1.1 --- a/src/work/klao/tag_demo.cc	Sun Apr 17 18:57:22 2005 +0000
     1.2 +++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.3 @@ -1,95 +0,0 @@
     1.4 -#include <iostream>
     1.5 -#include <boost/utility.hpp>
     1.6 -
     1.7 -using namespace std;
     1.8 -using namespace boost;
     1.9 -
    1.10 -struct True {
    1.11 -  static const bool value = true;
    1.12 -};
    1.13 -struct False {
    1.14 -  static const bool value = false;
    1.15 -};
    1.16 -
    1.17 -// Here are some graph structures. Some of them define the type "OneTag"
    1.18 -// to True or False, some does not. Not defining a tag is (or at least
    1.19 -// should be) equivalent to defining it to "False".
    1.20 -struct Graph1 {};
    1.21 -struct Graph2 {
    1.22 -  typedef True OneTag;
    1.23 -};
    1.24 -struct Graph3 {
    1.25 -  typedef False OneTag;
    1.26 -};
    1.27 -
    1.28 -
    1.29 -/**************** The first method to use tags ****************/
    1.30 -
    1.31 -template <typename Graph, typename Enable = void>
    1.32 -struct HasOneTag {
    1.33 -  typedef False TheTag;
    1.34 -};
    1.35 -
    1.36 -// specialization for those graphs which defined the tag to be true:
    1.37 -template <typename Graph>
    1.38 -struct HasOneTag<Graph, typename enable_if<typename Graph::OneTag>::type > {
    1.39 -  typedef True TheTag;
    1.40 -};
    1.41 -
    1.42 -template <typename Graph>
    1.43 -int cn1(const Graph &, False) {
    1.44 -  return 0;
    1.45 -}
    1.46 -
    1.47 -template <typename Graph>
    1.48 -int cn1(const Graph &, True) {
    1.49 -  return 1;
    1.50 -}
    1.51 -
    1.52 -template <typename Graph>
    1.53 -int cn1(const Graph &g) {
    1.54 -  return cn1(g, typename HasOneTag<Graph>::TheTag());
    1.55 -}
    1.56 -
    1.57 -/**************** The second method ****************/
    1.58 -
    1.59 -// An artificial type to provoke a conversion to avoid ambuguity...
    1.60 -template <typename T>
    1.61 -struct Wrap {
    1.62 -  const T &value;
    1.63 -  Wrap(const T &t) : value(t) {}
    1.64 -};
    1.65 -
    1.66 -template <typename Graph>
    1.67 -typename enable_if<typename Graph::OneTag, int>::type
    1.68 -_cn2(const Graph &) {
    1.69 -  return 1;
    1.70 -}
    1.71 -
    1.72 -template <typename Graph>
    1.73 -int _cn2(Wrap<Graph>) {
    1.74 -  return 0;
    1.75 -}
    1.76 -
    1.77 -template <typename Graph>
    1.78 -int cn2(const Graph& g) {
    1.79 -  return _cn2<Graph>(g);
    1.80 -}
    1.81 -
    1.82 -
    1.83 -int main() {
    1.84 -  Graph1 g1;
    1.85 -  Graph2 g2;
    1.86 -  Graph3 g3;
    1.87 -
    1.88 -  cout << "The first method:\n";
    1.89 -  cout << "G1: " << cn1(g1) << endl;
    1.90 -  cout << "G2: " << cn1(g2) << endl;
    1.91 -  cout << "G3: " << cn1(g3) << endl;
    1.92 -
    1.93 -  cout << "The second method:\n";
    1.94 -  cout << "G1: " << cn2(g1) << endl;
    1.95 -  cout << "G2: " << cn2(g2) << endl;
    1.96 -  cout << "G3: " << cn2(g3) << endl;
    1.97 -
    1.98 -}