Ayte :: Utility :: Predicate

Tired of .filter(collection -> collection.stream().anyMatch(CONSTANT::equals))? We're here.

Coordinates

This project is separated into two packages, io.ayte.utility.predicate:api with interfaces and io.ayte.utility.predicate:kit with actual implementations. Contents are both Java 8-compatible and exposed as io.ayte.utility.predicate.api / io.ayte.utility.predicate.kit java 9+ modules.

Check utility repository for better explanation of internal organization.

What's all the fuzz about?

Using streams, optionals and custom classes that use filtering is an everyday life as for now. However, there are common points of pain that this library tries to eliminate:

• Repeating long and ugly pieces of code, e.g.:

  .filter(collection -> collection.stream().allMatch(x -> x >= 3))
  

• Debugging hell with lambdas, when you have an instance of predicate but don't know where does it come from and how it calculates the result:

  // that's basic xor operation, you know
  .filter(value -> alpha.test(value) != beta.test(value))
  

This library provides set of named classes to address both of those issues:

.filter(Predicates.allMatch(Predicates.gte(3)))

.filter(Predicates.xor(Predicates.gte(3), Predicates.keyOf(map)))

Or, with static imports:

.filter(allMatch(gte(3)))

.filter(xor(gte(3), keyOf(map)))

Or, speaking about xor operation:

.filter(gte(3).xor(keyOf(map)))

All those operations return named classes (AllMatch, GreaterThan, KeyOf), which will help you debug the issues. Developer friendliness is a top priority here, so this library tries to simplify things when possible, e.g. if OneOf factory method is called with two or more ConstantTrue's, it will immediately shortcut to ConstantFalse, and of course we try to keep naming concise.

API

api jar provides end user with three interfaces: UnaryPredicate, BinaryPredicate and TernaryPredicate. First two simply extend Predicate and BiPredicate, adding .xor() method and augmenting standard methods (and(), or(), negate()) with named classes, and third one doesn't inherit anything but follows same conventions.

kit jar exposes Predicates, BinaryPredicates and TernaryPredicates static factory classes, which should be sufficient to use library at full power.

It is not recommended to call classes factory methods directly since their signature and location may change without warning.

Licensing

MIT / UPL-1.0

Ayte Labs, 2019

Do what comes natural.