mathjs/src/utils/bignumber/bitXor.js

'use strict'
const bitwise = require('./bitwise')
const bitNot = require('./bitNot')

/**
 * Bitwise XOR for BigNumbers
 *
 * Special Cases:
 *   N ^  n =  N
 *   n ^  0 =  n
 *   n ^  n =  0
 *   n ^ -1 = ~n
 *   I ^  n =  I
 *   I ^ -n = -I
 *   I ^ -I = -1
 *  -I ^  n = -I
 *  -I ^ -n =  I
 *
 * @param {BigNumber} x
 * @param {BigNumber} y
 * @return {BigNumber} Result of `x` ^ `y`, fully precise
 *
 */
module.exports = function bitXor (x, y) {
  if ((x.isFinite() && !x.isInteger()) || (y.isFinite() && !y.isInteger())) {
    throw new Error('Integers expected in function bitXor')
  }

  const BigNumber = x.constructor
  if (x.isNaN() || y.isNaN()) {
    return new BigNumber(NaN)
  }
  if (x.isZero()) {
    return y
  }
  if (y.isZero()) {
    return x
  }

  if (x.eq(y)) {
    return new BigNumber(0)
  }

  const negOne = new BigNumber(-1)
  if (x.eq(negOne)) {
    return bitNot(y)
  }
  if (y.eq(negOne)) {
    return bitNot(x)
  }

  if (!x.isFinite() || !y.isFinite()) {
    if (!x.isFinite() && !y.isFinite()) {
      return negOne
    }
    return new BigNumber(x.isNegative() === y.isNegative()
      ? Infinity
      : -Infinity)
  }
  return bitwise(x, y, function (a, b) { return a ^ b })
}