# See the License for the specific language governing permissions and
# limitations under the License.
-# Object model of the Nit language
+# Classes, types and properties
#
-# This module define the entities of the Nit meta-model like modules,
-# classes, types and properties
-#
-# It also provide an API to build and query models.
-#
-# All model classes starts with the M letter (`MModule`, `MClass`, etc.)
-#
-# TODO: better doc
+# All three concepts are defined in this same module because these are strongly connected:
+# * types are based on classes
+# * classes contains properties
+# * some properties are types (virtual types)
#
# TODO: liearization, extern stuff
# FIXME: better handling of the types
module model
-import poset
-import location
import mmodule
import mdoc
import ordered_tree
redef class Model
# All known classes
- var mclasses: Array[MClass] = new Array[MClass]
+ var mclasses = new Array[MClass]
# All known properties
- var mproperties: Array[MProperty] = new Array[MProperty]
+ var mproperties = new Array[MProperty]
# Hierarchy of class definition.
#
# Each classdef is associated with its super-classdefs in regard to
# its module of definition.
- var mclassdef_hierarchy: POSet[MClassDef] = new POSet[MClassDef]
+ var mclassdef_hierarchy = new POSet[MClassDef]
# Class-type hierarchy restricted to the introduction.
#
# This poset will evolve in a monotonous way:
# * Two non connected nodes will remain unconnected
# * New nodes can appear with new edges
- private var intro_mtype_specialization_hierarchy: POSet[MClassType] = new POSet[MClassType]
+ private var intro_mtype_specialization_hierarchy = new POSet[MClassType]
# Global overlapped class-type hierarchy.
# The hierarchy when all modules are combined.
# This poset will evolve in an anarchic way. Loops can even be created.
#
# FIXME decide what to do on loops
- private var full_mtype_specialization_hierarchy: POSet[MClassType] = new POSet[MClassType]
+ private var full_mtype_specialization_hierarchy = new POSet[MClassType]
# Collections of classes grouped by their short name
- private var mclasses_by_name: MultiHashMap[String, MClass] = new MultiHashMap[String, MClass]
+ private var mclasses_by_name = new MultiHashMap[String, MClass]
# Return all class named `name`.
#
end
# Collections of properties grouped by their short name
- private var mproperties_by_name: MultiHashMap[String, MProperty] = new MultiHashMap[String, MProperty]
+ private var mproperties_by_name = new MultiHashMap[String, MProperty]
# Return all properties named `name`.
#
end
# The only null type
- var null_type: MNullType = new MNullType(self)
+ var null_type = new MNullType(self)
# Build an ordered tree with from `concerns`
fun concerns_tree(mconcerns: Collection[MConcern]): ConcernsTree do
redef class MModule
# All the classes introduced in the module
- var intro_mclasses: Array[MClass] = new Array[MClass]
+ var intro_mclasses = new Array[MClass]
# All the class definitions of the module
# (introduction and refinement)
- var mclassdefs: Array[MClassDef] = new Array[MClassDef]
+ var mclassdefs = new Array[MClassDef]
# Does the current module has a given class `mclass`?
# Return true if the mmodule introduces, refines or imports a class.
return res
end
- # Sort a given array of classes using the linerarization order of the module
+ # Sort a given array of classes using the linearization order of the module
# The most general is first, the most specific is last
fun linearize_mclasses(mclasses: Array[MClass])
do
self.flatten_mclass_hierarchy.sort(mclasses)
end
- # Sort a given array of class definitions using the linerarization order of the module
+ # Sort a given array of class definitions using the linearization order of the module
# the refinement link is stronger than the specialisation link
# The most general is first, the most specific is last
fun linearize_mclassdefs(mclassdefs: Array[MClassDef])
sorter.sort(mclassdefs)
end
- # Sort a given array of property definitions using the linerarization order of the module
+ # Sort a given array of property definitions using the linearization order of the module
# the refinement link is stronger than the specialisation link
# The most general is first, the most specific is last
fun linearize_mpropdefs(mpropdefs: Array[MPropDef])
private var object_type_cache: nullable MClassType
+ # The type `Pointer`, super class to all extern classes
+ var pointer_type: MClassType = self.get_primitive_class("Pointer").mclass_type is lazy
+
# The primitive type `Bool`
fun bool_type: MClassType
do
return get_primitive_class("Sys").mclass_type
end
+ # The primitive type `Finalizable`
+ # Used to tag classes that need to be finalized.
+ fun finalizable_type: nullable MClassType
+ do
+ var clas = self.model.get_mclasses_by_name("Finalizable")
+ if clas == null then return null
+ return get_primitive_class("Finalizable").mclass_type
+ end
+
# Force to get the primitive class named `name` or abort
fun get_primitive_class(name: String): MClass
do
var cla = self.model.get_mclasses_by_name(name)
if cla == null then
- if name == "Bool" then
- var c = new MClass(self, name, 0, enum_kind, public_visibility)
- var cladef = new MClassDef(self, c.mclass_type, new Location(null, 0,0,0,0), new Array[String])
+ if name == "Bool" and self.model.get_mclasses_by_name("Object") != null then
+ # Bool is injected because it is needed by engine to code the result
+ # of the implicit casts.
+ var c = new MClass(self, name, null, enum_kind, public_visibility)
+ var cladef = new MClassDef(self, c.mclass_type, new Location(null, 0,0,0,0))
+ cladef.set_supertypes([object_type])
+ cladef.add_in_hierarchy
return c
end
print("Fatal Error: no primitive class {name}")
var msg = "Fatal Error: more than one primitive class {name}:"
for c in cla do msg += " {c.full_name}"
print msg
- exit(1)
+ #exit(1)
end
return cla.first
end
end
private class MClassDefSorter
- super AbstractSorter[MClassDef]
+ super Comparator
+ redef type COMPARED: MClassDef
var mmodule: MModule
redef fun compare(a, b)
do
end
private class MPropDefSorter
- super AbstractSorter[MPropDef]
+ super Comparator
+ redef type COMPARED: MPropDef
var mmodule: MModule
redef fun compare(pa, pb)
do
#
# This characteristic helps the reasoning about classes in a program since a
# single `MClass` object always denote the same class.
-# However, because a `MClass` is global, it does not really have properties nor
-# belong to a hierarchy since the property and the
-# hierarchy of a class depends of a module.
+#
+# The drawback is that classes (`MClass`) contain almost nothing by themselves.
+# These do not really have properties nor belong to a hierarchy since the property and the
+# hierarchy of a class depends of the refinement in the modules.
+#
+# Most services on classes require the precision of a module, and no one can asks what are
+# the super-classes of a class nor what are properties of a class without precising what is
+# the module considered.
+#
+# For instance, during the typing of a source-file, the module considered is the module of the file.
+# eg. the question *is the method `foo` exists in the class `Bar`?* must be reformulated into
+# *is the method `foo` exists in the class `Bar` in the current module?*
+#
+# During some global analysis, the module considered may be the main module of the program.
class MClass
super MEntity
redef var name: String
# The canonical name of the class
+ #
+ # It is the name of the class prefixed by the full_name of the `intro_mmodule`
# Example: `"owner::module::MyClass"`
- fun full_name: String
- do
- return "{self.intro_mmodule.full_name}::{name}"
- end
+ redef var full_name is lazy do return "{self.intro_mmodule.full_name}::{name}"
+
+ redef var c_name is lazy do return "{intro_mmodule.c_name}__{name.to_cmangle}"
# The number of generic formal parameters
# 0 if the class is not generic
- var arity: Int
-
- # The kind of the class (interface, abstract class, etc.)
- # In Nit, the kind of a class cannot evolve in refinements
- var kind: MClassKind
+ var arity: Int is noinit
- # The visibility of the class
- # In Nit, the visibility of a class cannot evolve in refinements
- var visibility: MVisibility
+ # Each generic formal parameters in order.
+ # is empty if the class is not generic
+ var mparameters = new Array[MParameterType]
- init(intro_mmodule: MModule, name: String, arity: Int, kind: MClassKind, visibility: MVisibility)
+ # Initialize `mparameters` from their names.
+ protected fun setup_parameter_names(parameter_names: nullable Array[String]) is
+ autoinit
do
- self.intro_mmodule = intro_mmodule
- self.name = name
- self.arity = arity
- self.kind = kind
- self.visibility = visibility
- intro_mmodule.intro_mclasses.add(self)
- var model = intro_mmodule.model
- model.mclasses_by_name.add_one(name, self)
- model.mclasses.add(self)
+ if parameter_names == null then
+ self.arity = 0
+ else
+ self.arity = parameter_names.length
+ end
# Create the formal parameter types
if arity > 0 then
+ assert parameter_names != null
var mparametertypes = new Array[MParameterType]
for i in [0..arity[ do
- var mparametertype = new MParameterType(self, i)
+ var mparametertype = new MParameterType(self, i, parameter_names[i])
mparametertypes.add(mparametertype)
end
+ self.mparameters = mparametertypes
var mclass_type = new MGenericType(self, mparametertypes)
self.mclass_type = mclass_type
- self.get_mtype_cache.add(mclass_type)
+ self.get_mtype_cache[mparametertypes] = mclass_type
else
self.mclass_type = new MClassType(self)
end
end
+ # The kind of the class (interface, abstract class, etc.)
+ # In Nit, the kind of a class cannot evolve in refinements
+ var kind: MClassKind
+
+ # The visibility of the class
+ # In Nit, the visibility of a class cannot evolve in refinements
+ var visibility: MVisibility
+
+ init
+ do
+ intro_mmodule.intro_mclasses.add(self)
+ var model = intro_mmodule.model
+ model.mclasses_by_name.add_one(name, self)
+ model.mclasses.add(self)
+ end
+
+ redef fun model do return intro_mmodule.model
+
# All class definitions (introduction and refinements)
- var mclassdefs: Array[MClassDef] = new Array[MClassDef]
+ var mclassdefs = new Array[MClassDef]
# Alias for `name`
redef fun to_s do return self.name
- # The definition that introduced the class
- # Warning: the introduction is the first `MClassDef` object associated
- # to self. If self is just created without having any associated
- # definition, this method will abort
- fun intro: MClassDef
- do
- assert has_a_first_definition: not mclassdefs.is_empty
- return mclassdefs.first
- end
+ # The definition that introduces the class.
+ #
+ # Warning: such a definition may not exist in the early life of the object.
+ # In this case, the method will abort.
+ var intro: MClassDef is noinit
# Return the class `self` in the class hierarchy of the module `mmodule`.
#
# To get other types based on a generic class, see `get_mtype`.
#
# ENSURE: `mclass_type.mclass == self`
- var mclass_type: MClassType
+ var mclass_type: MClassType is noinit
# Return a generic type based on the class
# Is the class is not generic, then the result is `mclass_type`
do
assert mtype_arguments.length == self.arity
if self.arity == 0 then return self.mclass_type
- for t in self.get_mtype_cache do
- if t.arguments == mtype_arguments then
- return t
- end
- end
- var res = new MGenericType(self, mtype_arguments)
- self.get_mtype_cache.add res
+ var res = get_mtype_cache.get_or_null(mtype_arguments)
+ if res != null then return res
+ res = new MGenericType(self, mtype_arguments)
+ self.get_mtype_cache[mtype_arguments.to_a] = res
return res
end
- private var get_mtype_cache: Array[MGenericType] = new Array[MGenericType]
+ private var get_mtype_cache = new HashMap[Array[MType], MGenericType]
end
#
# A `MClassDef` is associated with an explicit (or almost) definition of a
# class. Unlike `MClass`, a `MClassDef` is a local definition that belong to
-# a specific module
+# a specific class and a specific module, and contains declarations like super-classes
+# or properties.
+#
+# It is the class definitions that are the backbone of most things in the model:
+# ClassDefs are defined with regard with other classdefs.
+# Refinement and specialization are combined to produce a big poset called the `Model::mclassdef_hierarchy`.
+#
+# Moreover, the extension and the intention of types is defined by looking at the MClassDefs.
class MClassDef
super MEntity
var mmodule: MModule
# The associated `MClass`
- var mclass: MClass
+ var mclass: MClass is noinit
# The bounded type associated to the mclassdef
#
# ENSURE: `bound_mtype.mclass == self.mclass`
var bound_mtype: MClassType
- # Name of each formal generic parameter (in order of declaration)
- var parameter_names: Array[String]
-
# The origin of the definition
var location: Location
# Internal name combining the module and the class
# Example: "mymodule#MyClass"
- redef var to_s: String
+ redef var to_s: String is noinit
- init(mmodule: MModule, bound_mtype: MClassType, location: Location, parameter_names: Array[String])
+ init
do
- assert bound_mtype.mclass.arity == parameter_names.length
- self.bound_mtype = bound_mtype
- self.mmodule = mmodule
self.mclass = bound_mtype.mclass
- self.location = location
mmodule.mclassdefs.add(self)
mclass.mclassdefs.add(self)
- self.parameter_names = parameter_names
+ if mclass.intro_mmodule == mmodule then
+ assert not isset mclass._intro
+ mclass.intro = self
+ end
self.to_s = "{mmodule}#{mclass}"
end
# Actually the name of the `mclass`
redef fun name do return mclass.name
+ # The module and class name separated by a '#'.
+ #
+ # The short-name of the class is used for introduction.
+ # Example: "my_module#MyClass"
+ #
+ # The full-name of the class is used for refinement.
+ # Example: "my_module#intro_module::MyClass"
+ redef var full_name is lazy do
+ if is_intro then
+ return "{mmodule.full_name}#{mclass.name}"
+ else
+ return "{mmodule.full_name}#{mclass.full_name}"
+ end
+ end
+
+ redef var c_name is lazy do
+ if is_intro then
+ return mclass.c_name
+ else
+ return "{mmodule.c_name}__{mclass.c_name.to_cmangle}"
+ end
+ end
+
+ redef fun model do return mmodule.model
+
# All declared super-types
# FIXME: quite ugly but not better idea yet
- var supertypes: Array[MClassType] = new Array[MClassType]
+ var supertypes = new Array[MClassType]
# Register some super-types for the class (ie "super SomeType")
#
fun is_intro: Bool do return mclass.intro == self
# All properties introduced by the classdef
- var intro_mproperties: Array[MProperty] = new Array[MProperty]
+ var intro_mproperties = new Array[MProperty]
# All property definitions in the class (introductions and redefinitions)
- var mpropdefs: Array[MPropDef] = new Array[MPropDef]
+ var mpropdefs = new Array[MPropDef]
end
# A global static type
super MEntity
redef fun name do return to_s
- # The model of the type
- fun model: Model is abstract
# Return true if `self` is an subtype of `sup`.
# The typing is done using the standard typing policy of Nit.
do
var sub = self
if sub == sup then return true
+
+ #print "1.is {sub} a {sup}? ===="
+
if anchor == null then
assert not sub.need_anchor
assert not sup.need_anchor
else
+ # First, resolve the formal types to the simplest equivalent forms in the receiver
assert sub.can_resolve_for(anchor, null, mmodule)
+ sub = sub.lookup_fixed(mmodule, anchor)
assert sup.can_resolve_for(anchor, null, mmodule)
- end
-
- # First, resolve the formal types to a common version in the receiver
- # The trick here is that fixed formal type will be associed to the bound
- # And unfixed formal types will be associed to a canonical formal type.
- if sub isa MParameterType or sub isa MVirtualType then
- assert anchor != null
- sub = sub.resolve_for(anchor.mclass.mclass_type, anchor, mmodule, false)
- end
- if sup isa MParameterType or sup isa MVirtualType then
- assert anchor != null
- sup = sup.resolve_for(anchor.mclass.mclass_type, anchor, mmodule, false)
+ sup = sup.lookup_fixed(mmodule, anchor)
end
# Does `sup` accept null or not?
end
# Now the case of direct null and nullable is over.
- # A unfixed formal type can only accept itself
- if sup isa MParameterType or sup isa MVirtualType then
- return sub == sup
- end
-
# If `sub` is a formal type, then it is accepted if its bound is accepted
- if sub isa MParameterType or sub isa MVirtualType then
+ while sub isa MParameterType or sub isa MVirtualType do
+ #print "3.is {sub} a {sup}?"
+
+ # A unfixed formal type can only accept itself
+ if sub == sup then return true
+
assert anchor != null
- sub = sub.anchor_to(mmodule, anchor)
+ sub = sub.lookup_bound(mmodule, anchor)
+
+ #print "3.is {sub} a {sup}?"
# Manage the second layer of null/nullable
if sub isa MNullableType then
return sup_accept_null
end
end
+ #print "4.is {sub} a {sup}? <- no more resolution"
assert sub isa MClassType # It is the only remaining type
+ # A unfixed formal type can only accept itself
+ if sup isa MParameterType or sup isa MVirtualType then
+ return false
+ end
+
if sup isa MNullType then
# `sup` accepts only null
return false
# types to their bounds.
#
# Example
+ #
# class A end
# class B super A end
# class X end
# super G[B]
# redef type U: Y
# end
+ #
# Map[T,U] anchor_to H #-> Map[B,Y]
#
# Explanation of the example:
# In Nit, for each super-class of a type, there is a equivalent super-type.
#
# Example:
+ #
+ # ~~~nitish
# class G[T, U] end
# class H[V] super G[V, Bool] end
+ #
# H[Int] supertype_to G #-> G[Int, Bool]
+ # ~~~
#
# REQUIRE: `super_mclass` is a super-class of `self`
# REQUIRE: `self.need_anchor implies anchor != null and self.can_resolve_for(anchor, null, mmodule)`
# Replace formals generic types in self with resolved values in `mtype`
# If `cleanup_virtual` is true, then virtual types are also replaced
- # with their bounds
+ # with their bounds.
#
# This function returns self if `need_anchor` is false.
#
# ## Example 1
#
- # class G[E] end
- # class H[F] super G[F] end
- # class X[Z] end
+ # ~~~
+ # class G[E] end
+ # class H[F] super G[F] end
+ # class X[Z] end
+ # ~~~
#
# * Array[E].resolve_for(H[Int]) #-> Array[Int]
# * Array[E].resolve_for(G[Z], X[Int]) #-> Array[Z]
#
# ## Example 2
#
- # class A[E]
- # fun foo(e:E):E is abstract
- # end
- # class B super A[Int] end
+ # ~~~
+ # class A[E]
+ # fun foo(e:E):E is abstract
+ # end
+ # class B super A[Int] end
+ # ~~~
#
# The signature on foo is (e: E): E
# If we resolve the signature for B, we get (e:Int):Int
#
# ## Example 3
#
- # class A[E]
- # fun foo(e:E) is abstract
- # end
- # class B[F]
- # var a: A[Array[F]]
- # fun bar do a.foo(x) # <- x is here
- # end
+ # ~~~nitish
+ # class A[E]
+ # fun foo(e:E):E is abstract
+ # end
+ # class C[F]
+ # var a: A[Array[F]]
+ # fun bar do a.foo(x) # <- x is here
+ # end
+ # ~~~
#
# The first question is: is foo available on `a`?
#
# The static type of a is `A[Array[F]]`, that is an open type.
# in order to find a method `foo`, whe must look at a resolved type.
#
- # A[Array[F]].anchor_to(B[nullable Object]) #-> A[Array[nullable Object]]
+ # A[Array[F]].anchor_to(C[nullable Object]) #-> A[Array[nullable Object]]
#
# the method `foo` exists in `A[Array[nullable Object]]`, therefore `foo` exists for `a`.
#
#
# the signature of `foo` is `foo(e:E)`, thus we must resolve the type E
#
- # E.resolve_for(A[Array[F]],B[nullable Object]) #-> Array[F]
+ # E.resolve_for(A[Array[F]],C[nullable Object]) #-> Array[F]
#
# The resolution can be done because `E` make sense for the class A (see `can_resolve_for`)
#
- # TODO: Explain the cleanup_virtual
- #
# FIXME: the parameter `cleanup_virtual` is just a bad idea, but having
# two function instead of one seems also to be a bad idea.
#
# ENSURE: `not self.need_anchor implies result == self`
fun resolve_for(mtype: MType, anchor: nullable MClassType, mmodule: MModule, cleanup_virtual: Bool): MType is abstract
+ # Resolve formal type to its verbatim bound.
+ # If the type is not formal, just return self
+ #
+ # The result is returned exactly as declared in the "type" property (verbatim).
+ # So it could be another formal type.
+ #
+ # In case of conflict, the method aborts.
+ fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType do return self
+
+ # Resolve the formal type to its simplest equivalent form.
+ #
+ # Formal types are either free or fixed.
+ # When it is fixed, it means that it is equivalent with a simpler type.
+ # When a formal type is free, it means that it is only equivalent with itself.
+ # This method return the most simple equivalent type of `self`.
+ #
+ # This method is mainly used for subtype test in order to sanely compare fixed.
+ #
+ # By default, return self.
+ # See the redefinitions for specific behavior in each kind of type.
+ fun lookup_fixed(mmodule: MModule, resolved_receiver: MType): MType do return self
+
# Can the type be resolved?
#
# In order to resolve open types, the formal types must make sence.
# class B[F]
# end
#
- # * E.can_resolve_for(A[Int]) #-> true, E make sense in A
- # * E.can_resolve_for(B[Int]) #-> false, E does not make sense in B
- # * B[E].can_resolve_for(A[F], B[Object]) #-> true,
- # B[E] is a red hearing only the E is important,
- # E make sense in A
+ # ~~~nitish
+ # E.can_resolve_for(A[Int]) #-> true, E make sense in A
+ #
+ # E.can_resolve_for(B[Int]) #-> false, E does not make sense in B
+ #
+ # B[E].can_resolve_for(A[F], B[Object]) #-> true,
+ # # B[E] is a red hearing only the E is important,
+ # # E make sense in A
+ # ~~~
#
# REQUIRE: `anchor != null implies not anchor.need_anchor`
# REQUIRE: `mtype.need_anchor implies anchor != null and mtype.can_resolve_for(anchor, null, mmodule)`
return res
end
+ # Return the not nullable version of the type
+ # Is the type is already not nullable, then self is returned.
+ #
+ # Note: this just remove the `nullable` notation, but the result can still contains null.
+ # For instance if `self isa MNullType` or self is a formal type bounded by a nullable type.
+ fun as_notnullable: MType
+ do
+ return self
+ end
+
private var as_nullable_cache: nullable MType = null
- # The deph of the type seen as a tree.
+ # The depth of the type seen as a tree.
#
# * A -> 1
# * G[A] -> 2
redef fun model do return self.mclass.intro_mmodule.model
- private init(mclass: MClass)
- do
- self.mclass = mclass
- end
+ # TODO: private init because strongly bounded to its mclass. see `mclass.mclass_type`
# The formal arguments of the type
# ENSURE: `result.length == self.mclass.arity`
- var arguments: Array[MType] = new Array[MType]
+ var arguments = new Array[MType]
redef fun to_s do return mclass.to_s
+ redef fun full_name do return mclass.full_name
+
+ redef fun c_name do return mclass.c_name
+
redef fun need_anchor do return false
redef fun anchor_to(mmodule: MModule, anchor: MClassType): MClassType
redef fun collect_mclasses(mmodule)
do
+ if collect_mclasses_last_module == mmodule then return collect_mclasses_last_module_cache
assert not self.need_anchor
var cache = self.collect_mclasses_cache
if not cache.has_key(mmodule) then
self.collect_things(mmodule)
end
- return cache[mmodule]
+ var res = cache[mmodule]
+ collect_mclasses_last_module = mmodule
+ collect_mclasses_last_module_cache = res
+ return res
end
+ private var collect_mclasses_last_module: nullable MModule = null
+ private var collect_mclasses_last_module_cache: Set[MClass] is noinit
+
redef fun collect_mtypes(mmodule)
do
assert not self.need_anchor
collect_mtypes_cache[mmodule] = types
end
- private var collect_mclassdefs_cache: HashMap[MModule, Set[MClassDef]] = new HashMap[MModule, Set[MClassDef]]
- private var collect_mclasses_cache: HashMap[MModule, Set[MClass]] = new HashMap[MModule, Set[MClass]]
- private var collect_mtypes_cache: HashMap[MModule, Set[MClassType]] = new HashMap[MModule, Set[MClassType]]
+ private var collect_mclassdefs_cache = new HashMap[MModule, Set[MClassDef]]
+ private var collect_mclasses_cache = new HashMap[MModule, Set[MClass]]
+ private var collect_mtypes_cache = new HashMap[MModule, Set[MClassType]]
end
class MGenericType
super MClassType
- private init(mclass: MClass, arguments: Array[MType])
+ redef var arguments
+
+ # TODO: private init because strongly bounded to its mclass. see `mclass.get_mtype`
+
+ init
do
- super(mclass)
assert self.mclass.arity == arguments.length
- self.arguments = arguments
self.need_anchor = false
for t in arguments do
self.to_s = "{mclass}[{arguments.join(", ")}]"
end
- # Recursively print the type of the arguments within brackets.
+ # The short-name of the class, then the full-name of each type arguments within brackets.
# Example: `"Map[String, List[Int]]"`
- redef var to_s: String
+ redef var to_s: String is noinit
+
+ # The full-name of the class, then the full-name of each type arguments within brackets.
+ # Example: `"standard::Map[standard::String, standard::List[standard::Int]]"`
+ redef var full_name is lazy do
+ var args = new Array[String]
+ for t in arguments do
+ args.add t.full_name
+ end
+ return "{mclass.full_name}[{args.join(", ")}]}"
+ end
+
+ redef var c_name is lazy do
+ var res = mclass.c_name
+ # Note: because the arity is known, a prefix notation is enough
+ for t in arguments do
+ res += "__"
+ res += t.c_name
+ end
+ return res.to_s
+ end
- redef var need_anchor: Bool
+ redef var need_anchor: Bool is noinit
redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual)
do
# The property associated with the type.
# Its the definitions of this property that determine the bound or the virtual type.
- var mproperty: MProperty
+ var mproperty: MVirtualTypeProp
redef fun model do return self.mproperty.intro_mclassdef.mmodule.model
- # Lookup the bound for a given resolved_receiver
- # The result may be a other virtual type (or a parameter type)
- #
- # The result is returned exactly as declared in the "type" property (verbatim).
- #
- # In case of conflict, the method aborts.
- fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType
+ redef fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType
+ do
+ return lookup_single_definition(mmodule, resolved_receiver).bound.as(not null)
+ end
+
+ private fun lookup_single_definition(mmodule: MModule, resolved_receiver: MType): MVirtualTypeDef
do
assert not resolved_receiver.need_anchor
var props = self.mproperty.lookup_definitions(mmodule, resolved_receiver)
if props.is_empty then
abort
else if props.length == 1 then
- return props.first.as(MVirtualTypeDef).bound.as(not null)
+ return props.first
end
var types = new ArraySet[MType]
+ var res = props.first
for p in props do
- types.add(p.as(MVirtualTypeDef).bound.as(not null))
+ types.add(p.bound.as(not null))
+ if not res.is_fixed then res = p
end
if types.length == 1 then
- return types.first
+ return res
end
abort
end
+ # A VT is fixed when:
+ # * the VT is (re-)defined with the annotation `is fixed`
+ # * the VT is (indirectly) bound to an enum class (see `enum_kind`) since there is no subtype possible
+ # * the receiver is an enum class since there is no subtype possible
+ redef fun lookup_fixed(mmodule: MModule, resolved_receiver: MType): MType
+ do
+ assert not resolved_receiver.need_anchor
+ resolved_receiver = resolved_receiver.as_notnullable
+ assert resolved_receiver isa MClassType # It is the only remaining type
+
+ var prop = lookup_single_definition(mmodule, resolved_receiver)
+ var res = prop.bound.as(not null)
+
+ # Recursively lookup the fixed result
+ res = res.lookup_fixed(mmodule, resolved_receiver)
+
+ # 1. For a fixed VT, return the resolved bound
+ if prop.is_fixed then return res
+
+ # 2. For a enum boud, return the bound
+ if res isa MClassType and res.mclass.kind == enum_kind then return res
+
+ # 3. for a enum receiver return the bound
+ if resolved_receiver.mclass.kind == enum_kind then return res
+
+ return self
+ end
+
redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual)
do
+ if not cleanup_virtual then return self
assert can_resolve_for(mtype, anchor, mmodule)
# self is a virtual type declared (or inherited) in mtype
# The point of the function it to get the bound of the virtual type that make sense for mtype
# But because mtype is maybe a virtual/formal type, we need to get a real receiver first
#print "{class_name}: {self}/{mtype}/{anchor}?"
- var resolved_reciever
+ var resolved_receiver
if mtype.need_anchor then
assert anchor != null
- resolved_reciever = mtype.resolve_for(anchor, null, mmodule, true)
+ resolved_receiver = mtype.resolve_for(anchor, null, mmodule, true)
else
- resolved_reciever = mtype
+ resolved_receiver = mtype
end
# Now, we can get the bound
- var verbatim_bound = lookup_bound(mmodule, resolved_reciever)
+ var verbatim_bound = lookup_bound(mmodule, resolved_receiver)
# The bound is exactly as declared in the "type" property, so we must resolve it again
var res = verbatim_bound.resolve_for(mtype, anchor, mmodule, cleanup_virtual)
- #print "{class_name}: {self}/{mtype}/{anchor} -> {self}/{resolved_reciever}/{anchor} -> {verbatim_bound}/{mtype}/{anchor} -> {res}"
-
- # What to return here? There is a bunch a special cases:
- # If 'cleanup_virtual' we must return the resolved type, since we cannot return self
- if cleanup_virtual then return res
- # If the reciever is a intern class, then the virtual type cannot be redefined since there is no possible subclass. self is just fixed. so simply return the resolution
- if resolved_reciever isa MNullableType then resolved_reciever = resolved_reciever.mtype
- if resolved_reciever.as(MClassType).mclass.kind == enum_kind then return res
- # If the resolved type isa MVirtualType, it means that self was bound to it, and cannot be unbound. self is just fixed. so return the resolution.
- if res isa MVirtualType then return res
- # It the resolved type isa intern class, then there is no possible valid redefinition is any potentiel subclass. self is just fixed. so simply return the resolution
- if res isa MClassType and res.mclass.kind == enum_kind then return res
- # TODO: Add 'fixed' virtual type in the specification.
- # TODO: What if bound to a MParameterType?
- # Note that Nullable types can always be redefined by the non nullable version, so there is no specific case on it.
- # If anything apply, then `self' cannot be resolved, so return self
- return self
+ return res
end
redef fun can_resolve_for(mtype, anchor, mmodule)
redef fun to_s do return self.mproperty.to_s
- init(mproperty: MProperty)
- do
- self.mproperty = mproperty
- end
+ redef fun full_name do return self.mproperty.full_name
+
+ redef fun c_name do return self.mproperty.c_name
end
-# The type associated the a formal parameter generic type of a class
+# The type associated to a formal parameter generic type of a class
#
# Each parameter type is associated to a specific class.
-# It's mean that all refinements of a same class "share" the parameter type,
-# but that a generic subclass has its on parameter types.
+# It means that all refinements of a same class "share" the parameter type,
+# but that a generic subclass has its own parameter types.
#
-# However, in the sense of the meta-model, the a parameter type of a class is
-# a valid types in a subclass. The "in the sense of the meta-model" is
+# However, in the sense of the meta-model, a parameter type of a class is
+# a valid type in a subclass. The "in the sense of the meta-model" is
# important because, in the Nit language, the programmer cannot refers
# directly to the parameter types of the super-classes.
#
# Example:
+#
# class A[E]
# fun e: E is abstract
# end
# class B[F]
# super A[Array[F]]
# end
+#
# In the class definition B[F], `F` is a valid type but `E` is not.
# However, `self.e` is a valid method call, and the signature of `e` is
# declared `e: E`.
#
# Note that parameter types are shared among class refinements.
# Therefore parameter only have an internal name (see `to_s` for details).
-# TODO: Add a `name_for` to get better messages.
class MParameterType
super MType
# FIXME: is `position` a better name?
var rank: Int
- # Internal name of the parameter type
- # Names of parameter types changes in each class definition
- # Therefore, this method return an internal name.
- # Example: return "G#1" for the second parameter of the class G
- # FIXME: add a way to get the real name in a classdef
- redef fun to_s do return "{mclass}#{rank}"
+ redef var name
+
+ redef fun to_s do return name
+
+ redef var full_name is lazy do return "{mclass.full_name}::{name}"
- # Resolve the bound for a given resolved_receiver
- # The result may be a other virtual type (or a parameter type)
- fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType
+ redef var c_name is lazy do return mclass.c_name + "__" + "#{name}".to_cmangle
+
+ redef fun lookup_bound(mmodule: MModule, resolved_receiver: MType): MType
do
assert not resolved_receiver.need_anchor
+ resolved_receiver = resolved_receiver.as_notnullable
+ assert resolved_receiver isa MClassType # It is the only remaining type
var goalclass = self.mclass
+ if resolved_receiver.mclass == goalclass then
+ return resolved_receiver.arguments[self.rank]
+ end
var supertypes = resolved_receiver.collect_mtypes(mmodule)
for t in supertypes do
if t.mclass == goalclass then
abort
end
+ # A PT is fixed when:
+ # * Its bound is a enum class (see `enum_kind`).
+ # The PT is just useless, but it is still a case.
+ # * More usually, the `resolved_receiver` is a subclass of `self.mclass`,
+ # so it is necessarily fixed in a `super` clause, either with a normal type
+ # or with another PT.
+ # See `resolve_for` for examples about related issues.
+ redef fun lookup_fixed(mmodule: MModule, resolved_receiver: MType): MType
+ do
+ assert not resolved_receiver.need_anchor
+ resolved_receiver = resolved_receiver.as_notnullable
+ assert resolved_receiver isa MClassType # It is the only remaining type
+ var res = self.resolve_for(resolved_receiver.mclass.mclass_type, resolved_receiver, mmodule, false)
+ return res
+ end
+
redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual)
do
assert can_resolve_for(mtype, anchor, mmodule)
#print "{class_name}: {self}/{mtype}/{anchor}?"
if mtype isa MGenericType and mtype.mclass == self.mclass then
- return mtype.arguments[self.rank]
+ var res = mtype.arguments[self.rank]
+ if anchor != null and res.need_anchor then
+ # Maybe the result can be resolved more if are bound to a final class
+ var r2 = res.anchor_to(mmodule, anchor)
+ if r2 isa MClassType and r2.mclass.kind == enum_kind then return r2
+ end
+ return res
end
# self is a parameter type of mtype (or of a super-class of mtype)
# The point of the function it to get the bound of the virtual type that make sense for mtype
# But because mtype is maybe a virtual/formal type, we need to get a real receiver first
- # FIXME: What happend here is far from clear. Thus this part must be validated and clarified
+ # FIXME: What happens here is far from clear. Thus this part must be validated and clarified
var resolved_receiver
if mtype.need_anchor then
assert anchor != null
resolved_receiver = anchor.arguments[resolved_receiver.rank]
if resolved_receiver isa MNullableType then resolved_receiver = resolved_receiver.mtype
end
- assert resolved_receiver isa MClassType
+ assert resolved_receiver isa MClassType # It is the only remaining type
# Eh! The parameter is in the current class.
# So we return the corresponding argument, no mater what!
end
return mtype.collect_mclassdefs(mmodule).has(mclass.intro)
end
-
- init(mclass: MClass, rank: Int)
- do
- self.mclass = mclass
- self.rank = rank
- end
end
# A type prefixed with "nullable"
redef fun model do return self.mtype.model
- init(mtype: MType)
+ init
do
- self.mtype = mtype
self.to_s = "nullable {mtype}"
end
- redef var to_s: String
+ redef var to_s: String is noinit
+
+ redef var full_name is lazy do return "nullable {mtype.full_name}"
+
+ redef var c_name is lazy do return "nullable__{mtype.c_name}"
redef fun need_anchor do return mtype.need_anchor
redef fun as_nullable do return self
+ redef fun as_notnullable do return mtype
redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual)
do
var res = self.mtype.resolve_for(mtype, anchor, mmodule, cleanup_virtual)
return self.mtype.can_resolve_for(mtype, anchor, mmodule)
end
+ # Efficiently returns `mtype.lookup_fixed(mmodule, resolved_receiver).as_nullable`
+ redef fun lookup_fixed(mmodule, resolved_receiver)
+ do
+ var t = mtype.lookup_fixed(mmodule, resolved_receiver)
+ if t == mtype then return self
+ return t.as_nullable
+ end
+
redef fun depth do return self.mtype.depth
redef fun length do return self.mtype.length
class MNullType
super MType
redef var model: Model
- protected init(model: Model)
- do
- self.model = model
- end
redef fun to_s do return "null"
+ redef fun full_name do return "null"
+ redef fun c_name do return "null"
redef fun as_nullable do return self
redef fun need_anchor do return false
redef fun resolve_for(mtype, anchor, mmodule, cleanup_virtual) do return self
end
# REQUIRE: 1 <= mparameters.count p -> p.is_vararg
- init(mparameters: Array[MParameter], return_mtype: nullable MType)
+ init
do
var vararg_rank = -1
for i in [0..mparameters.length[ do
vararg_rank = i
end
end
- self.mparameters = mparameters
- self.return_mtype = return_mtype
self.vararg_rank = vararg_rank
end
# The rank of the ellipsis (`...`) for vararg (starting from 0).
# value is -1 if there is no vararg.
# Example: for "(a: Int, b: Bool..., c: Char)" #-> vararg_rank=1
- var vararg_rank: Int
+ var vararg_rank: Int is noinit
# The number or parameters
fun arity: Int do return mparameters.length
# A parameter in a signature
class MParameter
+ super MEntity
+
# The name of the parameter
- var name: String
+ redef var name: String
# The static type of the parameter
var mtype: MType
end
end
+ # Returns a new parameter with the `mtype` resolved.
+ # See `MType::resolve_for` for details.
fun resolve_for(mtype: MType, anchor: nullable MClassType, mmodule: MModule, cleanup_virtual: Bool): MParameter
do
if not self.mtype.need_anchor then return self
var res = new MParameter(self.name, newtype, self.is_vararg)
return res
end
+
+ redef fun model do return mtype.model
end
# A service (global property) that generalize method, attribute, etc.
# The (short) name of the property
redef var name: String
- # The canonical name of the property
- # Example: "owner::my_module::MyClass::my_method"
- fun full_name: String
- do
- return "{self.intro_mclassdef.mmodule.full_name}::{self.intro_mclassdef.mclass.name}::{name}"
+ # The canonical name of the property.
+ #
+ # It is the short-`name` prefixed by the short-name of the class and the full-name of the module.
+ # Example: "my_project::my_module::MyClass::my_method"
+ redef var full_name is lazy do
+ return "{intro_mclassdef.mmodule.full_name}::{intro_mclassdef.mclass.name}::{name}"
+ end
+
+ redef var c_name is lazy do
+ return "{intro_mclassdef.mmodule.c_name}__{intro_mclassdef.mclass.c_name}__{name.to_cmangle}"
end
# The visibility of the property
var visibility: MVisibility
- init(intro_mclassdef: MClassDef, name: String, visibility: MVisibility)
+ init
do
- self.intro_mclassdef = intro_mclassdef
- self.name = name
- self.visibility = visibility
intro_mclassdef.intro_mproperties.add(self)
var model = intro_mclassdef.mmodule.model
model.mproperties_by_name.add_one(name, self)
# All definitions of the property.
# The first is the introduction,
# The other are redefinitions (in refinements and in subclasses)
- var mpropdefs: Array[MPROPDEF] = new Array[MPROPDEF]
+ var mpropdefs = new Array[MPROPDEF]
+
+ # The definition that introduces the property.
+ #
+ # Warning: such a definition may not exist in the early life of the object.
+ # In this case, the method will abort.
+ var intro: MPROPDEF is noinit
- # The definition that introduced the property
- # Warning: the introduction is the first `MPropDef` object
- # associated to self. If self is just created without having any
- # associated definition, this method will abort
- fun intro: MPROPDEF do return mpropdefs.first
+ redef fun model do return intro.model
# Alias for `name`
redef fun to_s do return name
fun lookup_definitions(mmodule: MModule, mtype: MType): Array[MPROPDEF]
do
assert not mtype.need_anchor
- if mtype isa MNullableType then mtype = mtype.mtype
+ mtype = mtype.as_notnullable
var cache = self.lookup_definitions_cache[mmodule, mtype]
if cache != null then return cache
return select_most_specific(mmodule, candidates)
end
- private var lookup_definitions_cache: HashMap2[MModule, MType, Array[MPROPDEF]] = new HashMap2[MModule, MType, Array[MPROPDEF]]
+ private var lookup_definitions_cache = new HashMap2[MModule, MType, Array[MPROPDEF]]
# Return the most specific property definitions inherited by a type.
# The selection knows that refinement is stronger than specialization;
fun lookup_super_definitions(mmodule: MModule, mtype: MType): Array[MPROPDEF]
do
assert not mtype.need_anchor
- if mtype isa MNullableType then mtype = mtype.mtype
+ mtype = mtype.as_notnullable
# First, select all candidates
var candidates = new Array[MPROPDEF]
# If you want to know the next properties in the linearization,
# look at `MPropDef::lookup_next_definition`.
#
- # FIXME: the linearisation is still unspecified
+ # FIXME: the linearization is still unspecified
#
# REQUIRE: `not mtype.need_anchor`
# REQUIRE: `mtype.has_mproperty(mmodule, self)`
return lookup_all_definitions(mmodule, mtype).first
end
- # Return all definitions in a linearisation order
- # Most speficic first, most general last
+ # Return all definitions in a linearization order
+ # Most specific first, most general last
fun lookup_all_definitions(mmodule: MModule, mtype: MType): Array[MPROPDEF]
do
assert not mtype.need_anchor
- if mtype isa MNullableType then mtype = mtype.mtype
+ mtype = mtype.as_notnullable
var cache = self.lookup_all_definitions_cache[mmodule, mtype]
if cache != null then return cache
return candidates
end
- private var lookup_all_definitions_cache: HashMap2[MModule, MType, Array[MPROPDEF]] = new HashMap2[MModule, MType, Array[MPROPDEF]]
+ private var lookup_all_definitions_cache = new HashMap2[MModule, MType, Array[MPROPDEF]]
end
# A global method
redef type MPROPDEF: MMethodDef
- init(intro_mclassdef: MClassDef, name: String, visibility: MVisibility)
- do
- super
- end
-
# Is the property defined at the top_level of the module?
# Currently such a property are stored in `Object`
- var is_toplevel: Bool writable = false
+ var is_toplevel: Bool = false is writable
# Is the property a constructor?
# Warning, this property can be inherited by subclasses with or without being a constructor
# therefore, you should use `is_init_for` the verify if the property is a legal constructor for a given class
- var is_init: Bool writable = false
+ var is_init: Bool = false is writable
- # The the property a 'new' contructor?
- var is_new: Bool writable = false
+ # The constructor is a (the) root init with empty signature but a set of initializers
+ var is_root_init: Bool = false is writable
+
+ # Is the property a 'new' constructor?
+ var is_new: Bool = false is writable
# Is the property a legal constructor for a given class?
# As usual, visibility is not considered.
redef type MPROPDEF: MAttributeDef
- init(intro_mclassdef: MClassDef, name: String, visibility: MVisibility)
- do
- super
- end
end
# A global virtual type
redef type MPROPDEF: MVirtualTypeDef
- init(intro_mclassdef: MClassDef, name: String, visibility: MVisibility)
- do
- super
- end
-
# The formal type associated to the virtual type property
- var mvirtualtype: MVirtualType = new MVirtualType(self)
+ var mvirtualtype = new MVirtualType(self)
end
# A definition of a property (local property)
# Self class
type MPROPDEF: MPropDef
- # The origin of the definition
- var location: Location
-
# The class definition where the property definition is
var mclassdef: MClassDef
# The associated global property
var mproperty: MPROPERTY
- init(mclassdef: MClassDef, mproperty: MPROPERTY, location: Location)
+ # The origin of the definition
+ var location: Location
+
+ init
do
- self.mclassdef = mclassdef
- self.mproperty = mproperty
- self.location = location
mclassdef.mpropdefs.add(self)
mproperty.mpropdefs.add(self)
+ if mproperty.intro_mclassdef == mclassdef then
+ assert not isset mproperty._intro
+ mproperty.intro = self
+ end
self.to_s = "{mclassdef}#{mproperty}"
end
# Actually the name of the `mproperty`
redef fun name do return mproperty.name
+ # The full-name of mpropdefs combine the information about the `classdef` and the `mproperty`.
+ #
+ # Therefore the combination of identifiers is awful,
+ # the worst case being
+ #
+ # ~~~nitish
+ # "{mclassdef.mmodule.full_name}#{mclassdef.mclass.intro_mmodule.full_name}::{mclassdef.name}#{mproperty.intro_mclassdef.mmodule.full_name}::{mproperty.intro_mclassdef.name}::{name}"
+ # ~~~
+ #
+ # Fortunately, the full-name is simplified when entities are repeated.
+ # The simplest form is "my_module#MyClass#my_property".
+ redef var full_name is lazy do
+ var res = new FlatBuffer
+ res.append mclassdef.mmodule.full_name
+ res.append "#"
+ if not mclassdef.is_intro then
+ res.append mclassdef.mclass.intro_mmodule.full_name
+ res.append "::"
+ end
+ res.append mclassdef.name
+ res.append "#"
+ if mproperty.intro_mclassdef.mmodule != mclassdef.mmodule then
+ res.append mproperty.intro_mclassdef.mmodule.full_name
+ res.append "::"
+ end
+ if mclassdef.mclass != mproperty.intro_mclassdef.mclass then
+ res.append mproperty.intro_mclassdef.mclass.name
+ res.append "::"
+ end
+ res.append name
+ return res.to_s
+ end
+
+ redef var c_name is lazy do
+ var res = new FlatBuffer
+ res.append mclassdef.c_name
+ res.append "__"
+ if is_intro then
+ res.append name.to_cmangle
+ else
+ res.append mproperty.c_name.to_cmangle
+ end
+ return res.to_s
+ end
+
+ redef fun model do return mclassdef.model
+
# Internal name combining the module, the class and the property
# Example: "mymodule#MyClass#mymethod"
- redef var to_s: String
+ redef var to_s: String is noinit
# Is self the definition that introduce the property?
fun is_intro: Bool do return mproperty.intro == self
redef type MPROPERTY: MMethod
redef type MPROPDEF: MMethodDef
- init(mclassdef: MClassDef, mproperty: MPROPERTY, location: Location)
- do
- super
- end
-
# The signature attached to the property definition
- var msignature: nullable MSignature writable = null
+ var msignature: nullable MSignature = null is writable
+
+ # The signature attached to the `new` call on a root-init
+ # This is a concatenation of the signatures of the initializers
+ #
+ # REQUIRE `mproperty.is_root_init == (new_msignature != null)`
+ var new_msignature: nullable MSignature = null is writable
+
+ # List of initialisers to call in root-inits
+ #
+ # They could be setters or attributes
+ #
+ # REQUIRE `mproperty.is_root_init == (new_msignature != null)`
+ var initializers = new Array[MProperty]
# Is the method definition abstract?
- var is_abstract: Bool writable = false
+ var is_abstract: Bool = false is writable
# Is the method definition intern?
- var is_intern writable = false
+ var is_intern = false is writable
# Is the method definition extern?
- var is_extern writable = false
+ var is_extern = false is writable
+
+ # An optional constant value returned in functions.
+ #
+ # Only some specific primitife value are accepted by engines.
+ # Is used when there is no better implementation available.
+ #
+ # Currently used only for the implementation of the `--define`
+ # command-line option.
+ # SEE: module `mixin`.
+ var constant_value: nullable Object = null is writable
end
# A local definition of an attribute
redef type MPROPERTY: MAttribute
redef type MPROPDEF: MAttributeDef
- init(mclassdef: MClassDef, mproperty: MPROPERTY, location: Location)
- do
- super
- end
-
# The static type of the attribute
- var static_mtype: nullable MType writable = null
+ var static_mtype: nullable MType = null is writable
end
# A local definition of a virtual type
redef type MPROPERTY: MVirtualTypeProp
redef type MPROPDEF: MVirtualTypeDef
- init(mclassdef: MClassDef, mproperty: MPROPERTY, location: Location)
- do
- super
- end
-
# The bound of the virtual type
- var bound: nullable MType writable = null
+ var bound: nullable MType = null is writable
+
+ # Is the bound fixed?
+ var is_fixed = false is writable
end
# A kind of class.
# Is a constructor required?
var need_init: Bool
- private init(s: String, need_init: Bool)
- do
- self.to_s = s
- self.need_init = need_init
- end
+
+ # TODO: private init because enumeration.
# Can a class of kind `self` specializes a class of kine `other`?
fun can_specialize(other: MClassKind): Bool
# no other case for interfaces
return false
else if self == extern_kind then
- # only compatible with themselve
+ # only compatible with themselves
return self == other
else if other == enum_kind or other == extern_kind then
# abstract_kind and concrete_kind are incompatible
end
end
+# The class kind `abstract`
fun abstract_kind: MClassKind do return once new MClassKind("abstract class", true)
+# The class kind `concrete`
fun concrete_kind: MClassKind do return once new MClassKind("class", true)
+# The class kind `interface`
fun interface_kind: MClassKind do return once new MClassKind("interface", false)
+# The class kind `enum`
fun enum_kind: MClassKind do return once new MClassKind("enum", false)
+# The class kind `extern`
fun extern_kind: MClassKind do return once new MClassKind("extern class", false)