Fix #499: Add object_from_json, map_to_object, and object_to_map functions (#676)

Add object_from_json as a non-breaking alternative to from_json that returns
a Dynamic_Object instead of a Map, enabling dot-access syntax on JSON fields
(e.g. obj.name instead of obj["name"]). Nested JSON objects become nested
Dynamic_Objects. Also add map_to_object and object_to_map for Python-style
interconversion between maps and objects.

Co-authored-by: leftibot <leftibot@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

include/chaiscript/utility/json_wrap.hpp

@@ -2,13 +2,17 @@
 #define CHAISCRIPT_SIMPLEJSON_WRAP_HPP
 
 #include "json.hpp"
+#include "../dispatchkit/dynamic_object.hpp"
 
 namespace chaiscript {
   class json_wrap {
   public:
     static Module &library(Module &m) {
       m.add(chaiscript::fun([](const std::string &t_str) { return from_json(t_str); }), "from_json");
+      m.add(chaiscript::fun([](const std::string &t_str) { return object_from_json(t_str); }), "object_from_json");
       m.add(chaiscript::fun(&json_wrap::to_json), "to_json");
+      m.add(chaiscript::fun(&json_wrap::map_to_object), "map_to_object");
+      m.add(chaiscript::fun(&json_wrap::object_to_map), "object_to_map");
 
       return m;
     }
@@ -57,6 +61,63 @@ namespace chaiscript {
       }
     }
 
+    static Boxed_Value object_from_json(const json::JSON &t_json) {
+      switch (t_json.JSONType()) {
+        case json::JSON::Class::Null:
+          return Boxed_Value();
+        case json::JSON::Class::Object: {
+          auto obj = dispatch::Dynamic_Object("JSON_Object");
+
+          for (const auto &p : t_json.object_range()) {
+            obj.get_attr(p.first) = object_from_json(p.second);
+          }
+
+          return Boxed_Value(std::move(obj));
+        }
+        case json::JSON::Class::Array: {
+          std::vector<Boxed_Value> vec;
+
+          for (const auto &p : t_json.array_range()) {
+            vec.emplace_back(object_from_json(p));
+          }
+
+          return Boxed_Value(vec);
+        }
+        case json::JSON::Class::String:
+          return Boxed_Value(t_json.to_string());
+        case json::JSON::Class::Floating:
+          return Boxed_Value(t_json.to_float());
+        case json::JSON::Class::Integral:
+          return Boxed_Value(t_json.to_int());
+        case json::JSON::Class::Boolean:
+          return Boxed_Value(t_json.to_bool());
+      }
+
+      throw std::runtime_error("Unknown JSON type");
+    }
+
+    static Boxed_Value object_from_json(const std::string &t_json) {
+      try {
+        return object_from_json(json::JSON::Load(t_json));
+      } catch (const std::out_of_range &) {
+        throw std::runtime_error("Unparsed JSON input");
+      }
+    }
+
+    static Boxed_Value map_to_object(const std::map<std::string, Boxed_Value> &t_map) {
+      auto obj = dispatch::Dynamic_Object("JSON_Object");
+
+      for (const auto &p : t_map) {
+        obj.get_attr(p.first) = p.second;
+      }
+
+      return Boxed_Value(std::move(obj));
+    }
+
+    static std::map<std::string, Boxed_Value> object_to_map(const dispatch::Dynamic_Object &t_obj) {
+      return t_obj.get_attrs();
+    }
+
     static std::string to_json(const Boxed_Value &t_bv) { return to_json_object(t_bv).dump(); }
 
     static json::JSON to_json_object(const Boxed_Value &t_bv) {

unittests/object_from_json_1.chai

@@ -0,0 +1,6 @@
+// object_from_json: returns Dynamic_Object with dot-access on JSON fields
+var obj = object_from_json("{\"name\":\"ChaiScript\",\"version\":6,\"active\":true}")
+assert_equal(obj.name, "ChaiScript")
+assert_equal(obj.version, 6)
+assert_equal(obj.active, true)
+assert_equal(obj.get_type_name(), "JSON_Object")

unittests/object_from_json_2.chai

@@ -0,0 +1,3 @@
+// object_from_json: nested objects become nested Dynamic_Objects
+var obj = object_from_json("{\"outer\":{\"inner\":42}}")
+assert_equal(obj.outer.inner, 42)

unittests/object_from_json_3.chai

@@ -0,0 +1,3 @@
+// object_from_json: arrays remain as vectors
+var obj = object_from_json("{\"items\":[1,2,3]}")
+assert_equal(obj.items, [1,2,3])

unittests/object_from_json_4.chai

@@ -0,0 +1,9 @@
+// object_to_map and map_to_object conversions
+var m = ["a": 1, "b": "hello"]
+var obj = map_to_object(m)
+assert_equal(obj.a, 1)
+assert_equal(obj.b, "hello")
+
+var m2 = object_to_map(obj)
+assert_equal(m2["a"], 1)
+assert_equal(m2["b"], "hello")

unittests/object_from_json_5.chai

@@ -0,0 +1,6 @@
+// object_from_json roundtrip through to_json
+var json_str = "{\"key\":\"value\"}"
+var obj = object_from_json(json_str)
+var result = to_json(obj)
+var obj2 = object_from_json(result)
+assert_equal(obj2.key, "value")