(*
 * Copyright (c) 2016 - 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.
 *)

open! IStd

(** Control-flow graph for a single procedure (as opposed to cfg.ml, which represents a cfg for a
    file). Defines useful wrappers that allows us to do tricks like turn a forward cfg to into a
    backward one, or view a cfg as having a single instruction per block *)

type index = Node_index | Instr_index of int

module type Node = sig
  type t
  type id

  val kind : t -> Procdesc.Node.nodekind
  val id : t -> id
  val hash : t -> int
  val loc : t -> Location.t
  val underlying_node : t -> Procdesc.Node.t
  val compare_id : id -> id -> int
  val pp_id : Format.formatter -> id -> unit
end

module type S = sig
  type t
  type node
  include (Node with type t := node)

  (** get the instructions from a node *)
  val instrs : node -> Sil.instr list

  (** explode a block into its instructions and an optional id for the instruction. the purpose of
      this is to specify a policy for fine-grained storage of invariants by the abstract
      interpreter. the interpreter will forget invariants at program points where the id is None,
      and remember them otherwise *)
  val instr_ids : node -> (Sil.instr * id option) list

  val succs : t -> node -> node list

  (** all predecessors (normal and exceptional) *)
  val preds : t -> node -> node list

  (** non-exceptional successors *)
  val normal_succs : t -> node -> node list

  (** non-exceptional predecessors *)
  val normal_preds : t -> node -> node list

  (** exceptional successors *)
  val exceptional_succs : t -> node -> node list

  (** exceptional predescessors *)
  val exceptional_preds : t -> node -> node list

  val start_node : t -> node

  val exit_node : t -> node

  val proc_desc : t -> Procdesc.t

  val nodes : t -> node list

  val from_pdesc : Procdesc.t -> t

  val is_loop_head : Procdesc.t -> node -> bool
end

module DefaultNode : Node with type t = Procdesc.Node.t and type id = Procdesc.Node.id

module InstrNode : Node with type t = Procdesc.Node.t and type id = Procdesc.Node.id * index

(** Forward CFG with no exceptional control-flow *)
module Normal : S with type t = Procdesc.t
                   and type node = DefaultNode.t
                   and type id = DefaultNode.id

(** Forward CFG with exceptional control-flow *)
module Exceptional : S with type t = Procdesc.t * DefaultNode.t list Procdesc.IdMap.t
                        and type node = DefaultNode.t
                        and type id = DefaultNode.id

(** Wrapper that reverses the direction of the CFG *)
module Backward (Base : S) : S with type t = Base.t
                                and type node = Base.node
                                and type id = Base.id

module OneInstrPerNode (Base : S with type node = DefaultNode.t and type id = DefaultNode.id) :
  S with type t = Base.t
     and type node = Base.node
     and type id = Base.id * index

module NodeIdMap (CFG : S) : Caml.Map.S with type key = CFG.id

module NodeIdSet (CFG : S) : Caml.Set.S with type elt = CFG.id