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/* -*- mode: C -*- */
/*
IGraph library.
Copyright (C) 2009-2012 Gabor Csardi <csardi.gabor@gmail.com>
334 Harvard street, Cambridge, MA 02139 USA
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA
*/
#ifndef IGRAPH_DATATYPE_H
#define IGRAPH_DATATYPE_H
#include "igraph_decls.h"
#include "igraph_types.h"
#include "igraph_vector.h"
__BEGIN_DECLS
struct igraph_i_property_cache_t;
typedef struct igraph_i_property_cache_t igraph_i_property_cache_t;
typedef enum {
/* Stores whether the graph has at least one self-loop. */
IGRAPH_PROP_HAS_LOOP = 0,
/* Stores whether the graph has at least one multi-edge, taking into account
* edge directions in directed graphs. In other words, this property should
* be false for a directed graph with edges (a, b) and (b, a), and true
* for a directed graph with edges (a, b) and (a, b) again. */
IGRAPH_PROP_HAS_MULTI,
/* Stores whether the graph has at least one reciprocal edge pair. Ignored
* in undirected graphs. This property should be true for a directed graph
* with edges (a, b) and (b, a), and false for a directed graph with
* edges (a, b) and (a, b) again. Self-loops (a, a) are not considered
* reciprocal. */
IGRAPH_PROP_HAS_MUTUAL,
/* Stores whether the graph is weakly connected. */
IGRAPH_PROP_IS_WEAKLY_CONNECTED,
/* Stores whether the graph is strongly connected. Ignored in undirected graphs. */
IGRAPH_PROP_IS_STRONGLY_CONNECTED,
/* Stores whether the graph is a directed acyclic graph. Not used for
* undirected graphs. */
IGRAPH_PROP_IS_DAG,
/* Stores whether the graph is a forest, i.e. an undirected or directed
* graph that is cycle-free even if we ignore edge directions. */
IGRAPH_PROP_IS_FOREST,
/* Dummy value used to count enum values */
IGRAPH_PROP_I_SIZE
} igraph_cached_property_t;
/**
* \ingroup internal
* \struct igraph_t
* \brief The internal data structure for storing graphs.
*
* It is simple and efficient. It has the following members:
* - <b>n</b> The number of vertices, redundant.
* - <b>directed</b> Whether the graph is directed.
* - <b>from</b> The first column of the edge list.
* - <b>to</b> The second column of the edge list.
* - <b>oi</b> The index of the edge list by the first column. Thus
* the first edge according to this order goes from
* \c from[oi[0]] to \c to[oi[0]]. The length of
* this vector is the same as the number of edges in the graph.
* - <b>ii</b> The index of the edge list by the second column.
* The length of this vector is the same as the number of edges.
* - <b>os</b> Contains pointers to the edgelist (\c from
* and \c to for every vertex. The first edge \em from
* vertex \c v is edge no. \c from[oi[os[v]]] if
* \c os[v]<os[v+1]. If \c os[v]==os[v+1] then
* there are no edges \em from node \c v. Its length is
* the number of vertices plus one, the last element is always the
* same as the number of edges and is contained only to ease the
* queries.
* - <b>is</b> This is basically the same as <b>os</b>, but this time
* for the incoming edges.
*
* For undirected graphs, the same edge list is stored, i.e. an
* undirected edge is stored only once. Currently, undirected edges
* are canonicalized so that the index of the 'from' vertex is not greater
* than the index of the 'to' vertex. Thus, if v1 <= v2, only the edge (v1, v2)
* needs to be searched for, not (v2, v1), to determine if v1 and v2 are connected.
* However, this fact is NOT guaranteed by the documented public API,
* and should not be relied upon by the implementation of any functions,
* except those belonging to the minimal API in type_indexededgelist.c.
*
* The storage requirements for a graph with \c |V| vertices
* and \c |E| edges is \c O(|E|+|V|).
*/
typedef struct igraph_s {
igraph_integer_t n;
igraph_bool_t directed;
igraph_vector_int_t from;
igraph_vector_int_t to;
igraph_vector_int_t oi;
igraph_vector_int_t ii;
igraph_vector_int_t os;
igraph_vector_int_t is;
void *attr;
igraph_i_property_cache_t *cache;
} igraph_t;
IGRAPH_EXPORT void igraph_invalidate_cache(const igraph_t* graph);
__END_DECLS
#endif
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