Kopama ("Kotlin pattern matching") enables some pattern matching
, e.g. in when expressions.
The syntax is similar to Hamcrest matchers, but shortened.
data class Person(val firstName: String, val lastName: String, val age: Int)
val p = Person("Alice", "Cooper", 74)
when(match(p)) {
Alien::class(any, any, any) -> println("Aliens!")
Person::class("Mick", "Jagger", gt(70)) -> println("Mick Jagger!")
Person::class("Alice", "Cooper", any) -> println("Alice Cooper!")
else -> println("I don't know this guy")
}The deconstruction for data classes is based on their componentN methods,
and for Iterable classes on their elements. The
patterns are not checked against type or range of the given object,
the pattern will simply not match in this case, but there will be
(hopefully) neither compile-time nor runtime-errors.
I don't consider this library ready for use in production. I did my best to test for the intended behavior, but with such ultra-flexible and rule-bending code it's hard to be absolutely sure that all edge cases behave in a sensible way. Further, the code uses reflection and might be too slow for your use case.
Also, I should mention that "kopama" means "anger" in Telugu.
I hope you have as much fun playing with the library as I have writing it.