Selector.hpp

/***********************************************************************
Copyright (c) 2017, Shushman Choudhury
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Authors: Shushman Choudhury <shushmanchoudhury@gmail.com>

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#ifndef BATCHING_POMP_UTIL_SELECTOR_HPP_
#define BATCHING_POMP_UTIL_SELECTOR_HPP_

#include <algorithm>
#include <stdexcept>
#include <memory>
#include <functional>
#include <boost/property_map/dynamic_property_map.hpp>
#include <boost/graph/graphml.hpp>
#include <boost/graph/adjacency_list.hpp>

namespace batching_pomp {
namespace util {


template<class Graph>
class Selector
{

typedef boost::graph_traits<Graph> GraphTypes;
typedef typename GraphTypes::edge_descriptor Edge;

public:

  Selector(const std::string& _type)
  : mType{_type}
  {
    if(mType == "normal") {
      
      mSelectEdgeFnPtr = std::bind(&Selector<Graph>::selectEdgesNormal,this,std::placeholders::_1,std::placeholders::_2);
    }
    else if(mType == "alternate") {
      mSelectEdgeFnPtr = std::bind(&Selector<Graph>::selectEdgesAlternate,this,std::placeholders::_1,std::placeholders::_2);
    }
    else if(mType == "failfast") {
      mSelectEdgeFnPtr = std::bind(&Selector<Graph>::selectEdgesFailFast,this,std::placeholders::_1,std::placeholders::_2);
    }
    else if(mType == "maxinf") {
      mSelectEdgeFnPtr = std::bind(&Selector<Graph>::selectEdgesMaxInf,this,std::placeholders::_1,std::placeholders::_2);
    }
    else {
      throw std::invalid_argument("Invalid selector type specified - "+mType+"!");
    }
  }

  std::string getType()
  {
    return mType;
  }

  std::vector<Edge> selectEdges(const Graph& g, const std::vector<Edge>& epath) const
  {
    return mSelectEdgeFnPtr(g,epath);
  }


private:
  // For a pair of edge and probability of collision
  using EdgePair = std::pair<double,Edge>;

  // Just return in order of edges on path
  std::vector<Edge> selectEdgesNormal(const Graph& g, const std::vector<Edge>& epath) const
  {
    return epath;
  }

  // Return reverse order of edges
  std::vector<Edge> selectEdgesAlternate(const Graph& g, const std::vector<Edge>& epath) const
  {
    std::vector<Edge> reverseEpath(epath);
    std::reverse(reverseEpath.begin(),reverseEpath.end());
    return reverseEpath;
  }

  // Return in order of highest probability of collision
  std::vector<Edge> selectEdgesFailFast(const Graph& g, const std::vector<Edge>& epath) const
  {
    std::vector < EdgePair > edgeProbList;
    edgeProbList.reserve(epath.size());
    for(Edge e : epath) {
      edgeProbList.push_back(std::make_pair(g[e].probFree,e));
    }

    std::sort(edgeProbList.begin(), edgeProbList.end());

    std::vector<Edge> orderedEdges;
    orderedEdges.reserve(edgeProbList.size());
    for(EdgePair ep : edgeProbList) {
      orderedEdges.push_back(ep.second);
    }

    return orderedEdges;
  }

  // Return in order or most uncertain (closest to 0.5 probability)
  std::vector<Edge> selectEdgesMaxInf(const Graph& g, const std::vector<Edge>& epath) const
  {
    std::vector < EdgePair > edgeProbList;
    edgeProbList.reserve(epath.size());
    for(Edge e : epath) {
      edgeProbList.push_back( std::make_pair(std::fabs(g[e].probFree-0.5),e) );
    }

    std::sort(edgeProbList.begin(), edgeProbList.end());

    std::vector<Edge> orderedEdges;
    orderedEdges.reserve(edgeProbList.size());
    for(EdgePair ep : edgeProbList) {
      orderedEdges.push_back(ep.second);
    }

    return orderedEdges;
  }

  std::string mType;
  std::function< std::vector<Edge>(const Graph& g, const std::vector<Edge>& epath) > mSelectEdgeFnPtr;

};

} // namespace util
} // namespace batching_pomp

#endif // BATCHING_POMP_UTIL_SELECTOR_HPP_