Avoid unncessary copy of objects lists for last event of events lists

Core/GDCore/Events/CodeGeneration/EventsCodeGenerationContext.cpp

@@ -33,6 +33,13 @@ void EventsCodeGenerationContext::InheritsFrom(const EventsCodeGenerationContext
     }
 }
 
+void EventsCodeGenerationContext::Reuse(const EventsCodeGenerationContext & parent_)
+{
+    InheritsFrom(parent_);
+    if (parent_.CanReuse())
+        contextDepth = parent_.GetContextDepth(); // Keep same context depth
+}
+
 void EventsCodeGenerationContext::ObjectsListNeeded(const gd::String & objectName)
 {
     if ( emptyObjectsListsToBeDeclared.find(objectName) == emptyObjectsListsToBeDeclared.end() )

Core/GDCore/Events/CodeGeneration/EventsCodeGenerationContext.h

@@ -32,7 +32,13 @@ class GD_CORE_API EventsCodeGenerationContext
      * Default constructor. You may want to call InheritsFrom just after.
      * \param maxDepthLevel Optional pointer to an unsigned integer that will be updated to contain the maximal scope depth reached.
      */
-    EventsCodeGenerationContext(unsigned int * maxDepthLevel_ = nullptr) : contextDepth(0), customConditionDepth(0), maxDepthLevel(maxDepthLevel_), parent(NULL) {};
+    EventsCodeGenerationContext(unsigned int * maxDepthLevel_ = nullptr) :
+        contextDepth(0),
+        customConditionDepth(0),
+        maxDepthLevel(maxDepthLevel_),
+        parent(NULL),
+        reuseExplicitlyForbidden(false)
+    {};
     virtual ~EventsCodeGenerationContext() {};
 
     /**
@@ -41,6 +47,28 @@ class GD_CORE_API EventsCodeGenerationContext
      */
     void InheritsFrom(const EventsCodeGenerationContext & parent);
 
+    /**
+     * \brief As InheritsFrom, mark the context as being the child of another one, but enabling
+     * the child context to use the same object lists.
+     *
+     * Used for example for optimizing the last event of a list.
+     */
+    void Reuse(const EventsCodeGenerationContext & parent);
+
+    /**
+     * \brief Forbid any optimization that would reuse and modify the object list from this context
+     * in children context.
+     *
+     * Used in while/for each/repeat or any event that have a loop and must ensure that
+     * the list of objects stay clean.
+     */
+    void ForbidReuse() { reuseExplicitlyForbidden = true; }
+
+    /**
+     * \brief Return false if the object lists of the context can not be reused in a child context.
+     */
+    bool CanReuse() const { return !reuseExplicitlyForbidden && parent != nullptr; }
+
     /**
      * \brief Returns the depth of the inheritance of the context.
      *
@@ -150,6 +178,7 @@ class GD_CORE_API EventsCodeGenerationContext
     unsigned int customConditionDepth; ///< The depth of the conditions being generated.
     unsigned int * maxDepthLevel; ///< A pointer to a unsigned int updated with the maximum depth reached.
     const EventsCodeGenerationContext * parent; ///< The parent of the current context. Can be NULL.
+    bool reuseExplicitlyForbidden; ///< If set to true, forbid children context to reuse this one without inheriting.
 };
 
 }

Core/GDCore/Events/CodeGeneration/EventsCodeGenerator.cpp

@@ -675,8 +675,17 @@ gd::String EventsCodeGenerator::GenerateEventsListCode(gd::EventsList & events,
     for ( std::size_t eId = 0; eId < events.size();++eId )
     {
         //Each event has its own context : Objects picked in an event are totally different than the one picked in another.
-        gd::EventsCodeGenerationContext context;
-        context.InheritsFrom(parentContext); //Events in the same "level" share the same context as their parent.
+        gd::EventsCodeGenerationContext newContext;
+        newContext.InheritsFrom(parentContext); //Events in the same "level" share the same context as their parent.
+
+        //*Optimization*: when the event is the last of a list, we can use the
+        //same lists of objects as the parent (as they will be discarded just after).
+        //This avoids a copy of the lists of objects which is an expensive operation.
+        bool reuseParentContext = parentContext.CanReuse() && eId == events.size()-1;
+        gd::EventsCodeGenerationContext reusedContext;
+        reusedContext.Reuse(parentContext);
+
+        auto & context = reuseParentContext ? reusedContext : newContext;
 
         gd::String eventCoreCode = events[eId].GenerateEventCode(*this, context);
         gd::String scopeBegin = GenerateScopeBegin(context);

Core/GDCore/Events/CodeGeneration/EventsCodeGenerator.h

@@ -46,7 +46,7 @@ class GD_CORE_API EventsCodeGenerator
     virtual ~EventsCodeGenerator() {};
 
     /**
-     * \brief Preprocess an events list ( Replacing for example links with the linked event ).
+     * \brief Preprocess an events list (replacing for example links with the linked events).
      *
      * This should be called before any code generation.
      */
@@ -57,7 +57,7 @@ class GD_CORE_API EventsCodeGenerator
      *
      * \param events std::vector of events
      * \param context Context used for generation
-     * \return C++ code
+     * \return Code
      */
     gd::String GenerateEventsListCode(gd::EventsList & events, const EventsCodeGenerationContext & context);
 

GDCpp/GDCpp/Extensions/Builtin/CommonInstructionsExtension.cpp

@@ -57,6 +57,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
                 //For example, two sub conditions using an object called "MyObject" will both have to declare a "MyObject" object list.
                 gd::EventsCodeGenerationContext context;
                 context.InheritsFrom(parentContext);
+                context.ForbidReuse(); //TODO: This may not be necessary
 
                 gd::String conditionCode = codeGenerator.GenerateConditionCode(conditions[cId], "condition"+gd::String::From(cId)+"IsTrue", context);
 
@@ -244,6 +245,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
             //Context is "reset" each time the event is repeated ( i.e. objects are picked again )
             gd::EventsCodeGenerationContext context;
             context.InheritsFrom(parentContext);
+            context.ForbidReuse();
             if ( event.HasInfiniteLoopWarning() && !codeGenerator.GenerateCodeForRuntime() ) codeGenerator.AddIncludeFile("GDCpp/Extensions/Builtin/RuntimeSceneTools.h");
 
             //Prepare codes
@@ -300,6 +302,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
             //Context is "reset" each time the event is repeated ( i.e. objects are picked again )
             gd::EventsCodeGenerationContext context;
             context.InheritsFrom(parentContext);
+            context.ForbidReuse();
 
             //Prepare conditions/actions codes
             gd::String conditionsCode = codeGenerator.GenerateConditionsListCode(event.GetConditions(), context);
@@ -347,6 +350,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
             //Context is "reset" each time the event is repeated ( i.e. objects are picked again )
             gd::EventsCodeGenerationContext context;
             context.InheritsFrom(parentContext);
+            context.ForbidReuse();
 
             //Prepare conditions/actions codes
             gd::String conditionsCode = codeGenerator.GenerateConditionsListCode(event.GetConditions(), context);

GDJS/GDJS/Events/CodeGeneration/EventsCodeGenerator.cpp

@@ -391,41 +391,52 @@ gd::String EventsCodeGenerator::GetObjectListName(const gd::String & name, const
 
 gd::String EventsCodeGenerator::GenerateObjectsDeclarationCode(gd::EventsCodeGenerationContext & context)
 {
+    auto declareObjectList = [this](gd::String object, gd::EventsCodeGenerationContext & context) {
+        gd::String newListName = GetObjectListName(object, context);
+        if (!context.GetParentContext())
+        {
+            std::cout << "ERROR: During code generation, a context tried to use an already declared object list without having a parent" << std::endl;
+            return "/* Could not declare " + newListName + " */";
+        }
+
+        //*Optimization*: Avoid expensive copy of the object list if we're using
+        //the same list as the one from the parent context. 
+        gd::String copiedListName = GetObjectListName(object, *context.GetParentContext());
+        if (newListName == copiedListName)
+            return "/* Reuse " + copiedListName + " */";
+
+        return newListName + ".createFrom("+copiedListName+");\n";
+    };
+
     gd::String declarationsCode;
-    for ( set<gd::String>::iterator it = context.GetObjectsListsToBeDeclared().begin() ; it != context.GetObjectsListsToBeDeclared().end(); ++it )
+    for (auto object : context.GetObjectsListsToBeDeclared())
     {
-        declarationsCode += GetObjectListName(*it, context);
-        if ( !context.ObjectAlreadyDeclared(*it) )
+        gd::String objectListDeclaration = "";
+        if ( !context.ObjectAlreadyDeclared(object) )
         {
-            declarationsCode += ".createFrom(runtimeScene.getObjects(\""+ConvertToString(*it)+"\"));\n";
-            context.SetObjectDeclared(*it);
+            objectListDeclaration += GetObjectListName(object, context) + ".createFrom(runtimeScene.getObjects(\"" + ConvertToString(object) + "\"));";
+            context.SetObjectDeclared(object);
         }
         else
-        {
-            if (context.GetParentContext())
-                declarationsCode += ".createFrom("+GetObjectListName(*it, *context.GetParentContext())+");\n";
-            else
-                std::cout << "ERROR: During code generation, a context tried tried to use an already declared object list without having a parent" << std::endl;
-        }
+            objectListDeclaration = declareObjectList(object, context);
+
+        declarationsCode += objectListDeclaration + "\n";
     }
-    for ( set<gd::String>::iterator it = context.GetObjectsListsToBeDeclaredEmpty().begin() ; it != context.GetObjectsListsToBeDeclaredEmpty().end(); ++it )
+    for (auto object : context.GetObjectsListsToBeDeclaredEmpty())
     {
-        declarationsCode += GetObjectListName(*it, context);
-        if ( !context.ObjectAlreadyDeclared(*it) )
+        gd::String objectListDeclaration = "";
+        if ( !context.ObjectAlreadyDeclared(object) )
         {
-            declarationsCode +=".length = 0;\n";
-            context.SetObjectDeclared(*it);
+            objectListDeclaration = GetObjectListName(object, context) + ".length = 0;\n";
+            context.SetObjectDeclared(object);
         }
         else
-        {
-            if (context.GetParentContext())
-                declarationsCode += ".createFrom("+GetObjectListName(*it, *context.GetParentContext())+");\n";
-            else
-                std::cout << "ERROR: During code generation, a context tried tried to use an already declared object list without having a parent" << std::endl;
-        }
+            objectListDeclaration = declareObjectList(object, context);
+
+        declarationsCode += objectListDeclaration + "\n";
     }
 
-    return declarationsCode ;
+    return declarationsCode;
 }
 
 gd::String EventsCodeGenerator::GenerateConditionsListCode(gd::InstructionsList & conditions, gd::EventsCodeGenerationContext & context)

GDJS/GDJS/Extensions/Builtin/CommonInstructionsExtension.cpp

@@ -97,6 +97,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
                 //For example, two sub conditions using an object called "MyObject" will both have to declare a "MyObject" object list.
                 gd::EventsCodeGenerationContext context;
                 context.InheritsFrom(parentContext);
+                context.ForbidReuse(); //TODO: This may not be necessary
 
                 gd::String conditionCode = codeGenerator.GenerateConditionCode(conditions[cId], "condition"+gd::String::From(cId)+"IsTrue", context);
 
@@ -231,6 +232,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
             //Context is "reset" each time the event is repeated ( i.e. objects are picked again )
             gd::EventsCodeGenerationContext context;
             context.InheritsFrom(parentContext);
+            context.ForbidReuse();
 
             //Prepare codes
             gd::String whileConditionsStr = codeGenerator.GenerateConditionsListCode(event.GetWhileConditions(), context);
@@ -285,6 +287,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
             //Context is "reset" each time the event is repeated ( i.e. objects are picked again )
             gd::EventsCodeGenerationContext context;
             context.InheritsFrom(parentContext);
+            context.ForbidReuse();
 
             //Prepare conditions/actions codes
             gd::String conditionsCode = codeGenerator.GenerateConditionsListCode(event.GetConditions(), context);
@@ -339,6 +342,7 @@ CommonInstructionsExtension::CommonInstructionsExtension()
             //Context is "reset" each time the event is repeated ( i.e. objects are picked again )
             gd::EventsCodeGenerationContext context;
             context.InheritsFrom(parentContext);
+            context.ForbidReuse();
 
             for (unsigned int i = 0;i<realObjects.size();++i)
                 context.ObjectsListNeeded(realObjects[i]);