Source file ast.ml

(* This file is part of the Catala compiler, a specification language for tax
   and social benefits computation rules. Copyright (C) 2020 Inria,
   contributors: Denis Merigoux <denis.merigoux@inria.fr>, Emile Rolley
   <emile.rolley@tuta.io>

   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. *)

(** Abstract syntax tree built by the Catala parser *)

[@@@ocaml.warning "-7"]

open Catala_utils
(** {1 Visitor classes for programs} *)

(** To allow for quick traversal and/or modification of this AST structure, we
    provide a {{:https://en.wikipedia.org/wiki/Visitor_pattern} visitor design
    pattern}. This feature is implemented via
    {{:https://gitlab.inria.fr/fpottier/visitors} François Pottier's OCaml
    visitors library}. *)

(** {1 Type definitions} *)

type uident = (string[@opaque])
[@@deriving
  visitors { variety = "map"; name = "uident_map"; nude = true },
    visitors { variety = "iter"; name = "uident_iter"; nude = true }]
(** Constructors are CamelCase *)

type lident = (string[@opaque])
[@@deriving
  visitors { variety = "map"; name = "lident_map"; nude = true },
    visitors { variety = "iter"; name = "lident_iter"; nude = true }]
(** Idents are snake_case *)

type path = uident Marked.pos list
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"; "uident_map"];
      name = "path_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"; "uident_iter"];
        name = "path_iter";
      }]

type scope_var = lident Marked.pos list
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"; "lident_map"];
      name = "scope_var_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"; "lident_iter"];
        name = "scope_var_iter";
      }]
(** [foo.bar] in binding position: used to specify variables of subscopes *)

type primitive_typ =
  | Integer
  | Decimal
  | Boolean
  | Money
  | Duration
  | Text
  | Date
  | Named of path * uident Marked.pos
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["path_map"; "uident_map"];
      name = "primitive_typ_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["path_iter"; "uident_iter"];
        name = "primitive_typ_iter";
      }]

type base_typ_data =
  | Primitive of primitive_typ
  | Collection of base_typ_data Marked.pos
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"; "primitive_typ_map"];
      name = "base_typ_data_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"; "primitive_typ_iter"];
        name = "base_typ_data_iter";
      }]

type base_typ = Condition | Data of base_typ_data
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["base_typ_data_map"];
      name = "base_typ_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["base_typ_data_iter"];
        name = "base_typ_iter";
        nude = true;
      }]

type func_typ = {
  arg_typ : (lident Marked.pos * base_typ Marked.pos) list;
  return_typ : base_typ Marked.pos;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["lident_map"; "base_typ_map"];
      name = "func_typ_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["lident_iter"; "base_typ_iter"];
        name = "func_typ_iter";
        nude = true;
      }]

type typ = naked_typ Marked.pos

and naked_typ = Base of base_typ | Func of func_typ
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["func_typ_map"];
      name = "typ_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["func_typ_iter"];
        name = "typ_iter";
        nude = true;
      }]

type struct_decl_field = {
  struct_decl_field_name : lident Marked.pos;
  struct_decl_field_typ : typ;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["typ_map"; "lident_map"];
      name = "struct_decl_field_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["typ_iter"; "lident_iter"];
        name = "struct_decl_field_iter";
      }]

type struct_decl = {
  struct_decl_name : uident Marked.pos;
  struct_decl_fields : struct_decl_field Marked.pos list;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["struct_decl_field_map"];
      name = "struct_decl_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["struct_decl_field_iter"];
        name = "struct_decl_iter";
      }]

type enum_decl_case = {
  enum_decl_case_name : uident Marked.pos;
  enum_decl_case_typ : typ option;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["typ_map"];
      name = "enum_decl_case_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["typ_iter"];
        name = "enum_decl_case_iter";
        nude = true;
      }]

type enum_decl = {
  enum_decl_name : uident Marked.pos;
  enum_decl_cases : enum_decl_case Marked.pos list;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["enum_decl_case_map"];
      name = "enum_decl_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["enum_decl_case_iter"];
        name = "enum_decl_iter";
        nude = true;
      }]

type match_case_pattern =
  (path * uident Marked.pos) Marked.pos list * lident Marked.pos option
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["path_map"; "lident_map"; "uident_map"; "Marked.pos_map"];
      name = "match_case_pattern_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          ["path_iter"; "lident_iter"; "uident_iter"; "Marked.pos_iter"];
        name = "match_case_pattern_iter";
      }]

type op_kind = KPoly | KInt | KDec | KMoney | KDate | KDuration
[@@deriving
  visitors { variety = "map"; name = "op_kind_map"; nude = true },
    visitors { variety = "iter"; name = "op_kind_iter"; nude = true }]

type binop =
  | And
  | Or
  | Xor
  | Add of op_kind
  | Sub of op_kind
  | Mult of op_kind
  | Div of op_kind
  | Lt of op_kind
  | Lte of op_kind
  | Gt of op_kind
  | Gte of op_kind
  | Eq
  | Neq
  | Concat
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["op_kind_map"];
      name = "binop_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["op_kind_iter"];
        name = "binop_iter";
        nude = true;
      }]

type unop = Not | Minus of op_kind
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["op_kind_map"];
      name = "unop_map";
      nude = true;
    },
    visitors
      {
        variety = "iter";
        ancestors = ["op_kind_iter"];
        name = "unop_iter";
        nude = true;
      }]

type builtin_expression =
  | Cardinal
  | ToDecimal
  | ToMoney
  | GetDay
  | GetMonth
  | GetYear
  | LastDayOfMonth
  | FirstDayOfMonth
  | Round
[@@deriving
  visitors { variety = "map"; name = "builtin_expression_map"; nude = true },
    visitors { variety = "iter"; name = "builtin_expression_iter"; nude = true }]

type literal_date = {
  literal_date_day : (int[@opaque]);
  literal_date_month : (int[@opaque]);
  literal_date_year : (int[@opaque]);
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"];
      name = "literal_date_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"];
        name = "literal_date_iter";
      }]

type literal_number =
  | Int of (string[@opaque])
  | Dec of (string[@opaque]) * (string[@opaque])
[@@deriving
  visitors { variety = "map"; name = "literal_number_map"; nude = true },
    visitors { variety = "iter"; name = "literal_number_iter"; nude = true }]

type literal_unit = Percent | Year | Month | Day
[@@deriving
  visitors { variety = "map"; name = "literal_unit_map"; nude = true },
    visitors { variety = "iter"; name = "literal_unit_iter"; nude = true }]

type money_amount = {
  money_amount_units : (string[@opaque]);
  money_amount_cents : (string[@opaque]);
}
[@@deriving
  visitors { variety = "map"; name = "money_amount_map"; nude = true },
    visitors { variety = "iter"; name = "money_amount_iter"; nude = true }]

type literal =
  | LNumber of literal_number Marked.pos * literal_unit Marked.pos option
  | LBool of bool
  | LMoneyAmount of money_amount
  | LDate of literal_date
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        [
          "literal_number_map";
          "money_amount_map";
          "literal_date_map";
          "literal_unit_map";
        ];
      name = "literal_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          [
            "literal_number_iter";
            "money_amount_iter";
            "literal_date_iter";
            "literal_unit_iter";
          ];
        name = "literal_iter";
      }]

type collection_op =
  | Exists of { predicate : lident Marked.pos * expression }
  | Forall of { predicate : lident Marked.pos * expression }
  | Map of { f : lident Marked.pos * expression }
  | Filter of { f : lident Marked.pos * expression }
  | AggregateSum of { typ : primitive_typ }
  (* it would be nice to remove the need for specifying the type here like for
     extremums, but we need an additionl overload for "neutral element for
     addition across types" *)
  | AggregateExtremum of { max : bool; default : expression }
  | AggregateArgExtremum of {
      max : bool;
      default : expression;
      f : lident Marked.pos * expression;
    }

and explicit_match_case = {
  match_case_pattern : match_case_pattern Marked.pos;
  match_case_expr : expression;
}

and match_case = WildCard of expression | MatchCase of explicit_match_case
and match_cases = match_case Marked.pos list
and expression = naked_expression Marked.pos

and naked_expression =
  | Paren of expression
  | MatchWith of expression * match_cases Marked.pos
  | IfThenElse of expression * expression * expression
  | Binop of binop Marked.pos * expression * expression
  | Unop of unop Marked.pos * expression
  | CollectionOp of collection_op * expression
  | MemCollection of expression * expression
  | TestMatchCase of expression * match_case_pattern Marked.pos
  | FunCall of expression * expression list
  | ScopeCall of
      (path * uident Marked.pos) Marked.pos
      * (lident Marked.pos * expression) list
  | LetIn of lident Marked.pos * expression * expression
  | Builtin of builtin_expression
  | Literal of literal
  | EnumInject of (path * uident Marked.pos) Marked.pos * expression option
  | StructLit of
      (path * uident Marked.pos) Marked.pos
      * (lident Marked.pos * expression) list
  | ArrayLit of expression list
  | Ident of path * lident Marked.pos
  | Dotted of expression * (path * lident Marked.pos) Marked.pos
      (** Dotted is for both struct field projection and sub-scope variables *)
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        [
          "primitive_typ_map";
          "match_case_pattern_map";
          "literal_map";
          "binop_map";
          "unop_map";
          "builtin_expression_map";
        ];
      name = "expression_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          [
            "primitive_typ_iter";
            "match_case_pattern_iter";
            "literal_iter";
            "binop_iter";
            "unop_iter";
            "builtin_expression_iter";
          ];
        name = "expression_iter";
      }]

type exception_to =
  | NotAnException
  | UnlabeledException
  | ExceptionToLabel of lident Marked.pos
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["lident_map"; "Marked.pos_map"];
      name = "exception_to_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["lident_iter"; "Marked.pos_iter"];
        name = "exception_to_iter";
      }]

type rule = {
  rule_label : lident Marked.pos option;
  rule_exception_to : exception_to;
  rule_parameter : lident Marked.pos list Marked.pos option;
  rule_condition : expression option;
  rule_name : scope_var Marked.pos;
  rule_id : Shared_ast.RuleName.t; [@opaque]
  rule_consequence : (bool[@opaque]) Marked.pos;
  rule_state : lident Marked.pos option;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["expression_map"; "scope_var_map"; "exception_to_map"];
      name = "rule_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["expression_iter"; "scope_var_iter"; "exception_to_iter"];
        name = "rule_iter";
      }]

type definition = {
  definition_label : lident Marked.pos option;
  definition_exception_to : exception_to;
  definition_name : scope_var Marked.pos;
  definition_parameter : lident Marked.pos list Marked.pos option;
  definition_condition : expression option;
  definition_id : Shared_ast.RuleName.t; [@opaque]
  definition_expr : expression;
  definition_state : lident Marked.pos option;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["expression_map"; "scope_var_map"; "exception_to_map"];
      name = "definition_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["expression_iter"; "scope_var_iter"; "exception_to_iter"];
        name = "definition_iter";
      }]

type variation_typ = Increasing | Decreasing
[@@deriving
  visitors { variety = "map"; name = "variation_typ_map" },
    visitors { variety = "iter"; name = "variation_typ_iter" }]

type meta_assertion =
  | FixedBy of scope_var Marked.pos * lident Marked.pos
  | VariesWith of
      scope_var Marked.pos * expression * variation_typ Marked.pos option
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["variation_typ_map"; "scope_var_map"; "expression_map"];
      name = "meta_assertion_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["variation_typ_iter"; "scope_var_iter"; "expression_iter"];
        name = "meta_assertion_iter";
      }]

type assertion = {
  assertion_condition : expression option;
  assertion_content : expression;
}
[@@deriving
  visitors
    { variety = "map"; ancestors = ["expression_map"]; name = "assertion_map" },
    visitors
      {
        variety = "iter";
        ancestors = ["expression_iter"];
        name = "assertion_iter";
      }]

type scope_use_item =
  | Rule of rule
  | Definition of definition
  | Assertion of assertion
  | MetaAssertion of meta_assertion
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        ["meta_assertion_map"; "definition_map"; "assertion_map"; "rule_map"];
      name = "scope_use_item_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          [
            "meta_assertion_iter";
            "definition_iter";
            "assertion_iter";
            "rule_iter";
          ];
        name = "scope_use_item_iter";
      }]

type scope_use = {
  scope_use_condition : expression option;
  scope_use_name : uident Marked.pos;
  scope_use_items : scope_use_item Marked.pos list;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["expression_map"; "scope_use_item_map"];
      name = "scope_use_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["expression_iter"; "scope_use_item_iter"];
        name = "scope_use_iter";
      }]

type io_input = Input | Context | Internal
[@@deriving
  visitors { variety = "map"; name = "io_input_map" },
    visitors { variety = "iter"; name = "io_input_iter" }]

type scope_decl_context_io = {
  scope_decl_context_io_input : io_input Marked.pos;
  scope_decl_context_io_output : bool Marked.pos;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["io_input_map"; "Marked.pos_map"];
      name = "scope_decl_context_io_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["io_input_iter"; "Marked.pos_iter"];
        name = "scope_decl_context_io_iter";
      }]

type scope_decl_context_scope = {
  scope_decl_context_scope_name : lident Marked.pos;
  scope_decl_context_scope_sub_scope : uident Marked.pos;
  scope_decl_context_scope_attribute : scope_decl_context_io;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        [
          "lident_map";
          "uident_map";
          "scope_decl_context_io_map";
          "Marked.pos_map";
        ];
      name = "scope_decl_context_scope_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          [
            "lident_iter";
            "uident_iter";
            "scope_decl_context_io_iter";
            "Marked.pos_iter";
          ];
        name = "scope_decl_context_scope_iter";
      }]

type scope_decl_context_data = {
  scope_decl_context_item_name : lident Marked.pos;
  scope_decl_context_item_typ : typ;
  scope_decl_context_item_parameters :
    (lident Marked.pos * typ) list Marked.pos option;
  scope_decl_context_item_attribute : scope_decl_context_io;
  scope_decl_context_item_states : lident Marked.pos list;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["typ_map"; "scope_decl_context_io_map"; "lident_map"];
      name = "scope_decl_context_data_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["typ_iter"; "scope_decl_context_io_iter"; "lident_iter"];
        name = "scope_decl_context_data_iter";
      }]

type scope_decl_context_item =
  | ContextData of scope_decl_context_data
  | ContextScope of scope_decl_context_scope
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        ["scope_decl_context_data_map"; "scope_decl_context_scope_map"];
      name = "scope_decl_context_item_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          ["scope_decl_context_data_iter"; "scope_decl_context_scope_iter"];
        name = "scope_decl_context_item_iter";
      }]

type scope_decl = {
  scope_decl_name : uident Marked.pos;
  scope_decl_context : scope_decl_context_item Marked.pos list;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["scope_decl_context_item_map"];
      name = "scope_decl_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["scope_decl_context_item_iter"];
        name = "scope_decl_iter";
      }]

type top_def = {
  topdef_name : lident Marked.pos;
  topdef_args :
    (lident Marked.pos * base_typ Marked.pos) list Marked.pos option;
      (** Empty list if this is not a function *)
  topdef_type : typ;
  topdef_expr : expression;
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["lident_map"; "typ_map"; "expression_map"];
      name = "top_def_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["lident_iter"; "typ_iter"; "expression_iter"];
        name = "top_def_iter";
      }]

type code_item =
  | ScopeUse of scope_use
  | ScopeDecl of scope_decl
  | StructDecl of struct_decl
  | EnumDecl of enum_decl
  | Topdef of top_def
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        [
          "scope_decl_map";
          "enum_decl_map";
          "struct_decl_map";
          "scope_use_map";
          "top_def_map";
        ];
      name = "code_item_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          [
            "scope_decl_iter";
            "enum_decl_iter";
            "struct_decl_iter";
            "scope_use_iter";
            "top_def_iter";
          ];
        name = "code_item_iter";
      }]

type code_block = code_item Marked.pos list
[@@deriving
  visitors
    { variety = "map"; ancestors = ["code_item_map"]; name = "code_block_map" },
    visitors
      {
        variety = "iter";
        ancestors = ["code_item_iter"];
        name = "code_block_iter";
      }]

type source_repr = (string[@opaque]) Marked.pos
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"];
      name = "source_repr_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"];
        name = "source_repr_iter";
      }]

type law_heading = {
  law_heading_name : (string[@opaque]) Marked.pos;
  law_heading_id : (string[@opaque]) option;
  law_heading_is_archive : bool; [@opaque]
  law_heading_precedence : (int[@opaque]);
}
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"];
      name = "law_heading_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"];
        name = "law_heading_iter";
      }]

type law_include =
  | PdfFile of (string[@opaque]) Marked.pos * (int[@opaque]) option
  | CatalaFile of (string[@opaque]) Marked.pos
  | LegislativeText of (string[@opaque]) Marked.pos
[@@deriving
  visitors
    {
      variety = "map";
      ancestors = ["Marked.pos_map"];
      name = "law_include_map";
    },
    visitors
      {
        variety = "iter";
        ancestors = ["Marked.pos_iter"];
        name = "law_include_iter";
      }]

type law_structure =
  | LawInclude of law_include
  | LawHeading of law_heading * law_structure list
  | LawText of (string[@opaque])
  | CodeBlock of code_block * source_repr * bool (* Metadata if true *)
[@@deriving
  visitors
    {
      variety = "map";
      ancestors =
        [
          "law_include_map";
          "code_block_map";
          "source_repr_map";
          "law_heading_map";
        ];
      name = "law_structure_map";
    },
    visitors
      {
        variety = "iter";
        ancestors =
          [
            "law_include_iter";
            "code_block_iter";
            "source_repr_iter";
            "law_heading_iter";
          ];
        name = "law_structure_iter";
      }]

type program = {
  program_items : law_structure list;
  program_source_files : (string[@opaque]) list;
}
[@@deriving
  visitors
    { variety = "map"; ancestors = ["law_structure_map"]; name = "program_map" },
    visitors
      {
        variety = "iter";
        ancestors = ["law_structure_iter"];
        name = "program_iter";
      }]

type source_file = law_structure list

(** {1 Helpers}*)

(** Translates a {!type: rule} into the corresponding {!type: definition} *)
let rule_to_def (rule : rule) : definition =
  let consequence_expr =
    Literal (LBool (Marked.unmark rule.rule_consequence))
  in
  {
    definition_label = rule.rule_label;
    definition_exception_to = rule.rule_exception_to;
    definition_name = rule.rule_name;
    definition_parameter = rule.rule_parameter;
    definition_condition = rule.rule_condition;
    definition_id = rule.rule_id;
    definition_expr = consequence_expr, Marked.get_mark rule.rule_consequence;
    definition_state = rule.rule_state;
  }

let type_from_args
    (args : (lident Marked.pos * base_typ Marked.pos) list Marked.pos option)
    (return_typ : base_typ Marked.pos) : typ =
  match args with
  | None -> Marked.map_under_mark (fun r -> Base r) return_typ
  | Some (arg_typ, _) ->
    Marked.mark (Marked.get_mark return_typ) (Func { arg_typ; return_typ })