Source file tail_analysis.ml

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     Copyright (C) 2013 - 2015  Frédéric Bour  <frederic.bour(_)lakaban.net>
                                Thomas Refis  <refis.thomas(_)gmail.com>
                                Simon Castellan  <simon.castellan(_)iuwt.fr>

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open Std
open Browse_raw
open Typedtree

let tail_operator = function
  | { exp_desc =
        Texp_ident
          ( _,
            _,
            { Types.val_kind =
                Types.Val_prim
                  { Primitive.prim_name = "%sequand" | "%sequor"; _ };
              _
            } );
      _
    } -> true
  | _ -> false

let expr_tail_positions = function
  | Texp_apply (callee, args) when tail_operator callee -> begin
    match List.last args with
    | None | Some (_, None) -> []
    | Some (_, Some expr) -> [ Expression expr ]
  end
  | Texp_instvar _
  | Texp_setinstvar _
  | Texp_override _
  | Texp_assert _
  | Texp_lazy _
  | Texp_object _
  | Texp_pack _
  | Texp_function _
  | Texp_apply _
  | Texp_tuple _
  | Texp_ident _
  | Texp_constant _
  | Texp_construct _
  | Texp_variant _
  | Texp_record _
  | Texp_field _
  | Texp_setfield _
  | Texp_array _
  | Texp_while _
  | Texp_for _
  | Texp_send _
  | Texp_new _
  | Texp_unreachable
  | Texp_extension_constructor _
  | Texp_letop _
  | Texp_hole -> []
  | Texp_match (_, cs, _) -> List.map cs ~f:(fun c -> Case c)
  | Texp_try (_, cs) -> List.map cs ~f:(fun c -> Case c)
  | Texp_letmodule (_, _, _, _, e)
  | Texp_letexception (_, e)
  | Texp_let (_, _, e)
  | Texp_sequence (_, e)
  | Texp_ifthenelse (_, e, None)
  | Texp_open (_, e) -> [ Expression e ]
  | Texp_ifthenelse (_, e1, Some e2) -> [ Expression e1; Expression e2 ]

let tail_positions = function
  | Expression expr -> expr_tail_positions expr.exp_desc
  | Case case -> [ Expression case.c_rhs ]
  | _ -> []

(* If the expression is a function, return all of its entry-points (which are
   in tail-positions). Returns an empty list otherwise *)
let expr_entry_points = function
  (* FIXME This was broken with the upgrade to 5.2
     It seems like that feature was already broket before that upgrade. *)
  (* | Texp_function (cases, _) -> List.map cases ~f:(fun c -> Case c) *)
  | _ -> []

let entry_points = function
  | Expression expr -> expr_entry_points expr.exp_desc
  | _ -> []

(* FIXME: what about method call? It should be translated to a Texp_apply,
   but I am not sure *)
let is_call = function
  | Expression { exp_desc = Texp_apply _; _ } -> true
  | _ -> false