Implement char deserialization and commit forgotten changes

1 files changed, 75 insertions, 0 deletions

diff --git a/src/OfJsonBasic.ml b/src/OfJsonBasic.ml
new file mode 100644
index 00000000..6e7bb4e9
--- /dev/null
+++ b/src/OfJsonBasic.ml
@@ -0,0 +1,75 @@
+(** This module defines various basic utilities for json deserialization.
+   
+ *)
+
+open Yojson.Basic
+
+type json = t
+
+let ( let* ) o f = match o with Error e -> Error e | Ok x -> f x
+
+let combine_error_msgs js msg res : ('a, string) result =
+  match res with
+  | Ok x -> Ok x
+  | Error e -> Error (msg ^ " failed on: " ^ show js ^ "\n" ^ e)
+
+let bool_of_json (js : json) : (bool, string) result =
+  match js with
+  | `Bool b -> Ok b
+  | _ -> Error ("bool_of_json: not a bool: " ^ show js)
+
+let int_of_json (js : json) : (int, string) result =
+  match js with
+  | `Int i -> Ok i
+  | _ -> Error ("int_of_json: not an int: " ^ show js)
+
+let char_of_json (js : json) : (char, string) result =
+  match js with
+  | `String c ->
+      if String.length c == 1 then Ok c.[0]
+      else Error ("char_of_json: stricly more than one character in: " ^ show js)
+  | _ -> Error ("char_of_json: not a char: " ^ show js)
+
+let rec of_json_list (a_of_json : json -> ('a, string) result) (jsl : json list)
+    : ('a list, string) result =
+  match jsl with
+  | [] -> Ok []
+  | x :: jsl' ->
+      let* x = a_of_json x in
+      let* jsl' = of_json_list a_of_json jsl' in
+      Ok (x :: jsl')
+
+let pair_of_json (a_of_json : json -> ('a, string) result)
+    (b_of_json : json -> ('b, string) result) (js : json) :
+    ('a * 'b, string) result =
+  match js with
+  | `List [ a; b ] ->
+      let* a = a_of_json a in
+      let* b = b_of_json b in
+      Ok (a, b)
+  | _ -> Error ("pair_of_json failed on: " ^ show js)
+
+let list_of_json (a_of_json : json -> ('a, string) result) (js : json) :
+    ('a list, string) result =
+  combine_error_msgs js "list_of_json"
+    (match js with
+    | `List jsl -> of_json_list a_of_json jsl
+    | _ -> Error ("not a list: " ^ show js))
+
+let string_of_json (js : json) : (string, string) result =
+  match js with
+  | `String str -> Ok str
+  | _ -> Error ("string_of_json: not a string: " ^ show js)
+
+let option_of_json (a_of_json : json -> ('a, string) result) (js : json) :
+    ('a option, string) result =
+  combine_error_msgs js "option_of_json"
+    (match js with
+    | `Null -> Ok None
+    | _ ->
+        let* x = a_of_json js in
+        Ok (Some x))
+
+let string_option_of_json (js : json) : (string option, string) result =
+  combine_error_msgs js "string_option_of_json"
+    (option_of_json string_of_json js)