cprover
grapht< N > Class Template Reference

A generic directed graph with a parametric node type. More...

#include <graph.h>

+ Inheritance diagram for grapht< N >:
+ Collaboration diagram for grapht< N >:

Classes

class  tarjant
 

Public Types

typedef N nodet
 
typedef nodet::edgest edgest
 
typedef std::vector< nodetnodest
 
typedef nodet::edget edget
 
typedef nodet::node_indext node_indext
 
typedef std::list< node_indextpatht
 

Public Member Functions

node_indext add_node ()
 
void swap (grapht &other)
 
bool has_edge (node_indext i, node_indext j) const
 
const nodetoperator[] (node_indext n) const
 
nodetoperator[] (node_indext n)
 
void resize (node_indext s)
 
std::size_t size () const
 
bool empty () const
 
const edgestin (node_indext n) const
 
const edgestout (node_indext n) const
 
void add_edge (node_indext a, node_indext b)
 
void remove_edge (node_indext a, node_indext b)
 
edgetedge (node_indext a, node_indext b)
 
void add_undirected_edge (node_indext a, node_indext b)
 
void remove_undirected_edge (node_indext a, node_indext b)
 
void remove_in_edges (node_indext n)
 
void remove_out_edges (node_indext n)
 
void remove_edges (node_indext n)
 
void clear ()
 
void shortest_path (node_indext src, node_indext dest, patht &path) const
 
void shortest_loop (node_indext node, patht &path) const
 
void visit_reachable (node_indext src)
 
std::vector< node_indextget_reachable (node_indext src, bool forwards) const
 Run depth-first search on the graph, starting from a single source node. More...
 
std::vector< node_indextget_reachable (const std::vector< node_indext > &src, bool forwards) const
 Run depth-first search on the graph, starting from multiple source nodes. More...
 
void disconnect_unreachable (node_indext src)
 Removes any edges between nodes in a graph that are unreachable from a given start node. More...
 
void disconnect_unreachable (const std::vector< node_indext > &src)
 Removes any edges between nodes in a graph that are unreachable from a vector of start nodes. More...
 
std::vector< typename N::node_indext > depth_limited_search (typename N::node_indext src, std::size_t limit) const
 Run recursive depth-limited search on the graph, starting from multiple source nodes, to find the nodes reachable within n steps. More...
 
std::vector< typename N::node_indext > depth_limited_search (std::vector< typename N::node_indext > &src, std::size_t limit) const
 Run recursive depth-limited search on the graph, starting from multiple source nodes, to find the nodes reachable within n steps. More...
 
void make_chordal ()
 Ensure a graph is chordal (contains no 4+-cycles without an edge crossing the cycle) by adding extra edges. More...
 
std::size_t connected_subgraphs (std::vector< node_indext > &subgraph_nr)
 Find connected subgraphs in an undirected graph. More...
 
std::size_t SCCs (std::vector< node_indext > &subgraph_nr) const
 Computes strongly-connected components of a graph and yields a vector expressing a mapping from nodes to components indices. More...
 
bool is_dag () const
 
std::list< node_indexttopsort () const
 Find a topological order of the nodes if graph is DAG, return empty list for non-DAG or empty graph. More...
 
std::vector< node_indextget_successors (const node_indext &n) const
 
void output_dot (std::ostream &out) const
 
void for_each_successor (const node_indext &n, std::function< void(const node_indext &)> f) const
 

Protected Member Functions

std::vector< typename N::node_indext > depth_limited_search (std::vector< typename N::node_indext > &src, std::size_t limit, std::vector< bool > &visited) const
 Run recursive depth-limited search on the graph, starting. More...
 
void tarjan (class tarjant &t, node_indext v) const
 
void shortest_path (node_indext src, node_indext dest, patht &path, bool non_trivial) const
 

Protected Attributes

nodest nodes
 

Detailed Description

template<class N = graph_nodet<empty_edget>>
class grapht< N >

A generic directed graph with a parametric node type.

The nodes of the graph are stored in the only field of the class, a std::vector named nodes. Nodes are instances of class graph_nodet<E> or a subclass of it. Graph edges contain a payload object of parametric type E (which has to be default-constructible). By default E is instantiated with an empty class (empty_edget).

Each node is identified by its offset inside the nodes vector. The incoming and outgoing edges of a node are stored as std::maps in the fields in and out of the graph_nodet<E>. These maps associate a node identifier (the offset) to the edge payload (of type E).

In fact, observe that two instances of E are stored per edge of the graph. For instance, assume that we want to create a graph with two nodes, A and B, and one edge from A to B, labelled by object e. We achieve this by inserting the pair (offsetof(B),e) in the map A.out and the pair (offsetof(A),e) in the map B.in.

Nodes are inserted in the graph using grapht::add_node(), which returns the identifier (offset) of the inserted node. Edges between nodes are created by grapht::add_edge(a,b), where a and b are the identifiers of nodes. Method add_edges adds a default-constructed payload object of type E. Adding a payload objet e to an edge seems to be only possibly by manually inserting e in the std::maps in and out of the two nodes associated to the edge.

Definition at line 167 of file graph.h.

Member Typedef Documentation

◆ edgest

template<class N = graph_nodet<empty_edget>>
typedef nodet::edgest grapht< N >::edgest

Definition at line 171 of file graph.h.

◆ edget

template<class N = graph_nodet<empty_edget>>
typedef nodet::edget grapht< N >::edget

Definition at line 173 of file graph.h.

◆ node_indext

template<class N = graph_nodet<empty_edget>>
typedef nodet::node_indext grapht< N >::node_indext

Definition at line 174 of file graph.h.

◆ nodest

template<class N = graph_nodet<empty_edget>>
typedef std::vector<nodet> grapht< N >::nodest

Definition at line 172 of file graph.h.

◆ nodet

template<class N = graph_nodet<empty_edget>>
typedef N grapht< N >::nodet

Definition at line 170 of file graph.h.

◆ patht

template<class N = graph_nodet<empty_edget>>
typedef std::list<node_indext> grapht< N >::patht

Definition at line 265 of file graph.h.

Member Function Documentation

◆ add_edge()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::add_edge ( node_indext  a,
node_indext  b 
)
inline

Definition at line 232 of file graph.h.

◆ add_node()

template<class N = graph_nodet<empty_edget>>
node_indext grapht< N >::add_node ( )
inline

Definition at line 180 of file graph.h.

◆ add_undirected_edge()

template<class N >
void grapht< N >::add_undirected_edge ( node_indext  a,
node_indext  b 
)

Definition at line 361 of file graph.h.

◆ clear()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::clear ( void  )
inline

Definition at line 260 of file graph.h.

◆ connected_subgraphs()

template<class N >
std::size_t grapht< N >::connected_subgraphs ( std::vector< node_indext > &  subgraph_nr)

Find connected subgraphs in an undirected graph.

Parameters
[out]subgraph_nrwill be resized to graph.size() and populated to map node indices onto subgraph numbers. The subgraph numbers are dense, in the range 0 - (number of subgraphs - 1)
Returns
Number of subgraphs found.

Definition at line 725 of file graph.h.

◆ depth_limited_search() [1/3]

template<class N>
std::vector< typename N::node_indext > grapht< N >::depth_limited_search ( typename N::node_indext  src,
std::size_t  limit 
) const

Run recursive depth-limited search on the graph, starting from multiple source nodes, to find the nodes reachable within n steps.

This function initialises the search.

Parameters
srcThe node to start the search from.
limitlimit on steps
Returns
a vector of reachable node indices

Definition at line 649 of file graph.h.

◆ depth_limited_search() [2/3]

template<class N>
std::vector< typename N::node_indext > grapht< N >::depth_limited_search ( std::vector< typename N::node_indext > &  src,
std::size_t  limit 
) const

Run recursive depth-limited search on the graph, starting from multiple source nodes, to find the nodes reachable within n steps.

This function initialises the search.

Parameters
srcThe nodes to start the search from.
limitlimit on steps
Returns
a vector of reachable node indices

Definition at line 664 of file graph.h.

◆ depth_limited_search() [3/3]

template<class N>
std::vector< typename N::node_indext > grapht< N >::depth_limited_search ( std::vector< typename N::node_indext > &  src,
std::size_t  limit,
std::vector< bool > &  visited 
) const
protected

Run recursive depth-limited search on the graph, starting.

Parameters
srcThe nodes to start the search from.
limitlimit on steps
visitedvector of booleans indicating whether a node has been visited
Returns
a vector of reachable node indices

Definition at line 686 of file graph.h.

◆ disconnect_unreachable() [1/2]

template<class N >
void grapht< N >::disconnect_unreachable ( node_indext  src)

Removes any edges between nodes in a graph that are unreachable from a given start node.

Used for computing cone of influence, by disconnecting unreachable nodes and then performing backwards reachability. Note nodes are not actually removed from the vector nodes, because this requires renumbering node indices. This copies the way nodes are "removed" in make_chordal.

Parameters
srcstart node

Definition at line 523 of file graph.h.

◆ disconnect_unreachable() [2/2]

template<class N >
void grapht< N >::disconnect_unreachable ( const std::vector< node_indext > &  src)

Removes any edges between nodes in a graph that are unreachable from a vector of start nodes.

Parameters
srcvector of indices of start nodes

Definition at line 533 of file graph.h.

◆ edge()

template<class N = graph_nodet<empty_edget>>
edget& grapht< N >::edge ( node_indext  a,
node_indext  b 
)
inline

Definition at line 244 of file graph.h.

◆ empty()

template<class N = graph_nodet<empty_edget>>
bool grapht< N >::empty ( ) const
inline

Definition at line 217 of file graph.h.

◆ for_each_successor()

template<class N >
void grapht< N >::for_each_successor ( const node_indext n,
std::function< void(const node_indext &)>  f 
) const

Definition at line 950 of file graph.h.

◆ get_reachable() [1/2]

template<class N >
std::vector< typename N::node_indext > grapht< N >::get_reachable ( node_indext  src,
bool  forwards 
) const

Run depth-first search on the graph, starting from a single source node.

Parameters
srcThe node to start the search from.
forwardstrue (false) if the forward (backward) reachability should be performed.

Definition at line 598 of file graph.h.

◆ get_reachable() [2/2]

template<class N >
std::vector< typename N::node_indext > grapht< N >::get_reachable ( const std::vector< node_indext > &  src,
bool  forwards 
) const

Run depth-first search on the graph, starting from multiple source nodes.

Parameters
srcThe nodes to start the search from.
forwardstrue (false) if the forward (backward) reachability should be performed.

Definition at line 612 of file graph.h.

◆ get_successors()

template<class N >
std::vector< typename grapht< N >::node_indext > grapht< N >::get_successors ( const node_indext n) const

Definition at line 938 of file graph.h.

◆ has_edge()

template<class N = graph_nodet<empty_edget>>
bool grapht< N >::has_edge ( node_indext  i,
node_indext  j 
) const
inline

Definition at line 192 of file graph.h.

◆ in()

template<class N = graph_nodet<empty_edget>>
const edgest& grapht< N >::in ( node_indext  n) const
inline

Definition at line 222 of file graph.h.

◆ is_dag()

template<class N = graph_nodet<empty_edget>>
bool grapht< N >::is_dag ( ) const
inline

Definition at line 308 of file graph.h.

◆ make_chordal()

template<class N >
void grapht< N >::make_chordal ( )

Ensure a graph is chordal (contains no 4+-cycles without an edge crossing the cycle) by adding extra edges.

Note this adds more edges than are required, including to acyclic graphs or acyclic subgraphs of cyclic graphs, but does at least ensure the graph is not chordal.

Definition at line 843 of file graph.h.

◆ operator[]() [1/2]

template<class N = graph_nodet<empty_edget>>
const nodet& grapht< N >::operator[] ( node_indext  n) const
inline

Definition at line 197 of file graph.h.

◆ operator[]() [2/2]

template<class N = graph_nodet<empty_edget>>
nodet& grapht< N >::operator[] ( node_indext  n)
inline

Definition at line 202 of file graph.h.

◆ out()

template<class N = graph_nodet<empty_edget>>
const edgest& grapht< N >::out ( node_indext  n) const
inline

Definition at line 227 of file graph.h.

◆ output_dot()

template<class N >
void grapht< N >::output_dot ( std::ostream &  out) const

Definition at line 961 of file graph.h.

◆ remove_edge()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::remove_edge ( node_indext  a,
node_indext  b 
)
inline

Definition at line 238 of file graph.h.

◆ remove_edges()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::remove_edges ( node_indext  n)
inline

Definition at line 254 of file graph.h.

◆ remove_in_edges()

template<class N >
void grapht< N >::remove_in_edges ( node_indext  n)

Definition at line 385 of file graph.h.

◆ remove_out_edges()

template<class N >
void grapht< N >::remove_out_edges ( node_indext  n)

Definition at line 400 of file graph.h.

◆ remove_undirected_edge()

template<class N >
void grapht< N >::remove_undirected_edge ( node_indext  a,
node_indext  b 
)

Definition at line 374 of file graph.h.

◆ resize()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::resize ( node_indext  s)
inline

Definition at line 207 of file graph.h.

◆ SCCs()

template<class N >
std::size_t grapht< N >::SCCs ( std::vector< node_indext > &  subgraph_nr) const

Computes strongly-connected components of a graph and yields a vector expressing a mapping from nodes to components indices.

For example, if nodes 1 and 3 are in SCC 0, and nodes 0, 2 and 4 are in SCC 1, this will leave subgraph_nr holding { 1, 0, 1, 0, 1 }, and the function will return 2 (the number of distinct SCCs). Lower-numbered SCCs are closer to the leaves, so in the particular case of a DAG, sorting by SCC number gives a topological sort, and for a cyclic graph the SCCs are topologically sorted but arbitrarily ordered internally.

Parameters
subgraph_nr[in, out]: should be pre-allocated with enough storage for one entry per graph node. Will be populated with the SCC indices of each node.
Returns
the number of distinct SCCs.

Definition at line 827 of file graph.h.

◆ shortest_loop()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::shortest_loop ( node_indext  node,
patht path 
) const
inline

Definition at line 275 of file graph.h.

◆ shortest_path() [1/2]

template<class N = graph_nodet<empty_edget>>
void grapht< N >::shortest_path ( node_indext  src,
node_indext  dest,
patht path 
) const
inline

Definition at line 267 of file graph.h.

◆ shortest_path() [2/2]

template<class N >
void grapht< N >::shortest_path ( node_indext  src,
node_indext  dest,
patht path,
bool  non_trivial 
) const
protected

Definition at line 415 of file graph.h.

◆ size()

template<class N = graph_nodet<empty_edget>>
std::size_t grapht< N >::size ( ) const
inline

Definition at line 212 of file graph.h.

◆ swap()

template<class N = graph_nodet<empty_edget>>
void grapht< N >::swap ( grapht< N > &  other)
inline

Definition at line 187 of file graph.h.

◆ tarjan()

template<class N >
void grapht< N >::tarjan ( class tarjant t,
node_indext  v 
) const
protected

Definition at line 769 of file graph.h.

◆ topsort()

template<class N >
std::list< typename grapht< N >::node_indext > grapht< N >::topsort ( ) const

Find a topological order of the nodes if graph is DAG, return empty list for non-DAG or empty graph.

Uses Kahn's algorithm running in O(n_edges+n_nodes).

Definition at line 874 of file graph.h.

◆ visit_reachable()

template<class N >
void grapht< N >::visit_reachable ( node_indext  src)

Definition at line 507 of file graph.h.

Member Data Documentation

◆ nodes

template<class N = graph_nodet<empty_edget>>
nodest grapht< N >::nodes
protected

Definition at line 177 of file graph.h.


The documentation for this class was generated from the following file: