+#ifndef BLANK_APP_STATECONTROL_HPP_
+#define BLANK_APP_STATECONTROL_HPP_
+
+#include <queue>
+
+
+namespace blank {
+
+class Application;
+class State;
+
+class StateControl {
+
+public:
+ void Push(State *s) {
+ cue.emplace(PUSH, s);
+ }
+
+ void Switch(State *s) {
+ cue.emplace(SWITCH, s);
+ }
+
+ void Pop() {
+ cue.emplace(POP);
+ }
+
+ void PopAll() {
+ cue.emplace(POP_ALL);
+ }
+
+
+ void Commit(Application &);
+
+private:
+ enum Command {
+ PUSH,
+ SWITCH,
+ POP,
+ POP_ALL,
+ };
+ struct Memo {
+ State *state;
+ Command cmd;
+ explicit Memo(Command c, State *s = nullptr): state(s), cmd(c) { }
+ };
+ std::queue<Memo> cue;
+
+};
+
+}
+
+#endif