more const correctness and an overhaul of the path data structure

Graphtheory/Edge.cpp

 #include "Edge.h"
 
-Edge::Edge(const Edge& remote_edge, const std::map<Node*, Node*>& node_lookup) : _description(remote_edge._description), _from(node_lookup.find(remote_edge._from)->second), _to(node_lookup.find(remote_edge._to)->second), _attributes(remote_edge._attributes) {
+Edge::Edge(const Edge& remote_edge, const std::map<const Node*, Node*>& node_lookup) : _description(remote_edge._description), _from(node_lookup.find(remote_edge._from)->second), _to(node_lookup.find(remote_edge._to)->second), _attributes(remote_edge._attributes) {
   this->_from->add_incident(this);
   this->_to->add_incident(this);
 }
@@ -50,7 +50,7 @@ void Edge::reconnect(){
   this->to()->incident().insert(this);
 }
 
-std::ostream& operator<<(std::ostream& os, Edge& e){
+std::ostream& operator<<(std::ostream& os, const Edge& e){
   if(&os == &std::cout){
     os << "\033[0;32m";
     os << "Edge " << e.description() << " ( ";

Graphtheory/Edge.h

@@ -24,7 +24,7 @@ class Edge{
 public:
   Edge(const Edge& local_edge) : _description(local_edge._description), _from(local_edge._from), _to(local_edge._to), _attributes(local_edge._attributes) {}
   Edge(Edge&& local_edge) : _description(std::move(local_edge._description)), _from(std::move(local_edge._from)), _to(std::move(local_edge._to)), _attributes(std::move(local_edge._attributes)) {}
-  Edge(const Edge& remote_edge, const std::map<Node*, Node*>& node_lookup);
+  Edge(const Edge& remote_edge, const std::map<const Node*, Node*>& node_lookup);
 
   Edge(Node* from, Node* to, std::string description, std::map<std::string, Attribute> attributes = {});
   Edge(std::istream& is, const std::map<std::string, Node* >& name_lookup);
@@ -37,21 +37,21 @@ public:
     return this->_description;
   }
 
-  Node* const & from() const {
+  Node* from() const {
     return this->_from;
   }
   Node*& from() {
     return this->_from;
   }
 
-  Node* const & to() const {
+  Node* to() const {
     return this->_to;
   }
   Node*& to() {
     return this->_to;
   }
 
-  Node* const & to(const Node* node) const {
+  Node* to(const Node* node) const {
     if(node != this->to() && node != this->from()) throw std::range_error("node not incident to edge");
     return node == this->from() ? this->to() : this->from();
   }
@@ -63,6 +63,7 @@ public:
   const std::map<std::string, Attribute>& attributes() const {
     return this->_attributes;
   }
+  
   std::map<std::string, Attribute>& attributes() {
     return this->_attributes;
   }
@@ -85,6 +86,16 @@ public:
     return search->second;
   }
 
+  const Attribute& attribute_throwing(const std::string& attr) const {
+    auto search = this->_attributes.find(attr);
+    if(search == this->_attributes.end()){
+      std::stringstream text;
+      text << "\"" << attr << "\" is not defined for Node " << this->description();
+      throw std::range_error(text.str());
+    }
+    return search->second;
+  }
+
   void disconnect();
 
   void reconnect();
@@ -109,6 +120,6 @@ public:
   void dump();
 };
 
-std::ostream& operator<<(std::ostream& os, Edge& e);
+std::ostream& operator<<(std::ostream& os, const Edge& e);
 
 #endif

Graphtheory/Generators/random_graph_generator.cpp

@@ -30,8 +30,12 @@ std::pair<std::pair<Node*, Node*>,Graph> random_graph_generator::next_acyclic_2_
   while(!random_graph_generator::grow_random_acyclic(g, this->_number_of_nodes, this->_number_of_edges, this->_edge_generator, this->_node_generator).first){
     std::cout << "generation failed; retrying!" << std::endl;
   }
-  auto tips = g.tip_fringes(this->_edge_generator, this->_node_generator);
-  return {tips, std::move(g)};
+  auto [source, target] = g.tip_fringes(this->_edge_generator, this->_node_generator);
+
+  source->add_attribute("Source", Attribute({fix, 1, Integral}) );
+  target->add_attribute("Target", Attribute({fix, 1, Integral}) );
+
+  return {{source, target}, std::move(g)};
 }
 
 std::pair<std::pair<Node*, Node*>, Graph> random_graph_generator::next_acyclic_in_steps_2_tips(size_t steps, size_t fading){
@@ -39,8 +43,12 @@ std::pair<std::pair<Node*, Node*>, Graph> random_graph_generator::next_acyclic_i
   while(!random_graph_generator::grow_random_acyclic_in_steps(g, this->_number_of_nodes/steps, this->_number_of_edges/steps, steps, fading, this->_edge_generator, this->_node_generator).first){
     std::cout << "generation failed; retrying!" << std::endl;
   }
-  auto tips = g.tip_fringes(this->_edge_generator, this->_node_generator);
-  return {tips, std::move(g)};
+  auto [source, target] = g.tip_fringes(this->_edge_generator, this->_node_generator);
+
+  source->add_attribute("Source", Attribute({fix, 1, Integral}) );
+  target->add_attribute("Target", Attribute({fix, 1, Integral}) );
+
+  return {{source, target}, std::move(g)};
 }
 
 

Graphtheory/Graph.h

@@ -37,10 +37,10 @@ public:
   Graph(Graph& graph);
   Graph(Graph&& graph);
 
-  Edge* const add_edge(Node* from, Node* to, const std::string& description, const std::map<std::string,Attribute>& edge_attributes = {});
-  Edge* const add_edge(Edge* remote_edge, const std::map<Node*, Node*>& node_lookup);
-  Node* const add_node(std::string description, const std::map<std::string, Attribute>& node_attributes = {});
-  Node* const add_node(Node* remote_node);
+  Edge* add_edge(Node* from, Node* to, const std::string& description, const std::map<std::string,Attribute>& edge_attributes = {});
+  Edge* add_edge(const Edge* remote_edge, const std::map<const Node*, Node*>& node_lookup);
+  Node* add_node(std::string description, const std::map<std::string, Attribute>& node_attributes = {});
+  Node* add_node(const Node* remote_node);
 
   void remove_node(Node* node);
   void remove_edge(Edge* edge);
@@ -53,7 +53,14 @@ public:
     return this->_nodes;
   }
 
-  std::pair<bool, Attribute> node_template(const std::string& attr) const{
+  std::set<const Edge*> edges() const {
+    return std::set<const Edge*>(this->_edges.begin(), this->_edges.end());
+  }
+  std::set<const Node*> nodes() const {
+    return std::set<const Node*>(this->_nodes.begin(), this->_nodes.end());
+  }
+
+  std::pair<bool, Attribute> node_template(const std::string& attr) const{ // TODO: change to returning iterator to support external manipulation and proper const functions
     auto search = this->_template_node_attributes.find(attr);
     if(search == this->_template_node_attributes.end()){
       return {false, {fix, 0}};
@@ -69,7 +76,27 @@ public:
     return {true, search->second};
   }
 
-  Attribute edge_template_throwing(const std::string& attr){
+  Attribute& edge_template_throwing(const std::string& attr){
+    auto search = this->_template_edge_attributes.find(attr);
+    if(search == this->_template_edge_attributes.end()){
+      std::stringstream text;
+      text << "\"" << attr << "\" is not defined by default for Edges in used Graph";
+      throw std::range_error(text.str());
+    }
+    return search->second;
+  }
+
+  Attribute& node_template_throwing(const std::string& attr){
+    auto search = this->_template_node_attributes.find(attr);
+    if(search == this->_template_node_attributes.end()){
+      std::stringstream text;
+      text << "\"" << attr << "\" is not defined by default for Nodes in used Graph";
+      throw std::range_error(text.str());
+    }
+    return search->second;
+  }
+
+  const Attribute& edge_template_throwing(const std::string& attr) const {
     auto search = this->_template_edge_attributes.find(attr);
     if(search == this->_template_edge_attributes.end()){
       std::stringstream text;
@@ -79,7 +106,7 @@ public:
     return search->second;
   }
 
-  Attribute node_template_throwing(const std::string& attr){
+  const Attribute& node_template_throwing(const std::string& attr) const {
     auto search = this->_template_node_attributes.find(attr);
     if(search == this->_template_node_attributes.end()){
       std::stringstream text;
@@ -106,6 +133,10 @@ public:
     Node* s, Node* t,
     std::function<bool(Node* from, Edge* via)> guide = [](Node* n, Edge* e)->bool {return e->from() == n;}
   );
+  std::pair<bool, const Path> directed_admissible_st_path(
+    const Node* s, const Node* t,
+    std::function<bool(const Node* from, const Edge* via)> guide = [](const Node* n, const Edge* e)->bool {return e->from() == n;}
+  ) const ;
   std::pair<bool, Path> directed_admissible_st_path(
     Node* s, Node* t,
     std::string opt_attr,
@@ -116,15 +147,19 @@ public:
   // _select_opertations
   std::set<Edge*> gather_edges(std::vector<std::string> attributes);
   std::set<Node*> gather_nodes(std::vector<std::string> attributes);
+  std::set<const Edge*> gather_edges(std::vector<std::string> attributes) const ;
+  std::set<const Node*> gather_nodes(std::vector<std::string> attributes) const ;
 
 
   // fringe_operations
   std::vector<Node*> select_targets();
+  std::vector<const Node*> select_targets() const ;
   Node* tip_targets(
     random_attribute_generator edge_attribute_generator = {{}},
     random_attribute_generator node_attribute_generator = {{}}
   );
   std::vector<Node*> select_sources();
+  std::vector<const Node*> select_sources() const ;
   Node* tip_sources(
     random_attribute_generator edge_attribute_generator = {{}},
     random_attribute_generator node_attribute_generator = {{}}
@@ -140,6 +175,14 @@ public:
     bool all_paths = false,
     std::function<bool(Node* from, Edge* via)> guide = [](Node* n, Edge* e)->bool {return e->from() == n;}
   );
+  void conditional_bfs_all_components(
+    std::function<void(const Node* from, const Edge* via, bool used_in_traversal)> edge_exec,
+    std::function<bool(const Edge* via, const Node* node)> node_exec,
+    std::deque<const Node*> starting_nodes = {},
+    bool all_paths = false,
+    std::function<bool(const Node* from, const Edge* via)> guide = [](const Node* n, const Edge* e)->bool {return e->from() == n;}
+  ) const ;
+
 
   // _flow_algorithms.cpp:
   double ford_fulkerson(Node* s, Node* t, std::string opt_attr, std::string lower_limit_attr, std::string upper_limit_attr);
@@ -147,19 +190,19 @@ public:
 
   // _special_members_and_operators:
   void operator=(const Graph& graph);
-  std::pair< Graph, std::map<Node*, Node*> > copy_ret_lookup() const;
+  std::pair< Graph, std::map<const Node*, Node*> > copy_ret_lookup() const;
   void operator=(Graph&& graph);
 
   // _debug_helpers (Graph.ipp)
   void dump();
 
   // friendships:
-  friend std::ostream& operator<<(std::ostream& os, Graph& g);
+  friend std::ostream& operator<<(std::ostream& os, const Graph& g);
 
   friend std::istream& operator>>(std::istream& is, Graph& g);
 };
 
-std::ostream& operator<<(std::ostream& os, Graph& g);
+std::ostream& operator<<(std::ostream& os, const Graph& g);
 
 std::istream& operator>>(std::istream& is, Graph& g);
 

Graphtheory/Graph.ipp

 Graph::Graph(std::map<std::string, Attribute> default_values_edge_attributes, std::map<std::string, Attribute> default_values_node_attributes) : _template_node_attributes(std::move(default_values_node_attributes)), _template_edge_attributes(std::move(default_values_edge_attributes)){}
 
-Edge* const Graph::add_edge(Node* from, Node* to, const std::string& description, const std::map<std::string, Attribute>& edge_attributes){
+Edge* Graph::add_edge(Node* from, Node* to, const std::string& description, const std::map<std::string, Attribute>& edge_attributes){
   std::map<std::string, Attribute> unified_attr = this->_template_edge_attributes;
   for(std::pair<std::string, Attribute> overriding_attr : edge_attributes){
     auto new_or_not = unified_attr.insert(overriding_attr);
@@ -9,18 +9,18 @@ Edge* const Graph::add_edge(Node* from, Node* to, const std::string& description
     }
   }
 
-  Edge* const ptr = new Edge(from, to, description, unified_attr);
+  Edge* ptr = new Edge(from, to, description, unified_attr);
   this->edges().insert(ptr);
   return ptr;
 }
 
-Edge* const Graph::add_edge(Edge* remote_edge, const std::map<Node*, Node*>& node_lookup){
-  Edge* const ptr = new Edge(*remote_edge, node_lookup);
+Edge* Graph::add_edge(const Edge* remote_edge, const std::map<const Node*, Node*>& node_lookup){
+  Edge* ptr = new Edge(*remote_edge, node_lookup);
   this->edges().insert(ptr);
   return ptr;
 }
 
-Node* const Graph::add_node(std::string description, const std::map<std::string, Attribute>& node_attributes){
+Node* Graph::add_node(std::string description, const std::map<std::string, Attribute>& node_attributes){
   std::map<std::string, Attribute> unified_attr = this->_template_node_attributes;
   for(std::pair<std::string, Attribute> overriding_attr : node_attributes){
     auto new_or_not = unified_attr.insert(overriding_attr);
@@ -29,13 +29,13 @@ Node* const Graph::add_node(std::string description, const std::map<std::string,
     }
   }
 
-  Node* const ptr = new Node(description, unified_attr);
+  Node* ptr = new Node(description, unified_attr);
   this->nodes().insert(ptr);
   return ptr;
 }
 
-Node* const Graph::add_node(Node* remote_node){
-  Node* const ptr = new Node(*remote_node);
+Node* Graph::add_node(const Node* remote_node){
+  Node* ptr = new Node(*remote_node);
   this->nodes().insert(ptr);
   return ptr;
 }
@@ -67,16 +67,16 @@ void Graph::reset_attribute_values(const std::set<std::string>& edge_attr, const
   }
 }
 
-std::ostream& operator<<(std::ostream& os, Graph& g){
+std::ostream& operator<<(std::ostream& os, const Graph& g){
   if(&os == &std::cout){
     os << "\033[0;31m";
     os << "Graph { Nodes { \n";
-    for(Node* n : g.nodes()){
+    for(const Node* n : g.nodes()){
       os << *n << "\n";
     }
     os << "\033[0;31m";
     os << "} Edges {" << "\n";
-    for(Edge* e : g.edges()){
+    for(const Edge* e : g.edges()){
       os << *e << "\n";
     }
     os << "\033[0;31m";
@@ -84,11 +84,11 @@ std::ostream& operator<<(std::ostream& os, Graph& g){
     os << "\033[0m";
   }else{
     os << "Graph { Nodes { \n";
-    for(Node* n : g.nodes()){
+    for(const Node* n : g.nodes()){
       os << *n << "\n";
     }
     os << "} Edges {" << "\n";
-    for(Edge* e : g.edges()){
+    for(const Edge* e : g.edges()){
       os << *e << "\n";
     }
     os << "} \nNode_Defaults { ";

Graphtheory/Graph_advanced.ipp

@@ -112,3 +112,55 @@ void Graph::conditional_bfs_all_components(
     }
   }
 }
+
+void Graph::conditional_bfs_all_components(
+  std::function<void(const Node* from, const Edge* via, bool used_in_traversal)> edge_exec,
+  std::function<bool(const Edge* via, const Node* node)> node_exec,
+  std::deque<const Node*> starting_nodes,
+  bool all_paths,
+  std::function<bool(const Node* from, const Edge* via)> guide
+) const {
+  /*
+    executes edge_exec and node_exec for every edge or node in visiting order. Also executes for unused edges that test positive w.r.t guide
+    !! possibly executes twice if guide allows !!
+    node_exec will be called with nullptr for via for start node
+    node_exec might be called with nullptr for via if the graph is not strongly connected
+
+    if node_exec returns true traversal over its incident edges will be forced no matter their visitation status
+  */
+
+
+  std::set<const Node*> uncharted = this->nodes();
+  std::deque<std::pair<const Edge*, const Node*>> active;
+  for(const Node* node : starting_nodes){
+    active.push_back({nullptr, node});
+  }
+
+  while(!uncharted.empty()){
+    if(active.empty()){
+      active.push_back({nullptr, *uncharted.begin()});
+      uncharted.erase(*uncharted.begin());
+    }
+    while(!active.empty()){
+      std::pair<const Edge*, const Node*> next = active.front(); active.pop_front();
+      bool local_all_paths = node_exec(next.first, next.second);
+
+      const Node* n = next.second;
+
+      for(const Edge* e : n->incident()){
+        bool used_in_traversal = false;
+
+        if(guide(n, e)){
+          if(uncharted.find(e->to(n)) != uncharted.end() || all_paths || local_all_paths) {
+            used_in_traversal = true;
+
+            active.push_back({e, e->to(n)});
+            uncharted.erase(e->to(n));
+          }
+
+          edge_exec(n, e, used_in_traversal);
+        }
+      }
+    }
+  }
+}

Graphtheory/Graph_fringe_operations.ipp

@@ -2,10 +2,28 @@
   targets
 */
 
-std::vector<Node*> Graph::select_targets(){
+std::vector<Node*> Graph::select_targets(){ // TODO: rename to terminal / extreme or similar
   std::vector<Node*> targets;
-  for(Node* n : this->nodes()){
-    if(n->is_target()){
+  for(Node* n : this->_nodes){
+    bool is_terminal_target = true;
+    for(Edge* e : n->incident()){
+      if(n == e->from()) is_terminal_target = false;
+    }
+    if(is_terminal_target){
+      targets.push_back(n);
+    }
+  }
+  return targets;
+}
+
+std::vector<const Node*> Graph::select_targets() const {
+  std::vector<const Node*> targets;
+  for(Node* n : this->_nodes){
+    bool is_terminal_target = true;
+    for(Edge* e : n->incident()){
+      if(n == e->from()) is_terminal_target = false;
+    }
+    if(is_terminal_target){
       targets.push_back(n);
     }
   }
@@ -42,8 +60,26 @@ Node* Graph::tip_targets(random_attribute_generator edge_attribute_generator, ra
 
 std::vector<Node*> Graph::select_sources(){
   std::vector<Node*> sources;
-  for(Node* n : this->nodes()){
-    if(n->is_source()){
+  for(Node* n : this->_nodes){
+    bool is_terminal_source = true;
+    for(Edge* e : n->incident()){
+      if(n == e->to()) is_terminal_source = false;
+    }
+    if(is_terminal_source){
+      sources.push_back(n);
+    }
+  }
+  return sources;
+}
+
+std::vector<const Node*> Graph::select_sources() const {
+  std::vector<const Node*> sources;
+  for(Node* n : this->_nodes){
+    bool is_terminal_source = true;
+    for(Edge* e : n->incident()){
+      if(n == e->to()) is_terminal_source = false;
+    }
+    if(is_terminal_source){
       sources.push_back(n);
     }
   }

Graphtheory/Graph_path_operations.ipp

 std::pair<bool, Path> Graph::directed_admissible_st_path(Node* s, Node* t, std::function<bool(Node* from, Edge* via)> guide){
-  std::map<const Node*, Edge*> predecessor;
+  std::unordered_map<Node*, Edge*> predecessor;
   std::queue<Node*> active;
   active.push(s);
 
@@ -20,7 +20,7 @@ std::pair<bool, Path> Graph::directed_admissible_st_path(Node* s, Node* t, std::
     }
   }
 
-  Path p = Path(this, predecessor,t);
+  Path p = Path(this, predecessor, t);
   if(predecessor.find(t) == predecessor.end() && s != t){
     return {false, p};
   }
@@ -35,3 +35,8 @@ std::pair<bool, Path> Graph::directed_admissible_st_path(Node* s, Node* t, std::
   };
   return this->directed_admissible_st_path(s, t, f);
 }
+
+std::pair<bool, const Path> Graph::directed_admissible_st_path(const Node* s, const Node* t, std::function<bool(const Node* from, const Edge* via)> guide) const {
+  std::cout << "calling path creation method for const graph" << std::endl;
+  return const_cast<Graph*>(this)->directed_admissible_st_path(const_cast<Node*>(s), const_cast<Node*>(t), [guide](Node* from, Edge* via){return guide(from, via);});
+}

Graphtheory/Graph_select_operations.ipp

@@ -29,3 +29,34 @@ std::set<Node*> Graph::gather_nodes(std::vector<std::string> attributes){
 
   return nodes;
 }
+
+
+std::set<const Edge*> Graph::gather_edges(std::vector<std::string> attributes) const {
+  std::set<const Edge*> edges;
+
+  for(Edge* e : this->_edges){
+    for(std::string attribute_name :  attributes){
+      auto attribute_search = e->attribute(attribute_name);
+      if(attribute_search.first && attribute_search.second.value()){
+        edges.insert(e);
+      }
+    }
+  }
+
+  return edges;
+}
+
+
+std::set<const Node*> Graph::gather_nodes(std::vector<std::string> attributes) const {
+  std::set<const Node*> nodes;
+  for(Node* n : this->_nodes){
+    for(std::string attribute_name :  attributes){
+      auto attribute_search = n->attribute(attribute_name);
+      if(attribute_search.first && attribute_search.second.value()){
+        nodes.insert(n);
+      }
+    }
+  }
+
+  return nodes;
+}

Graphtheory/Graph_special_members_and_operators.ipp

@@ -11,17 +11,17 @@ Graph::Graph(Graph&& graph)
   graph._template_edge_attributes = {};
 }
 
-std::pair< Graph, std::map<Node*, Node*> > Graph::copy_ret_lookup() const{
+std::pair< Graph, std::map<const Node*, Node*> > Graph::copy_ret_lookup() const{
   Graph copy (this->_template_edge_attributes, this->_template_node_attributes);
 
-  std::map<Node*, Node*> node_lookup;
+  std::map<const Node*, Node*> node_lookup;
 
-  for(Node* node : this->_nodes){
+  for(const Node* node : this->_nodes){
       Node* new_node = copy.add_node(node);
       node_lookup.insert({node, new_node});
   }
 
-  for(Edge* edge : this->_edges){
+  for(const Edge* edge : this->_edges){
     copy.add_edge(edge, node_lookup);
   }
 

Graphtheory/Node.cpp

@@ -31,7 +31,7 @@ Node::Node(std::istream& is){
     }
   }
 }
-
+/*
 bool Node::is_target() const {
   for(Edge* e : this->incident()){
     if(this == e->from()) return false;
@@ -45,14 +45,14 @@ bool Node::is_source() const {
   }
   return true;
 }
-
+*/
 Node::~Node(){
   while(this->incident().begin() != this->incident().end()){
     delete *this->incident().begin();
   }
 }
 
-std::ostream& operator<<(std::ostream& os, Node& n){
+std::ostream& operator<<(std::ostream& os, const Node& n){
   if(&os == &std::cout){
     os << "\033[0;36m";
     os << "Node " << n.description() << " ( ";

Graphtheory/Node.h

@@ -85,17 +85,28 @@ public:
     return search->second;
   }
 
+  Attribute& add_attribute(const std::string attr_name, Attribute attr){
+    auto [iter, success] = this->_attributes.insert({attr_name, attr});
+
+    if(!success) {
+      std::stringstream text;
+      text << "\"" << attr << "\" is could not be added to Node " << this->description();
+      throw std::range_error(text.str());
+    }
+    return iter->second;
+  }
+/*
   bool is_target() const;
 
   bool is_source() const;
-
+*/
   ~Node();
 
   // _debug_helpers
   void dump();
 };
 
-std::ostream& operator<<(std::ostream& os, Node& n);
+std::ostream& operator<<(std::ostream& os, const Node& n);
 std::istream& operator>>(std::istream& is, Node& n);
 
 #endif

Graphtheory/Path.cpp

 #include "Path.h"
+#include <cfloat>
+
+Path::Path(Graph* graph, std::unordered_map<Node*, Edge*>& successor_matrix, Node* start, bool invert_order) : _owner(graph){
+  std::unordered_map<Node*, Edge*>& given_dir = this->_next_edge;
+  std::unordered_map<Node*, Edge*>& opposing_dir = this->_prev_edge;
+
+  if(invert_order){
+    given_dir = this->_prev_edge;
+    opposing_dir = this->_next_edge;
+  }
 
-Path::Path(Graph* graph, std::map<const Node*, Edge*>& successor_matrix, Node* start, bool invert_order) : _owner(graph){
   Node* curr = start;
+  auto curr_iter = successor_matrix.find(curr);
+  while(curr_iter != successor_matrix.end()){
+    given_dir.insert({curr, curr_iter->second});
+    opposing_dir.insert({curr_iter->second->to(curr), curr_iter->second});
 
-  while(successor_matrix.find(curr) != successor_matrix.end()){
-    if(!invert_order){
-      this->edges().push_back(successor_matrix.find