equatable_utils.dart

import 'dart:collection';

import 'package:collection/collection.dart';
import 'package:equatable/equatable.dart';

/// Returns a `hashCode` for [props].
int mapPropsToHashCode(Iterable? props) =>
    _finish(props == null ? 0 : props.fold(0, _combine));

const DeepCollectionEquality _equality = DeepCollectionEquality();

/// Determines whether [list1] and [list2] are equal.
bool equals(List? list1, List? list2) {
  if (identical(list1, list2)) return true;
  if (list1 == null || list2 == null) return false;
  final length = list1.length;
  if (length != list2.length) return false;

  for (var i = 0; i < length; i++) {
    final dynamic unit1 = list1[i];
    final dynamic unit2 = list2[i];

    if (_isEquatable(unit1) && _isEquatable(unit2)) {
      if (unit1 != unit2) return false;
    } else if (unit1 is Iterable || unit1 is Map) {
      if (!_equality.equals(unit1, unit2)) return false;
    } else if (unit1?.runtimeType != unit2?.runtimeType) {
      return false;
    } else if (unit1 != unit2) {
      return false;
    }
  }
  return true;
}

bool _isEquatable(dynamic object) {
  return object is Equatable || object is EquatableMixin;
}

/// Jenkins Hash Functions
/// https://en.wikipedia.org/wiki/Jenkins_hash_function
int _combine(int hash, dynamic object) {
  if (object is Map) {
    object.keys
        .sorted((dynamic a, dynamic b) => a.hashCode - b.hashCode)
        .forEach((dynamic key) {
      hash = hash ^ _combine(hash, <dynamic>[key, object[key]]);
    });
    return hash;
  }
  if (object is Set) {
    // this is needed to have a consistent iteration order so that the produced
    // hash is consistent independently of the Set insertion order
    object = SplayTreeSet<dynamic>.from(object);
  }
  if (object is Iterable) {
    for (final value in object) {
      hash = hash ^ _combine(hash, value);
    }
    return hash ^ object.length;
  }

  hash = 0x1fffffff & (hash + object.hashCode);
  hash = 0x1fffffff & (hash + ((0x0007ffff & hash) << 10));
  return hash ^ (hash >> 6);
}

int _finish(int hash) {
  hash = 0x1fffffff & (hash + ((0x03ffffff & hash) << 3));
  hash = hash ^ (hash >> 11);
  return 0x1fffffff & (hash + ((0x00003fff & hash) << 15));
}

/// Returns a string for [props].
String mapPropsToString(Type runtimeType, List<Object?> props) =>
    '$runtimeType(${props.map((prop) => prop.toString()).join(', ')})';