From 5c95ae60327ece0c3036c5eea0a4f2cd450c5cc5 Mon Sep 17 00:00:00 2001
From: Robert Soeldner <r.soeldner@gmail.com>
Date: Tue, 15 Oct 2024 16:38:50 +0200
Subject: [PATCH] add getKeys to json lib

---
 examples/json/Json.sig |  3 +++
 examples/json/Json.sml | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/examples/json/Json.sig b/examples/json/Json.sig
index 0d0bf5920d..5bb6bec4d4 100644
--- a/examples/json/Json.sig
+++ b/examples/json/Json.sig
@@ -26,6 +26,9 @@ sig
   val getObject      : json -> string -> json option
   val getObject'     : json -> string -> json
 
+  val getKeys        : json -> (string list) option
+  val getKeys'       : json -> string list
+
   val getBool        : json -> bool option
   val getBool'       : json -> bool
 
diff --git a/examples/json/Json.sml b/examples/json/Json.sml
index edd37ebc84..9eee8dd02e 100644
--- a/examples/json/Json.sml
+++ b/examples/json/Json.sml
@@ -290,6 +290,17 @@ fun getObject' json k =
         SOME v => v
      | NONE => raise ERR "getObject'" "expects object."
 
+
+fun getKeys json =
+    case json of
+        AList l => SOME (map #1 l)
+      | _ => NONE
+
+fun getKeys' json =
+    case json of
+        AList l => map #1 l
+      | _ =>  raise ERR "getKeys'" "expects object."
+
 fun getBool json =
   case json of
       Boolean b => SOME b
@@ -349,6 +360,8 @@ fun foldArray' json (f: json -> 'a) =
       | NONE => raise ERR "foldArray'" "expects value."
 
 (* val json = hd (#1 (parse ([],Substring.full "{\"foo\" : [1, 23, 4], \"bar\" : 2}"))) *)
+(* val keys = getKeys json *)
+(* val keys' = getKeys' json *)
 (* val foo = getObject json "foo" *)
 (* val foo' = getObject' json "foo" *)
 (* val foo_ints = foldlArray foo' getInt *)