@numio/bigmath/src/round/utils.js

@numio/bigmath is an arbitrary-precision arithmetic library. It can be used for basic operations with decimal numbers (integers and float)

import { DOWN, HALF_DOWN, HALF_EVEN, HALF_ODD, HALF_UP, UP, } from "./constants.js";
export const handleTail = (array, isFloat) => {
    let lastIdx = array.length - 1;
    while (isFloat && array[lastIdx] <= 48) {
        if (array[lastIdx] === 46 || array.length === 1)
            isFloat = false;
        array.length > 1 && array.pop();
        lastIdx -= 1;
    }
};
export const handleCarryOver = (array, isFloat) => {
    var _a;
    let hasCarryOver = true;
    let idx = array.length - 1;
    const mapFloat = new Map([
        [57, () => {
                array.pop();
                idx -= 1;
            }],
        [46, () => {
                array.pop();
                idx -= 1;
                isFloat = false;
            }],
        [0, () => {
                array[idx] += 1;
                hasCarryOver = false;
            }],
    ]);
    const mapInt = new Map([
        [57, () => {
                array[idx] = 48;
                idx -= 1;
            }],
        [0, () => {
                array[idx] += 1;
                hasCarryOver = false;
            }],
    ]);
    while (hasCarryOver && idx >= 0) {
        const map = isFloat ? mapFloat : mapInt;
        const key = map.has(array[idx]) ? array[idx] : 0;
        (_a = map.get(key)) === null || _a === void 0 ? void 0 : _a();
    }
    hasCarryOver && array.unshift(49);
    return [array, isFloat];
};
export const calcLast = (current, next, roundMode) => {
    const isEven = current % 2 === 1;
    const map = {
        [UP]: current + (next > 48 ? 1 : 0),
        [DOWN]: current,
        [HALF_UP]: current + (next >= 53 ? 1 : 0),
        [HALF_DOWN]: current + (next > 53 ? 1 : 0),
        [HALF_EVEN]: current + ((isEven && next >= 53) ? 1 : 0),
        [HALF_ODD]: current + ((!isEven && next >= 53) ? 1 : 0),
    };
    return map[roundMode] > 57 ? [48, true] : [map[roundMode], false];
};