Source file range.ml

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(**************************************************************************)
(*  This file is part of the Codex semantics library                      *)
(*    (Union-find lattice subcomponent).                                  *)
(*                                                                        *)
(*  Copyright (C) 2026                                                    *)
(*    CEA (Commissariat à l'énergie atomique et aux énergies              *)
(*         alternatives)                                                  *)
(*                                                                        *)
(*  you can redistribute it and/or modify it under the terms of the GNU   *)
(*  Lesser General Public License as published by the Free Software       *)
(*  Foundation, version 2.1.                                              *)
(*                                                                        *)
(*  It is distributed in the hope that it will be useful,                 *)
(*  but WITHOUT ANY WARRANTY; without even the implied warranty of        *)
(*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *)
(*  GNU Lesser General Public License for more details.                   *)
(*                                                                        *)
(*  See the GNU Lesser General Public License version 3.0                 *)
(*  for more details (enclosed in the file LICENSE).                      *)
(*                                                                        *)
(**************************************************************************)

type t = {
  start: int; (** included *)
  stop: int;  (** excluded *)
  step: int
}

let upto stop = { start=0; stop; step=1 }
let interval start stop = { start; stop; step=1 }
let inclusive_interval start stop = interval start (stop+1)

let end_iteration r n = if r.step > 0 then n >= r.stop else n <= r.stop

let rec iter f range pos =
  if end_iteration range pos then ()
  else (f pos; iter f range (pos+range.step))
let iter f range = iter f range range.start

let rec forall f range pos =
  if end_iteration range pos then true
  else (f pos && forall f range (pos+range.step))
let forall f range = forall f range range.start

let rec exists f range pos =
  if end_iteration range pos then false
  else (f pos || exists f range (pos+range.step))
let exists f range = exists f range range.start

let rec fold f range pos acc =
  if end_iteration range pos then acc
  else (fold f range (pos+range.step) (f pos acc))
let fold f range acc = fold f range range.start acc

let sum f range = fold (fun i acc -> f i + acc) range 0
let count f range = fold (fun i acc -> if f i then acc+1 else acc) range 0

let pp fmt = function
  | { start; stop; step=1; } -> Format.fprintf fmt "[%d:%d[" start stop
  | { start; stop; step } -> Format.fprintf fmt "[%d:%d:%d[" start stop step

let to_list t = fold List.cons t [] |> List.rev
let to_seq t =
  let rec seq pos () = if end_iteration t pos then Seq.Nil else Seq.Cons(pos, seq (pos+t.step)) in
  seq t.start