
        switch (token.char) {
            case '%':
                res.unit = { style: token.style };
                if (isPrefix)
                    inFmt = true;
                else
                    str = '';
                break;
            case '¤':
                if (!currency) {
                    const msg = `The ¤ pattern requires a currency`;
                    onError(new PatternError('¤', msg));
                    break;
                }
                res.unit = { style: 'currency', currency };
                switch (token.currency) {
                    case 'iso-code':
                        res.unitWidth = 'unit-width-iso-code';
                        break;
                    case 'full-name':
                        res.unitWidth = 'unit-width-full-name';
                        break;
                    case 'narrow':
                        res.unitWidth = 'unit-width-narrow';
                        break;
                }
                if (isPrefix)
                    inFmt = true;
                else
                    str = '';
                break;
            case '*':
                // TODO
                break;
            case '+':
                if (!inFmt)
                    str += '+';
                break;
            case "'":
                if (!inFmt)
                    str += token.str;
                break;
        }
    }
    return str;
}
function getNegativeAffix(affixTokens, isPrefix) {
    let inFmt = false;
    let str = '';
    for (const token of affixTokens) {
        switch (token.char) {
            case '%':
            case '¤':
                if (isPrefix)
                    inFmt = true;
                else
                    str = '';
                break;
            case '-':
                if (!inFmt)
                    str += '-';
                break;
            case "'":
                if (!inFmt)
                    str += token.str;
                break;
        }
    }
    return str;
}
/**
 * Parse an {@link
 * http://unicode.org/reports/tr35/tr35-numbers.html#Number_Format_Patterns |
 * ICU NumberFormatter pattern} string into a {@link Skeleton} structure.
 *
 * @public
 * @param src - The pattern string
 * @param currency - If the pattern includes ¤ tokens, their skeleton
 *   representation requires a three-letter currency code.
 * @param onError - Called when the parser encounters a syntax error. The
 *   function will still return a {@link Skeleton}, but it will be incomplete
 *   and/or inaccurate. If not defined, the error will be thrown instead.
 *
 * @remarks
 * Unlike the skeleton parser, the pattern parser is not able to return partial
 * results on error, and will instead throw. Output padding is not supported.
 *
 * @example
 * ```js
 * import { parseNumberPattern } from 'messageformat-number-skeleton'
 *
 * parseNumberPattern('#,##0.00 ¤', 'EUR', console.error)
 * // {
 * //   group: 'group-auto',
 * //   precision: {
 * //     style: 'precision-fraction',
 * //     minFraction: 2,
 * //     maxFraction: 2
 * //   },
 * //   unit: { style: 'currency', currency: 'EUR' }
 * // }
 * ```
 */
export function parseNumberPattern(src, currency, onError = error => {
    throw error;
}) {
    const { tokens, negative } = parseTokens(src, onError);
    const res = parseNumberAsSkeleton(tokens.number, onError);
    const prefix = handleAffix(tokens.prefix, res, currency, onError, true);
    const suffix = handleAffix(tokens.suffix, res, currency, onError, false);
    if (negative) {
        const negPrefix = getNegativeAffix(negative.prefix, true);
        const negSuffix = getNegativeAffix(negative.suffix, false);
        res.affix = { pos: [prefix, suffix], neg: [negPrefix, negSuffix] };
        res.sign = 'sign-never';
    }
    else if (prefix || suffix) {
        res.affix = { pos: [prefix, suffix] };
    }
    return res;
}