equals method

@override bool equals(Map<K, V>? map1, Map<K, V>? map2)

Compare two elements for being equal.

This should be a proper equality relation.

Implementation

@override
bool equals(Map<K, V>? map1, Map<K, V>? map2) {
  if (identical(map1, map2)) return true;
  if (map1 == null || map2 == null) return false;
  var length = map1.length;
  if (length != map2.length) return false;

  // Zero-allocation fast-path for standard key lookup
  if (_keyEquality is DefaultEquality ||
      _keyEquality is DeepCollectionEquality) {
    for (var entry in map1.entries) {
      if (!map2.containsKey(entry.key)) return false;
      if (!_valueEquality.equals(entry.value, map2[entry.key] as V)) {
        return false;
      }
    }
    return true;
  }

  Map<_MapEntry, int> equalElementCounts = HashMap();
  for (var key in map1.keys) {
    var entry = _MapEntry(this, key, map1[key]);
    var count = equalElementCounts[entry] ?? 0;
    equalElementCounts[entry] = count + 1;
  }
  for (var key in map2.keys) {
    var entry = _MapEntry(this, key, map2[key]);
    var count = equalElementCounts[entry];
    if (count == null || count == 0) return false;
    equalElementCounts[entry] = count - 1;
  }
  return true;
}