index.js

/* globals Symbol: false, Uint8Array: false, WeakMap: false */
/*!
 * deep-eql
 * Copyright(c) 2013 Jake Luer <jake@alogicalparadox.com>
 * MIT Licensed
 */

function type(obj) {
  if (typeof obj === 'undefined') {
    return 'undefined';
  }

  if (obj === null) {
    return 'null';
  }

  const stringTag = obj[Symbol.toStringTag];
  if (typeof stringTag === 'string') {
    return stringTag;
  }
  const sliceStart = 8;
  const sliceEnd = -1;
  return Object.prototype.toString.call(obj).slice(sliceStart, sliceEnd);
}

function FakeMap() {
  this._key = 'chai/deep-eql__' + Math.random() + Date.now();
}

FakeMap.prototype = {
  get: function get(key) {
    return key[this._key];
  },
  set: function set(key, value) {
    if (Object.isExtensible(key)) {
      Object.defineProperty(key, this._key, {
        value: value,
        configurable: true,
      });
    }
  },
};

export var MemoizeMap = typeof WeakMap === 'function' ? WeakMap : FakeMap;
/*!
 * Check to see if the MemoizeMap has recorded a result of the two operands
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {MemoizeMap} memoizeMap
 * @returns {Boolean|null} result
*/
function memoizeCompare(leftHandOperand, rightHandOperand, memoizeMap) {
  // Technically, WeakMap keys can *only* be objects, not primitives.
  if (!memoizeMap || isPrimitive(leftHandOperand) || isPrimitive(rightHandOperand)) {
    return null;
  }
  var leftHandMap = memoizeMap.get(leftHandOperand);
  if (leftHandMap) {
    var result = leftHandMap.get(rightHandOperand);
    if (typeof result === 'boolean') {
      return result;
    }
  }
  return null;
}

/*!
 * Set the result of the equality into the MemoizeMap
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {MemoizeMap} memoizeMap
 * @param {Boolean} result
*/
function memoizeSet(leftHandOperand, rightHandOperand, memoizeMap, result) {
  // Technically, WeakMap keys can *only* be objects, not primitives.
  if (!memoizeMap || isPrimitive(leftHandOperand) || isPrimitive(rightHandOperand)) {
    return;
  }
  var leftHandMap = memoizeMap.get(leftHandOperand);
  if (leftHandMap) {
    leftHandMap.set(rightHandOperand, result);
  } else {
    leftHandMap = new MemoizeMap();
    leftHandMap.set(rightHandOperand, result);
    memoizeMap.set(leftHandOperand, leftHandMap);
  }
}

/*!
 * Primary Export
 */

export default deepEqual;

/**
 * Assert deeply nested sameValue equality between two objects of any type.
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {Object} [options] (optional) Additional options
 * @param {Array} [options.comparator] (optional) Override default algorithm, determining custom equality.
 * @param {Array} [options.memoize] (optional) Provide a custom memoization object which will cache the results of
    complex objects for a speed boost. By passing `false` you can disable memoization, but this will cause circular
    references to blow the stack.
 * @return {Boolean} equal match
 */
function deepEqual(leftHandOperand, rightHandOperand, options) {
  // If we have a comparator, we can't assume anything; so bail to its check first.
  if (options && options.comparator) {
    return extensiveDeepEqual(leftHandOperand, rightHandOperand, options);
  }

  var simpleResult = simpleEqual(leftHandOperand, rightHandOperand);
  if (simpleResult !== null) {
    return simpleResult;
  }

  // Deeper comparisons are pushed through to a larger function
  return extensiveDeepEqual(leftHandOperand, rightHandOperand, options);
}

/**
 * Many comparisons can be canceled out early via simple equality or primitive checks.
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @return {Boolean|null} equal match
 */
function simpleEqual(leftHandOperand, rightHandOperand) {
  // Equal references (except for Numbers) can be returned early
  if (leftHandOperand === rightHandOperand) {
    // Handle +-0 cases
    return leftHandOperand !== 0 || 1 / leftHandOperand === 1 / rightHandOperand;
  }

  // handle NaN cases
  if (
    leftHandOperand !== leftHandOperand && // eslint-disable-line no-self-compare
    rightHandOperand !== rightHandOperand // eslint-disable-line no-self-compare
  ) {
    return true;
  }

  // Anything that is not an 'object', i.e. symbols, functions, booleans, numbers,
  // strings, and undefined, can be compared by reference.
  if (isPrimitive(leftHandOperand) || isPrimitive(rightHandOperand)) {
    // Easy out b/c it would have passed the first equality check
    return false;
  }
  return null;
}

/*!
 * The main logic of the `deepEqual` function.
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {Object} [options] (optional) Additional options
 * @param {Array} [options.comparator] (optional) Override default algorithm, determining custom equality.
 * @param {Array} [options.memoize] (optional) Provide a custom memoization object which will cache the results of
    complex objects for a speed boost. By passing `false` you can disable memoization, but this will cause circular
    references to blow the stack.
 * @return {Boolean} equal match
*/
function extensiveDeepEqual(leftHandOperand, rightHandOperand, options) {
  options = options || {};
  options.memoize = options.memoize === false ? false : options.memoize || new MemoizeMap();
  var comparator = options && options.comparator;

  // Check if a memoized result exists.
  var memoizeResultLeft = memoizeCompare(leftHandOperand, rightHandOperand, options.memoize);
  if (memoizeResultLeft !== null) {
    return memoizeResultLeft;
  }
  var memoizeResultRight = memoizeCompare(rightHandOperand, leftHandOperand, options.memoize);
  if (memoizeResultRight !== null) {
    return memoizeResultRight;
  }

  // If a comparator is present, use it.
  if (comparator) {
    var comparatorResult = comparator(leftHandOperand, rightHandOperand);
    // Comparators may return null, in which case we want to go back to default behavior.
    if (comparatorResult === false || comparatorResult === true) {
      memoizeSet(leftHandOperand, rightHandOperand, options.memoize, comparatorResult);
      return comparatorResult;
    }
    // To allow comparators to override *any* behavior, we ran them first. Since it didn't decide
    // what to do, we need to make sure to return the basic tests first before we move on.
    var simpleResult = simpleEqual(leftHandOperand, rightHandOperand);
    if (simpleResult !== null) {
      // Don't memoize this, it takes longer to set/retrieve than to just compare.
      return simpleResult;
    }
  }

  var leftHandType = type(leftHandOperand);
  if (leftHandType !== type(rightHandOperand)) {
    memoizeSet(leftHandOperand, rightHandOperand, options.memoize, false);
    return false;
  }

  // Temporarily set the operands in the memoize object to prevent blowing the stack
  memoizeSet(leftHandOperand, rightHandOperand, options.memoize, true);

  var result = extensiveDeepEqualByType(leftHandOperand, rightHandOperand, leftHandType, options);
  memoizeSet(leftHandOperand, rightHandOperand, options.memoize, result);
  return result;
}

function extensiveDeepEqualByType(leftHandOperand, rightHandOperand, leftHandType, options) {
  switch (leftHandType) {
    case 'String':
    case 'Number':
    case 'Boolean':
    case 'Date':
      // If these types are their instance types (e.g. `new Number`) then re-deepEqual against their values
      return deepEqual(leftHandOperand.valueOf(), rightHandOperand.valueOf());
    case 'Promise':
    case 'Symbol':
    case 'function':
    case 'WeakMap':
    case 'WeakSet':
      return leftHandOperand === rightHandOperand;
    case 'Error':
      return keysEqual(leftHandOperand, rightHandOperand, [ 'name', 'message', 'code' ], options);
    case 'Arguments':
    case 'Int8Array':
    case 'Uint8Array':
    case 'Uint8ClampedArray':
    case 'Int16Array':
    case 'Uint16Array':
    case 'Int32Array':
    case 'Uint32Array':
    case 'Float32Array':
    case 'Float64Array':
    case 'Array':
      return iterableEqual(leftHandOperand, rightHandOperand, options);
    case 'RegExp':
      return regexpEqual(leftHandOperand, rightHandOperand);
    case 'Generator':
      return generatorEqual(leftHandOperand, rightHandOperand, options);
    case 'DataView':
      return iterableEqual(new Uint8Array(leftHandOperand.buffer), new Uint8Array(rightHandOperand.buffer), options);
    case 'ArrayBuffer':
      return iterableEqual(new Uint8Array(leftHandOperand), new Uint8Array(rightHandOperand), options);
    case 'Set':
      return entriesEqual(leftHandOperand, rightHandOperand, options);
    case 'Map':
      return entriesEqual(leftHandOperand, rightHandOperand, options);
    case 'Temporal.PlainDate':
    case 'Temporal.PlainTime':
    case 'Temporal.PlainDateTime':
    case 'Temporal.Instant':
    case 'Temporal.ZonedDateTime':
    case 'Temporal.PlainYearMonth':
    case 'Temporal.PlainMonthDay':
      return leftHandOperand.equals(rightHandOperand);
    case 'Temporal.Duration':
      return leftHandOperand.total('nanoseconds') === rightHandOperand.total('nanoseconds');
    case 'Temporal.TimeZone':
    case 'Temporal.Calendar':
      return leftHandOperand.toString() === rightHandOperand.toString();
    default:
      return objectEqual(leftHandOperand, rightHandOperand, options);
  }
}

/*!
 * Compare two Regular Expressions for equality.
 *
 * @param {RegExp} leftHandOperand
 * @param {RegExp} rightHandOperand
 * @return {Boolean} result
 */

function regexpEqual(leftHandOperand, rightHandOperand) {
  return leftHandOperand.toString() === rightHandOperand.toString();
}

/*!
 * Compare two Sets/Maps for equality. Faster than other equality functions.
 *
 * @param {Set} leftHandOperand
 * @param {Set} rightHandOperand
 * @param {Object} [options] (Optional)
 * @return {Boolean} result
 */

function entriesEqual(leftHandOperand, rightHandOperand, options) {
  try {
    // IE11 doesn't support Set#entries or Set#@@iterator, so we need manually populate using Set#forEach
    if (leftHandOperand.size !== rightHandOperand.size) {
      return false;
    }
    if (leftHandOperand.size === 0) {
      return true;
    }
  } catch (sizeError) {
    // things that aren't actual Maps or Sets will throw here
    return false;
  }
  var leftHandItems = [];
  var rightHandItems = [];
  leftHandOperand.forEach(function gatherEntries(key, value) {
    leftHandItems.push([ key, value ]);
  });
  rightHandOperand.forEach(function gatherEntries(key, value) {
    rightHandItems.push([ key, value ]);
  });
  return iterableEqual(leftHandItems.sort(), rightHandItems.sort(), options);
}

/*!
 * Simple equality for flat iterable objects such as Arrays, TypedArrays or Node.js buffers.
 *
 * @param {Iterable} leftHandOperand
 * @param {Iterable} rightHandOperand
 * @param {Object} [options] (Optional)
 * @return {Boolean} result
 */

function iterableEqual(leftHandOperand, rightHandOperand, options) {
  var length = leftHandOperand.length;
  if (length !== rightHandOperand.length) {
    return false;
  }
  if (length === 0) {
    return true;
  }
  var index = -1;
  while (++index < length) {
    if (deepEqual(leftHandOperand[index], rightHandOperand[index], options) === false) {
      return false;
    }
  }
  return true;
}

/*!
 * Simple equality for generator objects such as those returned by generator functions.
 *
 * @param {Iterable} leftHandOperand
 * @param {Iterable} rightHandOperand
 * @param {Object} [options] (Optional)
 * @return {Boolean} result
 */

function generatorEqual(leftHandOperand, rightHandOperand, options) {
  return iterableEqual(getGeneratorEntries(leftHandOperand), getGeneratorEntries(rightHandOperand), options);
}

/*!
 * Determine if the given object has an @@iterator function.
 *
 * @param {Object} target
 * @return {Boolean} `true` if the object has an @@iterator function.
 */
function hasIteratorFunction(target) {
  return typeof Symbol !== 'undefined' &&
    typeof target === 'object' &&
    typeof Symbol.iterator !== 'undefined' &&
    typeof target[Symbol.iterator] === 'function';
}

/*!
 * Gets all iterator entries from the given Object. If the Object has no @@iterator function, returns an empty array.
 * This will consume the iterator - which could have side effects depending on the @@iterator implementation.
 *
 * @param {Object} target
 * @returns {Array} an array of entries from the @@iterator function
 */
function getIteratorEntries(target) {
  if (hasIteratorFunction(target)) {
    try {
      return getGeneratorEntries(target[Symbol.iterator]());
    } catch (iteratorError) {
      return [];
    }
  }
  return [];
}

/*!
 * Gets all entries from a Generator. This will consume the generator - which could have side effects.
 *
 * @param {Generator} target
 * @returns {Array} an array of entries from the Generator.
 */
function getGeneratorEntries(generator) {
  var generatorResult = generator.next();
  var accumulator = [ generatorResult.value ];
  while (generatorResult.done === false) {
    generatorResult = generator.next();
    accumulator.push(generatorResult.value);
  }
  return accumulator;
}

/*!
 * Gets all own and inherited enumerable keys from a target.
 *
 * @param {Object} target
 * @returns {Array} an array of own and inherited enumerable keys from the target.
 */
function getEnumerableKeys(target) {
  var keys = [];
  for (var key in target) {
    keys.push(key);
  }
  return keys;
}

function getEnumerableSymbols(target) {
  var keys = [];
  var allKeys = Object.getOwnPropertySymbols(target);
  for (var i = 0; i < allKeys.length; i += 1) {
    var key = allKeys[i];
    if (Object.getOwnPropertyDescriptor(target, key).enumerable) {
      keys.push(key);
    }
  }
  return keys;
}

/*!
 * Determines if two objects have matching values, given a set of keys. Defers to deepEqual for the equality check of
 * each key. If any value of the given key is not equal, the function will return false (early).
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {Array} keys An array of keys to compare the values of leftHandOperand and rightHandOperand against
 * @param {Object} [options] (Optional)
 * @return {Boolean} result
 */
function keysEqual(leftHandOperand, rightHandOperand, keys, options) {
  var length = keys.length;
  if (length === 0) {
    return true;
  }
  for (var i = 0; i < length; i += 1) {
    if (deepEqual(leftHandOperand[keys[i]], rightHandOperand[keys[i]], options) === false) {
      return false;
    }
  }
  return true;
}

/*!
 * Recursively check the equality of two Objects. Once basic sameness has been established it will defer to `deepEqual`
 * for each enumerable key in the object.
 *
 * @param {Mixed} leftHandOperand
 * @param {Mixed} rightHandOperand
 * @param {Object} [options] (Optional)
 * @return {Boolean} result
 */
function objectEqual(leftHandOperand, rightHandOperand, options) {
  var leftHandKeys = getEnumerableKeys(leftHandOperand);
  var rightHandKeys = getEnumerableKeys(rightHandOperand);
  var leftHandSymbols = getEnumerableSymbols(leftHandOperand);
  var rightHandSymbols = getEnumerableSymbols(rightHandOperand);
  leftHandKeys = leftHandKeys.concat(leftHandSymbols);
  rightHandKeys = rightHandKeys.concat(rightHandSymbols);

  if (leftHandKeys.length && leftHandKeys.length === rightHandKeys.length) {
    if (iterableEqual(mapSymbols(leftHandKeys).sort(), mapSymbols(rightHandKeys).sort()) === false) {
      return false;
    }
    return keysEqual(leftHandOperand, rightHandOperand, leftHandKeys, options);
  }

  var leftHandEntries = getIteratorEntries(leftHandOperand);
  var rightHandEntries = getIteratorEntries(rightHandOperand);
  if (leftHandEntries.length && leftHandEntries.length === rightHandEntries.length) {
    leftHandEntries.sort();
    rightHandEntries.sort();
    return iterableEqual(leftHandEntries, rightHandEntries, options);
  }

  if (leftHandKeys.length === 0 &&
      leftHandEntries.length === 0 &&
      rightHandKeys.length === 0 &&
      rightHandEntries.length === 0) {
    return true;
  }

  return false;
}

/*!
 * Returns true if the argument is a primitive.
 *
 * This intentionally returns true for all objects that can be compared by reference,
 * including functions and symbols.
 *
 * @param {Mixed} value
 * @return {Boolean} result
 */
function isPrimitive(value) {
  return value === null || typeof value !== 'object';
}

function mapSymbols(arr) {
  return arr.map(function mapSymbol(entry) {
    if (typeof entry === 'symbol') {
      return entry.toString();
    }

    return entry;
  });
}