node/lib/internal/util/comparisons.js

'use strict';

const {
  ArrayIsArray,
  ArrayPrototypeFilter,
  ArrayPrototypePush,
  BigIntPrototypeValueOf,
  BooleanPrototypeValueOf,
  DatePrototypeGetTime,
  Error,
  NumberIsNaN,
  NumberPrototypeValueOf,
  ObjectGetOwnPropertySymbols: getOwnSymbols,
  ObjectGetPrototypeOf,
  ObjectIs,
  ObjectKeys,
  ObjectPrototypeHasOwnProperty: hasOwn,
  ObjectPrototypePropertyIsEnumerable: hasEnumerable,
  ObjectPrototypeToString,
  SafeSet,
  StringPrototypeValueOf,
  SymbolPrototypeValueOf,
  TypedArrayPrototypeGetByteLength: getByteLength,
  TypedArrayPrototypeGetSymbolToStringTag,
  Uint8Array,
} = primordials;

const { compare } = internalBinding('buffer');
const assert = require('internal/assert');
const { isURL } = require('internal/url');
const { isError } = require('internal/util');
const types = require('internal/util/types');
const {
  isAnyArrayBuffer,
  isArrayBufferView,
  isDate,
  isMap,
  isRegExp,
  isSet,
  isNativeError,
  isBoxedPrimitive,
  isNumberObject,
  isStringObject,
  isBooleanObject,
  isBigIntObject,
  isSymbolObject,
  isFloat32Array,
  isFloat64Array,
  isKeyObject,
  isCryptoKey,
  isWeakMap,
  isWeakSet,
} = types;
const {
  constants: {
    ONLY_ENUMERABLE,
    SKIP_SYMBOLS,
  },
  getOwnNonIndexProperties,
} = internalBinding('util');

const kStrict = 1;
const kLoose = 0;
const kPartial = 2;

const kNoIterator = 0;
const kIsArray = 1;
const kIsSet = 2;
const kIsMap = 3;

let kKeyObject;

// Check if they have the same source and flags
function areSimilarRegExps(a, b) {
  return a.source === b.source &&
         a.flags === b.flags &&
         a.lastIndex === b.lastIndex;
}

function isPartialUint8Array(a, b) {
  const lenA = getByteLength(a);
  const lenB = getByteLength(b);
  if (lenA < lenB) {
    return false;
  }
  let offsetA = 0;
  for (let offsetB = 0; offsetB < lenB; offsetB++) {
    while (!ObjectIs(a[offsetA], b[offsetB])) {
      offsetA++;
      if (offsetA > lenA - lenB + offsetB) {
        return false;
      }
    }
    offsetA++;
  }
  return true;
}

function isPartialArrayBufferView(a, b) {
  if (a.byteLength < b.byteLength) {
    return false;
  }
  return isPartialUint8Array(
    new Uint8Array(a.buffer, a.byteOffset, a.byteLength),
    new Uint8Array(b.buffer, b.byteOffset, b.byteLength),
  );
}

function areSimilarFloatArrays(a, b) {
  const len = getByteLength(a);
  if (len !== getByteLength(b)) {
    return false;
  }
  for (let offset = 0; offset < len; offset++) {
    if (a[offset] !== b[offset]) {
      return false;
    }
  }
  return true;
}

function areSimilarTypedArrays(a, b) {
  if (a.byteLength !== b.byteLength) {
    return false;
  }
  return compare(new Uint8Array(a.buffer, a.byteOffset, a.byteLength),
                 new Uint8Array(b.buffer, b.byteOffset, b.byteLength)) === 0;
}

function areEqualArrayBuffers(buf1, buf2) {
  return buf1.byteLength === buf2.byteLength &&
    compare(new Uint8Array(buf1), new Uint8Array(buf2)) === 0;
}

function isEqualBoxedPrimitive(val1, val2) {
  if (isNumberObject(val1)) {
    return isNumberObject(val2) &&
           ObjectIs(NumberPrototypeValueOf(val1),
                    NumberPrototypeValueOf(val2));
  }
  if (isStringObject(val1)) {
    return isStringObject(val2) &&
           StringPrototypeValueOf(val1) === StringPrototypeValueOf(val2);
  }
  if (isBooleanObject(val1)) {
    return isBooleanObject(val2) &&
           BooleanPrototypeValueOf(val1) === BooleanPrototypeValueOf(val2);
  }
  if (isBigIntObject(val1)) {
    return isBigIntObject(val2) &&
           BigIntPrototypeValueOf(val1) === BigIntPrototypeValueOf(val2);
  }
  if (isSymbolObject(val1)) {
    return isSymbolObject(val2) &&
          SymbolPrototypeValueOf(val1) === SymbolPrototypeValueOf(val2);
  }
  /* c8 ignore next */
  assert.fail(`Unknown boxed type ${val1}`);
}

function isEnumerableOrIdentical(val1, val2, prop, mode, memos, method) {
  return hasEnumerable(val2, prop) || // This is handled by Object.keys()
      (mode === kPartial && (val2[prop] === undefined || (prop === 'message' && val2[prop] === ''))) ||
      innerDeepEqual(val1[prop], val2[prop], mode, memos);
}

// Notes: Type tags are historical [[Class]] properties that can be set by
// FunctionTemplate::SetClassName() in C++ or Symbol.toStringTag in JS
// and retrieved using Object.prototype.toString.call(obj) in JS
// See https://tc39.github.io/ecma262/#sec-object.prototype.tostring
// for a list of tags pre-defined in the spec.
// There are some unspecified tags in the wild too (e.g. typed array tags).
// Since tags can be altered, they only serve fast failures
//
// For strict comparison, objects should have
// a) The same built-in type tag.
// b) The same prototypes.

function innerDeepEqual(val1, val2, mode, memos) {
  // All identical values are equivalent, as determined by ===.
  if (val1 === val2) {
    return val1 !== 0 || ObjectIs(val1, val2) || mode === kLoose;
  }

  // Check more closely if val1 and val2 are equal.
  if (mode !== kLoose) {
    if (typeof val1 === 'number') {
      return NumberIsNaN(val1) && NumberIsNaN(val2);
    }
    if (typeof val2 !== 'object' ||
        typeof val1 !== 'object' ||
        val1 === null ||
        val2 === null ||
        (mode === kStrict && ObjectGetPrototypeOf(val1) !== ObjectGetPrototypeOf(val2))) {
      return false;
    }
  } else {
    if (val1 === null || typeof val1 !== 'object') {
      return (val2 === null || typeof val2 !== 'object') &&
             // eslint-disable-next-line eqeqeq
             (val1 == val2 || (NumberIsNaN(val1) && NumberIsNaN(val2)));
    }
    if (val2 === null || typeof val2 !== 'object') {
      return false;
    }
  }
  const val1Tag = ObjectPrototypeToString(val1);
  const val2Tag = ObjectPrototypeToString(val2);

  if (val1Tag !== val2Tag) {
    return false;
  }

  if (ArrayIsArray(val1)) {
    // Check for sparse arrays and general fast path
    if (!ArrayIsArray(val2) ||
        (val1.length !== val2.length && (mode !== kPartial || val1.length < val2.length))) {
      return false;
    }

    const filter = mode !== kLoose ? ONLY_ENUMERABLE : ONLY_ENUMERABLE | SKIP_SYMBOLS;
    const keys2 = getOwnNonIndexProperties(val2, filter);
    if (mode !== kPartial &&
        keys2.length !== getOwnNonIndexProperties(val1, filter).length) {
      return false;
    }
    return keyCheck(val1, val2, mode, memos, kIsArray, keys2);
  } else if (val1Tag === '[object Object]') {
    return keyCheck(val1, val2, mode, memos, kNoIterator);
  } else if (isDate(val1)) {
    if (!isDate(val2) ||
        DatePrototypeGetTime(val1) !== DatePrototypeGetTime(val2)) {
      return false;
    }
  } else if (isRegExp(val1)) {
    if (!isRegExp(val2) || !areSimilarRegExps(val1, val2)) {
      return false;
    }
  } else if (isArrayBufferView(val1)) {
    if (TypedArrayPrototypeGetSymbolToStringTag(val1) !==
        TypedArrayPrototypeGetSymbolToStringTag(val2)) {
      return false;
    }
    if (mode === kPartial && val1.byteLength !== val2.byteLength) {
      if (!isPartialArrayBufferView(val1, val2)) {
        return false;
      }
    } else if (mode === kLoose && (isFloat32Array(val1) || isFloat64Array(val1))) {
      if (!areSimilarFloatArrays(val1, val2)) {
        return false;
      }
    } else if (!areSimilarTypedArrays(val1, val2)) {
      return false;
    }
    // Buffer.compare returns true, so val1.length === val2.length. If they both
    // only contain numeric keys, we don't need to exam further than checking
    // the symbols.
    const filter = mode !== kLoose ? ONLY_ENUMERABLE : ONLY_ENUMERABLE | SKIP_SYMBOLS;
    const keys2 = getOwnNonIndexProperties(val2, filter);
    if (mode !== kPartial &&
        keys2.length !== getOwnNonIndexProperties(val1, filter).length) {
      return false;
    }
    return keyCheck(val1, val2, mode, memos, kNoIterator, keys2);
  } else if (isSet(val1)) {
    if (!isSet(val2) ||
        (val1.size !== val2.size && (mode !== kPartial || val1.size < val2.size))) {
      return false;
    }
    return keyCheck(val1, val2, mode, memos, kIsSet);
  } else if (isMap(val1)) {
    if (!isMap(val2) ||
        (val1.size !== val2.size && (mode !== kPartial || val1.size < val2.size))) {
      return false;
    }
    return keyCheck(val1, val2, mode, memos, kIsMap);
  } else if (isAnyArrayBuffer(val1)) {
    if (!isAnyArrayBuffer(val2)) {
      return false;
    }
    if (mode !== kPartial || val1.byteLength === val2.byteLength) {
      if (!areEqualArrayBuffers(val1, val2)) {
        return false;
      }
    } else if (!isPartialUint8Array(new Uint8Array(val1), new Uint8Array(val2))) {
      return false;
    }
  } else if (isError(val1)) {
    // Do not compare the stack as it might differ even though the error itself
    // is otherwise identical.
    if (!isError(val2) ||
        !isEnumerableOrIdentical(val1, val2, 'message', mode, memos) ||
        !isEnumerableOrIdentical(val1, val2, 'name', mode, memos) ||
        !isEnumerableOrIdentical(val1, val2, 'cause', mode, memos) ||
        !isEnumerableOrIdentical(val1, val2, 'errors', mode, memos)) {
      return false;
    }
    const hasOwnVal2Cause = hasOwn(val2, 'cause');
    if ((hasOwnVal2Cause !== hasOwn(val1, 'cause') && (mode !== kPartial || hasOwnVal2Cause))) {
      return false;
    }
  } else if (isBoxedPrimitive(val1)) {
    if (!isEqualBoxedPrimitive(val1, val2)) {
      return false;
    }
  } else if (ArrayIsArray(val2) ||
             isArrayBufferView(val2) ||
             isSet(val2) ||
             isMap(val2) ||
             isDate(val2) ||
             isRegExp(val2) ||
             isAnyArrayBuffer(val2) ||
             isBoxedPrimitive(val2) ||
             isNativeError(val2) ||
             val2 instanceof Error) {
    return false;
  } else if (isKeyObject(val1)) {
    if (!isKeyObject(val2) || !val1.equals(val2)) {
      return false;
    }
  } else if (isCryptoKey(val1)) {
    kKeyObject ??= require('internal/crypto/util').kKeyObject;
    if (!isCryptoKey(val2) ||
      val1.extractable !== val2.extractable ||
      !innerDeepEqual(val1.algorithm, val2.algorithm, mode, memos) ||
      !innerDeepEqual(val1.usages, val2.usages, mode, memos) ||
      !innerDeepEqual(val1[kKeyObject], val2[kKeyObject], mode, memos)
    ) {
      return false;
    }
  } else if (isWeakMap(val1) || isWeakSet(val1)) {
    return false;
  } else if (isURL(val1)) {
    if (!isURL(val2) || val1.href !== val2.href) {
      return false;
    }
  }

  return keyCheck(val1, val2, mode, memos, kNoIterator);
}

function getEnumerables(val, keys) {
  return ArrayPrototypeFilter(keys, (key) => hasEnumerable(val, key));
}

function keyCheck(val1, val2, mode, memos, iterationType, keys2) {
  // For all remaining Object pairs, including Array, objects and Maps,
  // equivalence is determined by having:
  // a) The same number of owned enumerable properties
  // b) The same set of keys/indexes (although not necessarily the same order)
  // c) Equivalent values for every corresponding key/index
  // d) For Sets and Maps, equal contents
  // Note: this accounts for both named and indexed properties on Arrays.
  const isArrayLikeObject = keys2 !== undefined;

  if (keys2 === undefined) {
    keys2 = ObjectKeys(val2);
  }

  // Cheap key test
  if (keys2.length > 0) {
    for (const key of keys2) {
      if (!hasEnumerable(val1, key)) {
        return false;
      }
    }
  }

  if (!isArrayLikeObject) {
    // The pair must have the same number of owned properties.
    if (mode === kPartial) {
      const symbolKeys = getOwnSymbols(val2);
      if (symbolKeys.length !== 0) {
        for (const key of symbolKeys) {
          if (hasEnumerable(val2, key)) {
            if (!hasEnumerable(val1, key)) {
              return false;
            }
            ArrayPrototypePush(keys2, key);
          }
        }
      }
    } else if (keys2.length !== ObjectKeys(val1).length) {
      return false;
    } else if (mode === kStrict) {
      const symbolKeysA = getOwnSymbols(val1);
      if (symbolKeysA.length !== 0) {
        let count = 0;
        for (const key of symbolKeysA) {
          if (hasEnumerable(val1, key)) {
            if (!hasEnumerable(val2, key)) {
              return false;
            }
            ArrayPrototypePush(keys2, key);
            count++;
          } else if (hasEnumerable(val2, key)) {
            return false;
          }
        }
        const symbolKeysB = getOwnSymbols(val2);
        if (symbolKeysA.length !== symbolKeysB.length &&
            getEnumerables(val2, symbolKeysB).length !== count) {
          return false;
        }
      } else {
        const symbolKeysB = getOwnSymbols(val2);
        if (symbolKeysB.length !== 0 &&
            getEnumerables(val2, symbolKeysB).length !== 0) {
          return false;
        }
      }
    }
  }

  if (keys2.length === 0 &&
      (iterationType === kNoIterator ||
        (iterationType === kIsArray && val2.length === 0) ||
        val2.size === 0)) {
    return true;
  }

  // Use memos to handle cycles.
  if (memos === undefined) {
    memos = {
      set: undefined,
      a: val1,
      b: val2,
      c: undefined,
      d: undefined,
      deep: false,
    };
    return objEquiv(val1, val2, mode, keys2, memos, iterationType);
  }

  if (memos.set === undefined) {
    if (memos.deep === false) {
      if (memos.a === val1) {
        return memos.b === val2;
      }
      if (memos.b === val2) {
        return false;
      }
      memos.c = val1;
      memos.d = val2;
      memos.deep = true;
      const result = objEquiv(val1, val2, mode, keys2, memos, iterationType);
      memos.deep = false;
      return result;
    }
    memos.set = new SafeSet();
    memos.set.add(memos.a);
    memos.set.add(memos.b);
    memos.set.add(memos.c);
    memos.set.add(memos.d);
  }

  const { set } = memos;

  const originalSize = set.size;
  set.add(val1);
  set.add(val2);
  if (originalSize !== set.size - 2) {
    return originalSize === set.size;
  }

  const areEq = objEquiv(val1, val2, mode, keys2, memos, iterationType);

  set.delete(val1);
  set.delete(val2);

  return areEq;
}

function setHasEqualElement(set, val1, mode, memo) {
  for (const val2 of set) {
    if (innerDeepEqual(val1, val2, mode, memo)) {
      // Remove the matching element to make sure we do not check that again.
      set.delete(val2);
      return true;
    }
  }

  return false;
}

// See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Equality_comparisons_and_sameness#Loose_equality_using
// Sadly it is not possible to detect corresponding values properly in case the
// type is a string, number, bigint or boolean. The reason is that those values
// can match lots of different string values (e.g., 1n == '+00001').
function findLooseMatchingPrimitives(prim) {
  switch (typeof prim) {
    case 'undefined':
      return null;
    case 'object': // Only pass in null as object!
      return undefined;
    case 'symbol':
      return false;
    case 'string':
      prim = +prim;
      // Loose equal entries exist only if the string is possible to convert to
      // a regular number and not NaN.
      // Fall through
    case 'number':
      if (NumberIsNaN(prim)) {
        return false;
      }
  }
  return true;
}

function setMightHaveLoosePrim(a, b, prim) {
  const altValue = findLooseMatchingPrimitives(prim);
  if (altValue != null)
    return altValue;

  return !b.has(altValue) && a.has(altValue);
}

function mapMightHaveLoosePrim(a, b, prim, item2, memo) {
  const altValue = findLooseMatchingPrimitives(prim);
  if (altValue != null) {
    return altValue;
  }
  const item1 = a.get(altValue);
  if ((item1 === undefined && !a.has(altValue)) ||
      !innerDeepEqual(item1, item2, kLoose, memo)) {
    return false;
  }
  return !b.has(altValue) && innerDeepEqual(item1, item2, kLoose, memo);
}

function partialObjectSetEquiv(a, b, mode, set, memo) {
  let aPos = 0;
  for (const val of a) {
    aPos++;
    if (!b.has(val) && setHasEqualElement(set, val, mode, memo) && set.size === 0) {
      return true;
    }
    if (a.size - aPos < set.size) {
      return false;
    }
  }
  /* c8 ignore next */
  assert.fail('Unreachable code');
}

function setObjectEquiv(a, b, mode, set, memo) {
  // Fast path for objects only
  if (mode !== kLoose && set.size === a.size) {
    for (const val of a) {
      if (!setHasEqualElement(set, val, mode, memo)) {
        return false;
      }
    }
    return true;
  }
  if (mode === kPartial) {
    return partialObjectSetEquiv(a, b, mode, set, memo);
  }

  for (const val of a) {
    // Primitive values have already been handled above.
    if (typeof val === 'object') {
      if (!b.has(val) && !setHasEqualElement(set, val, mode, memo)) {
        return false;
      }
    } else if (mode === kLoose &&
              !b.has(val) &&
              !setHasEqualElement(set, val, mode, memo)) {
      return false;
    }
  }
  return set.size === 0;
}

function setEquiv(a, b, mode, memo) {
  // This is a lazily initiated Set of entries which have to be compared
  // pairwise.
  let set = null;
  for (const val of b) {
    if (!a.has(val)) {
      if ((typeof val !== 'object' || val === null) &&
          (mode !== kLoose || !setMightHaveLoosePrim(a, b, val))) {
        return false;
      }

      if (set === null) {
        if (a.size === 1) {
          return innerDeepEqual(a.values().next().value, val, mode, memo);
        }
        set = new SafeSet();
      }
      // If the specified value doesn't exist in the second set it's a object
      // (or in loose mode: a non-matching primitive). Find the
      // deep-(mode-)equal element in a set copy to reduce duplicate checks.
      set.add(val);
    }
  }

  if (set !== null) {
    return setObjectEquiv(a, b, mode, set, memo);
  }

  return true;
}

function mapHasEqualEntry(set, map, key1, item1, mode, memo) {
  // To be able to handle cases like:
  //   Map([[{}, 'a'], [{}, 'b']]) vs Map([[{}, 'b'], [{}, 'a']])
  // ... we need to consider *all* matching keys, not just the first we find.
  for (const key2 of set) {
    if (innerDeepEqual(key1, key2, mode, memo) &&
      innerDeepEqual(item1, map.get(key2), mode, memo)) {
      set.delete(key2);
      return true;
    }
  }

  return false;
}

function partialObjectMapEquiv(a, b, mode, set, memo) {
  let aPos = 0;
  for (const { 0: key1, 1: item1 } of a) {
    aPos++;
    if (typeof key1 === 'object' &&
        key1 !== null &&
        mapHasEqualEntry(set, b, key1, item1, mode, memo) &&
        set.size === 0) {
      return true;
    }
    if (a.size - aPos < set.size) {
      return false;
    }
  }
  /* c8 ignore next */
  assert.fail('Unreachable code');
}

function mapObjectEquivalence(a, b, mode, set, memo) {
  // Fast path for objects only
  if (mode !== kLoose && set.size === a.size) {
    for (const { 0: key1, 1: item1 } of a) {
      if (!mapHasEqualEntry(set, b, key1, item1, mode, memo)) {
        return false;
      }
    }
    return true;
  }
  if (mode === kPartial) {
    return partialObjectMapEquiv(a, b, mode, set, memo);
  }
  for (const { 0: key1, 1: item1 } of a) {
    if (typeof key1 === 'object' && key1 !== null) {
      if (!mapHasEqualEntry(set, b, key1, item1, mode, memo))
        return false;
    } else if (set.size === 0) {
      return true;
    } else if (mode === kLoose &&
              (!b.has(key1) ||
                !innerDeepEqual(item1, b.get(key1), mode, memo)) &&
              !mapHasEqualEntry(set, b, key1, item1, mode, memo)) {
      return false;
    }
  }
  return set.size === 0;
}

function mapEquiv(a, b, mode, memo) {
  let set = null;

  for (const { 0: key2, 1: item2 } of b) {
    if (typeof key2 === 'object' && key2 !== null) {
      if (set === null) {
        if (a.size === 1) {
          const { 0: key1, 1: item1 } = a.entries().next().value;
          return innerDeepEqual(key1, key2, mode, memo) &&
                 innerDeepEqual(item1, item2, mode, memo);
        }
        set = new SafeSet();
      }
      set.add(key2);
    } else {
      // By directly retrieving the value we prevent another b.has(key2) check in
      // almost all possible cases.
      const item1 = a.get(key2);
      if (((item1 === undefined && !a.has(key2)) ||
          !innerDeepEqual(item1, item2, mode, memo))) {
        if (mode !== kLoose)
          return false;
        // Fast path to detect missing string, symbol, undefined and null
        // keys.
        if (!mapMightHaveLoosePrim(a, b, key2, item2, memo))
          return false;
        if (set === null) {
          set = new SafeSet();
        }
        set.add(key2);
      }
    }
  }

  if (set !== null) {
    return mapObjectEquivalence(a, b, mode, set, memo);
  }

  return true;
}

function partialSparseArrayEquiv(a, b, mode, memos, startA, startB) {
  let aPos = 0;
  const keysA = ObjectKeys(a).slice(startA);
  const keysB = ObjectKeys(b).slice(startB);
  if (keysA.length < keysB.length) {
    return false;
  }
  for (let i = 0; i < keysB.length; i++) {
    const keyB = keysB[i];
    while (!innerDeepEqual(a[keysA[aPos]], b[keyB], mode, memos)) {
      aPos++;
      if (aPos > keysA.length - keysB.length + i) {
        return false;
      }
    }
    aPos++;
  }
  return true;
}

function partialArrayEquiv(a, b, mode, memos) {
  let aPos = 0;
  for (let i = 0; i < b.length; i++) {
    let isSparse = b[i] === undefined && !hasOwn(b, i);
    if (isSparse) {
      return partialSparseArrayEquiv(a, b, mode, memos, aPos, i);
    }
    while (!(isSparse = a[aPos] === undefined && !hasOwn(a, aPos)) &&
           !innerDeepEqual(a[aPos], b[i], mode, memos)) {
      aPos++;
      if (aPos > a.length - b.length + i) {
        return false;
      }
    }
    if (isSparse) {
      return partialSparseArrayEquiv(a, b, mode, memos, aPos, i);
    }
    aPos++;
  }
  return true;
}

function sparseArrayEquiv(a, b, mode, memos, i) {
  // TODO(BridgeAR): Use internal method to only get index properties. The
  // same applies to the partial implementation.
  const keysA = ObjectKeys(a);
  const keysB = ObjectKeys(b);
  if (keysA.length !== keysB.length) {
    return false;
  }
  for (; i < keysB.length; i++) {
    const key = keysB[i];
    if ((a[key] === undefined && !hasOwn(a, key)) || !innerDeepEqual(a[key], b[key], mode, memos)) {
      return false;
    }
  }
  return true;
}

function objEquiv(a, b, mode, keys2, memos, iterationType) {
  // The pair must have equivalent values for every corresponding key.
  if (keys2.length > 0) {
    for (const key of keys2) {
      if (!innerDeepEqual(a[key], b[key], mode, memos)) {
        return false;
      }
    }
  }

  if (iterationType === kIsArray) {
    if (mode === kPartial) {
      return partialArrayEquiv(a, b, mode, memos);
    }
    for (let i = 0; i < a.length; i++) {
      if (b[i] === undefined) {
        if (!hasOwn(b, i))
          return sparseArrayEquiv(a, b, mode, memos, i);
        if (a[i] !== undefined || !hasOwn(a, i))
          return false;
      } else if (a[i] === undefined || !innerDeepEqual(a[i], b[i], mode, memos)) {
        return false;
      }
    }
  } else if (iterationType === kIsSet) {
    if (!setEquiv(a, b, mode, memos)) {
      return false;
    }
  } else if (iterationType === kIsMap) {
    if (!mapEquiv(a, b, mode, memos)) {
      return false;
    }
  }

  return true;
}

module.exports = {
  isDeepEqual(val1, val2) {
    return innerDeepEqual(val1, val2, kLoose);
  },
  isDeepStrictEqual(val1, val2) {
    return innerDeepEqual(val1, val2, kStrict);
  },
  isPartialStrictEqual(val1, val2) {
    return innerDeepEqual(val1, val2, kPartial);
  },
};