X-Git-Url: http://nitlanguage.org

diff --git a/src/metamodel/static_type.nit b/src/metamodel/static_type.nit
index 2720fa4..7d57090 100644
--- a/src/metamodel/static_type.nit
+++ b/src/metamodel/static_type.nit
@@ -22,13 +22,13 @@ intrude import abstractmetamodel
 
 redef class MMLocalClass
 	# Cached result of get_type
-	attr _base_type_cache: MMType
+	attr _base_type_cache: nullable MMType
 
 	# Return the type of self for this class
 	meth get_type: MMType
 	do
 		if _base_type_cache == null then _base_type_cache = new MMTypeSimpleClass(self)
-		return _base_type_cache
+		return _base_type_cache.as(not null)
 	end
 
 	# Register a new ancestor
@@ -40,28 +40,24 @@ redef class MMLocalClass
 	end
 
 	# Array of ancestor that associate each superclass with the corresponding ancestor
-	readable attr _ancestors: Map[MMLocalClass, MMAncestor]
+	readable attr _ancestors: nullable Map[MMLocalClass, MMAncestor]
 
 	# The ancestor type for a given superclass
 	meth ancestor(c: MMLocalClass): MMType
 	do
-		assert _ancestors != null
-		if _ancestors.has_key(c) then
-			return _ancestors[c].stype
-		end
-		return null
+		return _ancestors[c].stype
 	end
 end
 
 redef class MMLocalProperty
 	# The signature of the property (where it is declared)
-	readable writable attr _signature: MMSignature
+	readable writable attr _signature: nullable MMSignature
 
 	attr _signatures_cache: HashMap[MMType, MMSignature] = new HashMap[MMType, MMSignature]
 
 	# Return the adapted signature of self for a receiver of type t
 	meth signature_for(t: MMType): MMSignature do
-		if t == local_class.get_type then return signature
+		if t == local_class.get_type then return signature.as(not null)
 
 		if _signatures_cache.has_key(t) then return _signatures_cache[t]
 
@@ -74,31 +70,34 @@ end
 # Signature for local properties
 class MMSignature
 	# The type of the reveiver
-	readable attr _recv: MMType 
+	readable attr _recv: MMType
 
 	# The parameter types
- 	attr _params: Array[MMType]
+	attr _params: Array[MMType]
 
 	# The return type
- 	readable attr _return_type: MMType 
+	readable attr _return_type: nullable MMType
+
+	# The closure parameters
+	readable attr _closures: Array[MMClosure] = new Array[MMClosure]
 
 	# Number of parameters
 	meth arity: Int
 	do
-		assert _params != null
 		return _params.length
 	end
 
 	# Is self a valid subtype of an other signature
 	meth <(s: MMSignature): Bool
 	do
-		assert s != null
 		if self == s then
 			return true
 		end
 		assert _recv.module == s.recv.module
-		if arity != s.arity or (_return_type == null) != (s.return_type == null) then return false
-		if _return_type != null and not _return_type < s.return_type then
+		var rt = _return_type
+		var srt = s.return_type
+		if arity != s.arity or (rt == null) != (srt == null) then return false
+		if rt != null and not rt < srt.as(not null) then
 			return false
 		end
 
@@ -107,6 +106,11 @@ class MMSignature
 				return false
 			end
 		end
+
+		if closures.length != s.closures.length then return false
+		for i in [0..closures.length[ do
+			if not s.closures[i] < closures[i] then return false
+		end
 		return true
 	end
 
@@ -119,8 +123,8 @@ class MMSignature
 
 	redef meth to_s
 	do
-		var s: String
-		if _params != null and _params.length > 0 then
+		var s = new Buffer
+		if _params.length > 0 then
 			var tmp: String
 			var a = new Array[String].with_capacity(_params.length)
 			for i in [0.._params.length[ do
@@ -129,14 +133,12 @@ class MMSignature
 				#a.add("{pn}: {p}")
 				a.add(p.to_s)
 			end
-			s = "({a.join(",")})"
-		else
-			s = ""
+			s.append("({a.join(",")})")
 		end
 		if _return_type != null then
 			s.append(": {_return_type}")
 		end
-		return s
+		return s.to_s
 	end
 
 	# Adapt the signature to a different receiver
@@ -146,36 +148,127 @@ class MMSignature
 			return self
 		end
 		var mod = r.module
-		var p = _params
-		if p != null then
-			p = new Array[MMType]
-			for i in _params do
-				p.add(i.for_module(mod).adapt_to(r))
-			end
+		var p = new Array[MMType]
+		for i in _params do
+			p.add(i.for_module(mod).adapt_to(r))
 		end
 		var rv = _return_type
 		if rv != null then
 			rv = rv.for_module(mod).adapt_to(r)
 		end
-		return new MMSignature(p,rv,r)
+		var res = new MMSignature(p,rv,r)
+		for clos in _closures do
+			res.closures.add(clos.adaptation_to(r))
+		end
+		return res
+	end
+
+	attr _not_for_self_cache: nullable MMSignature = null
+
+	# Return a type approximation if the reveiver is not self
+	# Useful for virtual types
+	meth not_for_self: MMSignature
+	do
+		if _not_for_self_cache != null then return _not_for_self_cache.as(not null)
+
+		var need_for_self = false
+		var p = new Array[MMType]
+		for i in _params do
+			var i2 = i.not_for_self
+			if i != i2 then need_for_self = true
+			p.add(i2)
+		end
+
+		var rv = _return_type
+		if rv != null then
+			rv = rv.not_for_self
+			if rv != _return_type then need_for_self = true
+		end
+
+		var clos = new Array[MMClosure]
+		for c in _closures do
+			var c2 = c.not_for_self
+			if c2 != c then need_for_self = true
+			clos.add(c2)
+		end
+
+		var res: MMSignature
+		if need_for_self then
+			res = new MMSignature(p, rv, _recv)
+			res.closures.add_all(clos)
+		else
+			res = self
+		end
+
+		_not_for_self_cache = res
+		return res
 	end
 
-	init(params: Array[MMType], return_type: MMType, r: MMType)
+	init(params: Array[MMType], return_type: nullable MMType, r: MMType)
 	do
-		assert params != null
 		_params = params
 		_return_type = return_type
 		_recv = r
 	end
 end
 
+# A closure in a signature
+class MMClosure
+	# The signature of the closure
+	readable attr _signature: MMSignature
+
+	# Is the closure a brek one
+	# aka is defined with the break keyword thus does not return
+	readable attr _is_break: Bool
+
+	# Is the closure optional?
+	# ie is there a default definition
+	readable attr _is_optional: Bool
+
+	# Adapt the signature to a different receiver
+	meth adaptation_to(r: MMType): MMClosure
+	do
+		return new MMClosure(_signature.adaptation_to(r), _is_break, _is_optional)
+	end
+
+	init(s: MMSignature, is_break: Bool, is_optional: Bool)
+	do
+		_signature = s
+		_is_break = is_break
+		_is_optional = is_optional
+	end
+
+	meth not_for_self: MMClosure
+	do
+		var sig = _signature.not_for_self
+		if sig != _signature then
+			return new MMClosure(sig, _is_break, _is_optional)
+		else
+			return self
+		end
+	end
+
+	meth <(c: MMClosure): Bool
+	do
+		if c.is_optional and not is_optional then return false
+		if not c.is_break and is_break then return false
+		return c.signature < signature
+	end
+end
+
 # Inheritance relation between two types
 abstract class MMAncestor
 	# The inherited type
-	readable writable attr _stype: MMType 
+	writable attr _stype: nullable MMType = null
+
+	# The inherited type
+	meth stype: MMType do return _stype.as(not null)
+
+	# The inheriter (heir) type
+	writable attr _inheriter: nullable MMType = null
 
 	# The inheriter (heir) type
-	readable writable attr _inheriter: MMType 
+	meth inheriter: MMType do return _inheriter.as(not null)
 
 	meth is_reffinement: Bool do
 		return stype.module != stype.module
@@ -190,7 +283,7 @@ abstract class MMAncestor
 
 	redef meth to_s
 	do
-		if stype == null then
+		if _stype == null then
 			return local_class.to_s
 		else
 			return stype.to_s
@@ -207,6 +300,10 @@ abstract class MMType
 	# The local class that self direclty or indirectly refers to
 	meth local_class: MMLocalClass is abstract
 
+	# Is the type a valid one
+	# For instance, circular dependency on formal types is invalid
+	meth is_valid: Bool do return true
+
 	# Is self a valid subtype of t
 	meth <(t : MMType): Bool is abstract
 
@@ -224,18 +321,105 @@ abstract class MMType
 
 	# Adapt self to another local class context
 	# Useful for genericity
+	# 'c' Must be a super-class of self
+	# Example:
+	#   class A[E]
+	#   class B[F] special A[F]
+	#   class C[G] special B[String]
+	#   class D special C[Float]
+	# 'A[Int]'.upcast_for('A') -> 'A[Int]'
+	# 'A[Int]'.upcast_for('B') -> abort
+	# 'B[Int]'.upcast_for('B') -> 'B[Int]'
+	# 'B[Int]'.upcast_for('A') -> 'A[Int]'
+	# 'B[Int]'.upcast_for('C') -> abort
+	# 'C[Int]'.upcast_for('C') -> 'C[Int]'
+	# 'C[Int]'.upcast_for('B') -> 'B[String]'
+	# 'C[Int]'.upcast_for('A') -> 'A[String]'
+	# 'D'.upcast_for('D') -> 'D'
+	# 'D'.upcast_for('C') -> 'C[Float]'
+	# 'D'.upcast_for('B') -> 'C[String]'
+	# 'D'.upcast_for('A') -> 'A[String]'
 	meth upcast_for(c: MMLocalClass): MMType is abstract
 
 	# Return a type approximation if the reveiver is not self
 	# Useful for virtual types
 	meth not_for_self: MMType do return self
+
+	# The nullable version of self (if needed)
+	attr _as_nullable_cache: nullable MMType = null
+
+	# IS the type can accept null?
+	meth is_nullable: Bool do return false
+
+	# Return the nullable version of the type
+	# Noop if already nullable
+	meth as_nullable: MMType do
+		var cache = _as_nullable_cache
+		if cache != null then return cache
+		var res = new MMNullableType(self)
+		_as_nullable_cache = res
+		return res
+	end
+
+	# Return the not null version of the type
+	# Noop if already not null
+	meth as_notnull: MMType do return self
+end
+
+class MMNullableType
+special MMType
+	attr _base_type: MMType
+	redef meth is_valid do return _base_type.is_valid
+	redef meth is_nullable: Bool do return true
+	redef meth as_notnull do return _base_type
+	redef meth as_nullable do return self
+	init(t: MMType) do _base_type = t
+
+	redef meth module do return _base_type.module
+
+	redef meth local_class do return _base_type.local_class
+
+	redef meth <(t)
+	do
+		return t isa MMNullableType and _base_type < t.as_notnull
+	end
+
+	redef meth to_s
+	do
+		return "nullable {_base_type}"
+	end
+
+	redef meth is_supertype(t)
+	do
+		return _base_type.is_supertype(t)
+	end
+
+	redef meth for_module(mod)
+	do
+		return _base_type.for_module(mod).as_nullable
+	end
+
+	redef meth adapt_to(recv)
+	do
+		return _base_type.adapt_to(recv).as_nullable
+	end
+
+	redef meth upcast_for(c)
+	do
+		return _base_type.upcast_for(c)
+	end
+
+	redef meth not_for_self
+	do
+		return _base_type.not_for_self.as_nullable
+	end
 end
 
 class MMTypeClass 
 special MMType
 	redef readable attr _local_class: MMLocalClass
 	redef meth module do return _local_class.module end
-	redef meth <(t) do return t != null and t.is_supertype(self)
+	redef meth <(t) do return t.is_supertype(self)
 
 	redef meth to_s
 	do
@@ -244,14 +428,10 @@ special MMType
 
 	redef meth upcast_for(c)
 	do
-		assert _local_class != null
-		assert c != null
-
 		var t: MMType = self
 		if _local_class != c then
 			t = _local_class.ancestor(c)
 		end
-		assert t != null
 		return t
 	end
 
@@ -274,13 +454,12 @@ special MMTypeClass
 		if module != mod then
 			t = _local_class.for_module(mod).get_type
 		end
-		assert t != null
 		return t
 	end
 
 	redef meth adapt_to(recv) do return self
 
-	redef init(c: MMLocalClass)
+	init(c: MMLocalClass)
 	do
 		super(c)
 	end
@@ -289,11 +468,15 @@ end
 # The type of null
 class MMTypeNone
 special MMType
- 	redef readable attr _module: MMModule
- 	redef meth <(t) do return true
- 	redef meth is_supertype(t) do return false
- 	redef meth local_class do abort
- 	redef meth upcast_for(c) do return self
+	redef readable attr _module: MMModule
+	redef meth is_nullable: Bool do return true
+	redef meth <(t) do return t isa MMTypeNone or t isa MMNullableType
+	redef meth to_s do return "null"
+	redef meth is_supertype(t) do return false
+	redef meth local_class do abort
+	redef meth upcast_for(c) do abort
+	redef meth as_nullable do return self
+	redef meth as_notnull do abort
 
 	private init(m: MMModule) do _module = m
 end