add object property proxy support

janssonxx.h

@@ -22,6 +22,7 @@ namespace jansson {
 	class Iterator;
 	class Value;
 	class _ArrayProxy;
+	class _ObjectProxy;
 
 	// base class for JSON value interface
 	template <typename _Base>
@@ -75,13 +76,20 @@ namespace jansson {
 		inline _ValueBase<_ArrayProxy> operator[](signed long index);
 		inline _ValueBase<_ArrayProxy> operator[](unsigned long index);
 
-		// get object property
+		// get object property (const version)
 		inline const Value get(const char* key) const;
 
 		inline const Value get(const std::string& key) const;
 		inline const Value operator[](const char* key) const;
 		inline const Value operator[](const std::string& key) const;
 
+		// get object property (non-const version)
+		inline _ValueBase<_ObjectProxy> get(const char* key);
+
+		inline _ValueBase<_ObjectProxy> get(const std::string& key);
+		inline _ValueBase<_ObjectProxy> operator[](const char* key);
+		inline _ValueBase<_ObjectProxy> operator[](const std::string& key);
+
 		// clear all array/object values
 		inline void clear();
 
@@ -156,9 +164,6 @@ namespace jansson {
 	// proxies an array element
 	class _ArrayProxy {
 	public:
-		// construct new Value with an undefined value
-		_ArrayProxy() : _array(0), _index(0) {}
-
 		// constructor
 		_ArrayProxy(json_t* array, unsigned int index) : _array(array), _index(index) {}
 
@@ -176,6 +181,26 @@ namespace jansson {
 		unsigned int _index;
 	};
 
+	// proxies an object property
+	class _ObjectProxy {
+	public:
+		// constructor
+		_ObjectProxy(json_t* array, const char* key) : _object(array), _key(key) {}
+
+		// assign to the proxied element
+		inline _ObjectProxy& operator=(const Value& value);
+
+		// get the proxied element
+		json_t* as_json() const { return json_object_get(_object, _key); }
+
+	private:
+		// array object we wrap
+		json_t* _object;
+
+		// key of property
+		const char* _key;
+	};
+
 	// represents any JSON value
 	class Value : public _ValueBase<_Value> {
 	public:
@@ -245,6 +270,11 @@ namespace jansson {
 			_iter = json_object_iter(_object.as_json());
 		}
 
+		// construct a new iterator for a given object
+		Iterator(const _ValueBase<_ObjectProxy>& value) : _object(value.as_json()), _iter(0) {
+			_iter = json_object_iter(_object.as_json());
+		}
+
 		// increment iterator
 		void next() {
 			_iter = json_object_iter_next(_object.as_json(), _iter);

janssonxx.tcc

@@ -45,7 +45,7 @@ jansson::_ValueBase<jansson::_ArrayProxy> jansson::_ValueBase<_Base>::operator[]
 template <typename _Base>
 jansson::_ValueBase<jansson::_ArrayProxy> jansson::_ValueBase<_Base>::operator[](unsigned long index) { return at(index); }
 
-// get object property
+// get object property (const version)
 template <typename _Base>
 const jansson::Value jansson::_ValueBase<_Base>::get(const char* key) const {
 	return jansson::Value(json_object_get(_Base::as_json(), key));
@@ -58,6 +58,19 @@ const jansson::Value jansson::_ValueBase<_Base>::operator[](const char* key) con
 template <typename _Base>
 const jansson::Value jansson::_ValueBase<_Base>::operator[](const std::string& key) const { return get(key.c_str()); }
 
+// get object property (non-const version)
+template <typename _Base>
+jansson::_ValueBase<jansson::_ObjectProxy> jansson::_ValueBase<_Base>::get(const char* key) {
+	return _ObjectProxy(_Base::as_json(), key);
+}
+
+template <typename _Base>
+jansson::_ValueBase<jansson::_ObjectProxy> jansson::_ValueBase<_Base>::get(const std::string& key) { return get(key.c_str()); }
+template <typename _Base>
+jansson::_ValueBase<jansson::_ObjectProxy> jansson::_ValueBase<_Base>::operator[](const char* key) { return get(key); }
+template <typename _Base>
+jansson::_ValueBase<jansson::_ObjectProxy> jansson::_ValueBase<_Base>::operator[](const std::string& key) { return get(key.c_str()); }
+
 // clear all array/object values
 template <typename _Base>
 void jansson::_ValueBase<_Base>::clear() {
@@ -137,3 +150,9 @@ jansson::_ArrayProxy& jansson::_ArrayProxy::operator=(const Value& value) {
 	json_array_set(_array, _index, value.as_json());
 	return *this;
 }
+
+// assign value to proxied object property
+jansson::_ObjectProxy& jansson::_ObjectProxy::operator=(const Value& value) {
+	json_object_set(_object, _key, value.as_json());
+	return *this;
+}

test.cc

@@ -148,8 +148,8 @@ int main() {
 	ASSERT_TRUE(e14.is_object(), "e14 is not an object after construction");
 	e14.set_key("foo", jansson::Value::object());
 	ASSERT_TRUE(e14["foo"].is_object(), "e14.foo is not an object after assignment");
-	//e14["foo"]["bar"] = jansson::Value::from(42);
+	e14["foo"]["bar"] = jansson::Value::from(42);
-	//ASSERT_EQ(e14["foo"]["bar"].as_integer(), 42, "e14.foo.bar has incorrect value after assignment");
+	ASSERT_EQ(e14["foo"]["bar"].as_integer(), 42, "e14.foo.bar has incorrect value after assignment");
 
 	jansson::Value e15(jansson::Value::array());
 	ASSERT_TRUE(e15.is_array(), "e15 is not an array after construction");