MontiCore - Types
Type systems are available in a variety of (programming) languages and
facilitate programming because typing errors can already be detected at compile
time. To express type usages a language component
hierarchy for modeling types was developed for MontiCore-based languages. It
consists of five language components
MCBasicTypes,
MCCollectionTypes,
MCSimpleGenericTypes,
MCFullGenericTypes, and
MCArrayTypes.
MCBasicTypes
The most basic language component is MCBasicTypes , which provides the central
interface nonterminal MCType. Besides this interface
nonterminal, this language component provides nonterminals that enable
modeling primitive types and qualified as well as non-qualified types.
Furthermore, it provides a return type, which can be an MCType or
void. These nonterminals are bundled as it provides a relativity small
yet useful collection of types for modeling.
When using this language component, types such as int,
Person, or java.lang.String are expressible.
MCCollectionTypes
The MCCollectionTypes language component builds upon the
basic types language component and enables to model four kinds of generics:
Set, List, Map, and Optional.
These generics cannot be nested as the purpose of this language component is to
provide some commonly used collection types but limit their functionality such
that it is useful for high-level models. Using this language component, types
such as List<Integer>, Set<char>, or
Map<java.lang.String, Person> are expressible.
MCSimpleGenericTypes
The language component MCSimpleGenericTypes
extends the language
component MCCollectionTypes and extends the expressible types with
custom generics of arbitrary classes with
arbitrary arguments. When using this language component, types such
as Person<String> or Map<Person<String>, Integer> are
expressible. Please note that these types still do not cover all
possible types
from Java, as Java additionally supports inner types of generic types,
which is not expressible using the language component
SimpleGenericTypes, e.g., types such as a.b.C<D>.E.F<G>.H are
not expressible.
MCFullGenericTypes
The language component MCFullGenericTypes
extends the language
component MCSimpleGenericTypes and extends the expressible types with
inner generics types of arbitrary classes with
arbitrary arguments including wild card types. When using this language component,
types such as Person<?>, Map<Person<String>, ? extends Person> or a.b.C<D>.E.F<G>.H are expressible.
MCArrayTypes
Arrays are orthogonal to the generic extensions. Thus
they can be combined with any of the above variants.
Language component MCArrayTypes provides
possibilities to add arrays, such as Person[] or int[][].