Add poc files

external/jsonwheel/json_in.ml

@@ -0,0 +1,51 @@
+type t = Json_type.t
+open Json_type
+
+
+let filter_result x =
+  Browse.assert_object_or_array x;
+  x
+
+
+let check_channel_is_utf8 ic =
+  let start = pos_in ic in
+  let encoding =
+    try
+      let c1 = input_char ic in
+      let c2 = input_char ic in
+      let c3 = input_char ic in
+      let c4 = input_char ic in
+      Json_lexer.detect_encoding c1 c2 c3 c4
+    with End_of_file -> `UTF8 in
+  if encoding <> `UTF8 then
+    json_error "Only UTF-8 encoding is supported";
+  (try seek_in ic start
+   with _ -> json_error "Not a regular file")
+
+(* from_channel and from_channel4 work 
+   only on seekable devices (regular files) *)
+let from_channel p recursive file ic = 
+  check_channel_is_utf8 ic;
+  let lexbuf = Lexing.from_channel ic in
+  Json_lexer.set_file_name lexbuf file;
+  let j =
+    Json_parser.main
+      (Json_lexer.token p)
+      lexbuf
+  in
+  if recursive then j
+  else filter_result j
+
+let load_json
+    ?allow_comments ?allow_nan ?big_int_mode ?(recursive = false)
+    file = 
+  let ic = open_in file in
+  let x =
+    let p =
+      Json_lexer.make_param ?allow_comments ?allow_nan ?big_int_mode () in
+    try `Result (from_channel p recursive file ic)
+    with e -> `Exn e in
+  close_in ic;
+  match x with
+      `Result x -> x
+    | `Exn e -> raise e