[nit.git] / src / parser / parser_nodes.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.

# AST nodes of the Nit language
# Was previously based on parser_abs.nit.
module parser_nodes

import location

# Root of the AST class-hierarchy
abstract class ANode
        # Location is set during AST building. Once built, location cannon be null.
        # However, manual instantiated nodes may need more care.
        var location: Location is writable, noinit

        # The location of the important part of the node (identifier or whatever)
        fun hot_location: Location do return location

        # Display a message for the colored location of the node
        fun debug(message: String)
        do
                sys.stderr.write "{hot_location} {self.class_name}: {message}\n{hot_location.colored_line("0;32")}\n"
        end

        # Parent of the node in the AST
        var parent: nullable ANode = null

        # The topmost ancestor of the element
        # This just apply `parent` until the first one
        fun root: ANode
        do
                var res = self
                loop
                        var p = res.parent
                        if p == null then return res
                        res = p
                end
        end

        # The most specific common parent between `self` and `other`
        # Return null if the two node are unrelated (distinct root)
        fun common_parent(other: ANode): nullable ANode
        do
                # First, get the same depth
                var s: nullable ANode = self
                var o: nullable ANode = other
                var d = s.depth - o.depth
                while d > 0 do
                        s = s.parent
                        d -= 1
                end
                while d < 0 do
                        o = o.parent
                        d += 1
                end
                assert o.depth == s.depth
                # Second, go up until same in found
                while s != o do
                        s = s.parent
                        o = o.parent
                end
                return s
        end

        # Number of nodes between `self` and the `root` of the AST
        # ENSURE `self == self.root implies result == 0 `
        # ENSURE `self != self.root implies result == self.parent.depth + 1`
        fun depth: Int
        do
                var n = self
                var res = 0
                loop
                        var p = n.parent
                        if p == null then return res
                        n = p
                        res += 1
                end
        end

        # Replace a child with an other node in the AST
        private fun replace_child(old_child: ANode, new_child: nullable ANode) is abstract

        # Detach a node from its parent
        # Aborts if the node is not detachable. use `replace_with` instead
        # REQUIRE: parent != null
        # REQUIRE: is_detachable
        # ENDURE: parent == null
        fun detach
        do
                assert parent != null
                parent.replace_child(self, null)
                parent = null
        end

        # Replace itself with an other node in the AST
        # REQUIRE: parent != null
        # ENSURE: node.parent == old(parent)
        # ENSURE: parent == null
        fun replace_with(node: ANode)
        do
                assert parent != null
                parent.replace_child(self, node)
                parent = null
        end

        # Visit all nodes in order.
        # Thus, call `v.enter_visit(e)` for each child `e`
        fun visit_all(v: Visitor) is abstract

        # Do a deep search and return an array of tokens that match a given text
        fun collect_tokens_by_text(text: String): Array[Token]
        do
                var v = new CollectTokensByTextVisitor(text)
                v.enter_visit(self)
                return v.result
        end

        # Do a deep search and return an array of node that are annotated
        # The attached node can be retrieved by two invocations of parent
        fun collect_annotations_by_name(name: String): Array[AAnnotation]
        do
                var v = new CollectAnnotationsByNameVisitor(name)
                v.enter_visit(self)
                return v.result
        end
end

private class CollectTokensByTextVisitor
        super Visitor
        var text: String
        var result = new Array[Token]
        redef fun visit(node)
        do
                node.visit_all(self)
                if node isa Token and node.text == text then result.add(node)
        end
end

private class CollectAnnotationsByNameVisitor
        super Visitor
        var name: String
        var result = new Array[AAnnotation]
        redef fun visit(node)
        do
                node.visit_all(self)
                if node isa AAnnotation and node.n_atid.n_id.text == name then result.add(node)
        end
end


# A sequence of nodes
# It is a specific class (instead of using a Array) to track the parent/child relation when nodes are added or removed
class ANodes[E: ANode]
        super Sequence[E]
        private var parent: ANode
        private var items = new Array[E]
        redef fun iterator do return items.iterator
        redef fun length do return items.length
        redef fun is_empty do return items.is_empty
        redef fun push(e)
        do
                hook_add(e)
                items.push(e)
        end
        redef fun pop
        do
                var res = items.pop
                hook_remove(res)
                return res
        end
        redef fun unshift(e)
        do
                hook_add(e)
                items.unshift(e)
        end
        redef fun shift
        do
                var res = items.shift
                hook_remove(res)
                return res
        end
        redef fun has(e)
        do
                return items.has(e)
        end
        redef fun [](index)
        do
                return items[index]
        end
        redef fun []=(index, e)
        do
                hook_remove(self[index])
                hook_add(e)
                items[index]=e
        end
        redef fun remove_at(index)
        do
                hook_remove(items[index])
                items.remove_at(index)
        end
        private fun hook_add(e: E)
        do
                #assert e.parent == null
                e.parent = parent
        end
        private fun hook_remove(e: E)
        do
                assert e.parent == parent
                e.parent = null
        end

        # Used in parent constructor to fill elements
        private fun unsafe_add_all(nodes: Collection[Object])
        do
                var parent = self.parent
                for n in nodes do
                        assert n isa E
                        add n
                        n.parent = parent
                end
        end

        private fun replace_child(old_child: ANode, new_child: nullable ANode): Bool
        do
                var parent = self.parent
                for i in [0..length[ do
                        if self[i] == old_child then
                                if new_child != null then
                                        assert new_child isa E
                                        self[i] = new_child
                                        new_child.parent = parent
                                else
                                        self.remove_at(i)
                                end
                                return true
                        end
                end
                return false
        end

        private fun visit_all(v: Visitor)
        do
                for n in self do v.enter_visit(n)
        end
end

# Ancestor of all tokens
# A token is a node that has a `text` but no children.
abstract class Token
        super ANode

        # The raw content on the token
        fun text: String is abstract

        # The raw content on the token
        fun text=(text: String) is abstract

        # The previous token in the Lexer.
        # May have disappeared in the AST
        var prev_token: nullable Token = null

        # The next token in the Lexer.
        # May have disappeared in the AST
        var next_token: nullable Token = null

        # The verbatim blank text between `prev_token` and `self`
        fun blank_before: String
        do
                if prev_token == null then return ""
                var from = prev_token.location.pend+1
                var to = location.pstart
                return location.file.string.substring(from,to-from)
        end

        redef fun to_s: String do
                return "'{text}'"
        end

        redef fun visit_all(v: Visitor) do end
        redef fun replace_child(old_child: ANode, new_child: nullable ANode) do end
end

redef class SourceFile
        # The first token parser by the lexer
        # May have disappeared in the final AST
        var first_token: nullable Token = null

        # The first token parser by the lexer
        # May have disappeared in the final AST
        var last_token: nullable Token = null
end

# Ancestor of all productions
# A production is a node without text but that usually has children.
abstract class Prod
        super ANode

        # All the annotations attached directly to the node
        var n_annotations: nullable AAnnotations = null is writable

        # Return all its annotations of a given name in the order of their declaration
        # Retun an empty array if no such an annotation.
        fun get_annotations(name: String): Array[AAnnotation]
        do
                var res = new Array[AAnnotation]
                var nas = n_annotations
                if nas == null then return res
                for na in nas.n_items do
                        if na.name != name then continue
                        res.add(na)
                end
                return res
        end

        redef fun replace_with(n: ANode)
        do
                super
                assert n isa Prod
                if not isset n._location and isset _location then n._location = _location
        end
end

# Abstract standard visitor on the AST
abstract class Visitor
        # What the visitor do when a node is visited
        # Concrete visitors should implement this method.
        # @toimplement
        protected fun visit(e: ANode) is abstract

        # Ask the visitor to visit a given node.
        # Usually automatically called by visit_all* methods.
        # This method should not be redefined
        fun enter_visit(e: nullable ANode)
        do
                if e == null then return
                var old = _current_node
                _current_node = e
                visit(e)
                _current_node = old
        end

        # The current visited node
        var current_node: nullable ANode = null is writable
end

# Token of end of line (basically `\n`)
class TEol
        super Token
        redef fun to_s
        do
                return "end of line"
        end
end

# Token of a line of comments
# Starts with the `#` and contains the final end-of-line (if any)
class TComment
        super Token
end

# A token associated with a keyword
abstract class TokenKeyword
        super Token
        redef fun to_s
        do
                return "keyword '{text}'"
        end
end

# The deprecated keyword `package`.
class TKwpackage
        super TokenKeyword
end

# The keyword `module`
class TKwmodule
        super TokenKeyword
end

# The keyword `import`
class TKwimport
        super TokenKeyword
end

# The keyword `class`
class TKwclass
        super TokenKeyword
end

# The keyword `abstract`
class TKwabstract
        super TokenKeyword
end

# The keyword `interface`
class TKwinterface
        super TokenKeyword
end

# The keywords `enum` ane `universal`
class TKwenum
        super TokenKeyword
end

# The keyword `end`
class TKwend
        super TokenKeyword
end

# The keyword `fun`
class TKwmeth
        super TokenKeyword
end

# The keyword `type`
class TKwtype
        super TokenKeyword
end

# The keyword `init`
class TKwinit
        super TokenKeyword
end

# The keyword `redef`
class TKwredef
        super TokenKeyword
end

# The keyword `is`
class TKwis
        super TokenKeyword
end

# The keyword `do`
class TKwdo
        super TokenKeyword
end

# The keyword `var`
class TKwvar
        super TokenKeyword
end

# The keyword `extern`
class TKwextern
        super TokenKeyword
end

# The keyword `public`
class TKwpublic
        super TokenKeyword
end

# The keyword `protected`
class TKwprotected
        super TokenKeyword
end

# The keyword `private`
class TKwprivate
        super TokenKeyword
end

# The keyword `intrude`
class TKwintrude
        super TokenKeyword
end

# The keyword `if`
class TKwif
        super TokenKeyword
end

# The keyword `then`
class TKwthen
        super TokenKeyword
end

# The keyword `else`
class TKwelse
        super TokenKeyword
end

# The keyword `while`
class TKwwhile
        super TokenKeyword
end

# The keyword `loop`
class TKwloop
        super TokenKeyword
end

# The keyword `for`
class TKwfor
        super TokenKeyword
end

# The keyword `in`
class TKwin
        super TokenKeyword
end

# The keyword `and`
class TKwand
        super TokenKeyword
end

# The keyword `or`
class TKwor
        super TokenKeyword
end

# The keyword `implies`
class TKwimplies
        super TokenKeyword
end

# The keyword `not`
class TKwnot
        super TokenKeyword
end

# The keyword `return`
class TKwreturn
        super TokenKeyword
end

# The keyword `continue`
class TKwcontinue
        super TokenKeyword
end

# The keyword `break`
class TKwbreak
        super TokenKeyword
end

# The keyword `abort`
class TKwabort
        super TokenKeyword
end

# The keyword `assert`
class TKwassert
        super TokenKeyword
end

# The keyword `new`
class TKwnew
        super TokenKeyword
end

# The keyword `isa`
class TKwisa
        super TokenKeyword
end

# The keyword `once`
class TKwonce
        super TokenKeyword
end

# The keyword `super`
class TKwsuper
        super TokenKeyword
end

# The keyword `self`
class TKwself
        super TokenKeyword
end

# The keyword `true`
class TKwtrue
        super TokenKeyword
end

# The keyword `false`
class TKwfalse
        super TokenKeyword
end

# The keyword `null`
class TKwnull
        super TokenKeyword
end

# The keyword `as`
class TKwas
        super TokenKeyword
end

# The keyword `nullable`
class TKwnullable
        super TokenKeyword
end

# The keyword `isset`
class TKwisset
        super TokenKeyword
end

# The keyword `label`
class TKwlabel
        super TokenKeyword
end

# The special keyword `__DEBUG__`
class TKwdebug
        super Token
end

# The symbol `(`
class TOpar
        super Token
end

# The symbol `)`
class TCpar
        super Token
end

# The symbol `[`
class TObra
        super Token
end

# The symbol `]`
class TCbra
        super Token
end

# The symbol `,`
class TComma
        super Token
end

# The symbol `:`
class TColumn
        super Token
end

# The symbol `::`
class TQuad
        super Token
end

# The symbol `=`
class TAssign
        super Token
end

# A token associated with an operator (and other lookalike symbols)
abstract class TokenOperator
        super Token
        redef fun to_s
        do
                return "operator '{text}'"
        end
end

# The operator `+=`
class TPluseq
        super TokenOperator
end

# The operator `-=`
class TMinuseq
        super TokenOperator
end

# The symbol `...`
class TDotdotdot
        super Token
end

# The symbol `..`
class TDotdot
        super Token
end

# The symbol `.`
class TDot
        super Token
end

# The operator `+`
class TPlus
        super TokenOperator
end

# The operator `-`
class TMinus
        super TokenOperator
end

# The operator `*`
class TStar
        super TokenOperator
end

# The operator `**`
class TStarstar
        super TokenOperator
end

# The operator `/`
class TSlash
        super TokenOperator
end

# The operator `+%
class TPercent
        super TokenOperator
end

# The operator `==`
class TEq
        super TokenOperator
end

# The operator `!=`
class TNe
        super TokenOperator
end

# The operator `<`
class TLt
        super TokenOperator
end

# The operator `<=`
class TLe
        super TokenOperator
end

# The operator `<<`
class TLl
        super TokenOperator
end

# The operator `>`
class TGt
        super TokenOperator
end

# The operator `>=`
class TGe
        super TokenOperator
end

# The operator `>>`
class TGg
        super TokenOperator
end

# The operator `<=>`
class TStarship
        super TokenOperator
end

# The operator `!`
class TBang
        super TokenOperator
end

# The symbol `@`
class TAt
        super Token
end

# A class (or formal type) identifier. They start with an uppercase.
class TClassid
        super Token
        redef fun to_s
        do
                do return "type identifier '{text}'"
        end
end

# A standard identifier (variable, method...). They start with a lowercase.
class TId
        super Token
        redef fun to_s
        do
                do return "identifier '{text}'"
        end
end

# An attribute identifier. They start with an underscore.
class TAttrid
        super Token
        redef fun to_s
        do
                do return "attribute '{text}'"
        end
end

# A token of a literal value (string, integer, etc).
abstract class TokenLiteral
        super Token
        redef fun to_s
        do
                do return "literal value '{text}'"
        end
end

# A literal decimal integer
class TNumber
        super TokenLiteral
end

# A literal hexadecimal integer
class THexNumber
        super TokenLiteral
end

# A literal floating point number
class TFloat
        super TokenLiteral
end

# A literal character
class TChar
        super TokenLiteral
end

# A literal string
class TString
        super TokenLiteral
end

# The starting part of a super string (between `"` and `{`)
class TStartString
        super TokenLiteral
end

# The middle part of a super string (between `}` and `{`)
class TMidString
        super TokenLiteral
end

# The final part of a super string (between `}` and `"`)
class TEndString
        super TokenLiteral
end

# A malformed string
class TBadString
        super Token
        redef fun to_s
        do
                do return "malformed string {text}"
        end
end

# A malformed char
class TBadChar
        super Token
        redef fun to_s
        do
                do return "malformed character {text}"
        end
end

# A extern code block
class TExternCodeSegment
        super Token
end

# A end of file
class EOF
        super Token
        redef fun to_s
        do
                return "end of file"
        end
end

# A mark of an error
class AError
        super EOF
end
# A lexical error (unexpected character)
class ALexerError
        super AError
end
# A syntactic error (unexpected token)
class AParserError
        super AError
end

# The main node of a Nit source-file
class AModule
        super Prod

        # The declaration part of the module
        var n_moduledecl: nullable AModuledecl = null is writable

        # List of importation clauses
        var n_imports = new ANodes[AImport](self)

        # List of extern blocks
        var n_extern_code_blocks = new ANodes[AExternCodeBlock](self)

        # List of class definition (including top-level methods and the main)
        var n_classdefs = new ANodes[AClassdef](self)
end

# Abstract class for definition of entities
abstract class ADefinition
        super Prod
        # The documentation
        var n_doc: nullable ADoc = null is writable

        # The `redef` keyword
        var n_kwredef: nullable TKwredef = null is writable

        # The declared visibility
        var n_visibility: nullable AVisibility = null is writable
end

# The declaration of the module with the documentation, name, and annotations
class AModuledecl
        super ADefinition

        # The `module` keyword
        var n_kwmodule: TKwmodule is writable, noinit

        # The declared module name
        var n_name: AModuleName is writable, noinit
end

# A import clause of a module
abstract class AImport
        super Prod

        # The declared visibility
        var n_visibility: AVisibility is writable, noinit

        # The `import` keyword
        var n_kwimport: TKwimport is writable, noinit
end

# A standard import clause. eg `import x`
class AStdImport
        super AImport
        # The imported module name
        var n_name: AModuleName is writable, noinit
end

# The special import clause of the kernel module. eg `import end`
class ANoImport
        super AImport
        # The `end` keyword, that indicate the root module
        var n_kwend: TKwend is writable, noinit
end

# A visibility modifier
#
# The public visibility is an empty production (no keyword).
#
# Note: even if some visibilities are only valid on some placse (for instance, no `protected` class or no `intrude` method)
# the parser has no such a restriction, therefore the semantic phases has to check that the visibilities make sense.
abstract class AVisibility
        super Prod
end

# An implicit or explicit public visibility modifier
class APublicVisibility
        super AVisibility
        # The `public` keyword, if any
        var n_kwpublic: nullable TKwpublic is writable
end
# An explicit private visibility modifier
class APrivateVisibility
        super AVisibility
        # The `private` keyword
        var n_kwprivate: TKwprivate is writable, noinit
end
# An explicit protected visibility modifier
class AProtectedVisibility
        super AVisibility
        # The `protected` keyword
        var n_kwprotected: TKwprotected is writable, noinit
end
# An explicit intrude visibility modifier
class AIntrudeVisibility
        super AVisibility
        # The `intrude` keyword
        var n_kwintrude: TKwintrude is writable, noinit
end

# A class definition
# While most definition are `AStdClassdef`
# There is tow special case of class definition
abstract class AClassdef
        super Prod
        # All the declared properties (including the main method)
        var n_propdefs = new ANodes[APropdef](self)
end

# A standard class definition with a name, superclasses and properties
class AStdClassdef
        super AClassdef
        super ADefinition

        # The class kind (interface, abstract class, etc.)
        var n_classkind: AClasskind is writable, noinit

        # The name of the class
        var n_id: nullable TClassid = null is writable

        # The list of formal parameter types
        var n_formaldefs = new ANodes[AFormaldef](self)

        # The extern block code
        var n_extern_code_block: nullable AExternCodeBlock = null is writable

        # The `end` keyword
        var n_kwend: TKwend is writable, noinit

        fun n_superclasses: Array[ASuperPropdef] do
                return [for d in n_propdefs do if d isa ASuperPropdef then d]
        end

        redef fun hot_location do return n_id.location
end

# The implicit class definition of the implicit main method
class ATopClassdef
        super AClassdef
end

# The implicit class definition of the top-level methods
class AMainClassdef
        super AClassdef
end

# The modifier for the kind of class (abstract, interface, etc.)
abstract class AClasskind
        super Prod
end

# A default, or concrete class modifier (just `class`)
class AConcreteClasskind
        super AClasskind

        # The `class` keyword.
        var n_kwclass: TKwclass is writable, noinit
end

# An abstract class modifier (`abstract class`)
class AAbstractClasskind
        super AClasskind

        # The `abstract` keyword.
        var n_kwabstract: TKwabstract is writable, noinit

        # The `class` keyword.
        var n_kwclass: TKwclass is writable, noinit
end

# An interface class modifier (`interface`)
class AInterfaceClasskind
        super AClasskind

        # The `interface` keyword.
        var n_kwinterface: TKwinterface is writable, noinit
end

# An enum/universal class modifier (`enum class`)
class AEnumClasskind
        super AClasskind

        # The `enum` keyword.
        var n_kwenum: TKwenum is writable, noinit
end

# An extern class modifier (`extern class`)
class AExternClasskind
        super AClasskind

        # The `extern` keyword.
        var n_kwextern: TKwextern is writable, noinit

        # The `class` keyword.
        var n_kwclass: nullable TKwclass = null is writable
end

# The definition of a formal generic parameter type. eg `X: Y`
class AFormaldef
        super Prod

        # The name of the parameter type
        var n_id: TClassid is writable, noinit

        # The bound of the parameter type
        var n_type: nullable AType = null is writable
end

# The definition of a property
abstract class APropdef
        super ADefinition
end

# A definition of an attribute
# For historical reason, old-syle and new-style attributes use the same `ANode` sub-class
class AAttrPropdef
        super APropdef

        # The identifier for a old-style attribute (null if new-style)
        var n_kwvar: TKwvar is writable, noinit

        # The identifier for a new-style attribute (null if old-style)
        var n_id2: TId is writable, noinit

        # The declared type of the attribute
        var n_type: nullable AType = null is writable

        # The initial value, if any (set with `=`)
        var n_expr: nullable AExpr = null is writable

        # The initial value, if any (set with `do return`)
        var n_block: nullable AExpr = null is writable

        redef fun hot_location
        do
                return n_id2.location
        end
end

# A definition of all kind of method (including constructors)
class AMethPropdef
        super APropdef

        # The `fun` keyword, if any
        var n_kwmeth: nullable TKwmeth = null is writable

        # The `init` keyword, if any
        var n_kwinit: nullable TKwinit = null is writable

        # The `new` keyword, if any
        var n_kwnew: nullable TKwnew = null is writable

        # The name of the method, if any
        var n_methid: nullable AMethid = null is writable

        # The signature of the method, if any
        var n_signature: nullable ASignature = null is writable

        # The body (in Nit) of the method, if any
        var n_block: nullable AExpr = null is writable

        # The list of declared callbacks (for extern methods)
        var n_extern_calls: nullable AExternCalls = null is writable

        # The body (in extern code) of the method, if any
        var n_extern_code_block: nullable AExternCodeBlock = null is writable

        redef fun hot_location
        do
                if n_methid != null then
                        return n_methid.location
                else if n_kwinit != null then
                        return n_kwinit.location
                else if n_kwnew != null then
                        return n_kwnew.location
                else
                        return location
                end
        end
end

# The implicit main method
class AMainMethPropdef
        super AMethPropdef
end

# A super-class. eg `super X`
class ASuperPropdef
        super APropdef

        # The super keyword
        var n_kwsuper: TKwsuper is writable, noinit

        # The super-class (indicated as a type)
        var n_type: AType is writable, noinit
end


# Declaration of callbacks for extern methods
class AExternCalls
        super Prod

        # The `import` keyword
        var n_kwimport: TKwimport is writable, noinit

        # The list of declared callbacks
        var n_extern_calls: ANodes[AExternCall] = new ANodes[AExternCall](self)
end

# A single callback declaration
abstract class AExternCall
        super Prod
end

# A single callback declaration on a method
abstract class APropExternCall
        super AExternCall
end

# A single callback declaration on a method on the current receiver
class ALocalPropExternCall
        super APropExternCall

        # The name of the called-back method
        var n_methid: AMethid is writable, noinit
end

# A single callback declaration on a method on an explicit receiver type.
class AFullPropExternCall
        super APropExternCall

        # The type of the receiver of the called-back method
        var n_type: AType is writable, noinit

        # The dot `.`
        var n_dot: nullable TDot = null is writable

        # The name of the called-back method
        var n_methid: AMethid is writable, noinit
end

# A single callback declaration on a method on a constructor
class AInitPropExternCall
        super APropExternCall

        # The allocated type
        var n_type: AType is writable, noinit
end

# A single callback declaration on a `super` call
class ASuperExternCall
        super AExternCall

        # The `super` keyword
        var n_kwsuper: TKwsuper is writable, noinit
end

# A single callback declaration on a cast
abstract class ACastExternCall
        super AExternCall
end

# A single callback declaration on a cast to a given type
class ACastAsExternCall
        super ACastExternCall

        # The origin type of the cast
        var n_from_type: AType is writable, noinit

        # The dot (`.`)
        var n_dot: nullable TDot = null is writable

        # The `as` keyword
        var n_kwas: TKwas is writable, noinit

        # The destination of the cast
        var n_to_type: AType is writable, noinit
end

# A single callback declaration on a cast to a nullable type
class AAsNullableExternCall
        super ACastExternCall

        # The origin type to cast as nullable
        var n_type: AType is writable, noinit

        # The `as` keyword
        var n_kwas: TKwas is writable, noinit

        # The `nullable` keyword
        var n_kwnullable: TKwnullable is writable, noinit
end

# A single callback declaration on a cast to a non-nullable type
class AAsNotNullableExternCall
        super ACastExternCall

        # The destination type on a cast to not nullable
        var n_type: AType is writable, noinit

        # The `as` keyword.
        var n_kwas: TKwas is writable, noinit

        # The `not` keyword
        var n_kwnot: TKwnot is writable, noinit

        # The `nullable` keyword
        var n_kwnullable: TKwnullable is writable, noinit
end

# A definition of a virtual type
class ATypePropdef
        super APropdef

        # The `type` keyword
        var n_kwtype: TKwtype is writable, noinit

        # The name of the virtual type
        var n_id: TClassid is writable, noinit

        # The bound of the virtual type
        var n_type: AType is writable, noinit
end

# The identifier of a method in a method declaration.
# There is a specific class because of operator and setters.
abstract class AMethid
        super Prod
end

# A method name with a simple identifier
class AIdMethid
        super AMethid

        # The simple identifier
        var n_id: TId is writable, noinit
end

# A method name `+`
class APlusMethid
        super AMethid

        # The `+` symbol
        var n_plus: TPlus is writable, noinit
end

# A method name `-`
class AMinusMethid
        super AMethid

        # The `-` symbol
        var n_minus: TMinus is writable, noinit
end

# A method name `*`
class AStarMethid
        super AMethid

        # The `*` symbol
        var n_star: TStar is writable, noinit
end

# A method name `**`
class AStarstarMethid
        super AMethid

        # The `**` symbol
        var n_starstar: TStarstar is writable, noinit
end

# A method name `/`
class ASlashMethid
        super AMethid

        # The `/` symbol
        var n_slash: TSlash is writable, noinit
end

# A method name `%`
class APercentMethid
        super AMethid

        # The `%` symbol
        var n_percent: TPercent is writable, noinit
end

# A method name `==`
class AEqMethid
        super AMethid

        # The `==` symbol
        var n_eq: TEq is writable, noinit
end

# A method name `!=`
class ANeMethid
        super AMethid

        # The `!=` symbol
        var n_ne: TNe is writable, noinit
end

# A method name `<=`
class ALeMethid
        super AMethid

        # The `<=` symbol
        var n_le: TLe is writable, noinit
end

# A method name `>=`
class AGeMethid
        super AMethid

        # The `>=` symbol
        var n_ge: TGe is writable, noinit
end

# A method name `<`
class ALtMethid
        super AMethid

        # The `<` symbol
        var n_lt: TLt is writable, noinit
end

# A method name `>`
class AGtMethid
        super AMethid

        # The `>` symbol
        var n_gt: TGt is writable, noinit
end

# A method name `<<`
class ALlMethid
        super AMethid

        # The `<<` symbol
        var n_ll: TLl is writable, noinit
end

# A method name `>>`
class AGgMethid
        super AMethid

        # The `>>` symbol
        var n_gg: TGg is writable, noinit
end

# A method name `[]`
class ABraMethid
        super AMethid

        # The `[` symbol
        var n_obra: TObra is writable, noinit

        # The `]` symbol
        var n_cbra: TCbra is writable, noinit
end

# A method name `<=>`
class AStarshipMethid
        super AMethid

        # The `<=>` symbol
        var n_starship: TStarship is writable, noinit
end

# A setter method name with a simple identifier (with a `=`)
class AAssignMethid
        super AMethid

        # The base identifier
        var n_id: TId is writable, noinit

        # The `=` symbol
        var n_assign: TAssign is writable, noinit
end

# A method name `[]=`
class ABraassignMethid
        super AMethid

        # The `[` symbol
        var n_obra: TObra is writable, noinit

        # The `]` symbol
        var n_cbra: TCbra is writable, noinit

        # The `=` symbol
        var n_assign: TAssign is writable, noinit
end

# A signature in a method definition. eg `(x,y:X,z:Z):T`
class ASignature
        super Prod

        # The `(` symbol
        var n_opar: nullable TOpar = null is writable

        # The list of parameters
        var n_params = new ANodes[AParam](self)

        # The `)` symbol
        var n_cpar: nullable TCpar = null is writable

        # The return type
        var n_type: nullable AType = null is writable
end

# A parameter definition in a signature. eg `x:X`
class AParam
        super Prod

        # The name of the parameter
        var n_id: TId is writable, noinit

        # The type of the parameter, if any
        var n_type: nullable AType = null is writable

        # The `...` symbol to indicate varargs
        var n_dotdotdot: nullable TDotdotdot = null is writable
end

# A static type. eg `nullable X[Y]`
class AType
        super Prod
        # The `nullable` keyword
        var n_kwnullable: nullable TKwnullable = null is writable

        # The name of the class or of the formal type
        var n_id: TClassid is writable, noinit

        # Type arguments for a generic type
        var n_types = new ANodes[AType](self)
end

# A label at the end of a block or in a break/continue statement. eg `label x`
class ALabel
        super Prod

        # The `label` keyword
        var n_kwlabel: TKwlabel is writable, noinit

        # The name of the label, if any
        var n_id: nullable TId is writable
end

# Expression and statements
# From a AST point of view there is no distinction between statement and expressions (even if the parser has to distinguish them)
abstract class AExpr
        super Prod
end

# A sequence of `AExpr` (usually statements)
# The last `AExpr` gives the value of the whole block
class ABlockExpr
        super AExpr

        # The list of statements in the bloc.
        # The last element is often considered as an expression that give the value of the whole block.
        var n_expr = new ANodes[AExpr](self)

        # The `end` keyword
        var n_kwend: nullable TKwend = null is writable
end

# A declaration of a local variable. eg `var x: X = y`
class AVardeclExpr
        super AExpr

        # The `var` keyword
        var n_kwvar: TKwvar is writable, noinit

        # The name of the local variable
        var n_id: TId is writable, noinit

        # The declaration type of the local variable
        var n_type: nullable AType = null is writable

        # The `=` symbol (for the initial value)
        var n_assign: nullable TAssign = null is writable

        # The initial value, if any
        var n_expr: nullable AExpr = null is writable
end

# A `return` statement. eg `return x`
class AReturnExpr
        super AExpr

        # The `return` keyword
        var n_kwreturn: nullable TKwreturn = null is writable

        # The return value, if any
        var n_expr: nullable AExpr = null is writable
end

# Something that has a label.
abstract class ALabelable
        super Prod

        # The associated label declatation
        var n_label: nullable ALabel = null is writable
end

# A `break` or a `continue`
abstract class AEscapeExpr
        super AExpr
        super ALabelable

        # The return value, if nay (unused currently)
        var n_expr: nullable AExpr = null is writable
end

# A `break` statement.
class ABreakExpr
        super AEscapeExpr

        # The `break` keyword
        var n_kwbreak: TKwbreak is writable, noinit
end

# An `abort` statement
class AAbortExpr
        super AExpr

        # The `abort` keyword
        var n_kwabort: TKwabort is writable, noinit
end

# A `continue` statement
class AContinueExpr
        super AEscapeExpr

        # The `continue` keyword.
        var n_kwcontinue: nullable TKwcontinue = null is writable
end

# A `do` statement
class ADoExpr
        super AExpr
        super ALabelable

        # The `do` keyword
        var n_kwdo: TKwdo is writable, noinit

        # The list of statements of the `do`.
        var n_block: nullable AExpr = null is writable
end

# A `if` statement
class AIfExpr
        super AExpr

        # The `if` keyword
        var n_kwif: TKwif is writable, noinit

        # The expression used as the condition of the `if`
        var n_expr: AExpr is writable, noinit

        # The body of the `then` part
        var n_then: nullable AExpr = null is writable

        # The body of the `else` part
        var n_else: nullable AExpr = null is writable
end

# A `if` expression (ternary conditional). eg. `if true then 1 else 0`
class AIfexprExpr
        super AExpr

        # The `if` keyword
        var n_kwif: TKwif is writable, noinit

        # The expression used as the condition of the `if`
        var n_expr: AExpr is writable, noinit

        # The `then` keyword
        var n_kwthen: TKwthen is writable, noinit

        # The expression in the `then` part
        var n_then: AExpr is writable, noinit

        # The `else` keyword
        var n_kwelse: TKwelse is writable, noinit

        # The expression in the `else` part
        var n_else: AExpr is writable, noinit
end

# A `while` statement
class AWhileExpr
        super AExpr
        super ALabelable

        # The `while` keyword
        var n_kwwhile:  TKwwhile is writable, noinit

        # The expression used as the condition of the `while`
        var n_expr: AExpr is writable, noinit

        # The `do` keyword
        var n_kwdo: TKwdo is writable, noinit

        # The body of the loop
        var n_block: nullable AExpr = null is writable
end

# A `loop` statement
class ALoopExpr
        super AExpr
        super ALabelable

        # The `loop` keyword
        var n_kwloop: TKwloop is writable, noinit

        # The body of the loop
        var n_block: nullable AExpr = null is writable
end

# A `for` statement
class AForExpr
        super AExpr
        super ALabelable

        # The `for` keyword
        var n_kwfor: TKwfor is writable, noinit

        # The list of name of the automatic variables
        var n_ids = new ANodes[TId](self)

        # The expression used as the collection to iterate on
        var n_expr: AExpr is writable, noinit

        # The `do` keyword
        var n_kwdo: TKwdo is writable, noinit

        # The body of the loop
        var n_block: nullable AExpr = null is writable
end

# An `assert` statement
class AAssertExpr
        super AExpr

        # The `assert` keyword
        var n_kwassert: TKwassert is writable, noinit

        # The name of the assert, if any
        var n_id: nullable TId = null is writable

        # The expression used as the condition of the `assert`
        var n_expr: AExpr is writable, noinit

        # The body to execute when the assert fails
        var n_else: nullable AExpr = null is writable
end

# Whatever is a simple assignment. eg `= something`
abstract class AAssignFormExpr
        super AExpr

        # The `=` symbol
        var n_assign: TAssign is writable, noinit

        # The right-value to assign.
        var n_value: AExpr is writable, noinit
end

# Whatever is a combined assignment. eg `+= something`
abstract class AReassignFormExpr
        super AExpr

        # The combined operator (eg. `+=`)
        var n_assign_op: AAssignOp is writable, noinit

        # The right-value to apply on the combined operator.
        var n_value: AExpr is writable, noinit
end

# A `once` expression. eg `once x`
class AOnceExpr
        super AExpr

        # The `once` keyword
        var n_kwonce: TKwonce is writable, noinit

        # The expression to evaluate only one time
        var n_expr: AExpr is writable, noinit
end

# A polymorphic invocation of a method
# The form of the invocation (name, arguments, etc.) are specific
abstract class ASendExpr
        super AExpr
        # The receiver of the method invocation
        var n_expr: AExpr is writable, noinit
end

# A binary operation on a method
abstract class ABinopExpr
        super ASendExpr
        # The second operand of the operation
        # Note: the receiver (`n_expr`) is the first operand
        var n_expr2: AExpr is writable, noinit
end

# Something that is boolean expression
abstract class ABoolExpr
        super AExpr
end

# Something that is binary boolean expression
abstract class ABinBoolExpr
        super ABoolExpr

        # The first boolean operand
        var n_expr: AExpr is writable, noinit

        # The second boolean operand
        var n_expr2: AExpr is writable, noinit
end

# A `or` expression
class AOrExpr
        super ABinBoolExpr
end

# A `and` expression
class AAndExpr
        super ABinBoolExpr
end

# A `or else` expression
class AOrElseExpr
        super ABinBoolExpr
end

# A `implies` expression
class AImpliesExpr
        super ABinBoolExpr
end

# A `not` expression
class ANotExpr
        super ABoolExpr

        # The `not` keyword
        var n_kwnot: TKwnot is writable, noinit

        # The boolean operand of the `not`
        var n_expr: AExpr is writable, noinit
end

# A `==` expression
class AEqExpr
        super ABinopExpr
end

# A `!=` expression
class ANeExpr
        super ABinopExpr
end

# A `<` expression
class ALtExpr
        super ABinopExpr
end

# A `<=` expression
class ALeExpr
        super ABinopExpr
end

# A `<<` expression
class ALlExpr
        super ABinopExpr
end

# A `>` expression
class AGtExpr
        super ABinopExpr
end

# A `>=` expression
class AGeExpr
        super ABinopExpr
end

# A `>>` expression
class AGgExpr
        super ABinopExpr
end

# A type-ckeck expression. eg `x isa T`
class AIsaExpr
        super ABoolExpr

        # The expression to check
        var n_expr: AExpr is writable, noinit

        # The destination type to check to
        var n_type: AType is writable, noinit
end

# A `+` expression
class APlusExpr
        super ABinopExpr
end

# A `-` expression
class AMinusExpr
        super ABinopExpr
end

# A `<=>` expression
class AStarshipExpr
        super ABinopExpr
end

# A `*` expression
class AStarExpr
        super ABinopExpr
end

# A `**` expression
class AStarstarExpr
        super ABinopExpr
end

# A `/` expression
class ASlashExpr
        super ABinopExpr
end

# A `%` expression
class APercentExpr
        super ABinopExpr
end

# A unary minus expression. eg `-x`
class AUminusExpr
        super ASendExpr

        # The `-` symbol
        var n_minus: TMinus is writable, noinit
end

# An explicit instantiation. eg `new T`
class ANewExpr
        super AExpr

        # The `new` keyword
        var n_kwnew: TKwnew is writable, noinit

        # The `type` keyword
        var n_type: AType is writable, noinit

        # The name of the named-constructor, if any
        var n_id: nullable TId = null is writable

        # The arguments of the `new`
        var n_args: AExprs is writable, noinit
end

# Whatever is a old-style attribute access
abstract class AAttrFormExpr
        super AExpr

        # The receiver of the attribute
        var n_expr: AExpr is writable, noinit

        # The name of the attribute
        var n_id: TAttrid is writable, noinit

end

# The read of an attribute. eg `x._a`
class AAttrExpr
        super AAttrFormExpr
end

# The assignment of an attribute. eg `x._a=y`
class AAttrAssignExpr
        super AAttrFormExpr
        super AAssignFormExpr
end

# Whatever looks-like a call with a standard method and any number of arguments.
abstract class ACallFormExpr
        super ASendExpr

        # The name of the method
        var n_id: TId is writable, noinit

        # The arguments of the call
        var n_args: AExprs is writable, noinit
end

# A complex setter call (standard or brackets)
abstract class ASendReassignFormExpr
        super ASendExpr
        super AReassignFormExpr
end

# A complex attribute assignment. eg `x._a+=y`
class AAttrReassignExpr
        super AAttrFormExpr
        super AReassignFormExpr
end

# A call with a standard method-name and any number of arguments. eg `x.m(y)`. OR just a simple id
# Note: because the parser cannot distinguish a variable read with a method call with an implicit receiver and no arguments, it always returns a `ACallExpr`.
# Semantic analysis have to transform them to instance of `AVarExpr`.
class ACallExpr
        super ACallFormExpr
end

# A setter call with a standard method-name and any number of arguments. eg `x.m(y)=z`. OR just a simple assignment.
# Note: because the parser cannot distinguish a variable write with a setter call with an implicit receiver and no arguments, it always returns a `ACallAssignExpr`.
# Semantic analysis have to transform them to instance of `AVarAssignExpr`.
class ACallAssignExpr
        super ACallFormExpr
        super AAssignFormExpr
end

# A complex setter call with a standard method-name and any number of arguments. eg `x.m(y)+=z`. OR just a simple complex assignment.
# Note: because the parser cannot distinguish a variable write with a complex setter call with an implicit receiver and no arguments, it always returns a `ACallReassignExpr`.
# Semantic analysis have to transform them to instance of `AVarReassignExpr`.
class ACallReassignExpr
        super ACallFormExpr
        super ASendReassignFormExpr
end

# A call to `super`. OR a call of a super-constructor
class ASuperExpr
        super AExpr

        # The qualifier part before the super (currenlty unused)
        var n_qualified: nullable AQualified = null is writable

        # The `super` keyword
        var n_kwsuper: TKwsuper is writable, noinit

        # The arguments of the super
        var n_args: AExprs is writable, noinit
end

# A call to the `init` constructor.
# Note: because `init` is a keyword and not a `TId`, the explicit call to init cannot be a `ACallFormExpr`.
class AInitExpr
        super ASendExpr

        # The `init` keyword
        var n_kwinit: TKwinit is writable, noinit

        # The arguments of the init
        var n_args: AExprs is writable, noinit
end

# Whatever looks-like a call of the brackets `[]` operator.
abstract class ABraFormExpr
        super ASendExpr

        # The arguments inside the brackets
        var n_args: AExprs is writable, noinit
end

# A call of the brackets operator. eg `x[y,z]`
class ABraExpr
        super ABraFormExpr
end

# A setter call of the bracket operator. eg `x[y,z]=t`
class ABraAssignExpr
        super ABraFormExpr
        super AAssignFormExpr
end

# Whatever is an access to a local variable
abstract class AVarFormExpr
        super AExpr

        # The name of the attribute
        var n_id: TId is writable, noinit
end

# A complex setter call of the bracket operator. eg `x[y,z]+=t`
class ABraReassignExpr
        super ABraFormExpr
        super ASendReassignFormExpr
end

# A local variable read access.
# The parser cannot instantiate them, see `ACallExpr`.
class AVarExpr
        super AVarFormExpr
end

# A local variable simple assignment access
# The parser cannot instantiate them, see `ACallAssignExpr`.
class AVarAssignExpr
        super AVarFormExpr
        super AAssignFormExpr
end

# A local variable complex assignment access
# The parser cannot instantiate them, see `ACallReassignExpr`.
class AVarReassignExpr
        super AVarFormExpr
        super AReassignFormExpr
end

# A literal range, open or closed
abstract class ARangeExpr
        super AExpr

        # The left (lower) element of the range
        var n_expr: AExpr is writable, noinit

        # The right (uppr) element of the range
        var n_expr2: AExpr is writable, noinit
end

# A closed literal range. eg `[x..y]`
class ACrangeExpr
        super ARangeExpr

        # The opening bracket `[`
        var n_obra: TObra is writable, noinit

        # The closing bracket `]`
        var n_cbra: TCbra is writable, noinit
end

# An open literal range. eg `[x..y[`
class AOrangeExpr
        super ARangeExpr

        # The opening bracket `[`
        var n_obra: TObra is writable, noinit

        # The closing bracket `[` (because open range)
        var n_cbra: TObra is writable, noinit
end

# A literal array. eg. `[x,y,z]`
class AArrayExpr
        super AExpr

        # The opening bracket `[`
        var n_obra: TObra is writable, noinit

        # The elements of the array
        var n_exprs = new ANodes[AExpr](self)

        # The type of the element of the array (if any)
        var n_type: nullable AType = null is writable

        # The closing bracket `]`
        var n_cbra: TCbra is writable, noinit
end

# A read of `self`
class ASelfExpr
        super AExpr

        # The `self` keyword
        var n_kwself: nullable TKwself is writable
end

# When there is no explicit receiver, `self` is implicit
class AImplicitSelfExpr
        super ASelfExpr
end

# A `true` boolean literal constant
class ATrueExpr
        super ABoolExpr

        # The `true` keyword
        var n_kwtrue: TKwtrue is writable, noinit
end

# A `false` boolean literal constant
class AFalseExpr
        super ABoolExpr

        # The `false` keyword
        var n_kwfalse: TKwfalse is writable, noinit
end

# A `null` literal constant
class ANullExpr
        super AExpr

        # The `null` keyword
        var n_kwnull: TKwnull is writable, noinit
end

# An integer literal
class AIntExpr
        super AExpr
end

# An integer literal in decimal format
class ADecIntExpr
        super AIntExpr

        # The decimal token
        var n_number: TNumber is writable, noinit
end

# An integer literal in hexadecimal format
class AHexIntExpr
        super AIntExpr

        # The hexadecimal token
        var n_hex_number: THexNumber is writable, noinit
end

# A float literal
class AFloatExpr
        super AExpr

        # The float token
        var n_float: TFloat is writable, noinit
end

# A character literal
class ACharExpr
        super AExpr

        # The character token
        var n_char: TChar is writable, noinit
end

# A string literal
abstract class AStringFormExpr
        super AExpr

        # The string token
        var n_string: Token is writable, noinit
end

# A simple string. eg. `"abc"`
class AStringExpr
        super AStringFormExpr
end

# The start of a superstring. eg `"abc{`
class AStartStringExpr
        super AStringFormExpr
end

# The middle of a superstring. eg `}abc{`
class AMidStringExpr
        super AStringFormExpr
end

# The end of a superstrng. eg `}abc"`
class AEndStringExpr
        super AStringFormExpr
end

# A superstring literal. eg `"a{x}b{y}c"`
# Each part is modeled a sequence of expression. eg. `["a{, x, }b{, y, }c"]`
class ASuperstringExpr
        super AExpr

        # The list of the expressions of the superstring
        var n_exprs = new ANodes[AExpr](self)
end

# A simple parenthesis. eg `(x)`
class AParExpr
        super AExpr

        # The opening parenthesis
        var n_opar: TOpar is writable, noinit

        # The inner expression
        var n_expr: AExpr is writable, noinit

        # The closing parenthesis
        var n_cpar: TCpar is writable, noinit
end

# A cast, against a type or `not null`
class AAsCastForm
        super AExpr

        # The expression to cast
        var n_expr: AExpr is writable, noinit

        # The `as` keyword
        var n_kwas: TKwas is writable, noinit

        # The opening parenthesis
        var n_opar: nullable TOpar = null is writable

        # The closing parenthesis
        var n_cpar: nullable TCpar = null is writable
end

# A type cast. eg `x.as(T)`
class AAsCastExpr
        super AAsCastForm

        # The target type to cast to
        var n_type: AType is writable, noinit
end

# A as-not-null cast. eg `x.as(not null)`
class AAsNotnullExpr
        super AAsCastForm

        # The `not` keyword
        var n_kwnot: TKwnot is writable, noinit

        # The `null` keyword
        var n_kwnull: TKwnull is writable, noinit
end

# A is-set check of old-style attributes. eg `isset x._a`
class AIssetAttrExpr
        super AAttrFormExpr

        # The `isset` keyword
        var n_kwisset: TKwisset is writable, noinit
end

# An ellipsis notation used to pass an expression as it, in a vararg parameter
class AVarargExpr
        super AExpr

        # The passed expression
        var n_expr: AExpr is writable, noinit

        # The `...` symbol
        var n_dotdotdot: TDotdotdot is writable, noinit
end

# A list of expression separated with commas (arguments for instance)
class AManyExpr
        super AExpr

        # The list of expressions
        var n_exprs = new ANodes[AExpr](self)
end

# A special expression that encapsulates a static type
# Can only be found in special construction like arguments of annotations.
class ATypeExpr
        super AExpr

        # The encapsulated type
        var n_type: AType is writable, noinit
end

# A special expression that encapsulates a method identifier
# Can only be found in special construction like arguments of annotations.
class AMethidExpr
        super AExpr

        # The receiver
        var n_expr: AExpr is writable, noinit

        # The encapsulated method identifier
        var n_id: AMethid is writable, noinit
end

# A special expression that encapsulate an annotation
# Can only be found in special construction like arguments of annotations.
#
# The encapsulated annotations are in `n_annotations`
class AAtExpr
        super AExpr
end

# A special expression to debug types
class ADebugTypeExpr
        super AExpr

        # The `debug` keyword
        var n_kwdebug: TKwdebug is writable, noinit

        # The `type` keyword
        var n_kwtype: TKwtype is writable, noinit

        # The expression to check
        var n_expr: AExpr is writable, noinit

        # The type to check
        var n_type: AType is writable, noinit
end

# A list of expression separated with commas (arguments for instance)
abstract class AExprs
        super Prod

        # The list of expressions
        var n_exprs = new ANodes[AExpr](self)
end

# A simple list of expressions
class AListExprs
        super AExprs
end

# A list of expressions enclosed in parentheses
class AParExprs
        super AExprs

        # The opening parenthesis
        var n_opar: TOpar is writable, noinit

        # The closing parenthesis
        var n_cpar: TCpar is writable, noinit
end

# A list of expressions enclosed in brackets
class ABraExprs
        super AExprs

        # The opening bracket
        var n_obra: TObra is writable, noinit

        # The closing bracket
        var n_cbra: TCbra is writable, noinit
end

# A complex assignment operator. (`+=` and `-=`)
abstract class AAssignOp
        super Prod
end

# The `+=` assignment operation
class APlusAssignOp
        super AAssignOp

        # The `+=` operator
        var n_pluseq: TPluseq is writable, noinit
end

# The `-=` assignment operator
class AMinusAssignOp
        super AAssignOp

        # The `-=` operator
        var n_minuseq: TMinuseq is writable, noinit
end

# A possibly fully-qualified module identifier
class AModuleName
        super Prod

        # The starting quad (`::`)
        var n_quad: nullable TQuad = null is writable

        # The list of quad-separated project/group identifiers
        var n_path = new ANodes[TId](self)

        # The final module identifier
        var n_id: TId is writable, noinit
end

# A language declaration for an extern block
class AInLanguage
        super Prod

        # The `in` keyword
        var n_kwin: TKwin is writable, noinit

        # The language name
        var n_string: TString is writable, noinit
end

# An full extern block
class AExternCodeBlock
        super Prod

        # The language declration
        var n_in_language: nullable AInLanguage = null is writable

        # The block of extern code
        var n_extern_code_segment: TExternCodeSegment is writable, noinit
end

# A possible full method qualifier.
class AQualified
        super Prod

        # The starting quad (`::`)
        var n_quad: nullable TQuad = null is writable

        # The list of quad-separated project/group/module identifiers
        var n_id = new ANodes[TId](self)

        # A class identifier
        var n_classid: nullable TClassid = null is writable
end

# A documentation of a definition
# It contains the block of comments just above the declaration
class ADoc
        super Prod

        # A list of lines of comment
        var n_comment = new ANodes[TComment](self)
end

# A group of annotation on a node
#
# This same class is used for the 3 kind of annotations:
#
# * *is* annotations. eg `module foo is bar`.
# * *at* annotations. eg `foo@bar` or `foo@(bar,baz)`.
# * *class* annotations, defined in classes.
class AAnnotations
        super Prod

        # The `@` symbol, for *at* annotations
        var n_at: nullable TAt = null is writable

        # The opening parenthesis in *at* annotations
        var n_opar: nullable TOpar = null is writable

        # The list of annotations
        var n_items = new ANodes[AAnnotation](self)

        # The closing parenthesis in *at* annotations
        var n_cpar: nullable TCpar = null is writable
end

# A single annotation
class AAnnotation
        super ADefinition

        # The name of the annotation
        var n_atid: AAtid is writable, noinit

        # The opening parenthesis of the arguments
        var n_opar: nullable TOpar = null is writable

        # The list of arguments
        var n_args = new ANodes[AExpr](self)

        # The closing parenthesis
        var n_cpar: nullable TCpar = null is writable

        # The name of the annotation
        fun name: String
        do
                return n_atid.n_id.text
        end
end

# An annotation name
abstract class AAtid
        super Prod

        # The identifier of the annotation.
        # Can be a TId of a keyword
        var n_id: Token is writable, noinit
end

# An annotation name based on an identifier
class AIdAtid
        super AAtid
end

# An annotation name based on the keyword `extern`
class AKwexternAtid
        super AAtid
end

# An annotation name based on the keyword `import`
class AKwimportAtid
        super AAtid
end

# An annotation name based on the keyword `abstract`
class AKwabstractAtid
        super AAtid
end

# The root of the AST
class Start
        super Prod

        # The main module
        var n_base: nullable AModule is writable

        # The end of file (or error) token
        var n_eof: EOF is writable
end