Source file range.ml

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(*****************************************************************************)
(*                                                                           *)
(*  Copyright (C) 2026 Yves Ndiaye                                           *)
(*                                                                           *)
(* This Source Code Form is subject to the terms of the Mozilla Public       *)
(* License, v. 2.0. If a copy of the MPL was not distributed with this       *)
(* file, You can obtain one at https://mozilla.org/MPL/2.0/.                 *)
(*                                                                           *)
(*****************************************************************************)

(** Operations on ranges. *)

(** type of range values. *)
type 'a t = Value of 'a | Range of 'a option * 'a option

(** [value v] is [Value v]. *)
let value e = Value e

(** [range lhs rhs] is [Range lhs rhs]. *)
let range lhs rhs = Range (lhs, rhs)

(** [to_string some range] is the string representation of [range] using [some].
*)
let to_string some = function
  | Value v ->
      some v
  | Range (lhs, rhs) ->
      let lhs = Option.fold ~none:String.empty ~some lhs in
      let rhs = Option.fold ~none:String.empty ~some rhs in
      Printf.sprintf "%s..%s" lhs rhs

(** [matches range v] tests whether [v] matches [ranges]. All extrema borns are
    included. *)
let matches range v =
  match range with
  | Range (None, None) ->
      true
  | Range (Some t, None) ->
      v >= t
  | Range (None, Some t) ->
      v <= t
  | Range (Some lhs, Some rhs) ->
      v >= lhs && v <= rhs
  | Value h ->
      v = h