1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2018 Dynamic Ledger Solutions, Inc. <contact@tezos.com>     *)
(*                                                                           *)
(* Permission is hereby granted, free of charge, to any person obtaining a   *)
(* copy of this software and associated documentation files (the "Software"),*)
(* to deal in the Software without restriction, including without limitation *)
(* the rights to use, copy, modify, merge, publish, distribute, sublicense,  *)
(* and/or sell copies of the Software, and to permit persons to whom the     *)
(* Software is furnished to do so, subject to the following conditions:      *)
(*                                                                           *)
(* The above copyright notice and this permission notice shall be included   *)
(* in all copies or substantial portions of the Software.                    *)
(*                                                                           *)
(* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR*)
(* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  *)
(* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL   *)
(* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER*)
(* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING   *)
(* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER       *)
(* DEALINGS IN THE SOFTWARE.                                                 *)
(*                                                                           *)
(*****************************************************************************)

module type QTY = sig
  val id : string
end

module type S = sig
  type qty

  type error +=
    | Addition_overflow of qty * qty (* `Temporary *)
    | Subtraction_underflow of qty * qty (* `Temporary *)
    | Multiplication_overflow of qty * int64 (* `Temporary *)
    | Negative_multiplicator of qty * int64 (* `Temporary *)
    | Invalid_divisor of qty * int64

  (* `Temporary *)

  val id : string

  val zero : qty

  val one_mutez : qty

  val one_cent : qty

  val fifty_cents : qty

  val one : qty

  val ( -? ) : qty -> qty -> qty tzresult

  val ( +? ) : qty -> qty -> qty tzresult

  val ( *? ) : qty -> int64 -> qty tzresult

  val ( /? ) : qty -> int64 -> qty tzresult

  val to_mutez : qty -> int64

  (** [of_mutez n] (micro tez) is None if n is negative *)
  val of_mutez : int64 -> qty option

  (** [of_mutez_exn n] fails if n is negative.
      It should only be used at toplevel for constants. *)
  val of_mutez_exn : int64 -> qty

  (** It should only be used at toplevel for constants. *)
  val add_exn : qty -> qty -> qty

  (** It should only be used at toplevel for constants. *)
  val mul_exn : qty -> int -> qty

  val encoding : qty Data_encoding.t

  val to_int64 : qty -> int64

  include Compare.S with type t := qty

  val pp : Format.formatter -> qty -> unit

  val of_string : string -> qty option

  val to_string : qty -> string
end

module Make (T : QTY) : S = struct
  type qty = int64 (* invariant: positive *)

  type error +=
    | Addition_overflow of qty * qty (* `Temporary *)
    | Subtraction_underflow of qty * qty (* `Temporary *)
    | Multiplication_overflow of qty * int64 (* `Temporary *)
    | Negative_multiplicator of qty * int64 (* `Temporary *)
    | Invalid_divisor of qty * int64

  (* `Temporary *)

  include Compare.Int64

  let zero = 0L

  (* all other constant are defined from the value of one micro tez *)
  let one_mutez = 1L

  let one_cent = Int64.mul one_mutez 10_000L

  let fifty_cents = Int64.mul one_cent 50L

  (* 1 tez = 100 cents = 1_000_000 mutez *)
  let one = Int64.mul one_cent 100L

  let id = T.id

  let of_string s =
    let triplets = function
      | hd :: tl ->
          let len = String.length hd in
          Compare.Int.(
            len <= 3 && len > 0
            && List.for_all (fun s -> String.length s = 3) tl)
      | [] ->
          false
    in
    let integers s = triplets (String.split_on_char ',' s) in
    let decimals s =
      let l = String.split_on_char ',' s in
      if Compare.Int.(List.length l > 2) then false else triplets (List.rev l)
    in
    let parse left right =
      let remove_commas s = String.concat "" (String.split_on_char ',' s) in
      let pad_to_six s =
        let len = String.length s in
        String.init 6 (fun i -> if Compare.Int.(i < len) then s.[i] else '0')
      in
      try
        Some
          (Int64.of_string
             (remove_commas left ^ pad_to_six (remove_commas right)))
      with _ -> None
    in
    match String.split_on_char '.' s with
    | [left; right] ->
        if String.contains s ',' then
          if integers left && decimals right then parse left right else None
        else if
          Compare.Int.(String.length right > 0)
          && Compare.Int.(String.length right <= 6)
        then parse left right
        else None
    | [left] ->
        if (not (String.contains s ',')) || integers left then parse left ""
        else None
    | _ ->
        None

  let pp ppf amount =
    let mult_int = 1_000_000L in
    let rec left ppf amount =
      let (d, r) = (Int64.(div amount 1000L), Int64.(rem amount 1000L)) in
      if d > 0L then Format.fprintf ppf "%a%03Ld" left d r
      else Format.fprintf ppf "%Ld" r
    in
    let right ppf amount =
      let triplet ppf v =
        if Compare.Int.(v mod 10 > 0) then Format.fprintf ppf "%03d" v
        else if Compare.Int.(v mod 100 > 0) then
          Format.fprintf ppf "%02d" (v / 10)
        else Format.fprintf ppf "%d" (v / 100)
      in
      let (hi, lo) = (amount / 1000, amount mod 1000) in
      if Compare.Int.(lo = 0) then Format.fprintf ppf "%a" triplet hi
      else Format.fprintf ppf "%03d%a" hi triplet lo
    in
    let (ints, decs) =
      (Int64.(div amount mult_int), Int64.(to_int (rem amount mult_int)))
    in
    Format.fprintf ppf "%a" left ints ;
    if Compare.Int.(decs > 0) then Format.fprintf ppf ".%a" right decs

  let to_string t = Format.asprintf "%a" pp t

  let ( - ) t1 t2 = if t2 <= t1 then Some (Int64.sub t1 t2) else None

  let ( -? ) t1 t2 =
    match t1 - t2 with
    | None ->
        error (Subtraction_underflow (t1, t2))
    | Some v ->
        ok v

  let ( +? ) t1 t2 =
    let t = Int64.add t1 t2 in
    if t < t1 then error (Addition_overflow (t1, t2)) else ok t

  let ( *? ) t m =
    let open Compare.Int64 in
    let open Int64 in
    let rec step cur pow acc =
      if cur = 0L then ok acc
      else
        pow +? pow
        >>? fun npow ->
        if logand cur 1L = 1L then
          acc +? pow >>? fun nacc -> step (shift_right_logical cur 1) npow nacc
        else step (shift_right_logical cur 1) npow acc
    in
    if m < 0L then error (Negative_multiplicator (t, m))
    else
      match step m t 0L with
      | Ok res ->
          Ok res
      | Error ([Addition_overflow _] as errs) ->
          Error (Multiplication_overflow (t, m) :: errs)
      | Error errs ->
          Error errs

  let ( /? ) t d =
    if d <= 0L then error (Invalid_divisor (t, d)) else ok (Int64.div t d)

  let add_exn t1 t2 =
    let t = Int64.add t1 t2 in
    if t <= 0L then invalid_arg "add_exn" else t

  let mul_exn t m =
    match t *? Int64.(of_int m) with
    | Ok v ->
        v
    | Error _ ->
        invalid_arg "mul_exn"

  let of_mutez t = if t < 0L then None else Some t

  let of_mutez_exn x =
    match of_mutez x with None -> invalid_arg "Qty.of_mutez" | Some v -> v

  let to_int64 t = t

  let to_mutez t = t

  let encoding =
    let open Data_encoding in
    check_size 10 (conv Z.of_int64 (Json.wrap_error Z.to_int64) n)

  let () =
    let open Data_encoding in
    register_error_kind
      `Temporary
      ~id:(T.id ^ ".addition_overflow")
      ~title:("Overflowing " ^ T.id ^ " addition")
      ~pp:(fun ppf (opa, opb) ->
        Format.fprintf
          ppf
          "Overflowing addition of %a %s and %a %s"
          pp
          opa
          T.id
          pp
          opb
          T.id)
      ~description:("An addition of two " ^ T.id ^ " amounts overflowed")
      (obj1 (req "amounts" (tup2 encoding encoding)))
      (function Addition_overflow (a, b) -> Some (a, b) | _ -> None)
      (fun (a, b) -> Addition_overflow (a, b)) ;
    register_error_kind
      `Temporary
      ~id:(T.id ^ ".subtraction_underflow")
      ~title:("Underflowing " ^ T.id ^ " subtraction")
      ~pp:(fun ppf (opa, opb) ->
        Format.fprintf
          ppf
          "Underflowing subtraction of %a %s and %a %s"
          pp
          opa
          T.id
          pp
          opb
          T.id)
      ~description:("An subtraction of two " ^ T.id ^ " amounts underflowed")
      (obj1 (req "amounts" (tup2 encoding encoding)))
      (function Subtraction_underflow (a, b) -> Some (a, b) | _ -> None)
      (fun (a, b) -> Subtraction_underflow (a, b)) ;
    register_error_kind
      `Temporary
      ~id:(T.id ^ ".multiplication_overflow")
      ~title:("Overflowing " ^ T.id ^ " multiplication")
      ~pp:(fun ppf (opa, opb) ->
        Format.fprintf
          ppf
          "Overflowing multiplication of %a %s and %Ld"
          pp
          opa
          T.id
          opb)
      ~description:
        ("A multiplication of a " ^ T.id ^ " amount by an integer overflowed")
      (obj2 (req "amount" encoding) (req "multiplicator" int64))
      (function Multiplication_overflow (a, b) -> Some (a, b) | _ -> None)
      (fun (a, b) -> Multiplication_overflow (a, b)) ;
    register_error_kind
      `Temporary
      ~id:(T.id ^ ".negative_multiplicator")
      ~title:("Negative " ^ T.id ^ " multiplicator")
      ~pp:(fun ppf (opa, opb) ->
        Format.fprintf
          ppf
          "Multiplication of %a %s by negative integer %Ld"
          pp
          opa
          T.id
          opb)
      ~description:
        ("Multiplication of a " ^ T.id ^ " amount by a negative integer")
      (obj2 (req "amount" encoding) (req "multiplicator" int64))
      (function Negative_multiplicator (a, b) -> Some (a, b) | _ -> None)
      (fun (a, b) -> Negative_multiplicator (a, b)) ;
    register_error_kind
      `Temporary
      ~id:(T.id ^ ".invalid_divisor")
      ~title:("Invalid " ^ T.id ^ " divisor")
      ~pp:(fun ppf (opa, opb) ->
        Format.fprintf
          ppf
          "Division of %a %s by non positive integer %Ld"
          pp
          opa
          T.id
          opb)
      ~description:
        ("Multiplication of a " ^ T.id ^ " amount by a non positive integer")
      (obj2 (req "amount" encoding) (req "divisor" int64))
      (function Invalid_divisor (a, b) -> Some (a, b) | _ -> None)
      (fun (a, b) -> Invalid_divisor (a, b))
end