1 /* Boost.Flyweight example of use of key-value flyweights.
2 *
3 * Copyright 2006-2008 Joaquin M Lopez Munoz.
4 * Distributed under the Boost Software License, Version 1.0.
5 * (See accompanying file LICENSE_1_0.txt or copy at
6 * http://www.boost.org/LICENSE_1_0.txt)
7 *
8 * See http://www.boost.org/libs/flyweight for library home page.
9 */
10
11 #include <boost/array.hpp>
12 #include <boost/flyweight.hpp>
13 #include <boost/flyweight/key_value.hpp>
14 #include <cstdlib>
15 #include <iostream>
16 #include <string>
17 #include <vector>
18
19 using namespace boost::flyweights;
20
21 /* A class simulating a texture resource loaded from file */
22
23 class texture
24 {
25 public:
texture(const std::string & filename)26 texture(const std::string& filename):filename(filename)
27 {
28 std::cout<<"loaded "<<filename<<" file"<<std::endl;
29 }
30
texture(const texture & x)31 texture(const texture& x):filename(x.filename)
32 {
33 std::cout<<"texture["<<filename<<"] copied"<<std::endl;
34 }
35
~texture()36 ~texture()
37 {
38 std::cout<<"unloaded "<<filename<<std::endl;
39 }
40
get_filename() const41 const std::string& get_filename()const{return filename;}
42
43 // rest of the interface
44
45 private:
46 std::string filename;
47 };
48
49 /* key extractor of filename strings from textures */
50
51 struct texture_filename_extractor
52 {
operator ()texture_filename_extractor53 const std::string& operator()(const texture& x)const
54 {
55 return x.get_filename();
56 }
57 };
58
59 /* texture flyweight */
60
61 typedef flyweight<
62 key_value<std::string,texture,texture_filename_extractor>
63 > texture_flyweight;
64
main()65 int main()
66 {
67 /* texture filenames */
68
69 const char* texture_filenames[]={
70 "grass.texture","sand.texture","water.texture","wood.texture",
71 "granite.texture","cotton.texture","concrete.texture","carpet.texture"
72 };
73 const int num_texture_filenames=
74 sizeof(texture_filenames)/sizeof(texture_filenames[0]);
75
76 /* create a massive vector of textures */
77
78 std::cout<<"creating flyweights...\n"<<std::endl;
79
80 std::vector<texture_flyweight> textures;
81 for(int i=0;i<50000;++i){
82 textures.push_back(
83 texture_flyweight(texture_filenames[std::rand()%num_texture_filenames]));
84 }
85
86 /* Just for the sake of making use of the key extractor,
87 * assign some flyweights with texture objects rather than strings.
88 */
89
90 for(int j=0;j<50000;++j){
91 textures.push_back(
92 texture_flyweight(
93 textures[std::rand()%textures.size()].get()));
94 }
95
96 std::cout<<"\n"<<textures.size()<<" flyweights created\n"<<std::endl;
97
98 return 0;
99 }
100