C++: Optimize PropertyProxy

When the property already exists in the object, we can store an
iterator pointing to that property, instead of duplicating the key.

When the property (key) is not present in the object, we still have to
duplicate the key.

2 files changed, 18 insertions, 6 deletions

diff --git a/src/jansson.hpp b/src/jansson.hpp
index ad6d177..efb4b52 100644
--- a/src/jansson.hpp
+++ b/src/jansson.hpp
@@ -201,6 +201,9 @@ namespace json {
             // array object we wrap
             json_t* _object;
 
+            // iterator pointing to property
+            void* _iter;
+
             // key of property
             char* _key;
         };
diff --git a/src/jansson.ipp b/src/jansson.ipp
index fd3a1bf..e965ef7 100644
--- a/src/jansson.ipp
+++ b/src/jansson.ipp
@@ -338,14 +338,17 @@ namespace json {
         }
 
         PropertyProxy::PropertyProxy(json_t* object, const char* key)
-            : _object(object) {
-            _key = strdup(key);
+            : _object(object), _key(0) {
+            _iter = json_object_iter_at(object, key);
+            if(!_iter)
+                _key = strdup(key);
             json_incref(_object);
         }
 
         PropertyProxy::PropertyProxy(const PropertyProxy& other)
-            : _object(other._object) {
-            _key = strdup(other._key);
+            : _object(other._object), _iter(other._iter), _key(0) {
+            if(other._key)
+                _key = strdup(other._key);
             json_incref(_object);
         }
 
@@ -356,12 +359,18 @@ namespace json {
 
         // assign value to proxied object property
         PropertyProxy& PropertyProxy::operator=(const Value& value) {
-            json_object_set(_object, _key, value.as_json());
+            if(_iter)
+                json_object_iter_set(_object, _iter, value.as_json());
+            else
+                json_object_set(_object, _key, value.as_json());
             return *this;
         }
 
         json_t* PropertyProxy::as_json() const {
-            return json_object_get(_object, _key);
+            if(_iter)
+                return json_object_iter_value(_iter);
+            else
+                return json_object_get(_object, _key);
         }
 
     } // namespace json::detail