pjbatista / decimal.js-i18n

 * decimal.js-i18n v0.2.6

 * Full internationalization support for decimal.js.

 * MIT License

 * Copyright (c) 2022 Pedro José Batista <[email protected]>

 * https://github.com/pjbatista/decimal.js-i18n

 */

import Decimal from "decimal.js";

import type BaseFormatOptions from "./baseOptions";

import type FormatCompactDisplay from "./compactDisplay";

import { BIGINT_MODIFIERS, ECMA_LIMIT, LOCALES, PLAIN_MODIFIERS } from "./constants";

import type FormatCurrency from "./currency";

import type FormatCurrencyDisplay from "./currencyDisplay";

import type FormatCurrencySign from "./currencySign";

import type FormatLocale from "./locale";

import type FormatLocaleMatcher from "./localeMatcher";

import type FormatNotation from "./notation";

import type FormatNumberingSystem from "./numberingSystem";

import type FormatOptions from "./options";

import { extend, resolve, toEcma, validate } from "./options";

import type FormatPart from "./part";

import { exponents, fractions, integerGroups, integers, PartValue } from "./part";

import type FormatPartTypes from "./partTypes";

import type ResolvedFormatOptions from "./resolvedFormatOptions";

import type FormatSignDisplay from "./signDisplay";

import type FormatStyle from "./style";

import type FormatTrailingZeroDisplay from "./trailingZeroDisplay";

import type FormatUnit from "./unit";

import type FormatUnitDisplay from "./unitDisplay";

import type FormatUseGrouping from "./useGrouping";

// Calculates an exponential value using base₁₀

const defaultLocales = LOCALES.slice();

const concatenate = <T extends PartValue>(filter: T[] | ((p: T) => boolean), parts: T[] = []) => {

    if (typeof filter === "function") {

        parts = parts.filter(filter);

    } else {

        parts = filter;

    }

    return parts.map(p => p.value).join("");

};

const pow10 = (exponent: Decimal.Value) => Decimal.pow(10, exponent);

/**

 * The `Decimal.Format` object enables language-sensitive decimal number formatting. It is entirely based on

 * `Intl.NumberFormat`, with the options of the latter being 100% compatible with it.

 *

 * This class, however, extend the numeric digits constraints of `Intl.NumberFormat` from 21 to 1000000000 in

 * order to fully take advantage of the arbitrary-precision of `decimal.js`.

 *

 * @template TNotation Numeric notation of formatting.

 * @template TStyle Numeric style of formatting.

 */

export class Format<TNotation extends FormatNotation = "standard", TStyle extends FormatStyle = "decimal"> {

    static readonly [Symbol.toPrimitive] = Format;

    readonly [Symbol.toStringTag] = "Decimal.Format";

    /**

     * Formats a number according to the locale and formatting options of this {@link Format} object.

     *

     * @param value A valid [Decimal.Value](https://mikemcl.github.io/decimal.js/#decimal) to format.

     * @returns Formatted localized string.

     */

    readonly format: (value: Decimal.Value) => string;

    /**

     * Allows locale-aware formatting of strings produced by `Decimal.Format` formatters.

     *

     * @param value A valid [Decimal.Value](https://mikemcl.github.io/decimal.js/#decimal) to format.

     * @returns An array of objects containing the formatted number in parts.

     */

    readonly formatToParts: (value: Decimal.Value) => FormatPart[];

    /**

     * Returns a new object with properties reflecting the locale and number formatting options computed during

     * initialization of this {@link Decimal.Format} object.

     *

     * @returns A new object with properties reflecting the locale and number formatting options computed

     *   during the initialization of this object.

     */

    readonly resolvedOptions: () => ResolvedFormatOptions<TNotation, TStyle>;

    /**

     * Creates a new instance of the `Decimal.Format` object.

     *

     * @param locales A string with a [BCP 47](https://www.rfc-editor.org/info/bcp47) language tag, or an array

     *   of such strings.

     *

     *   For the general form and interpretation of this parameter, see the [Intl page on

     *   MDN](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl).

     * @param options Object used to configure the behavior of the string localization.

     * @throws `RangeError` when an invalid option is given.

     */

    constructor(locales?: FormatLocale | FormatLocale[], options?: FormatOptions<TNotation, TStyle>) {

        options ??= {};

        // 1. Check if options do not extrapolate the limits of decimal.js

        const valid = validate(options);

        if (valid !== true) {

            // -> it will either be exactly true or contain an array with all faulty properties:

            throw new RangeError(`${valid.join()} value${valid.length === 1 ? " is" : "s are"} out of range."`);

        }

        // 2. Create a baseline native formatter native

        const ecmaOptions = toEcma(options);

        const ecmaFormat = new Intl.NumberFormat(locales, ecmaOptions);

        // 3. Resolve this object's options, using the native resolution as a baseline

        const resolved = resolve(options, ecmaFormat.resolvedOptions());

        const { minimumIntegerDigits: minID, notation, rounding, style } = resolved;

        // 4. Create two auxiliary formatters:

        // One for the integer part, which can have up to a billion minimum digits...

        const bigintOptions = extend(ecmaOptions, BIGINT_MODIFIERS);

        const bigintFormat = new Intl.NumberFormat(locales, bigintOptions);

        // ...and another for a plain, localized reference, used for decimals and constants

        const plainOptions = extend(bigintOptions, PLAIN_MODIFIERS);

        const plainFormat = new Intl.NumberFormat(locales, plainOptions);

        // 5. Localized numeric constants

        const numbers = Array(10)

            .fill(null)

            .map((_, index) => plainFormat.format(index));

        const numberMatch = new RegExp("[" + numbers.join("") + "]", "g");

        const minusSign = /−/gu;

        // 5.1. Localized zero and one used in substitutions

        const [zero, one] = numbers;

        // 5.2. Helper functions

        const indexOfValue = (value: string) => numbers.indexOf(value).toString();

        const convert = (text: string) => text.replaceAll(numberMatch, indexOfValue).replaceAll(minusSign, "-");

        const zeroFill = (size: number) => Array(size).fill(zero).join("");

        const zeroTrim = (text: string) => {

            let result = text;

            while (result[0] === zero && result.length > 1) {

                result = result.substring(1);

            }

            return result;

        };

        // #region Step 6. Main format method - - - - - - - - - - - - - - - - - - - - - - - - - - - -

        const _formatToParts = (value: Decimal.Value) => {

            value = new Decimal(value);

            const sign = value.s;

            // 6.1. Create a baseline part array

            const ecmaParts = ecmaFormat.formatToParts(value.toNumber());

            // -> if the value is non-numeric or an infinity, the baseline is good enough

            if ((value.isFinite && !value.isFinite()) || (value.isNaN && value.isNaN())) {

                return ecmaParts;

            }

            // 6.2. Splitting the parts for easier assembly

            const ecmaExponentValue = concatenate(exponents, ecmaParts) || "0";

            const ecmaIntegerParts = ecmaParts.filter(integerGroups);

            const ecmaIntegerTrimmed = zeroTrim(concatenate(integers, ecmaIntegerParts));

            const ecmaIntegerDigits = concatenate(integers, ecmaIntegerParts).length;

            const ecmaIntegerTrimmedDigits = ecmaIntegerTrimmed.length;

            const ecmaFractionValue = concatenate(fractions, ecmaParts);

            const ecmaFractionDigits = ecmaFractionValue.length;

            // 6.3. Shifting exponents according to notation/style

            // 6.3.1. Compact notation: calculate the shift in integer digits, and therefore exponent

            if (notation === "compact" && !value.eq(0)) {

                const baseInteger = value.abs().trunc().toFixed();

                const baseIntegerDigits = baseInteger.length;

                const correctionDigits = baseIntegerDigits - ecmaIntegerTrimmedDigits;

                if (correctionDigits > 0) {

                    value = value.mul(pow10(-correctionDigits));

                }

            }

            // 6.3.2. Engr./Scientific notations: evaluate the exponent from the text

            if ((notation === "engineering" || notation === "scientific") && ecmaExponentValue !== zero) {

                const exponential = new Decimal(convert(ecmaExponentValue));

                value = value.mul(pow10(exponential.mul(-1))).abs().mul(sign); // prettier-ignore

            }

            // 6.3.3. Percent style: shift the value accordingly (non numeric parts will remain the same)

            if (style === "percent") value = value.mul(100);

            // 6.4. Parsing the information about the numeric parts

            const integer = value.abs().trunc().mul(sign);

            const fraction = value.sub(integer).abs();

            const integerDigits = !value.eq(0) && integer.eq(0) ? 0 : value.abs().trunc().toFixed().length;

            const fractionDigits = value.dp();

            const maxSD = resolved.maximumSignificantDigits ?? resolved.maximumFractionDigits! + integerDigits;

            const maxFD = resolved.maximumFractionDigits ?? maxSD - integerDigits;

            const minSD = resolved.minimumSignificantDigits ?? resolved.minimumFractionDigits! + integerDigits;

            const minFD = resolved.minimumFractionDigits ?? minSD - integerDigits;

            // 6.5. Check for the possibility of the native formatter to have accomplished the desired output

            const integerCheck = !ecmaIntegerParts.length || (minID <= ECMA_LIMIT && ecmaIntegerDigits >= minID);

            const fractionCheck = !ecmaFractionDigits || (minFD < ECMA_LIMIT && ecmaFractionDigits >= minFD);

            // -> if the native formatter is good enough for our decimal value, leave it as-is

            if (integerCheck && fractionCheck) {

                return ecmaParts as FormatPart[];

            }

            // 6.6. Create the integer value

            const integerParts = (() => {

                if (integerCheck) return ecmaIntegerParts;

                // Expanding the integer part

                const targetDigits = Math.max(integerDigits, minID);

                // Creates a base 10 power of the target digits

                const bigint = BigInt(pow10(targetDigits - 1).toFixed());

                // Format using the bigint formatter and cut it before joining with the ECMA parts

                const bigintIntegerParts = bigintFormat.formatToParts(bigint).filter(integerGroups);

                // We need to replace the first 'one' (from the base 10 power) with a 'zero'

                bigintIntegerParts[0].value = bigintIntegerParts[0].value.replace(new RegExp(one), zero);

                // Merge the first part with the bigint part

                ecmaIntegerParts[0].value =

                    bigintIntegerParts[ecmaIntegerParts.length - 1].value.slice(0, -ecmaIntegerParts[0].value.length) +

                    ecmaIntegerParts[0].value;

                return [...bigintIntegerParts.slice(0, -ecmaIntegerParts.length), ...ecmaIntegerParts];

            })();

            // 6.7. Create the fraction value

            const fractionValue = (() => {

                if (fractionCheck) return ecmaFractionValue;

                // Simpler formatting if there is actually no fraction

                if (fraction.eq(0)) {

                    return plainFormat.format(BigInt(pow10(minFD).toFixed())).slice(1);

                }

                let suffix = "";

                // Exponential value of the fraction (converting from decimal to bigint)

                const exponential = fraction.toDP(maxFD, rounding).mul(pow10(maxFD)).toFixed();

                // First, create a zero-filled right-side expansion if the digits are insufficient

                if (fractionDigits < minFD) {

                    suffix = zeroFill(minFD - maxFD);

                }

                const fractionValue = plainFormat.format(BigInt(exponential)) + suffix;

                // If the value is still not enough, it needs more left-zero-filling

                if (fractionValue.length < minFD) {

                    return zeroFill(minFD - fractionValue.length) + fractionValue;

                }

                // If it's bigger than the maximum, slice it

                else if (fractionValue.length > maxFD) {

                    return fractionValue.slice(0, maxFD);

                }

                return fractionValue;

            })();

            // 6.8. Parsing the numeric fragments in a unified part array

            const result: FormatPart[] = [];

            let integerDone = false;

            let fractionDone = false;

            while (ecmaParts.length) {

                const { type, value } = ecmaParts.shift()!;

                if (type === "integer" || type === "group") {

                    if (!integerDone) {

                        integerDone = true;

                        result.push(...integerParts);

                    }

                    continue;

                }

                if (type === "fraction") {

                    if (!fractionDone) {

                        fractionDone = true;

                        result.push({ type, value: fractionValue });

                    }

                    continue;

                }

                result.push({ type, value });

            }

            return result;

        };

        //#endregion

        this.format = value => concatenate(_formatToParts(value));

        this.formatToParts = value => _formatToParts(value);

        this.resolvedOptions = () => ({ ...resolved });

    }

    /**

     * Returns an array containing the default locales available to the environment, based on a default

     * dictionary of locales and regions.

     *

     * **Note:** This method is non-standard and not available on `Intl` formatters.

     *

     * @returns Array of strings with the available locales.

     */

    static supportedLocales(): FormatLocale[] {

        return Intl.NumberFormat.supportedLocalesOf(defaultLocales);

    }

}

// eslint-disable-next-line @typescript-eslint/no-namespace

export declare namespace Format {

    export type {

        BaseFormatOptions,

        FormatCompactDisplay,

        FormatCurrency,

        FormatCurrencyDisplay,

        FormatCurrencySign,

        FormatLocale,

        FormatLocaleMatcher,

        FormatNotation,

        FormatNumberingSystem,

        FormatOptions,

        FormatPart,

        FormatPartTypes,

        ResolvedFormatOptions,

        FormatSignDisplay,

        FormatStyle,

        FormatTrailingZeroDisplay,

        FormatUnit,

        FormatUnitDisplay,

        FormatUseGrouping,

    };

}

export type {

    BaseFormatOptions,

    FormatCompactDisplay,

    FormatCurrency,

    FormatCurrencyDisplay,

    FormatCurrencySign,

    FormatLocale,

    FormatLocaleMatcher,

    FormatNotation,

    FormatNumberingSystem,

    FormatOptions,

    FormatPart,

    FormatPartTypes,

    ResolvedFormatOptions,

    FormatSignDisplay,

    FormatStyle,

    FormatTrailingZeroDisplay,

    FormatUnit,

    FormatUnitDisplay,

    FormatUseGrouping,

};

export default Format;