(*
 * Copyright (c) 2009 - 2013 Monoidics ltd.
 * Copyright (c) 2013 - present Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *)

(** The Smallfoot Intermediate Language: Binary Operators *)
open! IStd
module L = Logging
module F = Format

(** Binary operations *)
type t =
  | PlusA  (** arithmetic + *)
  | PlusPI  (** pointer + integer *)
  | MinusA  (** arithmetic - *)
  | MinusPI  (** pointer - integer *)
  | MinusPP  (** pointer - pointer *)
  | Mult  (** * *)
  | Div  (** / *)
  | Mod  (** % *)
  | Shiftlt  (** shift left *)
  | Shiftrt  (** shift right *)
  | Lt  (** <  (arithmetic comparison) *)
  | Gt  (** >  (arithmetic comparison) *)
  | Le  (** <= (arithmetic comparison) *)
  | Ge  (** >= (arithmetic comparison) *)
  | Eq  (** == (arithmetic comparison) *)
  | Ne  (** != (arithmetic comparison) *)
  | BAnd  (** bitwise and *)
  | BXor  (** exclusive-or *)
  | BOr  (** inclusive-or *)
  | LAnd  (** logical and. Does not always evaluate both operands. *)
  | LOr  (** logical or. Does not always evaluate both operands. *)
  [@@deriving compare]

let equal = [%compare.equal : t]

(** This function returns true if the operation is injective
    wrt. each argument: op(e,-) and op(-, e) is injective for all e.
    The return value false means "don't know". *)
let injective = function PlusA | PlusPI | MinusA | MinusPI | MinusPP -> true | _ -> false

(** This function returns true if 0 is the right unit of [binop].
    The return value false means "don't know". *)
let is_zero_runit = function PlusA | PlusPI | MinusA | MinusPI | MinusPP -> true | _ -> false

let text = function
  | PlusA ->
      "+"
  | PlusPI ->
      "+"
  | MinusA | MinusPP ->
      "-"
  | MinusPI ->
      "-"
  | Mult ->
      "*"
  | Div ->
      "/"
  | Mod ->
      "%"
  | Shiftlt ->
      "<<"
  | Shiftrt ->
      ">>"
  | Lt ->
      "<"
  | Gt ->
      ">"
  | Le ->
      "<="
  | Ge ->
      ">="
  | Eq ->
      "=="
  | Ne ->
      "!="
  | BAnd ->
      "&"
  | BXor ->
      "^"
  | BOr ->
      "|"
  | LAnd ->
      "&&"
  | LOr ->
      "||"


(** Pretty print a binary operator. *)
let str pe binop =
  match pe.Pp.kind with
  | HTML -> (
    match binop with
    | Ge ->
        " &gt;= "
    | Le ->
        " &lt;= "
    | Gt ->
        " &gt; "
    | Lt ->
        " &lt; "
    | Shiftlt ->
        " &lt;&lt; "
    | Shiftrt ->
        " &gt;&gt; "
    | _ ->
        text binop )
  | _ ->
      text binop