messageformat-number-skeleton/lib/get-formatter.js

A parser & formatter for ICU NumberFormat skeleton strings & patterns

import { getNumberFormatLocales } from './numberformat/locales.js';
import { getNumberFormatModifier, getNumberFormatModifierSource } from './numberformat/modifier.js';
import { getNumberFormatOptions } from './numberformat/options.js';
import { parseNumberPattern } from './parse-pattern.js';
import { parseNumberSkeleton } from './parse-skeleton.js';
/**
 * Returns a number formatter function for the given locales and number skeleton
 *
 * @remarks
 * Uses `Intl.NumberFormat` internally, including features provided by the
 * {@link https://github.com/tc39/proposal-unified-intl-numberformat | Unified
 * API Proposal}.
 *
 * @public
 * @param locales - One or more valid BCP 47 language tags, e.g. `fr` or `en-CA`
 * @param skeleton - An ICU NumberFormatter pattern or `::`-prefixed skeleton
 *   string, or a parsed `Skeleton` structure
 * @param currency - If `skeleton` is a pattern string that includes ¤ tokens,
 *   their skeleton representation requires a three-letter currency code.
 * @param onError - If defined, will be called separately for each encountered
 *   parsing error and unsupported feature.
 * @example
 * ```js
 * import { getNumberFormatter } from 'messageformat-number-skeleton'
 *
 * let src = ':: currency/CAD unit-width-narrow'
 * let fmt = getNumberFormatter('en-CA', src, console.error)
 * fmt(42) // '$42.00'
 *
 * src = '::percent scale/100'
 * fmt = getNumberFormatter('en', src, console.error)
 * fmt(0.3) // '30%'
 * ```
 */
export function getNumberFormatter(locales, skeleton, currency, onError) {
    if (typeof skeleton === 'string') {
        skeleton =
            skeleton.indexOf('::') === 0
                ? parseNumberSkeleton(skeleton.slice(2), onError)
                : parseNumberPattern(skeleton, currency, onError);
    }
    const lc = getNumberFormatLocales(locales, skeleton);
    const opt = getNumberFormatOptions(skeleton, onError);
    const mod = getNumberFormatModifier(skeleton);
    const nf = new Intl.NumberFormat(lc, opt);
    if (skeleton.affix) {
        const [p0, p1] = skeleton.affix.pos;
        const [n0, n1] = skeleton.affix.neg || ['', ''];
        return (value) => {
            const n = nf.format(mod(value));
            return value < 0 ? `${n0}${n}${n1}` : `${p0}${n}${p1}`;
        };
    }
    return (value) => nf.format(mod(value));
}
/**
 * Returns a string of JavaScript source that evaluates to a number formatter
 * function with the same `(value: number) => string` signature as the function
 * returned by {@link getNumberFormatter}.
 *
 * @remarks
 * The returned function will memoize an `Intl.NumberFormat` instance that makes
 * use of features provided by the {@link
 * https://github.com/tc39/proposal-unified-intl-numberformat | Unified API
 * Proposal}.
 *
 * @public
 * @param locales - One or more valid BCP 47 language tags, e.g. `fr` or `en-CA`
 * @param skeleton - An ICU NumberFormatter pattern or `::`-prefixed skeleton
 *   string, or a parsed `Skeleton` structure
 * @param currency - If `skeleton` is a pattern string that includes ¤ tokens,
 *   their skeleton representation requires a three-letter currency code.
 * @param onError - If defined, will be called separately for each encountered
 *   parsing error and unsupported feature.
 * @example
 * ```js
 * import { getNumberFormatterSource } from 'messageformat-number-skeleton'
 *
 * getNumberFormatterSource('en', '::percent', console.error)
 * // '(function() {\n' +
 * // '  var opt = {"style":"percent"};\n' +
 * // '  var nf = new Intl.NumberFormat(["en"], opt);\n' +
 * // '  var mod = function(n) { return n * 0.01; };\n' +
 * // '  return function(value) { return nf.format(mod(value)); }\n' +
 * // '})()'
 *
 * const src = getNumberFormatterSource('en-CA', ':: currency/CAD unit-width-narrow', console.error)
 * // '(function() {\n' +
 * // '  var opt = {"style":"currency","currency":"CAD","currencyDisplay":"narrowSymbol","unitDisplay":"narrow"};\n' +
 * // '  var nf = new Intl.NumberFormat(["en-CA"], opt);\n'
 * // '  return function(value) { return nf.format(value); }\n' +
 * // '})()'
 * const fmt = new Function(`return ${src}`)()
 * fmt(42) // '$42.00'
 * ```
 */
export function getNumberFormatterSource(locales, skeleton, currency, onError) {
    if (typeof skeleton === 'string') {
        skeleton =
            skeleton.indexOf('::') === 0
                ? parseNumberSkeleton(skeleton.slice(2), onError)
                : parseNumberPattern(skeleton, currency, onError);
    }
    const lc = getNumberFormatLocales(locales, skeleton);
    const opt = getNumberFormatOptions(skeleton, onError);
    const modSrc = getNumberFormatModifierSource(skeleton);
    const lines = [
        `(function() {`,
        `var opt = ${JSON.stringify(opt)};`,
        `var nf = new Intl.NumberFormat(${JSON.stringify(lc)}, opt);`
    ];
    let res = 'nf.format(value)';
    if (modSrc) {
        lines.push(`var mod = ${modSrc};`);
        res = 'nf.format(mod(value))';
    }
    if (skeleton.affix) {
        const [p0, p1] = skeleton.affix.pos.map(s => JSON.stringify(s));
        if (skeleton.affix.neg) {
            const [n0, n1] = skeleton.affix.neg.map(s => JSON.stringify(s));
            res = `value < 0 ? ${n0} + ${res} + ${n1} : ${p0} + ${res} + ${p1}`;
        }
        else {
            res = `${p0} + ${res} + ${p1}`;
        }
    }
    lines.push(`return function(value) { return ${res}; }`);
    return lines.join('\n  ') + '\n})()';
}