package octez-libs

  1. Overview
  2. Docs
package octez-libs
Legend:
Page
Library
Module
Module type
Parameter
Class
Class type
Source

Source file decoding.ml

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
(*****************************************************************************)
(*                                                                           *)
(* Open Source License                                                       *)
(* Copyright (c) 2022 TriliTech <contact@trili.tech>                         *)
(* Copyright (c) 2022 Nomadic Labs <contact@nomadic-labs.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.                                                 *)
(*                                                                           *)
(*****************************************************************************)

type key = string list

exception Key_not_found of key

exception No_tag_matched_on_decoding

exception Decode_error of {key : key; error : Data_encoding.Binary.read_error}

(** Given the tail key, construct a full key. *)
type prefix_key = key -> key

(** [of_key key] constructs a [prefix_key] where [key] is the prefix. *)
let of_key key tail =
  let rec go = function [] -> tail | x :: xs -> x :: go xs in
  go key

(** [append_key prefix key] append [key] to [prefix] in order to create a new
      [prefix_key]. *)
let append_key prefix key tail = prefix (of_key key tail)

type 'a t = {
  decode : 'tree. 'tree Tree.backend -> 'tree -> prefix_key -> 'a Lwt.t;
}
[@@unboxed]

type ('tag, 'a) case =
  | Case : {
      tag : 'tag;
      extract : 'b -> 'a Lwt.t;
      decode : 'b t;
    }
      -> ('tag, 'a) case

let delayed f = {decode = (fun backend -> (f ()).decode backend)}

let of_lwt lwt = {decode = (fun _backend _tree _prefix -> lwt)}

let map f {decode} =
  {decode = (fun backend tree prefix -> Lwt.map f (decode backend tree prefix))}

let map_lwt f {decode} =
  {
    decode = (fun backend tree prefix -> Lwt.bind (decode backend tree prefix) f);
  }

module Syntax = struct
  let return value = {decode = (fun _backend _tree _prefix -> Lwt.return value)}

  let bind {decode} f =
    {
      decode =
        (fun backend tree prefix ->
          Lwt.bind (decode backend tree prefix) (fun x ->
              (f x).decode backend tree prefix));
    }

  let both lhs rhs =
    {
      decode =
        (fun backend tree prefix ->
          Lwt.both
            (lhs.decode backend tree prefix)
            (rhs.decode backend tree prefix));
    }

  let ( let+ ) m f = map f m

  let ( and+ ) = both

  let ( let* ) = bind

  let ( and* ) = ( and+ )
end

let run backend {decode} tree = decode backend tree Fun.id

let raw key =
  {
    decode =
      (fun backend tree prefix ->
        let open Lwt_syntax in
        let key = prefix key in
        let+ value = Tree.find backend tree key in
        match value with
        | Some value -> value
        | None -> raise (Key_not_found key));
  }

let value_option key decoder =
  {
    decode =
      (fun backend tree prefix ->
        let open Lwt_syntax in
        let key = prefix key in
        let* value = Tree.find backend tree key in
        match value with
        | Some value -> (
            match Data_encoding.Binary.of_bytes decoder value with
            | Ok value -> return_some value
            | Error error -> raise (Decode_error {key; error}))
        | None -> return_none);
  }

let value ?default key decoder =
  {
    decode =
      (fun backend tree prefix ->
        let open Lwt_syntax in
        let* value = (value_option key decoder).decode backend tree prefix in
        match (value, default) with
        | Some value, _ -> return value
        | None, Some default -> return default
        | None, None -> raise (Key_not_found (prefix key)));
  }

let subtree backend tree prefix =
  let open Lwt_syntax in
  let tmp_directory = "tmp" in
  let* subtree = Tree.find_tree backend tree (prefix []) in
  let+ subtree =
    match subtree with
    | Some subtree -> return subtree
    | None -> (
        let* tree =
          Tree.add backend tree (prefix [tmp_directory]) (Bytes.of_string "")
        in
        let* subtree = Tree.find_tree backend tree (prefix []) in
        match subtree with
        | Some subtree -> Tree.remove backend subtree [tmp_directory]
        | None ->
            (* This case is impossible, because we have added something
               in the tree to avoid it. *)
            assert false)
  in
  subtree

let scope key {decode} =
  {
    decode =
      (fun backend tree prefix -> decode backend tree (append_key prefix key));
  }

let lazy_mapping to_key field_enc =
  {
    decode =
      (fun backend input_tree input_prefix ->
        let open Lwt_syntax in
        let produce_value index =
          (scope (to_key index) field_enc).decode
            backend
            input_tree
            input_prefix
        in
        let+ tree = subtree backend input_tree input_prefix in
        (Some (Tree.Wrapped_tree (tree, backend)), produce_value));
  }

let case_lwt tag decode extract = Case {tag; decode; extract}

let case tag decode extract =
  case_lwt tag decode (fun x -> Lwt.return @@ extract x)

let tagged_union ?default decode_tag cases =
  {
    decode =
      (fun backend input_tree prefix ->
        let open Lwt_syntax in
        Lwt.try_bind
          (fun () ->
            (scope ["tag"] decode_tag).decode backend input_tree prefix)
          (fun target_tag ->
            (* Search through the cases to find a matching branch. *)
            let candidate =
              List.find_map
                (fun (Case {tag; decode; extract}) ->
                  if tag = target_tag then
                    Some
                      ((map_lwt extract (scope ["value"] decode)).decode
                         backend
                         input_tree
                         prefix)
                  else None)
                cases
            in
            match candidate with
            | Some case -> case
            | None -> raise No_tag_matched_on_decoding)
          (function
            | Key_not_found _ as exn -> (
                match default with
                | Some default -> return (default ())
                | None -> Lwt.reraise exn)
            | exn -> Lwt.reraise exn));
  }

let wrapped_tree =
  {
    decode =
      (fun backend tree prefix ->
        let open Lwt.Syntax in
        let+ tree = subtree backend tree prefix in
        Tree.Wrapped_tree (tree, backend));
  }
OCaml

Innovation. Community. Security.

GitHub Discord Twitter Peertube RSS
About
Changelog Releases Industrial Users Academic Users Why OCaml
Ecosystem
Packages Community Events OCaml Planet Jobs
Resources
Install OCaml Get Started Platform Tools Language Manual Standard Library API Books Exercises Papers OCaml Playground Logo
Policies
Carbon Footprint Governance Privacy Code of Conduct