fast_immutable_equatable 1.0.0 fast_immutable_equatable: ^1.0.0 copied to clipboard
A simple Dart package that provides immutable equatable's with the option to store the hashes.
Overview #
This is a Dart package derived from fast_equatable
but which adds immutability to the code, making it compatible with equatable.
The hashes are cached using a double lookup trick on a static map which keeps the immutability.
Note that in terms of speed this library is a bit slower than the fast_equatable
package due to the double lookup, but still faster than equatable
package, especially if you do a lot of comparisons.
You can use with IFastEquatable
just like a mixin (this is the preferred option, since it is easier to integrate into existing code),
or you can extends IFastEquatable
as a class.
The library offers hash caching to improve the speed of e.g. List
, Map
's and Set
's.
By default the widely spread Jenkins hash function is used, but you are free to also implement and provide your own hash engine. If you want create a PR with your new hash engine implementation.
Objects of any kind are allowed into hashParameters
(this works the same way as props
in the equatable package). Simple types and the standard collections like List
, Iterable
, Map
and Set
are supported by default.
In order to use the immutable collections from fast_immutable_collections
like IList
, ISet
and IMap
you just need to enable deep equality and hashed:
defaultConfig = ConfigList(isDeepEquals: true, cacheHashCode: true);
.
However, since IFastEquatable
is marked immutable, you can also use regular List
s, Map
s and Set
s without worrying that they will be modified.
How to use IFastEquatable #
Using the mixedin approach (recommended):
class A with IFastEquatable {
final String arg1;
final Map<String> arg2;
const A(this.arg1, this.arg2);
@override
bool get cacheHash => true;
@override
List<Object?> get hashParameters => [arg1, arg2];
}
How to subclass A #
The library forces you to adhere to a certain style when dealing with subclasses and hashParameters. It's important that hashParameters are called with a spread operator, otherwise you will get a warning from the compiler.
class AB extends A {
final IList<int> arg3;
AB(super.arg1, super.arg2, this.arg3);
@override
bool get cacheHash => true;
@override
List<Object?> get hashParameters => [...super.hashParameters, arg3];
}
Benchmark #
In the example
you will find a benchmark code, showing off the resulting speed improvement.
However, this is not really comparable, since the test doesn't try multiple comparisons with the same object.
If that were the case, fast_immutable_equatable
is much faster.
equatable for 1000000 elements(RunTime): 4789464.0 us.
fast_immutable_equatable (uncached) for 1000000 elements(RunTime): 4467237.0 us.
fast_immutable_equatable (cached) for 1000000 elements(RunTime): 3723849.5 us.