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Arbitrary-precision arithmetic
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class AssertionError extends Error { | |
/** | |
* @param {String|void} message | |
*/ | |
constructor (message) { | |
super(message); | |
this.name = 'AssertionError | |
if (Error.captureStackTrace instanceof Function) { | |
Error.captureStackTrace(this, AssertionError); | |
} | |
} | |
toJSON () { | |
return { name: this.name, message: this.message, stack: this.stack }; | |
} | |
/** | |
* @param {Boolean} value | |
* @param {String|void} message | |
*/ | |
static assert (value, message) { | |
if (typeof value !== 'boolean') { | |
throw new Error('assert(value, message?), "value" must be a boolean.'); | |
} | |
if (message !== undefined && typeof message !== 'string') { | |
throw new Error('assert(value, message?), "message" must be a string.'); | |
} | |
if (value === false) { | |
throw new AssertionError(message); | |
} | |
} | |
} | |
let precision = 2; | |
let precision_multiplier = 10n ** BigInt(precision); | |
let min_safe_integer = BigInt(Number.MIN_SAFE_INTEGER) * precision_multiplier; | |
let max_safe_integer = BigInt(Number.MAX_SAFE_INTEGER) * precision_multiplier; | |
/** | |
* @param {Number} value | |
*/ | |
const set_precision = (value) => { | |
AssertionError.assert(typeof value === 'number'); | |
AssertionError.assert(Number.isFinite(value) === true); | |
AssertionError.assert(Number.isInteger(value) === true); | |
AssertionError.assert(value >= 0 && value <= 15); | |
precision = value; | |
precision_multiplier = 10n ** BigInt(precision); | |
min_safe_integer = BigInt(Number.MIN_SAFE_INTEGER) * precision_multiplier; | |
max_safe_integer = BigInt(Number.MAX_SAFE_INTEGER) * precision_multiplier; | |
}; | |
/** | |
* @param {Number} value | |
*/ | |
const to_bigint = (value) => { | |
AssertionError.assert(typeof value === 'number'); | |
AssertionError.assert(Number.isFinite(value) === true); | |
return BigInt(value.toFixed(precision).replace('.', '')); | |
}; | |
/** | |
* @param {BigInt} value | |
* @param {Number} decimal_places | |
*/ | |
const to_number = (value) => { | |
AssertionError.assert(typeof value === 'bigint'); | |
AssertionError.assert(value <= max_safe_integer && value >= min_safe_integer); | |
const value_string = value.toString().padStart(2 + precision, '0'); | |
const whole = value_string.substring(0, value_string.length - precision); | |
const decimal = value_string.substring(value_string.length - precision, value_string.length); | |
const result = Number(`${whole}.${decimal}`); | |
return result; | |
}; | |
/** | |
* @param {Number[]} values | |
*/ | |
const add = (...values) => to_number(values.reduce((previous, current) => previous === null ? to_bigint(current) : previous + to_bigint(current), null)); | |
const subtract = (...values) => to_number(values.reduce((previous, current) => previous === null ? to_bigint(current) : previous - to_bigint(current), null)); | |
const multiply = (...values) => to_number(values.reduce((previous, current) => previous === null ? to_bigint(current) : (previous * to_bigint(current)) / precision_multiplier, null)); | |
const divide = (...values) => to_number(values.reduce((previous, current) => previous === null ? to_bigint(current) : (previous * precision_multiplier) / to_bigint(current), null)); | |
const arbitrary = { set_precision, add, subtract, multiply, divide }; | |
module.exports = arbitrary; |
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