summaryrefslogtreecommitdiff
path: root/lib/internal/util/comparisons.js
blob: b26012923c80c5c1e1eca14e3ec3286efdf1fc08 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
'use strict';

const {
  ArrayIsArray,
  BigIntPrototypeValueOf,
  BooleanPrototypeValueOf,
  DatePrototypeGetTime,
  NumberIsNaN,
  NumberPrototypeValueOf,
  ObjectGetOwnPropertySymbols,
  ObjectGetPrototypeOf,
  ObjectIs,
  ObjectKeys,
  ObjectPrototypeHasOwnProperty,
  ObjectPrototypePropertyIsEnumerable,
  ObjectPrototypeToString,
  StringPrototypeValueOf,
  SymbolPrototypeValueOf,
} = primordials;

const { compare } = internalBinding('buffer');
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);
  }
  return false;
}

function isIdenticalTypedArrayType(a, b) {
  // Fast path to reduce type checks in the common case.
  const check = types[`is${a[Symbol.toStringTag]}`];
  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);
    }
  }
  return false;
}

// 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 || (NumberIsNaN(val1) && NumberIsNaN(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
};