feat: move PerProvider data to new provider when saving memory provider into file provider (#1264)

lib/libimhex/include/hex/api/event.hpp

@@ -245,4 +245,10 @@ namespace hex {
      * @brief Send an event to the main Imhex instance
      */
     EVENT_DEF(SendMessageToMainInstance, const std::string, const std::vector<u8>&);
+
+    /**
+     * Move the data from all PerProvider instances from one provider to another.
+     * The 'from' provider should not have any per provider data after this, and should be immediately deleted
+    */
+    EVENT_DEF(MovePerProviderData, prv::Provider *, prv::Provider *);
 }

lib/libimhex/include/hex/providers/provider_data.hpp

@@ -82,6 +82,22 @@ namespace hex {
             EventManager::subscribe<EventImHexClosing>(this, [this] {
                 this->m_data.clear();
             });
+
+            // moves the data of this PerProvider instance from one provider to another
+            EventManager::subscribe<MovePerProviderData>(this, [this](prv::Provider *from, prv::Provider *to) {
+                // get the value from the old provider, (removes it from the map)
+                auto node = m_data.extract(from);
+
+                // ensure the value existed
+                if (node.empty()) return;
+
+                // delete the value from the new provider, that we want to replace
+                this->m_data.erase(to);
+
+                // re-insert it with the key of the new provider
+                node.key() = to;
+                this->m_data.insert(std::move(node));
+            });
         }
 
         void onDestroy() {

plugins/builtin/source/content/providers/memory_file_provider.cpp

@@ -53,6 +53,8 @@ namespace hex::plugin::builtin {
                 if (!fileProvider->open())
                     ImHexApi::Provider::remove(newProvider);
                 else {
+                    EventManager::post<MovePerProviderData>(this, fileProvider);
+
                     fileProvider->markDirty(false);
                     EventManager::post<EventProviderOpened>(newProvider);
                     ImHexApi::Provider::remove(this, true);