Game Engine SFML in C++ Errors - c++

Question

This is a Game Engine for SFML builded in c++. I get some errors that i don't know how to fix it. If someone can solve this problem i will apriciated a lot.
I'm still learning c so por someone could same an obious problem or solucion but i just copied the code from another page and I do exactly the same and mine code isn't working
Errors:
Error C2065: 'StateSystem' : undeclared identifier
Error C2923: 'std::unique_ptr' : 'StateSystem' is not a valid template type
argument for parameter '_Ty'
Error C3203: 'unique_ptr' : unspecialized class template can't be used as a
template argument for template parameter '_Ty', expected a real type
Error C2512: 'std::unique_ptr' : no appropriate default constructor
available
Error C2780: '_OutTy *std::move(_InIt,_InIt,_OutTy (&)[_OutSize])' : expects
3 arguments - 1 provided
1> c:\program files (x86)\microsoft visual studio
12.0\vc\include\xutility(2510) : see declaration of 'std::move'
Error C2893: Failed to specialize function template
'remove_reference<_Ty>::type &&std::move(_Ty &&) throw()'
1> With the following template arguments:
1> '_Ty=Victor::StateRef &'
Error C2227: left of '->Resume' must point to class/struct/union/generic
type
1> type is 'int'
Error C2780: '_OutTy *std::move(_InIt,_InIt,_OutTy (&)[_OutSize])' : expects
3 arguments - 1 provided
1> c:\program files (x86)\microsoft visual studio
12.0\vc\include\xutility(2510) : see declaration of 'std::move'
Error C2893:
Failed to specialize function template 'remove_reference<_Ty>::type
&&std::move(_Ty &&) throw()'
1> With the following template arguments:
1> '_Ty=Victor::StateRef &'
Error C2227: left of '->Initialize' must point to class/struct/union/generic
type
1> type is 'int'
Error C2440: 'return' : cannot convert from 'int' to 'Victor::StateRef &'
And This is the code that provides errors.
State.h
#pragma once
class State
{
public:
virtual void Initialize() = 0;
virtual void HandleInput() = 0;
virtual void Update() = 0;
virtual void Draw(float DeltaTime) = 0;
virtual void Pause()
{
}
virtual void Resume()
{
}
};
StateSystem.h
#pragma once
#include <memory>
#include <stack>
#include "State.h"
typedef std::unique_ptr <StateSystem> StateRef;
class StateSystem
{
public:
StateSystem()
{
}
~StateSystem()
{
}
void AddState(StateRef newStat, bool isReplacing = true);
void RemoveState();
void ProcessStateChanges();
StateRef &GetActiveState();
private:
std::stack<StateRef> _states;
StateRef _newState;
bool _isRemoving;
bool _isAdding;
bool _isReplacing;
};
StateSystem.cpp
#include "StateSystem.h"
void StateSystem::AddState(StateRef newState, bool isRepalcing)
{
this->_isAdding = true;
this->_isReplacing = isRepalcing;
this->_newState = std::move(newState);
}
void StateSystem::RemoveState()
{
this->_isRemoving = true;
}
void StateSystem::ProcessStateChanges()
{
if (this->_isRemoving && !this->_states.empty())
{
this->_states.pop();
if (!this->_states.empty())
{
this->_states.top()->Resume();
}
this->_isRemoving = false;
}
if (this->_isAdding)
{
if (!this->_states.empty())
{
if (this->_isReplacing)
{
this->_states.pop();
}
else
{
this->_states.top()->Pause();
}
}
this->_states.push(std::move(this->_newState));
this->_states.top()->Initialize();
this->_isAdding = false;
}
}
StateRef &StateSystem::GetActiveState()
{
return this->_states.top();
}

Answer 1

there's no StateSystem before typedef std::unique_ptr <StateSystem> StateRef; just add class StateSystem before it.

Answer 2

it says it cannot find the StateSystem class. you have to declare it first like this:
class StateSystem;
typedef std::unique_ptr <StateSystem> StateRef;
class StateSystem
{
//members
};
or put your typedef after the StateSystem definition like this:
class StateSystem
{
//members
};
typedef std::unique_ptr <StateSystem> StateRef;