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-rw-r--r--src/fromjson.sml35
1 files changed, 35 insertions, 0 deletions
diff --git a/src/fromjson.sml b/src/fromjson.sml
new file mode 100644
index 00000000..6a9bd71b
--- /dev/null
+++ b/src/fromjson.sml
@@ -0,0 +1,35 @@
+structure FromJson :> FROMJSON = struct
+fun getO (s: string) (l: Json.json): Json.json option =
+ case l of
+ Json.Obj pairs =>
+ (case List.find (fn tup => #1 tup = s) pairs of
+ NONE => NONE
+ | SOME tup => SOME (#2 tup))
+ | _ => raise Fail ("Expected JSON object, got: " ^ Json.print l)
+fun get (s: string) (l: Json.json): Json.json =
+ (case getO s l of
+ NONE => raise Fail ("Failed to find JSON object key " ^ s ^ " in " ^ Json.print l)
+ | SOME a => a)
+
+fun asInt (j: Json.json): int =
+ case j of
+ Json.Int i => i
+ | _ => raise Fail ("Expected JSON int, got: " ^ Json.print j)
+
+fun asString (j: Json.json): string =
+ case j of
+ Json.String s => s
+ | _ => raise Fail ("Expected JSON string, got: " ^ Json.print j)
+
+fun asOptionalInt (j: Json.json): int option =
+ case j of
+ Json.Null => NONE
+ | Json.Int i => SOME i
+ | _ => raise Fail ("Expected JSON int or null, got: " ^ Json.print j)
+
+fun asOptionalString (j: Json.json): string option =
+ case j of
+ Json.Null => NONE
+ | Json.String s => SOME s
+ | _ => raise Fail ("Expected JSON string or null, got: " ^ Json.print j)
+end