lodash-es/_equalByTag.js

import Symbol from './_Symbol';
import Uint8Array from './_Uint8Array';
import equalArrays from './_equalArrays';
import mapToArray from './_mapToArray';
import setToArray from './_setToArray';

/** Used to compose bitmasks for comparison styles. */
var UNORDERED_COMPARE_FLAG = 1,
    PARTIAL_COMPARE_FLAG = 2;

/** `Object#toString` result references. */
var boolTag = '[object Boolean]',
    dateTag = '[object Date]',
    errorTag = '[object Error]',
    mapTag = '[object Map]',
    numberTag = '[object Number]',
    regexpTag = '[object RegExp]',
    setTag = '[object Set]',
    stringTag = '[object String]',
    symbolTag = '[object Symbol]';

var arrayBufferTag = '[object ArrayBuffer]',
    dataViewTag = '[object DataView]';

/** Used to convert symbols to primitives and strings. */
var symbolProto = Symbol ? Symbol.prototype : undefined,
    symbolValueOf = symbolProto ? symbolProto.valueOf : undefined;

/**
 * A specialized version of `baseIsEqualDeep` for comparing objects of
 * the same `toStringTag`.
 *
 * **Note:** This function only supports comparing values with tags of
 * `Boolean`, `Date`, `Error`, `Number`, `RegExp`, or `String`.
 *
 * @private
 * @param {Object} object The object to compare.
 * @param {Object} other The other object to compare.
 * @param {string} tag The `toStringTag` of the objects to compare.
 * @param {Function} equalFunc The function to determine equivalents of values.
 * @param {Function} customizer The function to customize comparisons.
 * @param {number} bitmask The bitmask of comparison flags. See `baseIsEqual`
 *  for more details.
 * @param {Object} stack Tracks traversed `object` and `other` objects.
 * @returns {boolean} Returns `true` if the objects are equivalent, else `false`.
 */
function equalByTag(object, other, tag, equalFunc, customizer, bitmask, stack) {
  switch (tag) {
    case dataViewTag:
      if ((object.byteLength != other.byteLength) ||
          (object.byteOffset != other.byteOffset)) {
        return false;
      }
      object = object.buffer;
      other = other.buffer;

    case arrayBufferTag:
      if ((object.byteLength != other.byteLength) ||
          !equalFunc(new Uint8Array(object), new Uint8Array(other))) {
        return false;
      }
      return true;

    case boolTag:
    case dateTag:
      // Coerce dates and booleans to numbers, dates to milliseconds and
      // booleans to `1` or `0` treating invalid dates coerced to `NaN` as
      // not equal.
      return +object == +other;

    case errorTag:
      return object.name == other.name && object.message == other.message;

    case numberTag:
      // Treat `NaN` vs. `NaN` as equal.
      return (object != +object) ? other != +other : object == +other;

    case regexpTag:
    case stringTag:
      // Coerce regexes to strings and treat strings, primitives and objects,
      // as equal. See http://www.ecma-international.org/ecma-262/6.0/#sec-regexp.prototype.tostring
      // for more details.
      return object == (other + '');

    case mapTag:
      var convert = mapToArray;

    case setTag:
      var isPartial = bitmask & PARTIAL_COMPARE_FLAG;
      convert || (convert = setToArray);

      if (object.size != other.size && !isPartial) {
        return false;
      }
      // Assume cyclic values are equal.
      var stacked = stack.get(object);
      if (stacked) {
        return stacked == other;
      }
      bitmask |= UNORDERED_COMPARE_FLAG;
      stack.set(object, other);

      // Recursively compare objects (susceptible to call stack limits).
      return equalArrays(convert(object), convert(other), equalFunc, customizer, bitmask, stack);

    case symbolTag:
      if (symbolValueOf) {
        return symbolValueOf.call(object) == symbolValueOf.call(other);
      }
  }
  return false;
}

export default equalByTag;