lts/lib/internal/util/comparisons.js
'use strict';
const {
ArrayIsArray,
BigIntPrototypeValueOf,
BooleanPrototypeValueOf,
DatePrototypeGetTime,
Error,
Map,
NumberIsNaN,
NumberPrototypeValueOf,
ObjectGetOwnPropertySymbols,
ObjectGetPrototypeOf,
ObjectIs,
ObjectKeys,
ObjectPrototypeHasOwnProperty,
ObjectPrototypePropertyIsEnumerable,
ObjectPrototypeToString,
Set,
StringPrototypeValueOf,
SymbolPrototypeValueOf,
SymbolToStringTag,
} = primordials;
const { compare } = internalBinding('buffer');
const assert = require('internal/assert');
const types = require('internal/util/types');
const {
isAnyArrayBuffer,
isArrayBufferView,
isDate,
isMap,
isRegExp,
isSet,
isNativeError,
isBoxedPrimitive,
isNumberObject,
isStringObject,
isBooleanObject,
isBigIntObject,
isSymbolObject,
isFloat32Array,
isFloat64Array,
isUint8Array,
isUint8ClampedArray,
isUint16Array,
isUint32Array,
isInt8Array,
isInt16Array,
isInt32Array,
isBigInt64Array,
isBigUint64Array
} = types;
const {
getOwnNonIndexProperties,
propertyFilter: {
ONLY_ENUMERABLE,
SKIP_SYMBOLS
}
} = internalBinding('util');
const kStrict = true;
const kLoose = false;
const kNoIterator = 0;
const kIsArray = 1;
const kIsSet = 2;
const kIsMap = 3;
// Check if they have the same source and flags
function areSimilarRegExps(a, b) {
return a.source === b.source && a.flags === b.flags;
}
function areSimilarFloatArrays(a, b) {
if (a.byteLength !== b.byteLength) {
return false;
}
for (let offset = 0; offset < a.byteLength; 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 ${val1}`);
}
function isIdenticalTypedArrayType(a, b) {
// Fast path to reduce type checks in the common case.
const check = types[`is${a[SymbolToStringTag]}`];
if (check !== undefined && check(a)) {
return check(b);
}
// Manipulated Symbol.toStringTag.
for (const check of [
isUint16Array,
isUint32Array,
isInt8Array,
isInt16Array,
isInt32Array,
isFloat32Array,
isFloat64Array,
isBigInt64Array,
isBigUint64Array,
isUint8ClampedArray,
isUint8Array
]) {
if (check(a)) {
return check(b);
}
}
/* c8 ignore next 4 */
assert.fail(
`Unknown TypedArray type checking ${a[SymbolToStringTag]} ${a}\n` +
`and ${b[SymbolToStringTag]} ${b}`
);
}
// 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, strict, memos) {
// All identical values are equivalent, as determined by ===.
if (val1 === val2) {
if (val1 !== 0)
return true;
return strict ? ObjectIs(val1, val2) : true;
}
// Check more closely if val1 and val2 are equal.
if (strict) {
if (typeof val1 !== 'object') {
return typeof val1 === 'number' && NumberIsNaN(val1) &&
NumberIsNaN(val2);
}
if (typeof val2 !== 'object' || val1 === null || val2 === null) {
return false;
}
if (ObjectGetPrototypeOf(val1) !== ObjectGetPrototypeOf(val2)) {
return false;
}
} else {
if (val1 === null || typeof val1 !== 'object') {
if (val2 === null || typeof val2 !== 'object') {
// eslint-disable-next-line eqeqeq
return val1 == val2;
}
return false;
}
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) {
return false;
}
const filter = strict ? ONLY_ENUMERABLE : ONLY_ENUMERABLE | SKIP_SYMBOLS;
const keys1 = getOwnNonIndexProperties(val1, filter);
const keys2 = getOwnNonIndexProperties(val2, filter);
if (keys1.length !== keys2.length) {
return false;
}
return keyCheck(val1, val2, strict, memos, kIsArray, keys1);
} else if (val1Tag === '[object Object]') {
return keyCheck(val1, val2, strict, 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 (isNativeError(val1) || val1 instanceof Error) {
// Do not compare the stack as it might differ even though the error itself
// is otherwise identical.
if ((!isNativeError(val2) && !(val2 instanceof Error)) ||
val1.message !== val2.message ||
val1.name !== val2.name) {
return false;
}
} else if (isArrayBufferView(val1)) {
if (!isIdenticalTypedArrayType(val1, val2))
return false;
if (!strict && (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 = strict ? ONLY_ENUMERABLE : ONLY_ENUMERABLE | SKIP_SYMBOLS;
const keys1 = getOwnNonIndexProperties(val1, filter);
const keys2 = getOwnNonIndexProperties(val2, filter);
if (keys1.length !== keys2.length) {
return false;
}
return keyCheck(val1, val2, strict, memos, kNoIterator, keys1);
} else if (isSet(val1)) {
if (!isSet(val2) || val1.size !== val2.size) {
return false;
}
return keyCheck(val1, val2, strict, memos, kIsSet);
} else if (isMap(val1)) {
if (!isMap(val2) || val1.size !== val2.size) {
return false;
}
return keyCheck(val1, val2, strict, memos, kIsMap);
} else if (isAnyArrayBuffer(val1)) {
if (!isAnyArrayBuffer(val2) || !areEqualArrayBuffers(val1, val2)) {
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;
}
return keyCheck(val1, val2, strict, memos, kNoIterator);
}
function getEnumerables(val, keys) {
return keys.filter((k) => ObjectPrototypePropertyIsEnumerable(val, k));
}
function keyCheck(val1, val2, strict, memos, iterationType, aKeys) {
// 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.
if (arguments.length === 5) {
aKeys = ObjectKeys(val1);
const bKeys = ObjectKeys(val2);
// The pair must have the same number of owned properties.
if (aKeys.length !== bKeys.length) {
return false;
}
}
// Cheap key test
let i = 0;
for (; i < aKeys.length; i++) {
if (!ObjectPrototypeHasOwnProperty(val2, aKeys[i])) {
return false;
}
}
if (strict && arguments.length === 5) {
const symbolKeysA = ObjectGetOwnPropertySymbols(val1);
if (symbolKeysA.length !== 0) {
let count = 0;
for (i = 0; i < symbolKeysA.length; i++) {
const key = symbolKeysA[i];
if (ObjectPrototypePropertyIsEnumerable(val1, key)) {
if (!ObjectPrototypePropertyIsEnumerable(val2, key)) {
return false;
}
aKeys.push(key);
count++;
} else if (ObjectPrototypePropertyIsEnumerable(val2, key)) {
return false;
}
}
const symbolKeysB = ObjectGetOwnPropertySymbols(val2);
if (symbolKeysA.length !== symbolKeysB.length &&
getEnumerables(val2, symbolKeysB).length !== count) {
return false;
}
} else {
const symbolKeysB = ObjectGetOwnPropertySymbols(val2);
if (symbolKeysB.length !== 0 &&
getEnumerables(val2, symbolKeysB).length !== 0) {
return false;
}
}
}
if (aKeys.length === 0 &&
(iterationType === kNoIterator ||
(iterationType === kIsArray && val1.length === 0) ||
val1.size === 0)) {
return true;
}
// Use memos to handle cycles.
if (memos === undefined) {
memos = {
val1: new Map(),
val2: new Map(),
position: 0
};
} else {
// We prevent up to two map.has(x) calls by directly retrieving the value
// and checking for undefined. The map can only contain numbers, so it is
// safe to check for undefined only.
const val2MemoA = memos.val1.get(val1);
if (val2MemoA !== undefined) {
const val2MemoB = memos.val2.get(val2);
if (val2MemoB !== undefined) {
return val2MemoA === val2MemoB;
}
}
memos.position++;
}
memos.val1.set(val1, memos.position);
memos.val2.set(val2, memos.position);
const areEq = objEquiv(val1, val2, strict, aKeys, memos, iterationType);
memos.val1.delete(val1);
memos.val2.delete(val2);
return areEq;
}
function setHasEqualElement(set, val1, strict, memo) {
// Go looking.
for (const val2 of set) {
if (innerDeepEqual(val1, val2, strict, 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, item, memo) {
const altValue = findLooseMatchingPrimitives(prim);
if (altValue != null) {
return altValue;
}
const curB = b.get(altValue);
if ((curB === undefined && !b.has(altValue)) ||
!innerDeepEqual(item, curB, false, memo)) {
return false;
}
return !a.has(altValue) && innerDeepEqual(item, curB, false, memo);
}
function setEquiv(a, b, strict, memo) {
// This is a lazily initiated Set of entries which have to be compared
// pairwise.
let set = null;
for (const val of a) {
// Note: Checking for the objects first improves the performance for object
// heavy sets but it is a minor slow down for primitives. As they are fast
// to check this improves the worst case scenario instead.
if (typeof val === 'object' && val !== null) {
if (set === null) {
set = new Set();
}
// If the specified value doesn't exist in the second set its an not null
// object (or non strict only: a not matching primitive) we'll need to go
// hunting for something thats deep-(strict-)equal to it. To make this
// O(n log n) complexity we have to copy these values in a new set first.
set.add(val);
} else if (!b.has(val)) {
if (strict)
return false;
// Fast path to detect missing string, symbol, undefined and null values.
if (!setMightHaveLoosePrim(a, b, val)) {
return false;
}
if (set === null) {
set = new Set();
}
set.add(val);
}
}
if (set !== null) {
for (const val of b) {
// We have to check if a primitive value is already
// matching and only if it's not, go hunting for it.
if (typeof val === 'object' && val !== null) {
if (!setHasEqualElement(set, val, strict, memo))
return false;
} else if (!strict &&
!a.has(val) &&
!setHasEqualElement(set, val, strict, memo)) {
return false;
}
}
return set.size === 0;
}
return true;
}
function mapHasEqualEntry(set, map, key1, item1, strict, 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, strict, memo) &&
innerDeepEqual(item1, map.get(key2), strict, memo)) {
set.delete(key2);
return true;
}
}
return false;
}
function mapEquiv(a, b, strict, memo) {
let set = null;
for (const [key, item1] of a) {
if (typeof key === 'object' && key !== null) {
if (set === null) {
set = new Set();
}
set.add(key);
} else {
// By directly retrieving the value we prevent another b.has(key) check in
// almost all possible cases.
const item2 = b.get(key);
if (((item2 === undefined && !b.has(key)) ||
!innerDeepEqual(item1, item2, strict, memo))) {
if (strict)
return false;
// Fast path to detect missing string, symbol, undefined and null
// keys.
if (!mapMightHaveLoosePrim(a, b, key, item1, memo))
return false;
if (set === null) {
set = new Set();
}
set.add(key);
}
}
}
if (set !== null) {
for (const [key, item] of b) {
if (typeof key === 'object' && key !== null) {
if (!mapHasEqualEntry(set, a, key, item, strict, memo))
return false;
} else if (!strict &&
(!a.has(key) ||
!innerDeepEqual(a.get(key), item, false, memo)) &&
!mapHasEqualEntry(set, a, key, item, false, memo)) {
return false;
}
}
return set.size === 0;
}
return true;
}
function objEquiv(a, b, strict, keys, memos, iterationType) {
// Sets and maps don't have their entries accessible via normal object
// properties.
let i = 0;
if (iterationType === kIsSet) {
if (!setEquiv(a, b, strict, memos)) {
return false;
}
} else if (iterationType === kIsMap) {
if (!mapEquiv(a, b, strict, memos)) {
return false;
}
} else if (iterationType === kIsArray) {
for (; i < a.length; i++) {
if (ObjectPrototypeHasOwnProperty(a, i)) {
if (!ObjectPrototypeHasOwnProperty(b, i) ||
!innerDeepEqual(a[i], b[i], strict, memos)) {
return false;
}
} else if (ObjectPrototypeHasOwnProperty(b, i)) {
return false;
} else {
// Array is sparse.
const keysA = ObjectKeys(a);
for (; i < keysA.length; i++) {
const key = keysA[i];
if (!ObjectPrototypeHasOwnProperty(b, key) ||
!innerDeepEqual(a[key], b[key], strict, memos)) {
return false;
}
}
if (keysA.length !== ObjectKeys(b).length) {
return false;
}
return true;
}
}
}
// The pair must have equivalent values for every corresponding key.
// Possibly expensive deep test:
for (i = 0; i < keys.length; i++) {
const key = keys[i];
if (!innerDeepEqual(a[key], b[key], strict, memos)) {
return false;
}
}
return true;
}
function isDeepEqual(val1, val2) {
return innerDeepEqual(val1, val2, kLoose);
}
function isDeepStrictEqual(val1, val2) {
return innerDeepEqual(val1, val2, kStrict);
}
module.exports = {
isDeepEqual,
isDeepStrictEqual
};