boost/libs/graph/example/file_dependencies.cpp

//=======================================================================
// Copyright 1997, 1998, 1999, 2000 University of Notre Dame.
// Authors: Andrew Lumsdaine, Lie-Quan Lee, Jeremy G. Siek
//
// 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)
//=======================================================================

// Some small modifications are done by Alexander Holler

/*

  Paul Moore's request:

  As an example of a practical problem which is not restricted to graph
  "experts", consider file dependencies. It's basically graph construction,
  plus topological sort, but it might make a nice "tutorial" example. Build a
  dependency graph of files, then use the algorithms to do things like

  1. Produce a full recompilation order (topological sort, by modified date)
  2. Produce a "parallel" recompilation order (same as above, but group files
  which can be built in parallel)
  3. Change analysis (if I change file x, which others need recompiling)
  4. Dependency changes (if I add a dependency between file x and file y, what
  are the effects)

*/

#include <boost/config.hpp> // put this first to suppress some VC++ warnings

#include <iostream>
#include <iterator>
#include <algorithm>
#include <time.h>

#include <boost/utility.hpp>
#include <boost/graph/adjacency_list.hpp>
#include <boost/graph/topological_sort.hpp>
#include <boost/graph/depth_first_search.hpp>
#include <boost/graph/dijkstra_shortest_paths.hpp>
#include <boost/graph/visitors.hpp>

using namespace std;
using namespace boost;

enum files_e
{
    dax_h,
    yow_h,
    boz_h,
    zow_h,
    foo_cpp,
    foo_o,
    bar_cpp,
    bar_o,
    libfoobar_a,
    zig_cpp,
    zig_o,
    zag_cpp,
    zag_o,
    libzigzag_a,
    killerapp,
    N
};
const char* name[] = { "dax.h", "yow.h", "boz.h", "zow.h", "foo.cpp", "foo.o",
    "bar.cpp", "bar.o", "libfoobar.a", "zig.cpp", "zig.o", "zag.cpp", "zag.o",
    "libzigzag.a", "killerapp" };

struct print_visitor : public bfs_visitor<>
{
    template < class Vertex, class Graph >
    void discover_vertex(Vertex v, Graph&)
    {
        cout << name[v] << " ";
    }
};

struct cycle_detector : public dfs_visitor<>
{
    cycle_detector(bool& has_cycle) : m_has_cycle(has_cycle) {}

    template < class Edge, class Graph > void back_edge(Edge, Graph&)
    {
        m_has_cycle = true;
    }

protected:
    bool& m_has_cycle;
};

int main(int, char*[])
{

    typedef pair< int, int > Edge;
    Edge used_by[] = { Edge(dax_h, foo_cpp), Edge(dax_h, bar_cpp),
        Edge(dax_h, yow_h), Edge(yow_h, bar_cpp), Edge(yow_h, zag_cpp),
        Edge(boz_h, bar_cpp), Edge(boz_h, zig_cpp), Edge(boz_h, zag_cpp),
        Edge(zow_h, foo_cpp), Edge(foo_cpp, foo_o), Edge(foo_o, libfoobar_a),
        Edge(bar_cpp, bar_o), Edge(bar_o, libfoobar_a),
        Edge(libfoobar_a, libzigzag_a), Edge(zig_cpp, zig_o),
        Edge(zig_o, libzigzag_a), Edge(zag_cpp, zag_o),
        Edge(zag_o, libzigzag_a), Edge(libzigzag_a, killerapp) };
    const std::size_t nedges = sizeof(used_by) / sizeof(Edge);

    typedef adjacency_list< vecS, vecS, bidirectionalS > Graph;
#if defined(BOOST_MSVC) && BOOST_MSVC <= 1300
    // VC++ can't handle the iterator constructor
    Graph g(N);
    for (std::size_t j = 0; j < nedges; ++j)
    {
        graph_traits< Graph >::edge_descriptor e;
        bool inserted;
        boost::tie(e, inserted)
            = add_edge(used_by[j].first, used_by[j].second, g);
    }
#else
    Graph g(used_by, used_by + nedges, N);
#endif
    typedef graph_traits< Graph >::vertex_descriptor Vertex;

    // Determine ordering for a full recompilation
    // and the order with files that can be compiled in parallel
    {
        typedef list< Vertex > MakeOrder;
        MakeOrder::iterator i;
        MakeOrder make_order;

        topological_sort(g, std::front_inserter(make_order));
        cout << "make ordering: ";
        for (i = make_order.begin(); i != make_order.end(); ++i)
            cout << name[*i] << " ";

        cout << endl << endl;

        // Parallel compilation ordering
        std::vector< int > time(N, 0);
        for (i = make_order.begin(); i != make_order.end(); ++i)
        {
            // Walk through the in_edges an calculate the maximum time.
            if (in_degree(*i, g) > 0)
            {
                Graph::in_edge_iterator j, j_end;
                int maxdist = 0;
                // Through the order from topological sort, we are sure that
                // every time we are using here is already initialized.
                for (boost::tie(j, j_end) = in_edges(*i, g); j != j_end; ++j)
                    maxdist = (std::max)(time[source(*j, g)], maxdist);
                time[*i] = maxdist + 1;
            }
        }

        cout << "parallel make ordering, " << endl
             << "vertices with same group number can be made in parallel"
             << endl;
        {
            graph_traits< Graph >::vertex_iterator i, iend;
            for (boost::tie(i, iend) = vertices(g); i != iend; ++i)
                cout << "time_slot[" << name[*i] << "] = " << time[*i] << endl;
        }
    }
    cout << endl;

    // if I change yow.h what files need to be re-made?
    {
        cout << "A change to yow.h will cause what to be re-made?" << endl;
        print_visitor vis;
        breadth_first_search(g, vertex(yow_h, g), visitor(vis));
        cout << endl;
    }
    cout << endl;

    // are there any cycles in the graph?
    {
        bool has_cycle = false;
        cycle_detector vis(has_cycle);
        depth_first_search(g, visitor(vis));
        cout << "The graph has a cycle? " << has_cycle << endl;
    }
    cout << endl;

    // add a dependency going from bar.cpp to dax.h
    {
        cout << "adding edge bar_cpp -> dax_h" << endl;
        add_edge(bar_cpp, dax_h, g);
    }
    cout << endl;

    // are there any cycles in the graph?
    {
        bool has_cycle = false;
        cycle_detector vis(has_cycle);
        depth_first_search(g, visitor(vis));
        cout << "The graph has a cycle now? " << has_cycle << endl;
    }

    return 0;
}