Merge branch 'upstream' into dfsg_clean20200209+dfsgdfsg_clean

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