OCaml library for JSONfeed parsing and creation
anil.recoil.org
1(*---------------------------------------------------------------------------
2 Copyright (c) 2024 Anil Madhavapeddy. All rights reserved.
3 SPDX-License-Identifier: ISC
4 ---------------------------------------------------------------------------*)
5
6module Rfc3339 = Rfc3339
7module Cito = Cito
8module Author = Author
9module Attachment = Attachment
10module Hub = Hub
11module Reference = Reference
12module Item = Item
13
14module Unknown = struct
15 type t = (string * Jsont.json) list
16
17 let empty = []
18 let is_empty = function [] -> true | _ -> false
19end
20
21type t = {
22 version : string;
23 title : string;
24 home_page_url : string option;
25 feed_url : string option;
26 description : string option;
27 user_comment : string option;
28 next_url : string option;
29 icon : string option;
30 favicon : string option;
31 authors : Author.t list option;
32 language : string option;
33 expired : bool option;
34 hubs : Hub.t list option;
35 items : Item.t list;
36 unknown : Unknown.t;
37}
38
39let create ~title ?home_page_url ?feed_url ?description ?user_comment ?next_url
40 ?icon ?favicon ?authors ?language ?expired ?hubs ~items
41 ?(unknown = Unknown.empty) () =
42 {
43 version = "https://jsonfeed.org/version/1.1";
44 title;
45 home_page_url;
46 feed_url;
47 description;
48 user_comment;
49 next_url;
50 icon;
51 favicon;
52 authors;
53 language;
54 expired;
55 hubs;
56 items;
57 unknown;
58 }
59
60let version t = t.version
61let title t = t.title
62let home_page_url t = t.home_page_url
63let feed_url t = t.feed_url
64let description t = t.description
65let user_comment t = t.user_comment
66let next_url t = t.next_url
67let icon t = t.icon
68let favicon t = t.favicon
69let authors t = t.authors
70let language t = t.language
71let expired t = t.expired
72let hubs t = t.hubs
73let items t = t.items
74let unknown t = t.unknown
75let equal a b = a.title = b.title && a.items = b.items
76
77let pp ppf t =
78 Format.fprintf ppf "Feed: %s (%d items)" t.title (List.length t.items)
79
80let pp_summary ppf t =
81 Format.fprintf ppf "%s (%d items)" t.title (List.length t.items)
82
83(* Jsont type *)
84
85let jsont =
86 let kind = "JSON Feed" in
87 let doc = "A JSON Feed document" in
88 let unknown_mems :
89 (Unknown.t, Jsont.json, Jsont.mem list) Jsont.Object.Mems.map =
90 let open Jsont.Object.Mems in
91 let dec_empty () = [] in
92 let dec_add _meta (name : string) value acc =
93 ((name, Jsont.Meta.none), value) :: acc
94 in
95 let dec_finish _meta mems =
96 List.rev_map (fun ((name, _meta), value) -> (name, value)) mems
97 in
98 let enc =
99 {
100 enc =
101 (fun (type acc)
102 (f : Jsont.Meta.t -> string -> Jsont.json -> acc -> acc)
103 unknown
104 (acc : acc)
105 ->
106 List.fold_left
107 (fun acc (name, value) -> f Jsont.Meta.none name value acc)
108 acc unknown);
109 }
110 in
111 map ~kind:"Unknown members" Jsont.json ~dec_empty ~dec_add ~dec_finish ~enc
112 in
113
114 (* Helper constructor that sets version automatically *)
115 let make_from_json _version title home_page_url feed_url description
116 user_comment next_url icon favicon authors language expired hubs items
117 unknown =
118 {
119 version = "https://jsonfeed.org/version/1.1";
120 title;
121 home_page_url;
122 feed_url;
123 description;
124 user_comment;
125 next_url;
126 icon;
127 favicon;
128 authors;
129 language;
130 expired;
131 hubs;
132 items;
133 unknown;
134 }
135 in
136
137 Jsont.Object.map ~kind ~doc make_from_json
138 |> Jsont.Object.mem "version" Jsont.string ~enc:version
139 |> Jsont.Object.mem "title" Jsont.string ~enc:title
140 |> Jsont.Object.opt_mem "home_page_url" Jsont.string ~enc:home_page_url
141 |> Jsont.Object.opt_mem "feed_url" Jsont.string ~enc:feed_url
142 |> Jsont.Object.opt_mem "description" Jsont.string ~enc:description
143 |> Jsont.Object.opt_mem "user_comment" Jsont.string ~enc:user_comment
144 |> Jsont.Object.opt_mem "next_url" Jsont.string ~enc:next_url
145 |> Jsont.Object.opt_mem "icon" Jsont.string ~enc:icon
146 |> Jsont.Object.opt_mem "favicon" Jsont.string ~enc:favicon
147 |> Jsont.Object.opt_mem "authors" (Jsont.list Author.jsont) ~enc:authors
148 |> Jsont.Object.opt_mem "language" Jsont.string ~enc:language
149 |> Jsont.Object.opt_mem "expired" Jsont.bool ~enc:expired
150 |> Jsont.Object.opt_mem "hubs" (Jsont.list Hub.jsont) ~enc:hubs
151 |> Jsont.Object.mem "items" (Jsont.list Item.jsont) ~enc:items
152 |> Jsont.Object.keep_unknown unknown_mems ~enc:unknown
153 |> Jsont.Object.finish
154
155(* Encoding and Decoding *)
156
157let decode ?layout ?locs ?file r =
158 Jsont_bytesrw.decode' ?layout ?locs ?file jsont r
159
160let decode_string ?layout ?locs ?file s =
161 Jsont_bytesrw.decode_string' ?layout ?locs ?file jsont s
162
163let encode ?format ?number_format feed ~eod w =
164 Jsont_bytesrw.encode' ?format ?number_format jsont feed ~eod w
165
166let encode_string ?format ?number_format feed =
167 Jsont_bytesrw.encode_string' ?format ?number_format jsont feed
168
169let of_string s = decode_string s
170
171let to_string ?(minify = false) feed =
172 let format = if minify then Jsont.Minify else Jsont.Indent in
173 encode_string ~format feed
174
175(* Validation *)
176
177let validate feed =
178 let errors = ref [] in
179 let add_error msg = errors := msg :: !errors in
180
181 (* Check required fields *)
182 if feed.title = "" then add_error "title is required and cannot be empty";
183
184 (* Check items have unique IDs *)
185 let ids = List.map Item.id feed.items in
186 let unique_ids = List.sort_uniq String.compare ids in
187 if List.length ids <> List.length unique_ids then
188 add_error "items must have unique IDs";
189
190 (* Validate authors *)
191 (match feed.authors with
192 | Some authors ->
193 List.iteri
194 (fun i author ->
195 if not (Author.is_valid author) then
196 add_error
197 (Printf.sprintf
198 "feed author %d is invalid (needs at least one field)" i))
199 authors
200 | None -> ());
201
202 (* Validate items *)
203 List.iteri
204 (fun i item ->
205 if Item.id item = "" then
206 add_error (Printf.sprintf "item %d has empty ID" i);
207
208 (* Validate item authors *)
209 match Item.authors item with
210 | Some authors ->
211 List.iteri
212 (fun j author ->
213 if not (Author.is_valid author) then
214 add_error (Printf.sprintf "item %d author %d is invalid" i j))
215 authors
216 | None -> ())
217 feed.items;
218
219 match !errors with [] -> Ok () | errs -> Error (List.rev errs)