#
# 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.
var res = props.first
for p in props do
types.add(p.bound.as(not null))
+ if not res.is_fixed then res = p
end
if types.length == 1 then
return res
abort
end
- # Is the virtual type fixed for a given resolved_receiver?
- fun is_fixed(mmodule: MModule, resolved_receiver: MType): Bool
+ # 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
- var props = self.mproperty.lookup_definitions(mmodule, resolved_receiver)
- if props.is_empty then
- abort
- end
- for p in props do
- if p.as(MVirtualTypeDef).is_fixed then return true
- end
- return false
+ 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)
# 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_receiver}/{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 receiver 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
- # If we are final, just return the resolution
- if is_fixed(mmodule, resolved_reciever) then return res
- # If the resolved type isa intern class, then there is no possible valid redefinition in any potential subclass. self is just fixed. so simply return the resolution
- if res isa MClassType and res.mclass.kind == enum_kind then return res
- # 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)
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 resolved_receiver isa MClassType
+ 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)
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
nitlanguage / nit.git / commitdiff