Haaf's Game Engine Texture Manager

//*
// Class created by Chris Armitt for use with HGE
//*

#pragma once
#include <hge.h>
#include <map>
#include <string>

#define TEXTURE_FOLDER "../Data/Images/"

using namespace std;

class TextureManager
{
private:
    HGE* m_pHge;
    map<string, HTEXTURE> m_Textures;

    TextureManager()
    {
        m_pHge = hgeCreate(HGE_VERSION);
    }

    ~TextureManager()
    {
        Flush();
        m_pHge->Release();
    }

public:
    static TextureManager& GetInstance()
    {
        static TextureManager tm;
        return tm;
    }

    void Flush()
    {
        auto it = m_Textures.begin();
        auto end = m_Textures.end();

        for (it; it != end; it++)
        {
            m_pHge->Texture_Free(it->second);
        }
        m_Textures.clear();
    }

    HTEXTURE GetTexture(string texture)
    {
        //Attempt to return texture
//-------------------------------------
        auto it = m_Textures.find(texture);
        auto end = m_Textures.end();

        if(it != end)
            return it->second;
//-------------------------------------

        //Load Texture and Store it
//-------------------------------------
        string filepath = TEXTURE_FOLDER;
        filepath += texture;

        HTEXTURE tex = m_pHge->Texture_Load(filepath.c_str());
        m_Textures.insert(make_pair(texture, tex));
//-------------------------------------

        return tex;
    }
};