decimal128/src/Decimal.mjs

Partial implementation of IEEE 754 Decimal128 decimal floating-point numbers

import { Rational } from "./Rational.mjs";
function _cohort(s) {
    if (s.match(/^-/)) {
        let c = _cohort(s.substring(1));
        if (c === "0") {
            return "-0";
        }
        return c.negate();
    }
    if (s.match(/^00+/)) {
        return _cohort(s.substring(1));
    }
    if (s.match(/^0([.]0+)?$/)) {
        return "0";
    }
    if (s.match(/^0[eE][+-]?[0-9]+$/)) {
        return "0";
    }
    return Rational.fromString(s);
}
function _quantum(s) {
    if (s.match(/^-/)) {
        return _quantum(s.substring(1));
    }
    if (s.match(/[.]/)) {
        let [_, rhs] = s.split(".");
        if (rhs.match(/[eE]/)) {
            let [dec, exp] = rhs.split(/[eE]/);
            return parseInt(exp) - dec.length;
        }
        return 0 - rhs.length;
    }
    if (s.match(/[eE]/)) {
        let [_, exp] = s.split(/[eE]/);
        return parseInt(exp);
    }
    return 0;
}
export class Decimal {
    constructor(x) {
        let v = typeof x === "string" ? _cohort(x) : x.cohort;
        let q = typeof x === "string" ? _quantum(x) : x.quantum;
        if (v instanceof Rational && v.isZero()) {
            throw new RangeError("A rational number cohort must not be zero.");
        }
        if (!Number.isInteger(q)) {
            throw new RangeError("The quantum must be an integer.");
        }
        if (Object.is(q, -0)) {
            throw new RangeError("The quantum cannot be negative zero.");
        }
        this.cohort = v;
        this.quantum = q;
    }
    negate() {
        let v = this.cohort;
        return new Decimal({
            cohort: v.negate(),
            quantum: this.quantum,
        });
    }
    coefficient() {
        let v = this.cohort;
        let q = this.quantum;
        let c = v.scale10(0 - q);
        return c.numerator;
    }
    isNegative() {
        let v = this.cohort;
        return v.isNegative;
    }
}