c++ - copy_graph - adjacency_list with bundled properties

Question

Here is a complete snippet to copy a graph with bundled properties, but results in bunch of compiler errors. What is needed to fix the problems?

struct NodeInfo1    {};
struct EdgeInfo1 {};

typedef boost::labeled_graph< boost::adjacency_list<
    boost::vecS, boost::vecS, boost::undirectedS, NodeInfo1, EdgeInfo1>,
    std::string> Graph1;

typedef std::pair<boost::graph_traits<Graph>::edge_descriptor, bool> Edge;


void TestCases::TestCopyGraph()
{
    Graph1 grid, g1;
    EdgeInfo1 ei;

    Edge e = add_edge_by_label("A", "B", ei, grid);
    copy_graph(grid, g1);
}

Answer 1

That's slightly misrepresenting the question. You're not actually copying the adjacency list, you're copying the labeled_graph adaptor, which happens to not satisfy the concepts required by copy_graph:

/** @name Labeled Mutable Graph
 * The labeled mutable graph hides the add_ and remove_ vertex functions from
 * the mutable graph concept. Note that the remove_vertex is hidden because
 * removing the vertex without its key could leave a dangling reference in
 * the map.
 */

Here's copying the adjacency_list: 1

typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, NodeInfo1, EdgeInfo1> AList;
typedef boost::labeled_graph<AList, std::string> Graph;

void TestCopyGraph()
{
    std::string names[3] = { "A", "B", "C" };
    Graph grid(3, names);
    EdgeInfo1 ei;

    /*auto e =*/ add_edge_by_label("C", "B", ei, grid);

    AList g1;
    copy_graph(grid, g1);
}

Copying the Labeled adaptor

Is much easier. No copy_graph required, just copy-construct the object:

#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/copy.hpp>
#include <boost/graph/labeled_graph.hpp>
#include <boost/graph/graph_utility.hpp>

struct NodeInfo1 { int i; };
struct EdgeInfo1 { int j; };

typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::undirectedS, NodeInfo1, EdgeInfo1> AList;
typedef boost::labeled_graph<AList, std::string> Graph;

auto TestCopyGraph()
{
    std::string names[3] = { "A", "B", "C" };
      NodeInfo1 props[3] = { {11}, {22}, {33} };
    Graph grid(3, names, props);
    /*auto e =*/ add_edge_by_label("C", "B", EdgeInfo1{17}, grid);

    Graph g1 = grid; // just copy-construct
    return g1;
}

int main() {
    auto copied = TestCopyGraph();

    print_graph(copied);

    // check that properties were copied: vertex B has NodeInfo1 22
    {
        auto pmap = boost::get(&NodeInfo1::i, copied);
        std::cout << "Vertex B NodeInfo1.i after copy: " << pmap[copied.vertex("B")] << "
";
    }

    // edge properties too:
    for (auto e : boost::make_iterator_range(edges(copied)))
        std::cout << "Edge has property EdgeInfo1 " << copied[e].j << "
";

    std::cout << "Removed A:
";
    copied.remove_vertex("A");
    print_graph(copied);
}

Prints

0 <--> 
1 <--> 2 
2 <--> 1 
Vertex B NodeInfo1.i after copy: 22
Edge has property EdgeInfo1 17
Removed A:
0 <--> 1 
1 <--> 0 

1 Note that you need this patch because of bugs in labeled_graph: https://github.com/boostorg/graph/pull/58