[nit.git] / src / astbuilder.nit

# This file is part of NIT ( http://www.nitlanguage.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.

# Instantiation and transformation of semantic nodes in the AST of expressions and statements
module astbuilder

intrude import semantize::typing
intrude import literal
intrude import parser
intrude import semantize::scope

# General factory to build semantic nodes in the AST of expressions
class ASTBuilder
        # The module used as reference for the building
        # It is used to gather types and other stuff
        var mmodule: MModule

        # The anchor used for some mechanism relying on types
        var anchor: nullable MClassType

        # Check mmodule to avoid a new instantiation of ASTBuilder
        fun check_mmodule(mmodule: MModule)
        do
                if self.mmodule != mmodule then self.mmodule = mmodule
        end

        # Make a new Int literal
        fun make_int(value: Int): AIntegerExpr
        do
                return new AIntegerExpr.make(value, mmodule.int_type)
        end

        # Make a new instantiation
        fun make_new(callsite: CallSite, args: nullable Array[AExpr]): ANewExpr
        do
                return new ANewExpr.make(callsite, args)
        end

        # Make a new message send
        fun make_call(recv: AExpr, callsite: CallSite, args: nullable Array[AExpr]): ACallExpr
        do
                return new ACallExpr.make(recv, callsite, args)
        end

        # Make a new, empty, sequence of statements
        fun make_block: ABlockExpr
        do
                return new ABlockExpr.make
        end

        # Make a new, empty, loop of statements
        fun make_loop: ALoopExpr
        do
                return new ALoopExpr.make
        end

        # Make a new variable read
        fun make_var_read(variable: Variable, mtype: MType): AVarExpr
        do
                return new AVarExpr.make(variable, mtype)
        end

        # Make a new variable assignment
        fun make_var_assign(variable: Variable, value: AExpr): AVarAssignExpr
        do
                return new AVarAssignExpr.make(variable, value)
        end

        # Make a new attribute read
        fun make_attr_read(recv: AExpr, attribute: MAttribute): AAttrExpr
        do
                var mtype = attribute.intro.static_mtype.resolve_for(recv.mtype.as(not null), anchor, mmodule, true)
                return new AAttrExpr.make(recv, attribute, mtype)
        end

        # Make a new attribute assignment
        fun make_attr_assign(recv: AExpr, attribute: MAttribute, value: AExpr): AAttrAssignExpr
        do
                return new AAttrAssignExpr.make(recv, attribute, value)
        end

        # Make a new escapable block
        fun make_do: ADoExpr
        do
                return new ADoExpr.make
        end

        # Make a new break for a given escapemark
        fun make_break(escapemark: EscapeMark): ABreakExpr
        do
                return new ABreakExpr.make(escapemark)
        end

        # Make a new conditional
        # `mtype` is the return type of the whole if, in case of a ternary operator.
        fun make_if(condition: AExpr, mtype: nullable MType): AIfExpr
        do
                return new AIfExpr.make(condition, mtype)
        end

        # Make a new assert
        fun make_assert(n_id : nullable TId , n_expr : AExpr , n_else : nullable AExpr): AAssertExpr
        do
                return new AAssertExpr.make(n_id , n_expr , n_else)
        end

        # Make a new method
        fun make_method(n_visibility: nullable AVisibility,
                                        tk_redef: nullable TKwredef,
                                        mmethoddef: nullable MMethodDef,
                                        n_signature: nullable ASignature,
                                        n_annotations: nullable AAnnotations,
                                        n_extern_calls: nullable AExternCalls,
                                        n_extern_code_block: nullable AExternCodeBlock,
                                        n_block: nullable AExpr): AMethPropdef
        do
                return new AMethPropdef.make(n_visibility, tk_redef, mmethoddef, n_signature, n_annotations, n_extern_calls, n_extern_code_block, n_block)
        end

        # Make a new or with two expr
        fun make_or(right_expr: AExpr, left_expr: AExpr): AOrExpr
        do
                return new AOrExpr.make(right_expr,left_expr)
        end

        # Make a new and with two expr
        fun make_and(right_expr: AExpr, left_expr: AExpr): AAndExpr
        do
                return new AAndExpr.make(right_expr,left_expr)
        end

        # Make a new parenthesis expr
        fun make_parenthesis(expr: AExpr, annotations: nullable AAnnotations): AParExpr
        do
                return new AParExpr.make(expr,annotations)
        end

        # Make a new message super
        fun make_super_call(args: nullable Array[AExpr], n_qualified: nullable AQualified): ASuperExpr
        do
                return new ASuperExpr.make(args,n_qualified)
        end

        # Make a new return
        fun make_return(expr: nullable AExpr): AReturnExpr
        do
                return new AReturnExpr.make(expr)
        end
        # Create a callsite with the given `mproperty`. Take the current method `actual_method` as a context
        fun create_callsite(modelbuilder: ModelBuilder, actual_method : AMethPropdef, mproperty: MMethod, is_self_call: Bool): CallSite
        do
                var type_visitor = new TypeVisitor(modelbuilder, actual_method.mpropdef.as(not null))
                var callsite = type_visitor.build_callsite_by_property(actual_method, mproperty.intro_mclassdef.bound_mtype, mproperty, is_self_call)
                assert callsite != null
                return callsite
        end
end

redef class AExpr
        # Return a new variable read that contains the value of the expression
        # This method take care efficiently of creating and initalising an anonymous local variable
        #
        # Note: since this method do side-effects (AST replacement), there could be unexpected effects when used as
        # argument of other methods related to AST transformations.
        fun make_var_read: AVarExpr
        do
                var variable = self.variable_cache
                if variable == null then
                        assert parent != null
                        var place = detach_with_placeholder
                        variable = new Variable("")
                        variable.declared_type = self.mtype
                        var nvar = new AVarAssignExpr.make(variable, self)
                        place.replace_with(nvar)
                        self.variable_cache = variable
                end
                return new AVarExpr.make(variable, variable.declared_type.as(not null))
        end

        private var variable_cache: nullable Variable

        # The `detach` method completely remove the node in the parent.
        # However, sometime, it is useful to keep the emplacement of the removed child.
        #
        # The standard use case is the insertion of a node between a parent `p` and a child `p.c`.
        # To create the new node `n`, we need to attach the child to it.
        # But, to put `n` where `c` was in `p`, the place has to be remembered.
        #
        # ~~~nitish
        # var p: AExpr
        # var c = p.c
        # var h = c.detach_with_placeholder
        # var n = astbuilder.make_XXX(c)
        # h.replace_with(n)
        # ~~~
        fun detach_with_placeholder: AExpr
        do
                var h = new APlaceholderExpr.make
                self.replace_with(h)
                return h
        end


        # Add `expr` at the end of the block
        #
        # REQUIRE: self isa ABlockExpr
        #
        # Note: this method, aimed to `ABlockExpr` is promoted to `AExpr` because of the limitations of the hierarchies generated by sablecc3
        fun add(expr: AExpr)
        do
                print "add not implemented in {inspect}"
                abort
        end

        redef fun accept_ast_validation(v)
        do
                super
                if mtype == null and not is_typed then
                        #debug "TYPING: untyped expression"
                end
        end
end

# A placeholder for a `AExpr` node
# Instances are transiantly used to mark some specific emplacements in the AST
# during complex transformations.
#
# Their must not appear in a valid AST
#
# @see AExpr::detach_with_placeholder
class APlaceholderExpr
        super AExpr
        private init make
        do
        end

        redef fun accept_ast_validation(v)
        do
                super
                debug "PARENT: remaining placeholder"
        end
end

redef class AReturnExpr
        private init make(expr: nullable AExpr)
        do
                self.init_areturnexpr(null, expr)
        end
end

redef class ASuperExpr
        private init make(args: nullable Array[AExpr], n_qualified: nullable AQualified)
        do
                var n_args = new AListExprs
                if args != null then
                        n_args.n_exprs.add_all(args)
                end
                self.init_asuperexpr(n_qualified, new TKwsuper, n_args)
        end
end

redef class AParExpr
        private init make(expr: AExpr, annotations: nullable AAnnotations)
        do
                self.location = expr.location
                self.init_aparexpr(new TOpar, expr, new TCpar, annotations)
        end
end

redef class AOrExpr
        private init make(right_expr: AExpr, left_expr: AExpr)
        do
                self.init_aorexpr(right_expr,new TKwor,left_expr)
        end
end

redef class AAndExpr
        private init make(right_expr: AExpr, left_expr: AExpr)
        do
                self.init_aandexpr(right_expr,new TKwand ,left_expr)
        end
end

redef class AMethPropdef
        private init make(n_visibility: nullable AVisibility,
                                        tk_redef: nullable TKwredef,
                                        mmethoddef: nullable MMethodDef,
                                        n_signature: nullable ASignature,
                                        n_annotations: nullable AAnnotations,
                                        n_extern_calls: nullable AExternCalls,
                                        n_extern_code_block: nullable AExternCodeBlock,
                                        n_block: nullable AExpr)
        do
                var n_tid = new TId
                var n_methid = new AIdMethid.init_aidmethid(n_tid)
                if n_signature == null then n_signature = new ASignature
                if n_visibility == null then n_visibility = new APublicVisibility
                self.init_amethpropdef(null,tk_redef,n_visibility,new TKwmeth,null,null,null,n_methid,n_signature,n_annotations,n_extern_calls,n_extern_code_block,new TKwdo,n_block,new TKwend)

                if mmethoddef != null then
                        self.n_methid.as(AIdMethid).n_id.text = mmethoddef.name
                        self.mpropdef = mmethoddef
                end
        end
end

redef class AAssertExpr
        private init make(n_id : nullable TId , n_expr : nullable AExpr , n_else : nullable AExpr)
        do
                n_kwassert = new TKwassert
                n_kwelse = null
                if n_else != null then n_kwelse = new TKwelse
                self.init_aassertexpr(n_kwassert, n_id , n_expr , n_kwelse , n_else)
        end
end

redef class ABlockExpr
        private init make
        do
                self.is_typed = true
        end

        redef fun add(expr)
        do
                n_expr.add expr
        end
end

redef class ALoopExpr
        private init make
        do
                _n_kwloop = new TKwloop
                self.is_typed = true
                n_block = new ABlockExpr
                n_block.is_typed = true
        end

        redef fun add(expr)
        do
                n_block.add expr
        end
end

redef class ADoExpr
        private init make
        do
                _n_kwdo = new TKwdo
                self.is_typed = true
                n_block = new ABlockExpr
                n_block.is_typed = true
        end

        # Make a new break expression of the given do
        fun make_break: ABreakExpr
        do
                var escapemark = self.break_mark
                if escapemark == null then
                        escapemark = new EscapeMark(null)
                        self.break_mark = escapemark
                end
                return new ABreakExpr.make(escapemark)
        end

        redef fun add(expr)
        do
                n_block.add expr
        end
end

redef class ABreakExpr
        private init make(escapemark: EscapeMark)
        do
                _n_kwbreak = new TKwbreak
                self.escapemark = escapemark
                escapemark.escapes.add self
                self.is_typed = true
        end
end

redef class AIfExpr
        private init make(condition: AExpr, mtype: nullable MType)
        do
                _n_kwif = new TKwif
                _n_expr = condition
                _n_expr.parent = self
                _n_kwthen = new TKwthen
                _n_then = new ABlockExpr.make
                _n_kwelse = new TKwelse
                _n_else = new ABlockExpr.make
                self.mtype = mtype
                self.is_typed = true
        end
end

redef class AType
        private init make
        do
                var n_id = new TClassid
                var n_qid = new AQclassid
                n_qid.n_id = n_id
                _n_qid = n_qid
        end
end

redef class AIntegerExpr
        private init make(value: Int, t: MType)
        do
                self.value = value
                self._n_integer = new TInteger # dummy
                self.mtype = t
        end
end

redef class ANewExpr
        private init make(callsite: CallSite, args: nullable Array[AExpr])
        do
                _n_kwnew = new TKwnew
                _n_type = new AType.make
                _n_args = new AListExprs
                if args != null then
                        n_args.n_exprs.add_all(args)
                end
                self.callsite = callsite
                self.recvtype = callsite.recv.as(MClassType)
                if callsite.mproperty.is_new then
                        self.mtype = callsite.msignature.return_mtype
                else
                        self.mtype = callsite.recv
                end
                self.is_typed = true
        end
end

redef class ACallExpr
        private init make(recv: AExpr, callsite: CallSite, args: nullable Array[AExpr])
        do
                self._n_expr = recv
                _n_args = new AListExprs
                _n_qid = new AQid
                _n_qid.n_id = new TId
                _n_qid.n_id.text = callsite.mproperty.name
                if args != null then
                        self.n_args.n_exprs.add_all(args)
                end
                self.callsite = callsite
                self.mtype = callsite.msignature.return_mtype
                self.is_typed = true
        end
end

redef class AAttrExpr
        private init make(recv: AExpr, attribute: MAttribute, t: MType)
        do
                _n_expr = recv
                recv.parent = self
                _n_id = new TAttrid
                mproperty = attribute
                mtype = t
        end
end

redef class AAttrAssignExpr
        private init make(recv: AExpr, attribute: MAttribute, value: AExpr)
        do
                _n_expr = recv
                recv.parent = self
                _n_id = new TAttrid
                _n_value = value
                value.parent = self
                _n_assign = new TAssign
                mproperty = attribute
                mtype = value.mtype
        end
end

redef class AVarExpr
        private init make(v: Variable, mtype: MType)
        do
                _n_id = new TId
                variable = v
                self.mtype = mtype
        end
end

redef class AVarAssignExpr
        private init make(v: Variable, value: AExpr)
        do
                _n_id = new TId
                _n_value = value
                value.parent = self
                _n_assign = new TAssign
                variable = v
                mtype = value.mtype
        end
end

# Check the consitency of AST
class ASTValidationVisitor
        super Visitor
        redef fun visit(node)
        do
                node.accept_ast_validation(self)
        end
        private var path = new CircularArray[ANode]
        private var seen = new HashSet[ANode]
end

redef class ANode
        # Recursively validate a AST node.
        # This ensure that location and parenting are defined and coherent.
        #
        # After complex low-level AST manipulation and construction,
        # it is recommended to call it.
        #
        # Note: this just instantiate and run an `ASTValidationVisitor`.
        fun validate
        do
                (new ASTValidationVisitor).enter_visit(self)
        end

        private fun accept_ast_validation(v: ASTValidationVisitor)
        do
                var parent = self.parent
                var path = v.path

                if path.length > 0 then
                        var path_parent = v.path.first
                        if parent == null then
                                self.parent = path_parent
                                #debug "PARENT: expected parent: {path_parent}"
                                v.seen.add(self)
                        else if parent != path_parent then
                                self.parent = path_parent
                                if v.seen.has(self) then
                                        debug "DUPLICATE (NOTATREE): already seen node with parent {parent} now with {path_parent}."
                                else
                                        v.seen.add(self)
                                        debug "PARENT: expected parent: {path_parent}, got {parent}"
                                end
                        end
                end

                if not isset _location then
                        #debug "LOCATION: unlocated node {v.path.join(", ")}"
                        _location = self.parent.location
                end

                path.unshift(self)
                visit_all(v)
                path.shift
        end
end

redef class AAnnotation
        redef fun accept_ast_validation(v)
        do
                # Do not enter in annotations
        end
end