I have attached a minimal working program to test the sort function on a list of
edges.
Compile with : g++ -O3 prog.cpp -o prog
The problem is line "myList.sort(SortByName< graph_t >);" near the
bottom of the page.
See comments.
//=======================================================================
// Sort Testing Program - prog.cpp
//=======================================================================
#include <iostream>
#include <string>
#include
#include
using namespace boost;
using namespace std;
struct vertex_properties
{
};
struct edge_properties
{
string eName;
};
typedef adjacency_list < vecS, vecS, bidirectionalS >::edge_descriptor edge_t;
typedef adjacency_list < vecS, vecS, bidirectionalS >::vertex_descriptor
vertex_t;
typedef adjacency_list < vecS, vecS, bidirectionalS, vertex_properties,
edge_properties > graph_t;
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
template < typename Graph >
void add_edges(Graph & g)
{ // Add some edges with names.
typename graph_traits<Graph>::edge_iterator edge_iter, edges_end;
std::pair< typename graph_traits<Graph>::edge_descriptor, bool > a =
add_edge(1,2,g); g[a.first].eName = "A";
std::pair< typename graph_traits<Graph>::edge_descriptor, bool > b =
add_edge(1,3,g); g[b.first].eName = "B";
std::pair< typename graph_traits<Graph>::edge_descriptor, bool > c =
add_edge(2,1,g); g[c.first].eName = "C";
std::pair< typename graph_traits<Graph>::edge_descriptor, bool > d =
add_edge(2,3,g); g[d.first].eName = "D";
cout << endl << " list of edges " << endl;
for (tie(edge_iter, edges_end) = edges(g); edge_iter != edges_end;
++edge_iter)
cout << " " << g[*edge_iter].eName << endl;
}
template < typename Graph >
struct SortByName
{ // The Predicate
template < typename edge_t >
bool operator()(const edge_t& a, const edge_t& b) const
{
return g[a].eName < g[b].eName;
}
Graph g;
};
template < typename Graph >
void Sort_Test(Graph & g)
{ // Test the sort function.
typedef std::list::edge_descriptor> edge_list;
typename graph_traits<Graph>::edge_iterator edge_iter, edges_end;
edge_list myList;
// Load myList with the edges of g
for (tie(edge_iter, edges_end) = edges(g); edge_iter != edges_end;
++edge_iter)
myList.push_back(*edge_iter);
// Write out myList
cout << endl << " myList " << endl;
for (edge_list::iterator i = myList.begin(); i != myList.end(); ++i)
cout << " " << g[*i].eName << endl;
// Sort myList
// If the following line is commented out the program compiles and runs OK.
myList.sort(SortByName< graph_t >);
//With the above line uncommented the compiler says:
// "prog.cpp:88: error: ‘graph_t’ is not a template" -- I'm stumped.
}
int main()
{
graph_t g;
add_edges(g);
Sort_Test(g);
}
________________________________
From: Cedric Laczny
To: boost-users@lists.boost.org
Sent: Sat, November 6, 2010 3:54:49 AM
Subject: Re: [Boost-users] [BGL] Unable to sort list of edge_descriptors
if my suggestion does not fix the problem, please include a complete example.
