metamodel: add nullable static types

[nit.git] / src / syntax / mmbuilder.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2008 Jean Privat <jean@pryen.org>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

# Build MM entity from NIT AST and check conformance of these entities.
# This module introduce specific MM class (MMSrcXXX) that specialize the abstract one from metamodel
#
package mmbuilder

import syntax_base

# Class specialization hierarchy sorter
private class CSHSorter
special AbstractSorter[MMLocalClass]
        redef meth compare(a, b)
        do
                return a.cshe.rank <=> b.cshe.rank
        end

        init do end
end

redef class MMSrcModule
        # Syntax analysis and MM construction for the module
        # Require that supermodules are processed
        meth do_mmbuilder(tc: ToolContext)
        do
                # Import global classes
                import_global_classes

                # Create local classes and attach them to global classes
                var mmbv = new ClassBuilderVisitor(tc, self)
                mmbv.visit(node)
                if tc.error_count > 0 then exit(1)

                # Import unrefined local classes and attach them to global classes
                import_local_classes

                # Resolve classes in super clauses
                var mmbv1 = new ClassSpecializationBuilderVisitor(tc, self)
                mmbv1.visit(node)
                if tc.error_count > 0 then exit(1)

                # Compute specialization relation
                for c in local_classes do
                        if visibility_for(c.global.intro.module) < c.global.visibility_level then
                                continue
                        end
                        c.compute_super_classes
                end

                # Class that we will process now are those in the hierarchy
                # Its mean all the visible classes and their super-classes
                # Note that leaves invisible classes are not in the 'classes' set
                var classes = class_specialization_hierarchy.to_a

                # Prepare class list to process the following in a right order
                var sorter = once new CSHSorter
                sorter.sort(classes)

                # Compute class ancestors types
                var mmbv1b = new ClassAncestorBuilder(tc, self)
                for c in classes do
                        c.accept_class_visitor(mmbv1b)
                        c.compute_ancestors
                end
                if tc.error_count > 0 then exit(1)

                # Check class conformity
                var mmbv1b = new ClassVerifierVisitor(tc, self)
                for c in classes do
                        c.accept_class_visitor(mmbv1b)
                end
                if tc.error_count > 0 then exit(1)

                # Property inhritance and introduction
                var mmbv2 = new PropertyBuilderVisitor(tc, self)
                for c in classes do
                        # Inherit global properties
                        c.inherit_global_properties

                        # Global property introduction and redefinition 
                        c.accept_class_visitor(mmbv2)

                        # Default and inherited constructor if needed
                        if c isa MMSrcLocalClass and c.global.intro == c and not c.global.is_universal and not c.global.is_interface then
                                c.process_default_constructors(mmbv2)
                        end

                        # Note that inherited unredefined property are processed on demand latter
                end
                if tc.error_count > 0 then exit(1)

                # Property signature analysis and inheritance conformance
                var mmbv3 = new PropertyVerifierVisitor(tc, self)
                for c in classes do
                        c.accept_properties_visitor(mmbv3)
                end

                # Check inherited local properties
                for c in classes do
                        for g in c.global_properties do
                                if visibility_for(g.intro.module) < g.visibility_level then continue
                                var p = c[g]
                        end
                end

                if tc.error_count > 0 then exit(1)
        end
end

redef class MMLocalClass
        # Accept a class visitor (on class nodes)
        private meth accept_class_visitor(v: AbsSyntaxVisitor)
        do
        end

        # Accept a class visitor (on class properties)
        private meth accept_properties_visitor(v: AbsSyntaxVisitor)
        do
        end
end

redef class MMSrcLocalClass
        redef meth accept_class_visitor(v)
        do
                for n in nodes do
                        v.visit(n)
                end
        end

        # Accept a class visitor (on class properties)
        redef meth accept_properties_visitor(v)
        do
                for n in nodes do
                        v.visit(n)
                end

                for p in src_local_properties do
                        p.accept_property_visitor(v)
                end
        end

        # Introduce or inherit default constructors
        private meth process_default_constructors(v: PropertyBuilderVisitor)
        do
                # Is there already a constructor ?
                for gp in global_properties do
                        if gp.is_init then
                                # Return if explicit constructor in the class
                                if gp.intro.local_class == self then return
                        end
                end

                # Collect visible constructors in super stateful classes
                var super_inits = new ArraySet[MMLocalProperty]
                var super_constructors = new ArraySet[MMGlobalProperty]
                for sc in che.direct_greaters do
                        if sc.global.is_universal or sc.global.is_interface then continue
                        for gp in sc.global_properties do
                                if not gp.is_init then continue
                                super_constructors.add(gp)
                        end
                        var initname = once ("init".to_symbol)
                        if sc.has_global_property_by_name(initname) then
                                var gp = sc.get_property_by_name(initname)
                                super_inits.add(self[gp])
                        end
                end

                # Collect unassigned attributes
                var unassigned_attributes = new Array[MMSrcAttribute]
                for a in src_local_properties do
                        if a isa MMSrcAttribute then
                                var n = a.node
                                assert n isa AAttrPropdef
                                if n.n_expr == null then unassigned_attributes.add(a)
                        end
                end

                if not super_constructors.is_empty then
                        # Select most specific classes introducing inheritable constructors
                        # Mixin classes are skipped
                        var supers = new Array[MMLocalClass]
                        for gp in super_constructors do
                                var sc = gp.local_class
                                if supers.has(sc) then continue
                                if not sc.global.is_mixin then
                                        supers.add(sc)
                                end
                        end
                        supers = che.order.select_smallests(supers)

                        # A mixin class can only have 0 or 1 most specific non-mixin superclass
                        var superclass: MMLocalClass = null # This most specific non-mixin superclass (if any)

                        if supers.length > 1 then
                                v.error(nodes.first, "Error: Explicit constructor required in {self} since multiple inheritance of constructor is forbiden. Conflicting classes are {supers.join(", ")}. Costructors are {super_constructors.join(", ")}.")
                                return
                        else if supers.length == 1 then
                                superclass = supers.first
                        end

                        for gp in super_constructors do
                                # Inherit constructors : the one of the non-mixin super class or all from the all mixin super-classes
                                if superclass == null or gp.local_class == superclass then
                                        make_visible_an_inherited_global_property(gp)
                                end
                        end
                        global.mixin_of = superclass.global
                else
                        # v.error(nodes.first, "Error, constructor required in {self} since no anonimous init found in {sc}.")

                        # unassigned attributes, then implicit consructors are generated
                        var p = new MMImplicitInit(self, unassigned_attributes, super_inits.to_a)
                        add_src_local_property(v, p)
                        #print("Create implicit init {p} in {self} from {super_inits.join(", ")} + {unassigned_attributes.length} args")
                end
        end

        # Add a source property
        # Register it to the class and attach it to global property
        private meth add_src_local_property(v: PropertyBuilderVisitor, prop: MMLocalProperty)
        do
                var pname = prop.name
                # Check double definition in the same class
                if src_local_properties.has_key(pname) then
                        v.error(prop.node, "Error: A property {pname} is already defined in class {name}.")
                        return
                end
                src_local_properties[pname] = prop

                # Intro or redefinition ?
                if has_global_property_by_name(pname) then
                        var globs = properties_by_name[pname]
                        if globs.length > 1 then
                                v.error(prop.node, "Name error: {self} inherits {globs.length} global properties named {pname}.")
                        end
                        var g = globs.first
                        prop.inherit_global(g)
                end

                if prop.global == null then
                        prop.new_global
                        prop.global.is_init = prop.is_init
                end
        end
end

redef class MMLocalProperty
        private meth accept_property_visitor(v: AbsSyntaxVisitor)
        do
        end
end

redef class MMImplicitInit
        readable attr _super_init: MMLocalProperty = null
        redef meth accept_property_visitor(v)
        do
                var base: MMLocalProperty = null
                for p in super_inits do
                        if p.signature.arity > 0 then
                                if base == null then
                                        base = p
                                else
                                        v.error(null, "Error: explicit constructor needed in {local_class} since both super-constructor {base.full_name} and {p.full_name} have paramters")
                                        return
                                end
                        end
                end
                _super_init = base

                var params = new Array[MMType]
                if base != null then
                        var sig = base.signature
                        for i in [0..sig.arity[ do
                                params.add(sig[i])
                        end
                end
                for a in unassigned_attributes do
                        params.add(a.signature.return_type)
                end
                signature = new MMSignature(params, null, local_class.get_type)
        end
end


# Concrete NIT class specialization relation
class MMSrcAncestor
special MMAncestor
        # The related AST node
        readable attr _node: ASuperclass
        redef readable attr _local_class: MMLocalClass

        init(n: ASuperclass, c: MMLocalClass)
        do
                _node = n
                _local_class = c
        end
end

###############################################################################

# A pass visitor for syntax analysis.
# * Build the classes and attach them to global classes
# * Collect generic formal parameters.
private class ClassBuilderVisitor
special AbsSyntaxVisitor
        # Current class arity
        readable writable attr _local_class_arity: Int 

        # Current class formal parameters
        readable writable attr _formals: Map[Symbol, MMTypeFormalParameter] 

        redef meth visit(n) do n.accept_class_builder(self)
        init(tc, m) do super
end

# Another pass visitor for syntax analysis.
# * Build ancertors (with only class informations not the type one)
private class ClassSpecializationBuilderVisitor
special AbsSyntaxVisitor
        redef meth visit(n) do n.accept_class_specialization_builder(self)
        init(tc, m) do super
end

# Another pass visitor for syntax analysis.
# * Compute types in ancestors
private class ClassAncestorBuilder
special AbsSyntaxVisitor
        redef meth visit(n) do n.accept_class_ancestor_builder(self)
        init(tc, m) do super
end

# Another pass visitor for syntax analysis.
# * Checks classes in regard to superclasses
private class ClassVerifierVisitor
special AbsSyntaxVisitor
        redef meth visit(n) do n.accept_class_verifier(self)
        init(tc, m) do super
end


# Another pass visitor for syntax analysis.
# * Build propertie names
# * Build local properties and attache them to global properties
# * Attach bound to formal types
private class PropertyBuilderVisitor
special AbsSyntaxVisitor
        redef meth visit(n) do n.accept_property_builder(self)
        init(tc, m) do super
end

# Another pass pass visitor for syntax analysis.
# * Check property conformance
private class PropertyVerifierVisitor
special AbsSyntaxVisitor

        # The signature currently build
        readable writable attr _signature_builder: SignatureBuilder

        redef meth visit(n) do n.accept_property_verifier(self)

        init(tc, m)
        do
                super
                _signature_builder = new SignatureBuilder
        end
end

# Information about a signature currently build
private class SignatureBuilder
        # Current visited parameter types
        readable writable attr _params: Array[PParam] = new Array[PParam]
        
        # Visited parameters without type information added
        readable writable attr _untyped_params: Array[PParam] = new Array[PParam]

        # Position of the current star parameter
        readable writable attr _vararg_rank: Int = -1

        # Current closure declarations
        readable writable attr _closure_decls: Array[AClosureDecl] = new Array[AClosureDecl]

        # Current signature
        readable writable attr _signature: MMSignature = null 
end

###############################################################################

redef class PNode
        private meth accept_class_builder(v: ClassBuilderVisitor) do accept_abs_syntax_visitor(v)
        private meth accept_class_specialization_builder(v: ClassSpecializationBuilderVisitor) do accept_abs_syntax_visitor(v)
        private meth accept_class_ancestor_builder(v: ClassAncestorBuilder) do accept_abs_syntax_visitor(v)
        private meth accept_class_verifier(v: ClassVerifierVisitor) do accept_abs_syntax_visitor(v)
        private meth accept_property_builder(v: PropertyBuilderVisitor) do accept_abs_syntax_visitor(v)
        private meth accept_property_verifier(v: PropertyVerifierVisitor) do accept_abs_syntax_visitor(v)
end

redef class AModule
        # Import supermodules and compute visibility
        meth import_super_modules(tc: ToolContext, mod: MMSrcModule)
        do
                # Import super-modules
                var module_names_to_import = new Array[Symbol]
                var module_visibility = new HashMap[Symbol, Int]
                var no_import: PImport = null
                for i in n_imports do
                        var n = i.module_name
                        if n != null then
                                module_names_to_import.add(n)
                                module_visibility[n] = i.visibility_level
                        else
                                no_import = i
                        end
                end
                if no_import != null then
                        if not module_names_to_import.is_empty then
                                tc.error("{no_import.locate}: Error: Top modules cannot import other modules.")
                        end
                else if module_names_to_import.is_empty then
                        var stdname = once "standard".to_symbol
                        module_names_to_import.add(stdname)
                        module_visibility[stdname] = 1
                end

                mod.import_supers_modules(module_names_to_import)

                for mname in module_names_to_import do
                        var level = module_visibility[mname]
                        var m = tc.get_module(mname, mod)
                        mod.add_super_module(m, level)
                end
        end
end

redef class APackagedecl
        redef meth accept_class_builder(v)
        do
                if n_id.to_symbol != v.module.name then
                        v.error(n_id, "Error: Package name missmatch between {v.module.name} and {n_id.to_symbol}")
                end
        end
end

redef class PImport
        # Imported module name (or null)
        meth module_name: Symbol is abstract

        # Visibility level (intrude/public/private)
        meth visibility_level: Int is abstract
end
redef class AImport
        redef meth module_name
        do
                return n_id.to_symbol
        end
        redef meth visibility_level
        do
                return n_visibility.level
        end
end
redef class ANoImport
        redef meth module_name
        do
                return null
        end
end

redef class PVisibility
        # Visibility level
        meth level: Int is abstract
end
redef class APublicVisibility
        redef meth level do return 1
end
redef class AProtectedVisibility
        redef meth level do return 2
end
redef class APrivateVisibility
        redef meth level do return 3
end
redef class AIntrudeVisibility
        redef meth level do return 0
end


redef class PClassdef
        redef readable attr _local_class: MMSrcLocalClass

        # Name of the class
        meth name: Symbol is abstract

        # Number of formal parameters
        meth arity: Int do return 0

        # Visibility of the class
        meth visibility_level: Int do return 1

        redef meth accept_class_builder(v)
        do
                var local_class: MMSrcLocalClass
                var mod = v.module
                var local_classes = mod.src_local_classes
                if (local_classes.has_key(name)) then
                        local_class = local_classes[name]
                        if self isa AClassdef then
                                # If we are not a special implicit class then rant
                                v.error(self, "Error: A class {name} is already defined at line {local_class.nodes.first.first_token.line}.")
                                return
                        end
                        local_class.nodes.add(self)
                else
                        local_class = new MMSrcLocalClass(mod, name, self, arity)
                        local_classes[name] = local_class
                        if not mod.has_global_class_named(name) then
                                local_class.new_global
                        else
                                local_class.set_global(mod.global_class_named(name))
                        end

                end
                _local_class = local_class
                v.local_class_arity = 0
                v.formals = new HashMap[Symbol, MMTypeFormalParameter]

                #####
                super
                #####

                _local_class.formal_dict = v.formals
                v.formals = null
        end

        redef meth accept_abs_syntax_visitor(v)
        do
                v.local_class = _local_class
                super
                v.local_class = null
        end
end

redef class PClasskind
        meth is_interface: Bool do return false
        meth is_universal: Bool do return false
        meth is_abstract: Bool do return false
end

redef class AInterfaceClasskind
        redef meth is_interface do return true
end
redef class AUniversalClasskind
        redef meth is_universal do return true
end
redef class AAbstractClasskind
        redef meth is_abstract do return true
end

redef class AClassdef
        redef meth name
        do
                return n_id.to_symbol
        end
        redef meth arity
        do
                return n_formaldefs.length
        end
        redef meth accept_class_verifier(v)
        do
                super
                var glob = _local_class.global
                if glob.intro == _local_class then
                        # Intro
                        glob.visibility_level = visibility_level
                        glob.is_interface = n_classkind.is_interface
                        glob.is_abstract = n_classkind.is_abstract
                        glob.is_universal = n_classkind.is_universal
                        if n_kwredef != null then
                                v.error(self, "Redef error: No class {name} is imported. Remove the redef keyword to define a new class.")
                        end

                        for c in _local_class.cshe.direct_greaters do
                                var cg = c.global
                                if glob.is_interface then
                                        if cg.is_universal then
                                                v.error(self, "Special error: Interface {name} try to specialise universal class {c.name}.")
                                        else if not cg.is_interface then
                                                v.error(self, "Special error: Interface {name} try to specialise class {c.name}.")
                                        end
                                else if glob.is_universal then
                                        if not cg.is_interface and not cg.is_universal then
                                                v.error(self, "Special error: Universal class {name} try to specialise class {c.name}.")
                                        end
                                else
                                        if cg.is_universal then
                                                v.error(self, "Special error: Class {name} try to specialise universal class {c.name}.")
                                        end
                                end

                        end
                        return
                end

                # Redef

                glob.check_visibility(v, self, v.module)
                if n_kwredef == null then
                        v.error(self, "Redef error: {name} is an imported class. Add the redef keyword to refine it.")
                        return
                end

                if glob.intro.arity != _local_class.arity then
                        v.error(self, "Redef error: Formal parameter arity missmatch; got {_local_class.arity}, expected {glob.intro.arity}.")
                end

                if 
                        not glob.is_interface and n_classkind.is_interface or
                        not glob.is_abstract and n_classkind.is_abstract or
                        not glob.is_universal and n_classkind.is_universal
                then
                        v.error(self, "Redef error: cannot change kind of class {name}.")
                end
        end

        redef meth visibility_level
        do
                return n_visibility.level
        end
end

redef class AMainClassdef
        redef meth name
        do
                return once "Sys".to_symbol
        end
end

redef class ATopClassdef
        redef meth name
        do
                return once "Object".to_symbol
        end
end

class MMSrcTypeFormalParameter
special MMTypeFormalParameter
        # The associated node
        readable attr _node: AFormaldef 

        init(name: Symbol, pos: Int, local_class: MMLocalClass, n: AFormaldef)
        do
                super(name, pos, local_class)
                _node = n
        end
end

redef class AFormaldef
        # The associated formal generic parameter (MM entity)
        attr _formal: MMSrcTypeFormalParameter

        redef meth accept_class_builder(v)
        do
                var name = n_id.to_symbol
                var formal_type = new MMSrcTypeFormalParameter(name, v.local_class_arity, v.local_class, self)
                _formal = formal_type
                v.local_class_arity = v.local_class_arity + 1
                v.local_class.register_formal(formal_type)
                v.formals[name] = formal_type
                super
        end

        redef meth accept_class_verifier(v)
        do
                super
                var c = v.local_class
                var o = c.global.intro
                if c == o then
                        if n_type == null then
                                _formal.bound = v.module.type_any.as_nullable
                        else
                                _formal.bound = n_type.get_stype(v)
                        end
                else
                        var ob = o.get_formal(_formal.position).bound.for_module(v.module)
                        if n_type == null then
                                _formal.bound = ob
                        else
                                _formal.bound = n_type.get_stype(v)
                                if _formal.bound != ob then
                                        v.error(self, "Redef error: Cannot change formal parameter type of class {c}; got {_formal.bound}, expected {ob}.")
                                end
                        end
                end
        end
end

redef class ASuperclass
        readable attr _ancestor: MMSrcAncestor

        redef meth accept_class_specialization_builder(v)
        do
                super
                var c = n_type.get_local_class(v)
                var ancestor = new MMSrcAncestor(self, c)
                _ancestor = ancestor
                v.local_class.add_direct_parent(ancestor)
        end

        redef meth accept_class_ancestor_builder(v)
        do
                super
                _ancestor.stype = n_type.get_unchecked_stype(v)
                _ancestor.inheriter = v.local_class.get_type
        end

        redef meth accept_class_verifier(v)
        do
                super
                n_type.check_conform(v)
        end
end

redef class PPropdef
        # Process and check properties of the property.
        # * Distinguish inits and methods
        # * Inherit or check visibility.
        # * Check redef errors.
        # * Check forbiden attribute definitions.
        # * Check signature conformance.
        private meth process_and_check(v: PropertyVerifierVisitor, prop: MMLocalProperty, has_redef: Bool, visibility_level: Int)
        do
                if prop.global.intro == prop then
                        do_and_check_intro(v, prop, has_redef, visibility_level)
                else
                        do_and_check_redef(v, prop, has_redef, visibility_level)
                end
        end

        # The part of process_and_check when prop is an introduction
        private meth do_and_check_intro(v: PropertyVerifierVisitor, prop: MMLocalProperty, has_redef: Bool, visibility_level: Int)
        do
                var glob = prop.global
                var gbc = prop.local_class.global
                if v.local_class.global.visibility_level >= 3 then
                        # Method of private classes are private
                        visibility_level = 3
                end
                glob.visibility_level = visibility_level
                if has_redef then
                        v.error(self, "Error: No property {prop.local_class}::{prop} is inherited. Remove the redef keyword to define a new property.")
                end
                if glob.is_attribute then
                        if gbc.is_interface then
                                v.error(self, "Error: Attempt to define attribute {prop} in the interface {prop.local_class}.")
                        else if gbc.is_universal then
                                v.error(self, "Error: Attempt to define attribute {prop} in the universal class {prop.local_class}.")
                        end
                else if glob.is_init then
                        if gbc.is_interface then
                                v.error(self, "Error: Attempt to define a constructor {prop} in the class {prop.local_class}.")
                        else if gbc.is_universal then
                                v.error(self, "Error: Attempt to define a constructor {prop} in the universal {prop.local_class}.")
                        end
                end
                if prop.signature == null then
                        if glob.is_init then
                                var supers = prop.local_class.super_methods_named(prop.name)
                                inherit_signature(v, prop, supers)
                        end
                        if prop.signature != null then
                                # ok
                        else if not v.signature_builder.untyped_params.is_empty then
                                v.error(v.signature_builder.untyped_params.first, "Error: Untyped parameter.")
                        else
                                prop.signature = new MMSignature(new Array[MMType], null, v.local_class.get_type)
                                if v.signature_builder.closure_decls != null then
                                        for clos in v.signature_builder.closure_decls do
                                                prop.signature.closures.add(clos.variable.closure)
                                        end
                                end
                        end
                end
        end

        private meth inherit_signature(v: PropertyVerifierVisitor, prop: MMLocalProperty, supers: Array[MMLocalProperty])
        do
                var s = prop.signature
                for ip in supers do
                        var isig = ip.signature.adaptation_to(v.local_class.get_type)

                        if s == null then
                                if v.signature_builder.params.length != isig.arity then
                                        #prop.node.printl("v.params.length {v.params.length} != isig.arity {isig.arity} ; {prop.full_name} vs {ip.full_name}")
                                        return
                                end
                                for p in v.signature_builder.params do
                                        var t = isig[p.position]
                                        p.stype = t
                                        if p.position == isig.vararg_rank then
                                                t = v.type_array(t)
                                        end
                                        p.variable.stype = t
                                end

                                s = isig
                                prop.signature = s
                        end
                end
        end

        # The part of process_and_check when prop is a redefinition
        private meth do_and_check_redef(v: PropertyVerifierVisitor, prop: MMLocalProperty, has_redef: Bool, visibility_level: Int)
        do
                var is_init = self isa AConcreteInitPropdef
                var glob = prop.global

                if not has_redef then
                        v.error(self, "Redef error: {prop.local_class}::{prop} is an inherited property. To redefine it, add the redef keyword.")
                        return
                end
                if glob.is_init and not is_init then
                        v.error(self, "Redef error: A method {prop.local_class}::{prop} cannot redefine a constructor.")
                else if not glob.is_init and is_init then
                        v.error(self, "Redef error: A constructor {prop.local_class}::{prop} cannot redefine a method.")
                end

                var s = prop.signature
                #print "process {prop.local_class.module}::{prop.local_class}::{prop} from global {prop.global.local_property.local_class.module}::{prop.global.local_property.local_class}::{prop.global.local_property}"
                for i in prop.prhe.direct_greaters do
                        var ip = i.local_class[prop.global]
                        var isig = i.signature.adaptation_to(v.local_class.get_type)

                        if s == null then
                                #print "{prop.full_name} inherits signature from {ip.full_name}"
                                if v.signature_builder.params.length != isig.arity then
                                        v.error(self, "Redef error: {prop.local_class}::{prop} redefines {ip.local_class}::{ip} with {isig.arity} parameter(s).")
                                        return
                                end
                                if v.signature_builder.closure_decls.length != isig.closures.length then
                                        v.error(self, "Redef error: {prop.local_class}::{prop} redefines {ip.local_class}::{ip} with {isig.arity} closure(s).")
                                        return
                                end
                                for p in v.signature_builder.params do
                                        var t = isig[p.position]
                                        p.stype = t
                                        if p.position == isig.vararg_rank then
                                                t = v.type_array(t)
                                        end
                                        p.variable.stype = t
                                end
                                s = isig
                                prop.signature = s
                                #print "s is null"
                        end

                        var nberr = v.tc.error_count
                        #print "Check {prop.local_class}::{prop}{s} vs {ip.local_class}::{ip}{isig}"
                        #print "s={s.object_id} isig={isig.object_id} isigorig={i.signature.object_id}"

                        #print "orig signature:  {i.signature.recv} . {i.signature}"
                        #print "inh signature:   {isig.recv} . {isig}"
                        #print "redef signature: {s.recv} . {s}"

                        if s.arity != isig.arity then
                                v.error(self, "Redef error: {prop.local_class}::{prop} redefines {ip.local_class}::{ip} with {isig.arity} parameter(s).")
                        else
                                for i in [0..s.arity[ do
                                        if s[i] != isig[i] then
                                                v.error(self, "Redef error: Expected {isig[i]} (as in {ip.local_class}::{ip}), got {s[i]} in {prop.local_class}::{prop}.")
                                        end
                                end
                        end

                        var srt = s.return_type
                        var isrt = isig.return_type
                        if srt == null and isrt != null then
                                v.error(self, "Redef error: The procedure {prop.local_class}::{prop} redefines the function {ip.local_class}::{ip}.")
                        else if srt != null and isrt == null then
                                v.error(self, "Redef error: The function {prop.local_class}::{prop} redefines the procedure {ip.local_class}::{ip}.")
                        else if srt != null and isrt != null and not srt < isrt then
                                v.error(self, "Redef error: Expected {isrt} (as in {ip.local_class}::{ip}), got {srt} in {prop.local_class}::{prop}.")
                        else if not s < isig and nberr == v.tc.error_count then
                                # Systematic fallback for conformance check
                                v.error(self, "Redef error: Incompatible redefinition of {ip.local_class}::{ip} with {prop.local_class}::{prop}")
                        else if srt != null and isrt != null and srt != isrt and prop isa MMAttribute then
                                # FIXME: To remove
                                v.warning(self, "Redef warning: Expected {isrt} (as in {ip.local_class}::{ip}), got {srt} in {prop.local_class}::{prop}.")
                        end
                end

                if visibility_level != 1 and glob.visibility_level != visibility_level then
                        v.error(self, "Redef error: {prop.local_class}::{prop} redefinition cannot change visibility.")
                end
                glob.check_visibility(v, self, v.module, true)
        end
end

redef class AAttrPropdef
        redef readable attr _readmethod: MMSrcMethod
        redef readable attr _writemethod: MMSrcMethod
        redef readable attr _prop: MMSrcAttribute 

        redef meth accept_property_builder(v)
        do
                super
                var name = n_id.to_symbol
                var prop = new MMSrcAttribute(name, v.local_class, self)
                _prop = prop
                v.local_class.add_src_local_property(v, prop)

                if n_readable != null then
                        name = n_id.text.substring_from(1).to_symbol
                        _readmethod = new MMReadImplementationMethod(name, v.local_class, self)
                        v.local_class.add_src_local_property(v, _readmethod)
                end
                if n_writable != null then
                        name = (n_id.text.substring_from(1) + "=").to_symbol
                        _writemethod = new MMWriteImplementationMethod(name, v.local_class, self)
                        v.local_class.add_src_local_property(v, _writemethod)
                end
        end
        
        redef meth accept_property_verifier(v)
        do
                super
                var t: MMType
                if n_type != null then
                        t = n_type.get_stype(v)
                else
                        v.error(self, "Not yet implemented: Attribute definition {_prop.local_class}::{_prop} requires an explicit type.")
                        return
                end

                var signature = new MMSignature(new Array[MMType], t, v.local_class.get_type)
                _prop.signature = signature
                var visibility_level = n_visibility.level
                process_and_check(v, _prop, n_kwredef != null, visibility_level)
                if n_readable != null then
                        _readmethod.signature = signature
                        process_and_check(v, _readmethod, n_readable.n_kwredef != null, visibility_level)
                        n_type.check_visibility(v, _readmethod)
                end
                if n_writable != null then
                        _writemethod.signature = new MMSignature(new Array[MMType].with_items(t), null, v.local_class.get_type)
                        process_and_check(v, _writemethod, n_writable.n_kwredef != null, visibility_level)
                        n_type.check_visibility(v, _writemethod)
                end
        end

        redef meth accept_abs_syntax_visitor(v)
        do
                v.local_property = prop
                super
                v.local_property = null
        end
end

redef class AMethPropdef
        # Name of the method
        readable attr _name: Symbol 

        redef readable attr _method: MMMethSrcMethod

        redef meth accept_property_builder(v)
        do
                super
                if n_methid == null then
                        if self isa AConcreteInitPropdef then
                                _name = once "init".to_symbol
                        else
                                _name = once "main".to_symbol
                        end
                else 
                        _name = n_methid.name
                        # FIXME: Add the 'unary' keyword
                        if n_methid.name == (once "-".to_symbol) then
                                var ns = n_signature
                                if ns isa ASignature and ns.n_params.length == 0 then
                                        _name = once "unary -".to_symbol
                                end
                        end
                end
                var prop = new MMMethSrcMethod(_name, v.local_class, self)
                _method = prop
                v.local_class.add_src_local_property(v, prop)
        end

        redef meth accept_property_verifier(v)
        do
                v.signature_builder = new SignatureBuilder
                super

                if v.signature_builder.signature == null then
                        #_method.signature = new MMSignature(new Array[MMType], null, v.local_class.get_type)
                else
                        _method.signature = v.signature_builder.signature
                end
                var visibility_level = 1
                if n_visibility != null and n_visibility.level > 1 then
                        visibility_level = n_visibility.level
                end
                process_and_check(v, _method, n_kwredef != null, visibility_level)
                if n_signature != null then n_signature.check_visibility(v, _method)
        end

        redef meth accept_abs_syntax_visitor(v)
        do
                v.local_property = method
                super
                v.local_property = null
        end
end

redef class AMainMethPropdef
        redef meth process_and_check(v, prop, has_redef, visibility_level)
        do
                prop.global.visibility_level = visibility_level
                prop.signature = new MMSignature(new Array[MMType], null, v.local_class.get_type)
                # Disable all checks for main
        end
end

redef class ATypePropdef
        redef readable attr _prop: MMSrcTypeProperty 

        redef meth accept_property_builder(v)
        do
                super
                var name = n_id.to_symbol
                var prop = new MMSrcTypeProperty(name, v.local_class, self)
                _prop = prop
                v.local_class.add_src_local_property(v, prop)
        end
        
        redef meth accept_property_verifier(v)
        do
                super
                var signature = new MMSignature(new Array[MMType], n_type.get_stype(v), v.local_class.get_type)
                _prop.signature = signature
                var visibility_level = n_visibility.level
                process_and_check(v, _prop, n_kwredef != null, visibility_level)
        end
        
        redef meth accept_abs_syntax_visitor(v)
        do
                v.local_property = prop
                super
                v.local_property = null
        end
end

# Visitor used to build a full method name from multiple tokens
private class MethidAccumulator
special Visitor
        readable attr _name: Buffer = new Buffer
        redef meth visit(n)
        do
                if n isa Token then
                        _name.append(n.text)
                else
                        n.visit_all(self)
                end
        end
end

redef class PMethid
        # Method name
        readable attr _name: Symbol 

        redef meth accept_property_builder(v)
        do
                var accumulator = new MethidAccumulator
                accumulator.visit(self)
                _name = accumulator.name.to_s.to_symbol
                super
        end
end

redef class PSignature
        # Check that visibilities of types in the signature are compatible with the visibility of the property.
        meth check_visibility(v: AbsSyntaxVisitor, p: MMLocalProperty) is abstract
end

redef class ASignature
        redef meth accept_property_verifier(v)
        do
                super
                if not v.signature_builder.untyped_params.is_empty then
                        if v.signature_builder.untyped_params.first != v.signature_builder.params.first or n_type != null then
                                v.error(v.signature_builder.untyped_params.first, "Syntax error: untyped parameter.")
                                return
                        end
                else if not v.signature_builder.params.is_empty or n_type != null then
                        var pars = new Array[MMType]
                        for p in v.signature_builder.params do
                                pars.add(p.stype)
                        end
                        var ret: MMType = null
                        if n_type != null then
                                ret = n_type.get_stype(v)
                        end
                        v.signature_builder.signature = new MMSignature(pars, ret, v.local_class.get_type)
                        if v.signature_builder.vararg_rank >= 0 then
                                v.signature_builder.signature.vararg_rank = v.signature_builder.vararg_rank
                        end
                        for clos in v.signature_builder.closure_decls do
                                v.signature_builder.signature.closures.add(clos.variable.closure)
                        end
                end
        end

        redef meth check_visibility(v, p)
        do
                if p.global.visibility_level >= 3 then return
                for n in n_params do
                        if n.n_type != null then n.n_type.check_visibility(v, p)
                end
                if n_type != null then n_type.check_visibility(v, p)
        end
end

redef class PParam
        redef readable attr _position: Int

        redef readable attr _variable: ParamVariable 

        # The type of the parameter in signature
        readable writable attr _stype: MMType

        redef meth accept_property_verifier(v)
        do
                super
                _position = v.signature_builder.params.length
                _variable = new ParamVariable(n_id.to_symbol, self)
                v.signature_builder.params.add(self)
                v.signature_builder.untyped_params.add(self)
                if n_type != null then
                        var stype = n_type.get_stype(v)
                        for p in v.signature_builder.untyped_params do
                                p.stype = stype
                                if is_vararg then
                                        if v.signature_builder.vararg_rank == -1 then
                                                v.signature_builder.vararg_rank = p.position
                                        else
                                                v.error(self, "Error: A vararg parameter is already defined.")
                                        end
                                        stype = v.type_array(stype) 
                                end
                                p.variable.stype = stype
                        end
                        v.signature_builder.untyped_params.clear
                end
        end

        meth is_vararg: Bool is abstract
end

redef class AParam
        redef meth is_vararg do return n_dotdotdot != null
end

redef class AClosureDecl
        redef readable attr _variable: ClosureVariable

        redef meth accept_property_verifier(v)
        do
                var old_signature_builder = v.signature_builder
                v.signature_builder = new SignatureBuilder
                super
                var sig = v.signature_builder.signature
                if sig == null then
                        sig = new MMSignature(new Array[MMType], null, v.local_class.get_type)
                end
                if sig.return_type != null and n_kwbreak != null then
                        v.error(self, "Syntax Error: A break block cannot have a return value.")
                end

                # Add the finalizer to the closure signature
                var finalize_sig = new MMSignature(new Array[MMType], null, null)
                var finalizer_clos = new MMClosure(finalize_sig, false, true)
                sig.closures.add(finalizer_clos)

                var clos = new MMClosure(sig, n_kwbreak != null, n_expr != null)
                v.signature_builder = old_signature_builder
                old_signature_builder.closure_decls.add(self)
                _variable = new ClosureVariable(n_id.to_symbol, self, clos)
        end
end

redef class PType
        # Check that visibilities of types in the signature are compatible with the visibility of the property.
        private meth check_visibility(v: AbsSyntaxVisitor, p: MMLocalProperty) is abstract
end

redef class AType
        redef meth check_visibility(v, p)
        do
                if p.global.visibility_level >= 3 then return
                var t = get_stype(v)
                if t == null then return
                var bc = t.local_class
                if bc == null then return
                if bc.global.visibility_level >= 3 then
                        v.error(self, "Access error: Class {bc} is private and cannot be used in the signature of the non-private property {p}.")
                end
                for n in n_types do
                        n.check_visibility(v, p)
                end
        end
end

redef class PExpr
        redef meth accept_class_builder(v) do end
        redef meth accept_property_builder(v) do end
        redef meth accept_property_verifier(v) do end
end