@formatjs/ecma402-abstract/NumberFormat/ToRawFixed.js

A collection of implementation for ECMAScript abstract operations

import "../types/number.js";
import { repeat } from "../utils.js";
import { ApplyUnsignedRoundingMode } from "./ApplyUnsignedRoundingMode.js";
import { getPowerOf10 } from "./decimal-cache.js";
//IMPL: Helper function to calculate raw fixed value
function ToRawFixedFn(n, f) {
	return n.times(getPowerOf10(-f));
}
//IMPL: Helper function to find n1 and r1
function findN1R1(x, f, roundingIncrement) {
	const nx = x.times(getPowerOf10(f)).floor();
	const n1 = nx.div(roundingIncrement).floor().times(roundingIncrement);
	const r1 = ToRawFixedFn(n1, f);
	return {
		n1,
		r1
	};
}
//IMPL: Helper function to find n2 and r2
function findN2R2(x, f, roundingIncrement) {
	const nx = x.times(getPowerOf10(f)).ceil();
	const n2 = nx.div(roundingIncrement).ceil().times(roundingIncrement);
	const r2 = ToRawFixedFn(n2, f);
	return {
		n2,
		r2
	};
}
/**
* https://tc39.es/ecma402/#sec-torawfixed
* @param x a finite non-negative Number or BigInt
* @param minFraction an integer between 0 and 20
* @param maxFraction an integer between 0 and 20
*/
export function ToRawFixed(x, minFraction, maxFraction, roundingIncrement, unsignedRoundingMode) {
	// 1. Let f be maxFraction.
	const f = maxFraction;
	// 2. Let n1 and r1 be the results of performing the maximized rounding of x to f fraction digits.
	const { n1, r1 } = findN1R1(x, f, roundingIncrement);
	// 3. Let n2 and r2 be the results of performing the minimized rounding of x to f fraction digits.
	const { n2, r2 } = findN2R2(x, f, roundingIncrement);
	// 4. Let r be ApplyUnsignedRoundingMode(x, r1, r2, unsignedRoundingMode).
	const r = ApplyUnsignedRoundingMode(x, r1, r2, unsignedRoundingMode);
	let n, xFinal;
	let m;
	// 5. If r is equal to r1, then
	if (r.eq(r1)) {
		// a. Let n be n1.
		n = n1;
		// b. Let xFinal be r1.
		xFinal = r1;
	} else {
		// 6. Else,
		// a. Let n be n2.
		n = n2;
		// b. Let xFinal be r2.
		xFinal = r2;
	}
	// 7. If n is 0, let m be "0".
	if (n.isZero()) {
		m = "0";
	} else {
		// 8. Else, let m be the String representation of n.
		m = n.toString();
	}
	let int;
	// 9. If f is not 0, then
	if (f !== 0) {
		// a. Let k be the length of m.
		let k = m.length;
		// b. If k < f, then
		if (k <= f) {
			// i. Let z be the String value consisting of f + 1 - k occurrences of the character "0".
			const z = repeat("0", f - k + 1);
			// ii. Set m to the string-concatenation of z and m.
			m = z + m;
			// iii. Set k to f + 1.
			k = f + 1;
		}
		// c. Let a be the substring of m from 0 to k - f.
		const a = m.slice(0, k - f);
		// d. Let b be the substring of m from k - f to k.
		const b = m.slice(m.length - f);
		// e. Set m to the string-concatenation of a, ".", and b.
		m = a + "." + b;
		// f. Let int be the length of a.
		int = a.length;
	} else {
		// 10. Else, let int be the length of m.
		int = m.length;
	}
	// 11. Let cut be maxFraction - minFraction.
	let cut = maxFraction - minFraction;
	// 12. Repeat, while cut > 0 and the last character of m is "0",
	while (cut > 0 && m[m.length - 1] === "0") {
		// a. Remove the last character from m.
		m = m.slice(0, m.length - 1);
		// b. Decrease cut by 1.
		cut--;
	}
	// 13. If the last character of m is ".", then
	if (m[m.length - 1] === ".") {
		// a. Remove the last character from m.
		m = m.slice(0, m.length - 1);
	}
	// 14. Return the Record { [[FormattedString]]: m, [[RoundedNumber]]: xFinal, [[IntegerDigitsCount]]: int, [[RoundingMagnitude]]: -f }.
	return {
		formattedString: m,
		roundedNumber: xFinal,
		integerDigitsCount: int,
		roundingMagnitude: -f
	};
}