Typing of closures

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

# Common syntax structures for syntax analysis of NIT AST.
package syntax_base

import parser
import mmloader

# Concrete NIT source module
class MMSrcModule
special MMModule
        # The related AST node
        readable attr _node: AModule

        # Concrete NIT source local classs by name
        readable attr _src_local_classes: Map[Symbol, MMSrcLocalClass]

        init(c: MMContext, source: AModule, dir: MMDirectory, name: Symbol)
        do
                super(name, dir, c)
                _node = source
                _src_local_classes = new HashMap[Symbol, MMSrcLocalClass]
        end
end

redef class MMGlobalClass
        # Check that a module can access a class
        meth check_visibility(v: AbsSyntaxVisitor, n: PNode, cm: MMSrcModule): Bool do
                var pm = intro.module
                assert pm isa MMSrcModule
                var vpm = cm.visibility_for(pm)
                if vpm == 3 then
                        return true
                else if vpm == 0 then
                        v.error(n, "Visibility error: Class {self} comes from the hidden module {cm}.") # TODO: should not occur
                        return false
                else if visibility_level >= 3 then
                        v.error(n, "Visibility error: Class {self} is private.")
                        return false
                end
                return true
        end
end

# Concrete NIT source local classes
class MMSrcLocalClass
special MMConcreteClass
        # The related AST nodes
        readable attr _nodes: Array[PClassdef]

        # Concrete NIT source generic formal parameter by name
        readable writable attr _formal_dict: Map[Symbol, MMTypeFormalParameter]

        # Concrete NIT source properties by name
        readable attr _src_local_properties: Map[Symbol, MMLocalProperty] 

        init(n: Symbol, cla: PClassdef, a: Int)
        do
                super(n, a)
                _nodes = [cla]
                _src_local_properties = new HashMap[Symbol, MMLocalProperty]
        end
end

redef class MMGlobalProperty
        # Check that a module can access a property
        meth check_visibility(v: AbsSyntaxVisitor, n: PNode, cm: MMSrcModule, allows_protected: Bool): Bool do
                var pm = local_class.module
                assert pm isa MMSrcModule
                var vpm = cm.visibility_for(pm)
                if vpm == 3 then
                        return true
                else if vpm == 0 then
                        # TODO: should not occurs 
                        v.error(n, "Visibility error: Property {self} comes from the hidden module {cm}.")
                        return false
                else if visibility_level >= 3 then
                        v.error(n, "Visibility error: Property {self} is private.")
                        return false
                else if visibility_level >= 2 and not allows_protected then
                        v.error(n, "Visibility error: Property {self} is protected and can only acceded by self.")
                        return false
                end
                return true
        end
end

redef class MMLocalProperty
        # The attached node (if any)
        meth node: PNode do return null

        # Is the concrete method defined as init
        meth is_init: Bool do return false
end

# Concrete NIT source attribute
class MMSrcAttribute
special MMAttribute
        redef readable attr _node: AAttrPropdef
        init(name: Symbol, cla: MMLocalClass, n: AAttrPropdef)
        do
                super(name, cla)
                _node = n
        end
end

# Concrete NIT source method
class MMSrcMethod
special MMMethod
end

# Concrete NIT source method for an automatic accesor
class MMAttrImplementationMethod
special MMSrcMethod
        redef readable attr _node: AAttrPropdef
        init(name: Symbol, cla: MMLocalClass, n: AAttrPropdef)
        do
                super(name, cla)
                _node = n
        end
end

# Concrete NIT source method for an automatic read accesor
class MMReadImplementationMethod
special MMAttrImplementationMethod
        init(name: Symbol, cla: MMLocalClass, n: AAttrPropdef)
        do
                super(name, cla, n)
        end
end

# Concrete NIT source method for an automatic write accesor
class MMWriteImplementationMethod
special MMAttrImplementationMethod
        init(name: Symbol, cla: MMLocalClass, n: AAttrPropdef)
        do
                super(name, cla, n)
        end
end

# Concrete NIT source method for an explicit method
class MMMethSrcMethod
special MMSrcMethod
        redef meth is_init do return _node isa AConcreteInitPropdef
        redef readable attr _node: AMethPropdef
        init(name: Symbol, cla: MMLocalClass, n: AMethPropdef)
        do
                super(name, cla)
                _node = n
        end
end

# Concrete NIT source virtual type
class MMSrcTypeProperty
special MMLocalProperty
special MMTypeProperty
        redef readable attr _node: ATypePropdef
        init(name: Symbol, cla: MMLocalClass, n: ATypePropdef)
        do
                super(name, cla)
                _node = n
        end
end

# Concrete NIT implicit constructor
class MMImplicitInit
special MMMethSrcMethod
        redef meth is_init do return true
        readable attr _unassigned_attributes: Array[MMSrcAttribute]
        readable attr _super_inits: Array[MMLocalProperty]
        init(cla: MMLocalClass, unassigned_attributes: Array[MMSrcAttribute], super_inits: Array[MMLocalProperty])
        do
                super(once "init".to_symbol, cla, null)
                _unassigned_attributes = unassigned_attributes
                _super_inits = super_inits
        end
end

# Local variables
abstract class Variable
        # Name of the variable
        readable attr _name: Symbol 

        # Declaration AST node
        readable attr _decl: PNode

        # Static type
        readable writable attr _stype: MMType 

        redef meth to_s do return _name.to_s

        meth kind: String is abstract

        init(n: Symbol, d: PNode)
        do
                #assert n != null
                #assert d != null
                _name = n
                _decl = d
        end
end

# Variable declared with 'var'
class VarVariable
special Variable
        redef meth kind do return once "variable"
        init(n: Symbol, d: PNode) do super
end

# Parameter of method (declared in signature)
class ParamVariable
special Variable
        redef meth kind do return once "parameter"
        init(n: Symbol, d: PNode) do super
end

# Automatic variable (like in the 'for' statement)
class AutoVariable
special Variable
        redef meth kind do return once "automatic variable"
        init(n: Symbol, d: PNode) do super
end

# False variable corresponding to closures declared in signatures
# Lives in the same namespace than variables
class ClosureVariable
special Variable
        redef meth kind do return once "closure"

        # The signature of the closure
        readable attr _signature: MMSignature

        init(n: Symbol, d: PNode, s: MMSignature)
        do
                super(n, d)
                _signature = s
        end
end

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

# Visitor used during the syntax analysis
class AbsSyntaxVisitor
special Visitor
        # The primitive type Bool
        meth type_bool: MMType
        do
                return _module.class_by_name(once ("Bool".to_symbol)).get_type
        end
        
        # The primitive type Int 
        meth type_int: MMType
        do
                return _module.class_by_name(once ("Int".to_symbol)).get_type
        end

        # The primitive type Float
        meth type_float: MMType
        do
                return _module.class_by_name(once ("Float".to_symbol)).get_type
        end

        # The primitive type Char
        meth type_char: MMType
        do
                return _module.class_by_name(once ("Char".to_symbol)).get_type
        end

        # The primitive type String
        meth type_string: MMType
        do
                return _module.class_by_name(once ("String".to_symbol)).get_type
        end

        # The primitive type Collection[Object]
        meth type_collection: MMType
        do
                return _module.class_by_name(once ("Collection".to_symbol)).get_type
        end

        # The primitive type Array[?]
        meth type_array(stype: MMType): MMType
        do
                return _module.class_by_name(once ("Array".to_symbol)).get_instantiate_type([stype])
        end

        # The primitive type Discrete
        meth type_discrete: MMType
        do
                return _module.class_by_name(once ("Discrete".to_symbol)).get_type
        end

        # The primitive type Range[?]
        meth type_range(stype: MMType): MMType
        do
                return _module.class_by_name(once ("Range".to_symbol)).get_instantiate_type([stype])
        end

        # The primitive type of null
        meth type_none: MMType
        do
                return _module.type_none
        end

        # The current module
        readable writable attr _module: MMSrcModule 

        # The current class
        readable writable attr _local_class: MMSrcLocalClass 

        # The current property
        readable writable attr _local_property: MMLocalProperty

        # The current tool configuration/status
        readable attr _tc: ToolContext 

        # Display an error for a given syntax node
        meth error(n: PNode, s: String)
        do
                _tc.error("{locate(n)}: {s}")
        end

        # Display a warning for a given syntax node
        meth warning(n: PNode, s: String)
        do
                _tc.warning("{locate(n)}: {s}")
        end

        #
        meth locate(n: PNode): String
        do
                if n != null then return n.locate
                return _module.filename
        end

        # Check conformity and display error
        meth check_conform(n: PNode, subtype: MMType, stype: MMType): Bool
        do
                if stype == null or subtype == null then
                        return false
                end
                if subtype < stype then
                        return true
                end
                #error(n, "Type error: expected {stype}'{stype.module}, got {subtype}'{subtype.module}")
                #abort
                error(n, "Type error: expected {stype}, got {subtype}")
                return false
        end
        
        # Check that an expression has a static type and that 
        # Display an error and return false if n is a statement
        # Require that the static type of n is known
        meth check_expr(n: PExpr): Bool
        do
                # FIXME: The tc.error_count is a workaround since currently there is no way
                # to distingate statements from buggy expressions: both have a null stype
                if tc.error_count == 0 and n.stype == null then
                        error(n, "Type error: expected expression.")
                        return false
                end
                return true
        end

        # Combine check_conform and check_expr
        meth check_conform_expr(n: PExpr, stype: MMType): Bool
        do
                if check_expr(n) then return check_conform(n, n.stype, stype) else return false
        end


        protected init(tc: ToolContext, module: MMSrcModule)
        do
                _tc = tc
                _module = module
        end
end

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

redef class PNode
        protected meth accept_abs_syntax_visitor(v: AbsSyntaxVisitor) do visit_all(v)
end

redef class Token
        attr _symbol: Symbol

        # Symbol associated with the text
        # Lazily computed
        meth to_symbol: Symbol
        do
                var s = _symbol
                if s == null then
                        s = text.to_symbol
                        _symbol = s
                end
                return s
        end
end

redef class PClassdef
        # Associated class (MM entity)
        meth local_class: MMSrcLocalClass is abstract
end

redef class AAttrPropdef
        # Associated attribute (MM entity)
        meth prop: MMSrcAttribute is abstract

        # Associated read accessor (MM entity)
        meth readmethod: MMSrcMethod is abstract

        # Associated write accessor (MM entity)
        meth writemethod: MMSrcMethod is abstract
end

redef class AMethPropdef
        # Associated method (MM entity)
        meth method: MMMethSrcMethod is abstract

        # Associated 'self' variable
        meth self_var: ParamVariable is abstract
end

redef class ATypePropdef
        # Associated formal type (MM entity)
        meth prop: MMSrcTypeProperty is abstract
end

redef class PParam
        # Position in the signature
        meth position: Int is abstract

        # Associated local variable
        meth variable: ParamVariable is abstract 
end

redef class PClosureDecl
        # The signature of the declared closure
        meth signature: MMSignature is abstract

        # Associated bloc variable
        meth variable: ClosureVariable is abstract
end

redef class PType
        # Retrieve the local class corresponding to the type.
        # Display an error and return null if there is no class
        # Display an error and return null if the type is not class based (formal one)
        meth get_local_class(v: AbsSyntaxVisitor): MMLocalClass is abstract

        # Retrieve corresponding static type.
        # Display an error and return null if there is a problem
        meth get_stype(v: AbsSyntaxVisitor): MMType is abstract

        # Retrieve corresponding static type.
        # Display an error and return null if there is a problem
        # But do not performs any subtype check.
        # get_unchecked_stype should be called to check that the static type is fully valid
        meth get_unchecked_stype(v: AbsSyntaxVisitor): MMType is abstract

        # Check that a static definition type is conform with regard to formal types
        # Useful with get_unchecked_stype
        # Remember that conformance check need that ancestors are totaly computed
        meth check_conform(v: AbsSyntaxVisitor) is abstract
end

redef class AType
        attr _stype_cache: MMType
        attr _stype_cached: Bool = false

        redef meth get_local_class(v)
        do
                var name = n_id.to_symbol
                var mod = v.module
                var cla = v.local_class

                if (cla.formal_dict != null and cla.formal_dict.has_key(name)) or (cla.global_properties != null and cla.has_global_property_by_name(name)) then
                        v.error(n_id, "Type error: {name} is a formal type")
                        _stype_cached = true
                        return null
                end

                if not mod.has_global_class_named(name) then
                        v.error(n_id, "Type error: class {name} not found in module {mod}.")
                        _stype_cached = true
                        return null
                end

                var local_class = mod.class_by_name(name)
                local_class.global.check_visibility(v, self, mod)
                return local_class
        end

        redef meth get_unchecked_stype(v)
        do
                if _stype_cached then return _stype_cache
                _stype_cached = true

                var name = n_id.to_symbol
                var mod = v.module
                var cla = v.local_class

                if cla.formal_dict.has_key(name) then
                        if n_types.length > 0 then
                                v.error(self, "Type error: formal type {name} cannot have formal parameters.")
                                return null
                        end
                        var formal = cla.formal_dict[name]
                        _stype_cache = formal
                        return formal
                end

                if cla.global_properties != null and cla.has_global_property_by_name(name) then
                        if n_types.length > 0 then
                                v.error(self, "Type error: formal type {name} cannot have formal parameters.")
                                return null
                        end
                        var t = cla.get_type.local_class.select_virtual_type(name).stype_for(cla.get_type)
                        if t == null then
                                v.error(self, "Type error: circular definition in formal type {name}.")
                                return null
                        end
                        _stype_cache = t
                        return t
                end

                var local_class = get_local_class(v)
                if local_class == null then return null

                var arity = n_types.length 
                if local_class.arity != arity then
                        v.error(self, "Type error: '{local_class}' has {local_class.arity} parameters which differs from the {arity} params.")
                        return null
                end

                if arity > 0 then
                        var tab = new Array[MMType]
                        for p in n_types do
                                tab.add(p.get_unchecked_stype(v))
                        end
                        var t = local_class.get_instantiate_type(tab)
                        _stype_cache = t
                        return t
                else
                        var t = local_class.get_type
                        _stype_cache = t
                        return t
                end
        end
        
        redef meth get_stype(v)
        do
                var t = get_unchecked_stype(v)
                if t != null then check_conform(v)
                return t
        end

        redef meth check_conform(v)
        do
                var st = get_unchecked_stype(v)
                if st == null then return 
                var local_class = st.local_class
                var arity = n_types.length
                if arity > 0 then
                        for i in [0..arity[ do
                                var p = n_types[i]
                                var pt = p.get_stype(v)
                                var bt = local_class.get_formal(i).bound
                                if bt == null then return
                                bt = bt.adapt_to(st) # We need to abapt because of F-genericity
                                v.check_conform(p, pt, bt)
                        end
                end
        end
end

redef class PExpr
        # Static type
        # Is null for statement and for erronus expression
        meth stype: MMType is abstract
end

redef class AVardeclExpr
        # Assiociated local variable
        readable writable attr _variable: VarVariable
end

redef class AForVardeclExpr
        # Associated automatic local variable
        readable writable attr _variable: AutoVariable
end

redef class ASelfExpr
        # Associated local variable
        readable writable attr _variable: ParamVariable 
end

redef class AVarFormExpr
        # Associated local variable
        readable writable attr _variable: Variable 
end

redef class AClosureCallExpr
        # Associated closure variable
        readable writable attr _variable: ClosureVariable
end

redef class PClosureDef
        # Associated signature
        readable writable attr _signature: MMSignature

        # Automatic variables
        readable writable attr _variables: Array[AutoVariable]
end