Implement history::State. Add history::ModuleAdd declaration.

include/history.hpp

@@ -1,5 +1,8 @@
 #pragma once
 #include "common.hpp"
+#include "math.hpp"
+#include "plugin/Model.hpp"
+#include <vector>
 
 
 namespace rack {
@@ -8,13 +11,26 @@ namespace history {
 
 struct Action {
 	virtual ~Action() {}
-	virtual void commit() {}
-	virtual void commitInverse() {}
+	virtual void undo() {}
+	virtual void redo() {}
+};
+
+
+struct ModuleAdd : Action {
+	Model *model;
+	int moduleId;
+	math::Vec pos;
+	void undo() override;
+	void redo() override;
 };
 
 
 
 struct State {
+	std::vector<Action*> actions;
+	int actionIndex = 0;
+
+	~State();
 	void push(Action *action);
 	void undo();
 	void redo();

src/history.cpp

@@ -5,16 +5,33 @@ namespace rack {
 namespace history {
 
 
-void State::push(Action *action) {
+State::~State() {
+	for (Action *action : actions) {
+		delete action;
+	}
+}
 
+void State::push(Action *action) {
+	for (int i = actionIndex; i < (int) actions.size(); i++) {
+		delete actions[i];
+	}
+	actions.resize(actionIndex);
+	actions.push_back(action);
+	actionIndex++;
 }
 
 void State::undo() {
-	DEBUG("undo");
+	if (actionIndex > 0) {
+		actionIndex--;
+		actions[actionIndex]->undo();
+	}
 }
 
 void State::redo() {
-	DEBUG("redo");
+	if ((int) actions.size() > actionIndex) {
+		actions[actionIndex]->redo();
+		actionIndex++;
+	}
 }