metamodel: give the burden of value conflict to the MMContext

[nit.git] / src / metamodel / inheritance.nit

# This file is part of NIT ( http://www.nitlanguage.org ).
#
# Copyright 2004-2008 Jean Privat <jean@pryen.org>
# Copyright 2006-2008 Floréal Morandat <morandat@lirmm.fr>
#
# 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.

# Compute importation of classes and inheritance of properties
package inheritance

intrude import static_type

redef class MMContext
        # Method to redefine to handle the property conflicts
        # FIXME: This is just a bad workaround because of a bad design
        fun handle_property_conflict(lc: MMLocalClass, impls2: Array[MMLocalProperty])
        do
                var glob = impls2.first.global
                stderr.write("Fatal error: inherit_local_property error\n")
                print("------- {lc.mmmodule}::{lc} {glob.intro.full_name}")
                for i in impls2 do
                        print("   {i.full_name}")
                end
                print("------- {glob.property_hierarchy.first}")
                print("------- {glob.property_hierarchy.to_dot}")
                exit(1)
        end
end

redef class MMModule
        # The root of the class hierarchy
        fun type_any: MMType
        do
                var c_name = class_by_name(once ("Object".to_symbol))
                return c_name.get_type
        end

        # Import global classes from supermodules
        fun import_global_classes
        do
                var globals = new HashMap[MMGlobalClass,HashSet[MMLocalClass]]
                assert mhe != null
                for mod in mhe.direct_greaters do
                        for glob in mod.global_classes do
                                if global_classes.has(glob) then continue
                                _global_classes.add(glob)
                                _global_class_by_name[glob.name] = glob
                        end
                end

        end 
        
        # Create implicit local classes for global classes that are not refined
        fun import_local_classes
        do
                for g in _global_classes do
                        if _local_class_by_global.has_key(g) then continue
                        var impl = new MMImplicitLocalClass(self, g) 
                end
        end
end

redef class MMLocalClass
        # List of all parents
        var _direct_parents: Array[MMAncestor] = new Array[MMAncestor]

        # Is the class computing super.
        # Used to detect specialization loops.
        var _computing_super: Bool = false 

        # Compute super classes of a class
        fun compute_super_classes
        do
                if computed_super_classes then
                        # do no recompute if allready done
                        return
                else if _computing_super then
                        stderr.write("Fatal error: Inheritance loop for class {self}\n")
                        exit(1)
                end
                _computing_super = true

                var supers = new Array[MMLocalClass]
                add_explicit_classes(supers)
                add_super_classes(supers)
                add_default_any_class(supers)
                compute_super_parents(supers)
                var set = new HashSet[MMLocalClass]
                set.add_all(supers)
                var u = set.to_a
                mmmodule.set_supers_class(self,u)
                assert _crhe != null
                assert _cshe != null
                _computing_super = false
        end

        # Compute ancestors for a class
        fun compute_ancestors
        do
                assert computed_super_classes
                if computed_ancestors then return

                var ancestors = group_ancestors(build_ancestors)
                _ancestors = new HashMap[MMLocalClass, MMAncestor]

                for set in ancestors do
                        if set.length == 1 then
                                add_ancestor(set.first)
                        else
                                var ma = merge_ancestors(set)
                                add_ancestor(merge_ancestors(set))
                        end
                end
        end

        var _are_global_properties_inherited: Bool = false

        # Inherit global properties for a class
        private fun inherit_global_properties
        do
                if _are_global_properties_inherited then return
                _are_global_properties_inherited = true

                var names = _properties_by_name
                var set = _global_properties
                for c in che.direct_greaters do
                        for glob in c.global_properties do
                                if set.has(glob) then continue

                                set.add(glob) # Add the global property

                                # Do not inherit constructors trough specialization
                                #print "{c.mmmodule}::{c} -> {mmmodule}::{self} for {glob.local_property.local_class.mmmodule}::{glob.local_property.local_class}::{glob.local_property} : {glob.is_init}"
                                if glob.is_init and glob.intro.local_class.global != global then
                                        #print "pass"
                                        continue
                                end

                                # Do not inherit new style attributes
                                if glob.intro.name.to_s[0] == '@' then continue

                                make_visible_an_inherited_global_property(glob)
                        end
                end
        end

        redef fun global_properties
        do
                if _are_global_properties_inherited then return _global_properties
                assert computed_super_classes
                inherit_global_properties
                return _global_properties
        end

        redef fun has_global_property(g)
        do
                # has_global_property can be called during the construction of the class
                # hierarchy to check that a type "X" is not a formal type.
                if not computed_super_classes then return false

                var set = _global_properties
                if set.has(g) then return true
                for c in che.direct_greaters do
                        if c.has_global_property(g) then
                                set.add(g)
                                return true
                        end
                end
                return false
        end

        redef fun has_global_property_by_name(n)
        do
                # has_global_property can be called during the construction of the class
                # hierarchy to check that a type "X" is not a formal type.
                if not computed_super_classes then return false

                # Ensure that super-classes are constructed
                compute_super_classes

                if _properties_by_name.has_key(n) then
                        return _properties_by_name[n].length == 1
                end
                var set = _global_properties
                var nset
                if _properties_by_name.has_key(n) then
                        nset = _properties_by_name[n]
                else
                        nset = new Array[MMGlobalProperty]
                        _properties_by_name[n] = nset
                end
                for c in che.direct_greaters do
                        if c.has_global_property_by_name(n) then
                                var g = c.get_property_by_name(n)
                                if not set.has(g) then set.add(g)
                                if g.is_init and g.intro.local_class.global != global then continue
                                if g.intro.name.to_s.first == '@' then continue # inherited new style attibutes are invisible
                                if nset.has(g) then continue
                                nset.add(g)
                        end
                end
                return nset.length == 1
        end

        # Make the name of a global property meaningful in the class
        fun make_visible_an_inherited_global_property(glob: MMGlobalProperty)
        do
                var names = _properties_by_name
                var gname = glob.intro.name
                var conf_set: Array[MMGlobalProperty]
                if names.has_key(gname) then
                        conf_set = names[gname]
                else
                        conf_set = new Array[MMGlobalProperty]
                        names[gname] = conf_set
                end
                conf_set.add(glob)
        end

        # Add super stype of this current local class
        fun add_direct_parent(p: MMAncestor)
        do
                _direct_parents.add(p)
        end

        # Are super-class already computed?
        fun computed_super_classes: Bool
        do
                return _crhe != null and _cshe != null
        end
        
        # Are ancestors already computed
        fun computed_ancestors: Bool
        do
                return _ancestors != null
        end

        # Get the ancestor for a given class
        # TODO: is this useful?
        private fun ancestor_for(c: MMLocalClass): MMAncestor
        do      
                assert ancestors != null

                if _ancestors.has_key(c) then
                        return _ancestors[c]
                end
                var a = c.for_module(mmmodule)
                assert cshe <= a
                var ra: MMAncestor
                if _ancestors.has_key(a) then
                        ra = _ancestors[a]
                else if c.global == _global then
                        ra = new MMRefineAncestor(self,c)
                else
                        ra = new MMSpecAncestor(get_type,c.get_type)
                end
                _ancestors[c] = ra
                return ra
        end

        redef fun [](glob)
        do
                if _local_property_by_global.has_key(glob) then
                        return _local_property_by_global[glob]
                else if has_global_property(glob) then
                        return inherit_local_property(glob)
                else
                        abort
                end
        end

        # Add default super class in direct parent and in super classes if this is not the Object class
        private fun add_default_any_class(supers: Array[MMLocalClass])
        do
                if supers.is_empty and name != once ("Object".to_symbol) then
                        var t_any = mmmodule.type_any
                        supers.add(t_any.local_class)
                        var default = new MMDefaultAncestor(self, t_any)
                        add_direct_parent(default)
                end
        end
        
        # Adding inherited class from previous refinement of self
        private fun add_super_classes(supers: Array[MMLocalClass])
        do
                assert _crhe != null
                for ref in _crhe.direct_greaters do
                        for sup in ref.cshe.direct_greaters do
                                var cla = sup.for_module(_mmmodule)
                                supers.add(cla)
                        end
                end
        end
        
        # Add self parents of this local class
        private fun add_explicit_classes(supers: Array[MMLocalClass])
        do
                for p in _direct_parents do
                        supers.add(p.local_class)
                end
        end

        # Ensure all super parents are computed
        private fun compute_super_parents(supers: Array[MMLocalClass])
        do
                for p in supers do
                        p.compute_super_classes
                end
        end

        # compute all ancestors for a class (multiple)
        private fun build_ancestors: Array[MMAncestor]
        do
                var all_ancestors = new Array[MMAncestor]
                # Refined classes are ancestors
                assert _crhe != null
                for p in _crhe.direct_greaters do
                        assert p != self
                        var anc = new MMRefineAncestor(self, p)
                        anc.add_in(all_ancestors)
                end
                for anc in _direct_parents do
                        assert anc.local_class != self
                        anc.add_in(all_ancestors)
                end
                return all_ancestors
        end

        # Build an ancestor map indexed by LocalClass
        private fun group_ancestors(all: Array[MMAncestor]): Map[MMLocalClass, Set[MMAncestor]]
        do
                #print "process {self}"
                var map = new HashMap[MMLocalClass, Set[MMAncestor]]
                for a in all do
                        var c = a.local_class
                        #print "ancestor is"
                        #print "  {c}"
                        var set: Set[MMAncestor]
                        c.compute_ancestors
                        if map.has_key(c) then
                                set = map[c]
                        else
                                set = new HashSet[MMAncestor]
                                map[c] = set
                        end
                        set.add(a)
                end
                return map
        end

        # Remove duplicate ancestors and merge if compatible, in the other case do an error
        private fun merge_ancestors(set: Set[MMAncestor]): MMAncestor
        do
                var marks = new HashSet[MMAncestor]
                var res = new Array[MMAncestor]
                for t in set do
                        var it = set.iterator
                        var search = true
                        while it.is_ok and search do
                                
                                var a = t == it.item
                                a = marks.has(it.item)
                                a = it.item.stype < t.stype
                                
                                if not(t == it.item or marks.has(it.item)) and
                                        (it.item.stype < t.stype) then
                                                marks.add(t)
                                                search = false
                                end
                                it.next
                        end
                        if not marks.has(t) then
                                res.add(t)
                        end
                end

                if res.length > 1 then
                        stderr.write("Fatal error: Incompatibles ancestors for {self.name}: {res.join(", ")}\n")
                        exit(1)
                end
                return res.first
        end

        # Inherit a local property
        # Is lazily called
        # FIXME: dont crash lazily
        private fun inherit_local_property(glob: MMGlobalProperty): MMLocalProperty
        do
                assert not _local_property_by_global.has_key(glob)

                var impl: MMLocalProperty

                var ghier = glob.property_hierarchy
                var supers = che.direct_greaters
                if ghier.length == 1 then
                        # Unredefined property
                        impl = glob.intro
                else if supers.length == 1 then
                        # Single inheritance
                        impl = supers.first[glob]
                else
                        # Hard multiple inheritance
                        # First compute the set of bottom properties
                        var impls = new ArraySet[MMLocalProperty]
                        for sc in supers do
                                if sc.has_global_property(glob) then impls.add(sc[glob])
                        end
                        # Second, extract most specific
                        var impls2 = ghier.select_smallests(impls)
                        # Conflict case (FIXME)
                        if impls2.length != 1 then
                                self.mmmodule.context.handle_property_conflict(self, impls2)
                        end
                        impl = impls2.first
                end

                # FIXME: Why these 3 lines ?
                #var ac = ancestor_for(impl.local_class)
                #ac.local_class.inherit_global_properties
                #var a = ac.stype
                #assert a.local_class != self

                # Register the local property
                _local_property_by_global[glob] = impl
                
                return impl
        end
end

redef class MMLocalProperty
        # Attach self to a global property
        fun inherit_global(g: MMGlobalProperty)
        do
                set_global(g)
                var impls = new Array[MMLocalProperty]
                for sc in local_class.che.direct_greaters do
                        if not sc.has_global_property(g) then continue
                        impls.add(sc[g])
                end
                g.add_local_property(self, impls)
        end
end

redef class MMAncestor
        # Add this ancestor and it's super one in tab
        private fun add_in(tab: Array[MMAncestor])
        do
                tab.add(self)
                stype.local_class.compute_ancestors
                for anc in stype.local_class.ancestors.as(not null) do
                        var aaa = anc.stype.for_module(stype.mmmodule)
                        var a = aaa.adapt_to(stype).for_module(inheriter.mmmodule)
                        if a.local_class != inheriter.local_class then
                                var it = tab.iterator
                                var b = true
                                while it.is_ok and b do
                                        b = not ( it.item.inheriter == inheriter and it.item.stype == a)
                                        it.next
                                end
                                if b then
                                        tab.add(new MMSpecAncestor(inheriter,a))
                                end
                        end
                end
        end
end

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

# A local class that is a pure importation of an other local class
class MMImplicitLocalClass
        super MMLocalClass
        init(mod: MMModule, g: MMGlobalClass)
        do
                var cla = g.intro
                super(mod, cla.name, cla.arity)
                set_global(g)
        end
end

class MMRefineAncestor
        super MMAncestor
        redef readable var _local_class: MMLocalClass

        init(b: MMLocalClass, a: MMLocalClass)
        do
                _local_class = a
                inheriter = b.get_type
                stype = _local_class.get_type
        end
end


class MMSpecAncestor
        super MMAncestor
        redef fun local_class do return stype.local_class

        init(inheriter: MMType, stype: MMType)
        do
                _inheriter = inheriter
                _stype = stype
        end
end

class MMDefaultAncestor
        super MMAncestor
        redef fun local_class do return stype.local_class

        init(b: MMLocalClass, anc: MMType)
        do
                inheriter = b.get_type
                stype = anc
        end
end