EqualOne #

equalone is a Dart utility package for deep equality, value-based comparison, and robust hashCode generation for any Dart object, including List, Map, Set, and nested collections. It solves common problems with object comparison, custom equality, and hashCode in Dart data classes, value objects, and collections. Use equalone to implement deep equality, shallow equality, and custom comparison logic for models, state objects, and when using objects as keys in Map or elements in Set. The package provides static methods, a wrapper class, and a mixin for easy integration with your Dart or Flutter projects.

Features #

• Deep equality for any Dart object, including nested collections (List, Map, Set, Iterable)
• Shallow (top-level) equality for fast comparison
• Customizable equality and emptiness logic
• Type-agnostic: works with any value, including null
• Easy integration with models, state objects, and value classes
• Mixin for value-based equality in your own classes

Getting started #

Add to your pubspec.yaml:

dependencies:
  equalone: 

Import in your Dart code:

import 'package:equalone/equalone.dart';

equalone is built on top of the popular collection package for advanced equality and hashing.

For convenience, you can access collection features via:

import 'package:equalone/collection.dart';

This simply re-exports the official collection package used be equalone.

Usage #

You can use the equalone package in three main ways:

• Static methods: Use static methods like Equalone.equals, Equalone.deepEquals, Equalone.shallowEquals, and Equalone.empty for quick, type-agnostic checks and comparisons.
• Wrapper class: Wrap any value or collection in the Equalone class to enable robust equality and hashCode logic, especially for use in sets, maps, or when comparing complex/nested objects.
• Mixin for custom classes: Add value-based equality to your own classes by mixing in EqualoneMixin and specifying which fields should participate in equality and hashCode calculations.

Static methods usage #

Equalone.empty(value) #

Checks if a value is empty (null, empty string, or empty collection). This method is customizable.

Equalone.empty(null);       // true
Equalone.empty('');         // true
Equalone.empty([]);         // true
Equalone.empty([1, 2, 3]);  // false
Equalone.empty('hello');    // false

Equalone.equals(a, b) #

Customizable equality check (uses deepEquals by default). Suitable for comparing any values, including collections and nested structures.

Equalone.equals([1, 2, 3], [1, 2, 3]);           // true
Equalone.equals({'a': 1}, {'a': 1});             // true
Equalone.equals([1, 2, 3], [3, 2, 1]);           // false
Equalone.equals([[1, 2], [3]], [[1, 2], [3]]);   // true, if customized with deepEquals
Equalone.equals('abc', 'abc');                   // true
Equalone.equals(null, null);                     // true

Equalone.deepEquals(a, b) #

Performs a deep recursive equality check for any values, including nested collections. Ignores reference identity and compares structure and contents.

Equalone.deepEquals([1, [2, 3]], [1, [2, 3]]);      // true
Equalone.deepEquals([1, [2, 3]], [1, [3, 2]]);      // false
Equalone.deepEquals({'x': [1, 2]}, {'x': [1, 2]});  // true
Equalone.deepEquals({'x': [1, 2]}, {'x': [2, 1]});  // false
Equalone.deepEquals([[1, 2], [3]], [[1, 2], [3]]);  // true

You can control type sensitivity with the ignoreType parameter (default: false).

Equalone.deepEquals([1, 2, 3], <num>[1, 2, 3]);                   // false 
Equalone.deepEquals([1, 2, 3], <num>[1, 2, 3], ignoreType: true); // true 

Equalone.shallowEquals(a, b) #

Performs a top-level (shallow) equality check for any values. For collections, only the first level of elements is compared (not nested contents).

Equalone.shallowEquals([1, [2, 3]], [1, [2, 3]]);      // false (see deepEquals)
Equalone.shallowEquals([1, 2, 3], [1, 2, 3]);          // true
Equalone.shallowEquals([1, 2, 3], [3, 2, 1]);          // false
Equalone.shallowEquals({'a': 1}, {'a': 1});            // true
Equalone.shallowEquals({'a': 1}, {'a': 2});            // false
Equalone.shallowEquals({'x': [1, 2]}, {'x': [1, 2]});  // false (see deepEquals)
Equalone.shallowEquals([[1, 2], [3]], [[1, 2], [3]]);  // false (see deepEquals)

You can control type sensitivity with the ignoreType parameter (default: false).

Equalone.shallowEquals([1, 2, 3], <num>[1, 2, 3]);                    // false 
Equalone.shallowEquals([1, 2, 3], <num>[1, 2, 3], ignoreType: true);  // true 

Customization #

You can globally override the equality and emptiness logic:

import 'package:equalone/collection.dart';

Equalone.initialize(
  equals: const DeepCollectionEquality().equals, // Type-insensitive deep equality
  empty: (v) => v is num ? v == 0 : Equalone.defaultEmpty(v),
);

print(Equalone.equals([1, 2, 3], <num>[1, 2, 3])); // true
print(Equalone.equals([1, 2, 3], [3, 2, 1]));      // false

print(Equalone.empty(0));    // true
print(Equalone.empty(1));    // false
print(Equalone.empty([]));   // true
print(Equalone.empty(null)); // true

Case-insensitive string comparison:

Equalone.initialize(
  equals: (a, b) => a is String && b is String
      ? a.toLowerCase() == b.toLowerCase()
      : Equalone.deepEquals(a, b),
);

print(Equalone.equals('Hello', 'hello')); // true
print(Equalone.equals('Hello', 'world')); // false

Use Equalone.initialize to globally customize default comparison and emptiness logic to match requirements of your app.

Equalone instances usage #

You can wrap any value, collection, or object in an Equalone instance to enable robust equality and hashCode logic. This is especially useful when you want to compare complex or nested structures, use them as keys in maps, or store them in sets.

Deep equality for collections #

final a = Equalone([1, 2, 3]);
final b = Equalone([1, 2, 3]);

print(a == b); // true (deep equality for lists)
print(a.hashCode == b.hashCode); // true

final c = Equalone({'x': 1, 'y': 2});
final d = Equalone({'x': 1, 'y': 2});

print(c == d); // true (deep equality for maps)

Comparing with regular collections #

You can even compare an Equalone instance with regular collections. However, avoid comparing regular collections directly to Equalone, as this may lead to unexpected or incorrect results

final e = Equalone([1, 2, 3]);
final f = [1, 2, 3];

print(e == f); // true
print(f == e); // false

Null comparison #

You cannot directly compare an Equalone instance with a regular null value. For consistent and correct results, always wrap null values in an Equalone instance before comparison.

final g = Equalone(null);
final h = Equalone(null);

print(g == h); // true
print(g.hashCode == null.hashCode); // true
print(g == null); // false
print(null == g); // false

Custom equality #

You can provide a custom equality function via the equalsMethod parameter. For example, to compare lists by their sum:

bool sumEquals(Object? a, Object? b) => (a is List<num> && b is List<num>)
       ? (a.fold<num>(0, (num s, v) => s + v) == b.fold<num>(0, (num s, v) => s + v))
       : false;

final a = Equalone([1, 2, 3], equalsMethod: sumEquals);
final b = Equalone([3, 3], equalsMethod: sumEquals);

print(a == b); // true (both sum to 6)

Type sensitivity #

You can control whether type differences are considered in equality checks using the ignoreType parameter. By default, ignoreType is set to true, so type differences are ignored. If you set ignoreType: false, values with different types (e.g., List<int> and List<num>) will not be considered equal, even if their contents match.

final c = Equalone([1, 2, 3], ignoreType: true);
final d = Equalone(<num>[1, 2, 3], ignoreType: false);

print(c == d); // true (ignores type differences)
print(d == c); // false (type differences matter for d)

Using EqualoneMixin in your classes #

You can add robust, value-based equality and hashCode logic to your own classes by mixing in EqualoneMixin. This is especially useful for data classes, value objects, and models where you want equality to depend on the values of specific fields rather than object identity.

To use EqualoneMixin, simply add with EqualoneMixin to your class declaration and override the equalones getter to return a list of all fields that should participate in equality and hashCode calculations. For collections or nested objects, wrap them in Equalone to ensure deep equality.

Benefits:

• Eliminates boilerplate code for == and hashCode.
• Ensures consistent, reliable equality logic across your codebase.
• Supports deep equality for collections and nested structures.

Simple value-based equality in your class #

class Point with EqualoneMixin {
  final int x;
  final int y;
  Point(this.x, this.y);
  @override
  List<Object?> get equalones => [x, y];
}

final a = Point(1, 2);
final b = Point(1, 2);
print(a == b); // true

Deep equality for collections #

class PersonDeep with EqualoneMixin {
  final String name;
  final List<int> scores;
  PersonDeep(this.name, this.scores);
  @override
  List<Object?> get equalones => [name, Equalone(scores)];
}

final a = Person('Alice', [1, 2, 3]);
final b = Person('Alice', [1, 2, 3]);
print(a == b); // true (deep equality for the list)

Shallow, but correct, equality for collections #

class PersonShallow with EqualoneMixin {
  final String name;
  final List<int> scores;
  PersonShallow(this.name, this.scores);
  @override
  List<Object?> get equalones => [name, ...scores];
}

final a = Person('Alice', [1, 2, 3]);
final b = Person('Alice', [1, 2, 3]);
print(a == b); // true 

Caveats & Warnings #

Asymmetric Comparison #

When comparing an Equalone instance with a regular collection, the result may be asymmetric.

final a = Equalone([1, 2, 3]);
final b = [1, 2, 3];
print(a == b); // true
print(b == a); // false

This is because the equality logic is determined by the left-hand operand. Always use Equalone as the left operand for consistent results.

Null Comparison #

Equality and hashCode behavior with null values can be non-intuitive.

final a = Equalone(null);
final b = null;
final c = Equalone(null);
print(a == b); // false
print(a == c); // true
print(a.hashCode == null.hashCode); // true

Comparing Equalone(null) with null using == returns false, but Equalone(null) == Equalone(null) returns true. The hashCode of Equalone(null) is equal to null.hashCode.

Customization Consistency #

Always use the same custom settings for all compared Equalone instances to avoid unexpected results.

final a = Equalone([1, 2, 3], ignoreType: true);
final b = Equalone(<num>[1, 2, 3], ignoreType: false);
print(a == b); // true
print(b == a); // false (different ignoreType)

final c = Equalone([1, 2, 3], ignoreType: true);
final d = Equalone(<num>[1, 2, 3], ignoreType: true);
print(c == d); // true 
print(d == c); // true 

If you use custom equalsMethod or ignoreType settings, ensure that all compared Equalone instances use the same settings. Comparing instances with different settings may lead to unexpected or asymmetric results.

Collections in EqualoneMixin #

When using EqualoneMixin, always wrap collections in Equalone for deep equality; otherwise, only reference equality is checked.

class Person with EqualoneMixin {
  final String name;
  final List<int> scores;
  Person(this.name, this.scores);
  @override
  List<Object?> get equalones => [name, scores]; // Not wrapped: shallow equality
}

final a = Person('Alice', [1, 2, 3]);
final b = Person('Alice', [1, 2, 3]);
print(a == b); // false (different list references)

class PersonDeep with EqualoneMixin {
  final String name;
  final List<int> scores;
  PersonDeep(this.name, this.scores);
  @override
  List<Object?> get equalones => [name, Equalone(scores)]; // Wrapped: deep equality
}

final c = PersonDeep('Alice', [1, 2, 3]);
final d = PersonDeep('Alice', [1, 2, 3]);
print(c == d); // true (deep equality)

When using EqualoneMixin, be careful with mutable collections in the equalones list. Prefer wrapping collections in Equalone to ensure deep equality and avoid unexpected behavior due to reference identity.

Equalone HashCode Limitations #

The hashCode for collections is based on their length and type, not their contents. This means that two collections with the same length but different elements may have the same hashCode.

final a = Equalone([1, 2, 3]);
final b = Equalone([4, 5, 6]);
print(a.hashCode == b.hashCode); // true (same length, same type)
print(a == b); // false (different contents)

For use as map keys, always rely on equality, not just hashCode.

However, you can still use Equalone as a value in a Set or as a key in a Map:

final set12 = {Equalone([1, 2])};
print(set12.contains(Equalone([1, 2]))); // true
print(set12.contains(Equalone([2, 1]))); // false

final map12 = {Equalone([1, 2]): "12"};
print(map12.containsKey(Equalone([1, 2]))); // true
print(map12.containsKey(Equalone([2, 1]))); // false

More examples and tests #

See the /example folder for more comparison scenarios.

Explore the /test folder for a suite of automated tests covering features, edge cases, and caveats of equalone.

Experiment by adding tests for your own cases

By studying the example and tests, you'll gain a deeper and more practical understanding of how to use equalone effectively and safely in your own projects.

License #

MIT