decimal128/src/common.mts

Partial implementation of IEEE 754 Decimal128 decimal floating-point numbers

export function countFractionalDigits(s: string): number {
    let [, fractional] = s.split(".");

    if (undefined === fractional) {
        return 0;
    }

    return fractional.length;
}

export type Digit = -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9; // -1 signals that we're moving from the integer part to the decimal part of a decimal number

export const ROUNDING_MODE_CEILING = "ceil";
export const ROUNDING_MODE_FLOOR = "floor";
export const ROUNDING_MODE_TRUNCATE = "trunc";
export const ROUNDING_MODE_HALF_EVEN = "halfEven";
export const ROUNDING_MODE_HALF_EXPAND = "halfExpand";

export type RoundingMode =
    | "ceil"
    | "floor"
    | "trunc"
    | "halfEven"
    | "halfExpand";

export const ROUNDING_MODES: RoundingMode[] = [
    ROUNDING_MODE_CEILING,
    ROUNDING_MODE_FLOOR,
    ROUNDING_MODE_TRUNCATE,
    ROUNDING_MODE_HALF_EVEN,
    ROUNDING_MODE_HALF_EXPAND,
];