Matcher

A matcher is a way to describe what kind of entites we are interested in.

They can be used to create Groups and Collectors
Which in turn can be used as Filters in Reactive Systems for example

Matcher are a small query language. GameMatcher means that we have a Game context and we can access all component types associated to this context. If we would write context.GetGroup(GameMatcher.Position); We would get a group of entites which have Position component. In order to define more complex groups, we can use AllOf, AnyOf and NoneOf methods. AllOf means that all the listed components has to be present on the entity in order for this entity to become part of the group. AnyOf means that one of the listed component has to be present. And in case of NoneOf we don't want the listed components to be present. NoneOf is not a stand alone description, meaning that you will not be able to write context.GetGroup(GameMatcher.NoneOf(GameMatcher.Position)); It is prohibited because it creates a very large set. NoneOf can be used only in combination with AllOf or AnyOf.

context.GetGroup(GameMatcher.AllOf(GameMatcher.Position, GameMatcher.Velocity).NoneOf(GameMatcher.NotMovable));

(adopted from EntitasCookbook/Groups )