libs/flyweight/example/key_value.cpp
/* Boost.Flyweight example of use of key-value flyweights.
*
* Copyright 2006-2008 Joaquin M Lopez Munoz.
* Distributed under the Boost Software License, Version 1.0.
* (See accompanying file LICENSE_1_0.txt or copy at
* http://www.boost.org/LICENSE_1_0.txt)
*
* See http://www.boost.org/libs/flyweight for library home page.
*/
#include <boost/array.hpp>
#include <boost/flyweight.hpp>
#include <boost/flyweight/key_value.hpp>
#include <cstdlib>
#include <iostream>
#include <string>
#include <vector>
using namespace boost::flyweights;
/* A class simulating a texture resource loaded from file */
class texture
{
public:
texture(const std::string& filename):filename(filename)
{
std::cout<<"loaded "<<filename<<" file"<<std::endl;
}
texture(const texture& x):filename(x.filename)
{
std::cout<<"texture["<<filename<<"] copied"<<std::endl;
}
~texture()
{
std::cout<<"unloaded "<<filename<<std::endl;
}
const std::string& get_filename()const{return filename;}
// rest of the interface
private:
std::string filename;
};
/* key extractor of filename strings from textures */
struct texture_filename_extractor
{
const std::string& operator()(const texture& x)const
{
return x.get_filename();
}
};
/* texture flyweight */
typedef flyweight<
key_value<std::string,texture,texture_filename_extractor>
> texture_flyweight;
int main()
{
/* texture filenames */
const char* texture_filenames[]={
"grass.texture","sand.texture","water.texture","wood.texture",
"granite.texture","cotton.texture","concrete.texture","carpet.texture"
};
const int num_texture_filenames=
sizeof(texture_filenames)/sizeof(texture_filenames[0]);
/* create a massive vector of textures */
std::cout<<"creating flyweights...\n"<<std::endl;
std::vector<texture_flyweight> textures;
for(int i=0;i<50000;++i){
textures.push_back(
texture_flyweight(texture_filenames[std::rand()%num_texture_filenames]));
}
/* Just for the sake of making use of the key extractor,
* assign some flyweights with texture objects rather than strings.
*/
for(int j=0;j<50000;++j){
textures.push_back(
texture_flyweight(
textures[std::rand()%textures.size()].get()));
}
std::cout<<"\n"<<textures.size()<<" flyweights created\n"<<std::endl;
return 0;
}