Added empty() operator-bang and isNull()

include/json/value.h

@@ -233,6 +233,7 @@ namespace Json {
       double asDouble() const;
       bool asBool() const;
 
+      bool isNull() const;
       bool isBool() const;
       bool isInt() const;
       bool isUInt() const;
@@ -248,7 +249,14 @@ namespace Json {
       /// Number of values in array or object
       UInt size() const;
 
-      /// Removes all object members and array elements.
+      /// \brief Return true if empty array, empty object, or null;
+      /// otherwise, false.
+      bool empty() const;
+
+      /// Return isNull()
+      bool operator!() const;
+
+      /// Remove all object members and array elements.
       /// \pre type() is arrayValue, objectValue, or nullValue
       /// \post type() is unchanged
       void clear();

src/lib_json/json_value.cpp

@@ -888,6 +888,23 @@ Value::size() const
 }
 
 
+bool 
+Value::empty() const
+{
+   if ( isNull() || isArray() || isObject() )
+      return size() == 0u;
+   else
+      return false;
+}
+
+
+bool
+Value::operator!() const
+{
+   return isNull();
+}
+
+
 void 
 Value::clear()
 {
@@ -1217,6 +1234,13 @@ Value::getMemberNames() const
 //# endif
 
 
+bool
+Value::isNull() const
+{
+   return type_ == nullValue;
+}
+
+
 bool 
 Value::isBool() const
 {