As keyword (for casts)

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

# Analysis property bodies, statements and expressions
package typing

import syntax_base

redef class MMSrcModule
        # Walk trough the module and type statments and expressions
        # Require than supermodules are processed
        meth do_typing(tc: ToolContext)
        do
                var tv = new TypingVisitor(tc, self)
                tv.visit(node)
        end
end

# Typing visitor
# * Associate local variables to nodes
# * Distinguish method call and local variable access
# * Resolve call and attribute access
# * Check type conformance
private class TypingVisitor
special AbsSyntaxVisitor
        redef meth visit(n)
        do
                if n != null then n.accept_typing(self)
        end

        # Current knowledge about variables names and types
        readable writable attr _variable_ctx: VariableContext

        # Type of the receiver
        readable writable attr _self_type: MMType

        # Block of the current method
        readable writable attr _top_block: PExpr

        # List of explicit invocation of constructors of super-classes
        readable writable attr _explicit_super_init_calls: Array[MMMethod]

        # Is a other constructor of the same class invoked
        readable writable attr _explicit_other_init_call: Bool

        init(tc, module) do super

        private meth get_default_constructor_for(n: PNode, c: MMLocalClass, prop: MMMethod): MMMethod
        do
                var v = self
                #var prop = v.local_property
                #assert prop isa MMMethod
                var candidates = new Array[MMMethod]
                var false_candidates = new Array[MMMethod]
                var parity = prop.signature.arity
                for g in c.global_properties do
                        if not g.is_init then continue
                        if g.intro.local_class != c then continue
                        var gp = c[g]
                        assert gp isa MMMethod
                        var garity = gp.signature.arity
                        if prop != null and g.intro.name == prop.name then
                                if garity == 0 or prop.signature < gp.signature then
                                        return gp
                                else
                                        false_candidates.add(gp)
                                end
                        else if garity == 0 then
                                candidates.add(gp)
                                false_candidates.add(gp)
                        else
                                false_candidates.add(gp)
                        end
                end
                if candidates.length == 1 then
                        return candidates.first
                else if candidates.length > 0 then
                        v.error(n, "Error: Conflicting default constructor to call for {c}: {candidates.join(", ")}.")
                        return null
                else if false_candidates.length > 0 then
                        v.error(n, "Error: there is no available compatible constrctor in {c}.")
                        return null
                else
                        v.warning(n, "Error: there is no available compatible constrctor in {c}.")
                        return null
                end
        end
end

# Associate symbols to variable and variables to type
# Can be nested
private class VariableContext
        # Look for the variable from its name
        # Return null if nothing found
        meth [](s: Symbol): Variable
        do
                if _dico.has_key(s) then
                        return _dico[s]
                else
                        return null
                end
        end

        # Register a new variable with its name
        meth add(v: Variable)
        do
                _dico[v.name] = v
        end


        # The effective static type of a given variable
        # May be different from the declaration static type
        meth stype(v: Variable): MMType
        do
                return v.stype
        end

        # Variables by name (in the current context only)
        attr _dico: Map[Symbol, Variable]

        # Build a new VariableContext
        meth sub: VariableContext
        do
                return new SubVariableContext.with(self, null, null)
        end

        # Build a nested VariableContext with new variable information
        meth sub_with(v: Variable, t: MMType): VariableContext
        do
                return new SubVariableContext.with(self, v, t)
        end

        init
        do 
                _dico = new HashMap[Symbol, Variable]
        end
end

private class SubVariableContext
special VariableContext
        readable attr _prev: VariableContext
        attr _variable: Variable
        attr _var_type: MMType

        redef meth [](s)
        do
                if _dico.has_key(s) then
                        return _dico[s]
                else
                        return prev[s]
                end
        end

        redef meth stype(v)
        do
                if _variable == v then
                        return _var_type
                end
                return prev.stype(v)
        end

        init with(p: VariableContext, v: Variable, t: MMType)
        do
                init
                _prev = p
                _variable = v
                _var_type =t
        end
end


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

redef class PNode
        private meth accept_typing(v: TypingVisitor) 
        do
                accept_abs_syntax_visitor(v)
                after_typing(v)
        end
        private meth after_typing(v: TypingVisitor) do end
end

redef class PClassdef
        redef meth accept_typing(v)
        do
                v.self_type = local_class.get_type
                super
        end
end

redef class AAttrPropdef
        redef meth accept_typing(v)
        do
                super
                if n_expr != null then
                        v.check_conform(n_expr, n_expr.stype, prop.signature.return_type)
                end
        end
end

redef class AMethPropdef
        redef meth accept_typing(v)
        do
                v.variable_ctx = new VariableContext
                super
        end
end

redef class AConcreteInitPropdef
        readable attr _super_init_calls: Array[MMMethod] = new Array[MMMethod]
        readable attr _explicit_super_init_calls: Array[MMMethod] = new Array[MMMethod]
        redef meth accept_typing(v)
        do
                v.top_block = n_block
                v.explicit_super_init_calls = explicit_super_init_calls
                v.explicit_other_init_call = false
                super
                if v.explicit_other_init_call then
                        # TODO: something?
                else 
                        var i = 0
                        var l = explicit_super_init_calls.length
                        var cur_m: MMMethod
                        var cur_c: MMLocalClass
                        if i < l then
                                cur_m = explicit_super_init_calls[i]
                                cur_c = cur_m.global.intro.local_class
                        end
                        var j = 0
                        while j < v.local_class.cshe.direct_greaters.length do
                                var c = v.local_class.cshe.direct_greaters[j]
                                if c.global.is_interface or c.global.is_universal then
                                        j += 1
                                else if cur_c != null and c.cshe <= cur_c then
                                        if c == cur_c then j += 1
                                        super_init_calls.add(cur_m)
                                        i += 1
                                        if i < l then
                                                cur_m = explicit_super_init_calls[i]
                                                cur_c = cur_m.global.intro.local_class
                                        else
                                                cur_m = null
                                                cur_c = null
                                        end
                                else
                                        var p = v.get_default_constructor_for(self, c, method)
                                        if p != null then
                                                super_init_calls.add(p)
                                        end
                                        j += 1
                                end
                        end
                end
        end
end

redef class PParam
        redef meth after_typing(v)
        do
                if v.variable_ctx != null then
                        v.variable_ctx.add(variable)
                end
        end
end

redef class PType
        readable attr _stype: MMType
        redef meth after_typing(v)
        do
                _stype = get_stype(v)
        end
end

redef class PExpr
        redef readable attr _stype: MMType
        
        # Is the expression the implicit receiver
        meth is_implicit_self: Bool do return false

        # Is the expression the current receiver (implicit or explicit)
        meth is_self: Bool do return false

        # Is the expression a variable access
        meth is_variable: Bool do return false

        # The variable type information if current boolean expression is true
        readable private attr _if_true_variable_ctx: VariableContext
end

redef class AVardeclExpr
        # Assiociated local variable
        readable attr _variable: Variable

        redef meth after_typing(v)
        do
                var va = new Variable(n_id.to_symbol, self)
                _variable = va
                v.variable_ctx.add(va)

                if n_type != null then
                        va.stype = n_type.stype
                        if n_expr != null then
                                v.check_conform(self, n_expr.stype, va.stype)
                        end
                else
                        va.stype = n_expr.stype
                end
        end
end

redef class ABlockExpr
        redef meth accept_typing(v)
        do
                var old_var_ctx = v.variable_ctx
                v.variable_ctx = v.variable_ctx.sub

                super

                v.variable_ctx = old_var_ctx
        end
end

redef class AReturnExpr
        redef meth after_typing(v)
        do
                var t = v.local_property.signature.return_type
                if n_expr == null and t != null then
                        v.error(self, "Error: Return without value in a function.")
                else if n_expr != null and t == null then
                        v.error(self, "Error: Return with value in a procedure.")
                else if n_expr != null and t != null then
                        v.check_conform(self, n_expr.stype, t)
                end
        end
end

redef class AIfExpr
        redef meth accept_typing(v)
        do
                var old_var_ctx = v.variable_ctx
                v.visit(n_expr)
                v.check_conform(self, n_expr.stype, v.type_bool)

                if n_expr.if_true_variable_ctx != null then
                        v.variable_ctx = n_expr.if_true_variable_ctx
                end

                v.visit(n_then)
                # Restore variable ctx
                v.variable_ctx = old_var_ctx

                if n_else != null then
                        v.visit(n_else)
                        v.variable_ctx = old_var_ctx
                end
        end
end

redef class AWhileExpr
        redef meth after_typing(v)
        do
                v.check_conform(self, n_expr.stype, v.type_bool)
        end
end

redef class AForExpr
        redef meth after_typing(v)
        do
                # pop context created in AForVardeclExpr
                var varctx = v.variable_ctx 
                assert varctx isa SubVariableContext
                v.variable_ctx = varctx.prev
        end
end

redef class AForVardeclExpr
        # Associated automatic local variable
        readable attr _variable: Variable

        redef meth after_typing(v)
        do
                v.variable_ctx = v.variable_ctx.sub
                var variable = new Variable(n_id.to_symbol, self)
                _variable = variable
                v.variable_ctx.add(variable)

                var expr_type = n_expr.stype
                if not v.check_conform(self, expr_type, v.type_collection) then
                        return
                end
                var prop = expr_type.select_method(once ("iterator".to_symbol))
                if prop == null then
                        v.error(self, "Error: Collection MUST have an iterate method")
                        return
                end
                var iter_type = prop.signature.return_type
                var prop2 = iter_type.select_method(once ("item".to_symbol))
                if prop2 == null then
                        v.error(self, "Error: {iter_type} MUST have an item method")
                        return
                end
                var t = prop2.signature.return_type
                if not n_expr.is_self then t = t.not_for_self
                variable.stype = t
        end
end

redef class AAssertExpr
        redef meth after_typing(v)
        do
                v.check_conform(self, n_expr.stype, v.type_bool)
                if n_expr.if_true_variable_ctx != null then v.variable_ctx = n_expr.if_true_variable_ctx
        end
end

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

redef class AVarExpr
        redef meth is_variable do return true

        redef meth after_typing(v)
        do
                _stype = v.variable_ctx.stype(variable)
        end
end

redef class AVarAssignExpr
        redef meth after_typing(v)
        do
                var t = v.variable_ctx.stype(variable)
                v.check_conform(self, n_value.stype, t)
        end
end

redef class AReassignFormExpr
        # Compute and check method used through the reassigment operator 
        private meth do_lvalue_typing(v: TypingVisitor, type_lvalue: MMType)
        do
                if type_lvalue == null then
                        return
                end
                var name = n_assign_op.method_name
                var prop = type_lvalue.select_method(name)
                if prop == null then
                        v.error(self, "Error: Method '{name}' doesn't exists in {type_lvalue}.")
                        return
                end
                prop.global.check_visibility(v, self, v.module, false)
                var psig = prop.signature
                _assign_method = prop
                v.check_conform(self, n_value.stype, psig[0].not_for_self)
                v.check_conform(self, psig.return_type.not_for_self, n_value.stype)
        end

        # Method used through the reassigment operator (once computed)
        readable attr _assign_method: MMMethod
end

redef class PAssignOp
        meth method_name: Symbol is abstract
end
redef class APlusAssignOp
        redef meth method_name do return once "+".to_symbol
end
redef class AMinusAssignOp
        redef meth method_name do return once "-".to_symbol
end

redef class AVarReassignExpr
        redef meth after_typing(v)
        do
                var t = v.variable_ctx.stype(variable)
                do_lvalue_typing(v, t)
        end
end

redef class ASelfExpr
        redef meth after_typing(v)
        do
                assert v.self_type != null
                _stype = v.self_type
        end

        redef meth is_self do return true
end

redef class AImplicitSelfExpr
        redef meth is_implicit_self do return true
end

redef class AIfexprExpr
        redef meth accept_typing(v)
        do
                var old_var_ctx = v.variable_ctx

                v.visit(n_expr)
                if n_expr.if_true_variable_ctx != null then v.variable_ctx = n_expr.if_true_variable_ctx
                v.visit(n_then)
                v.variable_ctx = old_var_ctx
                v.visit(n_else)

                v.check_conform(self, n_expr.stype, v.type_bool)

                var t = n_then.stype
                var te = n_else.stype
                if t < te then
                        t = te
                else if not te < t then
                        v.error(self, "Type error: {te} is not a subtype of {t}.")
                        return
                end
                
                _stype = t
        end
end

redef class ABoolExpr
        redef meth after_typing(v)
        do
                _stype = v.type_bool
        end
end

redef class AOrExpr
        redef meth after_typing(v)
        do
                v.check_conform(self, n_expr.stype, v.type_bool)
                v.check_conform(self, n_expr2.stype, v.type_bool)
                _stype = v.type_bool
        end
end

redef class AAndExpr
        redef meth accept_typing(v)
        do
                var old_var_ctx = v.variable_ctx

                v.visit(n_expr)
                if n_expr.if_true_variable_ctx != null then v.variable_ctx = n_expr.if_true_variable_ctx

                v.visit(n_expr2)
                if n_expr2.if_true_variable_ctx != null then 
                        _if_true_variable_ctx = n_expr2.if_true_variable_ctx
                else
                        _if_true_variable_ctx = v.variable_ctx
                end

                v.variable_ctx = old_var_ctx

                v.check_conform(self, n_expr.stype, v.type_bool)
                v.check_conform(self, n_expr2.stype, v.type_bool)
                _stype = v.type_bool
        end
end

redef class ANotExpr
        redef meth after_typing(v)
        do
                v.check_conform(self, n_expr.stype, v.type_bool)
                _stype = v.type_bool
        end
end

redef class AIntExpr
        redef meth after_typing(v)
        do
                _stype = v.type_int

        end
end

redef class AFloatExpr
        redef meth after_typing(v)
        do
                _stype = v.type_float
        end
end

redef class ACharExpr
        redef meth after_typing(v)
        do
                _stype = v.type_char
        end
end

redef class AStringFormExpr
        redef meth after_typing(v)
        do
                _stype = v.type_string
        end
end

redef class ASuperstringExpr
        redef meth after_typing(v)
        do
                _stype = v.type_string
        end
end

redef class ANullExpr
        redef meth after_typing(v)
        do
                _stype = v.type_none
        end
end

redef class AArrayExpr
        private meth stype=(t: MMType) do _stype = t

        redef meth after_typing(v)
        do
                var stype: MMType
                for n in n_exprs do
                        var ntype = n.stype
                        if stype == null or (ntype != null and stype < ntype) then
                                stype = ntype
                        end
                end
                for n in n_exprs do
                        v.check_conform(self, n.stype, stype)
                end
                _stype = v.type_array(stype)
        end
end

redef class ARangeExpr
        redef meth after_typing(v)
        do
                var ntype = n_expr.stype
                var ntype2 = n_expr2.stype
                if ntype == null or ntype == null then
                        return
                end
                if ntype < ntype2 then
                        ntype = ntype2
                else if not ntype2 < ntype then
                        v.error(self, "Type error: {ntype} incompatible with {ntype2}.")
                        return
                end
                var dtype = v.type_discrete
                v.check_conform(self, ntype, dtype)
                _stype = v.type_range(ntype)
        end
end

redef class ASuperExpr
special ASuperInitCall
        # readable attr _prop: MMSrcMethod
        readable attr _init_in_superclass: MMMethod
        redef meth after_typing(v)
        do
                var precs: Array[MMLocalProperty] = v.local_property.cprhe.direct_greaters
                if not precs.is_empty then
                        v.local_property.need_super = true
                else if v.local_property.global.is_init then
                        var base_precs = v.local_class.super_methods_named(v.local_property.name)
                        for p in base_precs do
                                if not p.global.is_init then
                                        v.error(self, "Error: {p.local_class}::{p} is not a constructor.")
                                else
                                        precs.add(v.self_type.select_property(p.global))
                                end
                        end
                        if precs.is_empty then
                                v.error(self, "Error: No contructor named {v.local_property.name} in superclasses.")
                                return
                        else if precs.length > 1 then
                                v.error(self, "Error: Conflicting contructors named {v.local_property.name} in superclasses: {precs.join(", ")}.")
                                return
                        end
                        var p = base_precs.first
                        assert p isa MMMethod
                        _init_in_superclass = p
                        register_super_init_call(v, p)
                        if n_args.length > 0 then
                                _arguments = process_signature(v, p, true, n_args.to_a)
                        end
                else
                        v.error(self, "Error: No super method to call for {v.local_property}.")
                        return
                end

                if precs.first.signature.return_type != null then
                        var stypes = new Array[MMType]
                        var stype: MMType
                        for prop in precs do
                                assert prop isa MMMethod
                                var t = prop.signature.return_type.for_module(v.module).adapt_to(v.local_property.signature.recv)
                                stypes.add(t)
                                if stype == null or stype < t then
                                        stype = t
                                end
                        end
                        for t in stypes do
                                v.check_conform(self, t, stype)
                        end
                        _stype = stype
                end
                var p = v.local_property
                assert p isa MMSrcMethod
                _prop = p
        end
end

redef class AAttrFormExpr
        # Attribute accessed
        readable attr _prop: MMAttribute

        # Compute the attribute accessed
        private meth do_typing(v: TypingVisitor)
        do
                var type_recv = n_expr.stype
                if type_recv == null then
                        return
                end
                var name = n_id.to_symbol
                var prop = type_recv.select_attribute(name)
                if prop == null then
                        v.error(self, "Error: Attribute {name} doesn't exists in {type_recv}.")
                        return
                else if v.module.visibility_for(prop.global.local_class.module) < 3 then
                        v.error(self, "Error: Attribute {name} from {prop.global.local_class.module} is invisible in {v.module}")
                end
                _prop = prop
        end
end

redef class AAttrExpr
        redef meth after_typing(v)
        do
                do_typing(v)
                if prop == null then
                        return
                end
                var attr_type = prop.signature.return_type
                if not n_expr.is_self then attr_type = attr_type.not_for_self
                _stype = attr_type
        end
end

redef class AAttrAssignExpr
        redef meth after_typing(v)
        do
                do_typing(v)
                if prop == null then
                        return
                end
                var attr_type = prop.signature.return_type
                if not n_expr.is_self then attr_type = attr_type.not_for_self
                v.check_conform(self, n_value.stype, attr_type)
        end
end

redef class AAttrReassignExpr
        redef meth after_typing(v)
        do
                do_typing(v)
                if prop == null then
                        return
                end
                var attr_type = prop.signature.return_type
                if not n_expr.is_self then attr_type = attr_type.not_for_self
                do_lvalue_typing(v, attr_type)
        end
end

class AAbsSendExpr
special PExpr
        # Compute the called global property
        private meth do_typing(v: TypingVisitor, type_recv: MMType, is_implicit_self: Bool, recv_is_self: Bool, name: Symbol, raw_args: Array[PExpr])
        do
                var prop = get_property(v, type_recv, is_implicit_self, name)
                if prop == null then return
                var args = process_signature(v, prop, recv_is_self, raw_args)
                if args == null then return
                _prop = prop
                _arguments = args
        end

        private meth get_property(v: TypingVisitor, type_recv: MMType, is_implicit_self: Bool, name: Symbol): MMMethod
        do
                if type_recv == null then return null
                var prop = type_recv.select_method(name)
                if prop == null and v.local_property.global.is_init then
                        var props = type_recv.local_class.super_methods_named(name)
                        if props.length > 1 then
                                v.error(self, "Error: Ambigous method name '{name}' for {props.join(", ")}. Use explicit designation.")
                                return null
                        else if props.length == 1 then 
                                var p = type_recv.select_property(props.first.global)
                                assert p isa MMMethod
                                prop = p
                        end

                end
                if prop == null then
                        if is_implicit_self then
                                v.error(self, "Error: Method or variable '{name}' unknown in {type_recv}.")
                        else
                                v.error(self, "Error: Method '{name}' doesn't exists in {type_recv}.")
                        end
                        return null
                end
                return prop
        end

        private meth process_signature(v: TypingVisitor, prop: MMMethod, recv_is_self: Bool, raw_args: Array[PExpr]): Array[PExpr]
        do
                prop.global.check_visibility(v, self, v.module, recv_is_self)
                var psig = prop.signature
                var par_vararg = psig.vararg_rank
                var par_arity = psig.arity
                var raw_arity: Int
                if raw_args == null then raw_arity = 0 else raw_arity = raw_args.length
                if par_arity > raw_arity or (par_arity != raw_arity and par_vararg == -1) then
                        v.error(self, "Error: Method '{prop}' arity missmatch.")
                        return null
                end
                var arg_idx = 0
                var args = new Array[PExpr]
                for par_idx in [0..par_arity[ do
                        var a: PExpr
                        var par_type = psig[par_idx]
                        if not recv_is_self then par_type = par_type.not_for_self
                        if par_idx == par_vararg then
                                var star = new Array[PExpr]
                                for i in [0..(raw_arity-par_arity)] do
                                        a = raw_args[arg_idx]
                                        v.check_conform(self, a.stype, par_type)
                                        star.add(a)
                                        arg_idx = arg_idx + 1
                                end
                                var aa = new AArrayExpr.init_aarrayexpr(star)
                                aa.stype = v.type_array(par_type)
                                a = aa
                        else
                                a = raw_args[arg_idx]
                                v.check_conform(self, a.stype, par_type)
                                arg_idx = arg_idx + 1
                        end
                        args.add(a)
                end
                return args
        end

        # The invoked method (once computed)
        readable attr _prop: MMMethod

        # The real arguments used (after star transformation) (once computed)
        readable attr _arguments: Array[PExpr]
end

# A possible call of constructor in a super class
# Could be an explicit call or with the 'super' keyword
class ASuperInitCall
special AAbsSendExpr
        private meth register_super_init_call(v: TypingVisitor, property: MMMethod)
        do
                if parent != v.top_block and self != v.top_block then
                        v.error(self, "Error: Constructor invocation {property} must not be in nested block.")
                end
                var cla = v.module[property.global.intro.local_class.global]
                var prev_class: MMLocalClass
                if not v.explicit_super_init_calls.is_empty then
                        prev_class = v.explicit_super_init_calls.last.global.intro.local_class
                end
                var order = v.local_class.cshe.reverse_linear_extension
                if cla == v.local_class then
                        v.explicit_other_init_call = true
                else if not order.has(cla) then
                        v.error(self, "Error: Constructor of class {cla} must be one in {order.join(", ")}.")
                else if cla == prev_class then
                        v.error(self, "Error: Only one super constructor invocation of class {cla} is allowed.")
                else
                        var last_is_found = prev_class == null
                        for c in order do
                                if c == prev_class then
                                        last_is_found = true
                                else if c == cla then
                                        if not last_is_found then
                                                v.error(self, "Error: Constructor of {c} must be invoked before constructor of {prev_class}")
                                        end
                                        v.explicit_super_init_calls.add(property)
                                        break
                                end
                        end
                end
        end

end

redef class ANewExpr
special AAbsSendExpr
        redef meth after_typing(v)
        do
                var t = n_type.stype
                if t == null then return
                if t.local_class.global.is_abstract then
                        v.error(self, "Error: try to instantiate abstract class {t.local_class}.")
                        return
                end
                var name: Symbol
                if n_id == null then
                        name = once "init".to_symbol
                else
                        name = n_id.to_symbol
                end

                do_typing(v, t, false, false, name, n_args.to_a)
                if not prop.global.is_init then
                        v.error(self, "Error: {prop} is not a constructor.")
                end
                _stype = t
        end
end


redef class ASendExpr
special ASuperInitCall
        # Name of the invoked property
        meth name: Symbol is abstract 

        # Raw arguments used (withour star transformation)
        meth raw_arguments: Array[PExpr] is abstract

        redef meth after_typing(v)
        do
                do_all_typing(v)
        end

        private meth do_all_typing(v: TypingVisitor)
        do
                do_typing(v, n_expr.stype, n_expr.is_implicit_self, n_expr.is_self, name, raw_arguments)
                if prop == null then return
                if prop.global.is_init then
                        if not v.local_property.global.is_init then
                                v.error(self, "Error: try to invoke constructor {prop} in a method.")
                        else if not n_expr.is_self then
                                v.error(self, "Error: constructor {prop} is not invoken on 'self'.")
                        else
                                register_super_init_call(v, prop)
                        end
                end
                var t = prop.signature.return_type
                if t != null and not n_expr.is_self then t = t.not_for_self
                _stype = t
        end
end

class ASendReassignExpr
special ASendExpr
special AReassignFormExpr
        readable attr _read_prop: MMMethod
        redef meth do_all_typing(v)
        do
                var raw_args = raw_arguments
                do_typing(v, n_expr.stype, n_expr.is_implicit_self, n_expr.is_self, name, raw_args)
                if prop == null then return
                if prop.global.is_init then
                        if not v.local_property.global.is_init then
                                v.error(self, "Error: try to invoke constructor {prop} in a method.")
                        else if not n_expr.is_self then
                                v.error(self, "Error: constructor {prop} is not invoken on 'self'.")
                        end
                end
                var t = prop.signature.return_type
                if not n_expr.is_self then t = t.not_for_self

                do_lvalue_typing(v, t)

                _read_prop = prop
                var old_args = arguments
                raw_args.add(n_value)

                do_typing(v, n_expr.stype, n_expr.is_implicit_self, n_expr.is_self, "{name}=".to_symbol, raw_args)
                if prop == null then return
                if prop.global.is_init then
                        if not v.local_property.global.is_init then
                                v.error(self, "Error: try to invoke constructor {prop} in a method.")
                        else if not n_expr.is_self then
                                v.error(self, "Error: constructor {prop} is not invoken on 'self'.")
                        end
                end

                _arguments = old_args # FIXME: What if star parameters do not match betwen the two methods?
        end
end

redef class ABinopExpr
        redef meth raw_arguments do return [n_expr2]
end
redef class AEqExpr
        redef meth name do return once "==".to_symbol
end
redef class ANeExpr
        redef meth name do return once "!=".to_symbol
end
redef class ALtExpr
        redef meth name do return once "<".to_symbol
end
redef class ALeExpr
        redef meth name do return once "<=".to_symbol
end
redef class AGtExpr
        redef meth name do return once ">".to_symbol
end
redef class AGeExpr
        redef meth name do return once ">=".to_symbol
end
redef class APlusExpr
        redef meth name do return once "+".to_symbol
end
redef class AMinusExpr
        redef meth name do return once "-".to_symbol
end
redef class AStarshipExpr
        redef meth name do return once "<=>".to_symbol
end
redef class AStarExpr
        redef meth name do return once "*".to_symbol
end
redef class ASlashExpr
        redef meth name do return once "/".to_symbol
end
redef class APercentExpr
        redef meth name do return once "%".to_symbol
end

redef class AUminusExpr
        redef meth name do return once "unary -".to_symbol
        redef meth raw_arguments do return null
end

redef class ACallFormExpr
        redef meth after_typing(v)
        do
                if n_expr.is_implicit_self then
                        var name = n_id.to_symbol
                        var variable = v.variable_ctx[name]
                        if variable != null then
                                if not n_args.is_empty then
                                        v.error(self, "Error: {name} is variable, not a function.")
                                end
                                var vform = variable_create(variable)
                                vform.variable = variable
                                replace_with(vform)
                                vform.after_typing(v)
                                return
                        end
                end
                super
        end

        # Create a variable acces corresponding to the call form
        meth variable_create(variable: Variable): AVarFormExpr is abstract
end

redef class ACallExpr
        redef meth variable_create(variable)
        do
                return new AVarExpr.init_avarexpr(n_id)
        end

        redef meth name do return n_id.to_symbol
        redef meth raw_arguments do return n_args.to_a
end

redef class ACallAssignExpr
        redef meth variable_create(variable)
        do
                return new AVarAssignExpr.init_avarassignexpr(n_id, n_assign, n_value)
        end

        redef meth name do return (n_id.text + "=").to_symbol
        redef meth raw_arguments do
                var res = n_args.to_a
                res.add(n_value)
                return res
        end
end

redef class ACallReassignExpr
special ASendReassignExpr
        redef meth variable_create(variable)
        do
                return new AVarReassignExpr.init_avarreassignexpr(n_id, n_assign_op, n_value)
        end

        redef meth name do return n_id.to_symbol
        redef meth raw_arguments do return n_args.to_a
end

redef class ABraExpr
        redef meth name do return once "[]".to_symbol
        redef meth raw_arguments do return n_args.to_a
end

redef class ABraAssignExpr
        redef meth name do return once "[]=".to_symbol
        redef meth raw_arguments do
                var res = n_args.to_a
                res.add(n_value)
                return res
        end
end

redef class ABraReassignExpr
special ASendReassignExpr
        redef meth name do return once "[]".to_symbol
        redef meth raw_arguments do return n_args.to_a
end

redef class AInitExpr
        redef meth name do return once "init".to_symbol
        redef meth raw_arguments do return n_args.to_a
end

redef class AIsaExpr
        redef meth after_typing(v)
        do
                if n_expr.is_variable then
                        var n = n_expr
                        assert n isa AVarExpr
                        _if_true_variable_ctx = v.variable_ctx.sub_with(n.variable, n_type.stype)
                end
                _stype = v.type_bool
        end
end

redef class AAsCastExpr
        redef meth after_typing(v)
        do
                _stype = n_type.stype
                var et = n_expr.stype
        end
end

redef class AProxyExpr
        redef meth after_typing(v)
        do
                _stype = n_expr.stype
        end
end