lyx_mirror/src/Graph.h
2020-12-05 17:17:02 -05:00

104 lines
3.0 KiB
C++

// -*- C++ -*-
/**
* \file Graph.h
* This file is part of LyX, the document processor.
* Licence details can be found in the file COPYING.
*
* \author Dekel Tsur (original code)
* \author Richard Kimberly Heck (re-implementation)
*
* Full author contact details are available in file CREDITS.
*/
#ifndef GRAPH_H
#define GRAPH_H
#include <list>
#include <queue>
#include <set>
#include <vector>
namespace lyx {
/// Represents a directed graph, possibly with multiple edges
/// connecting the vertices.
class Graph {
public:
Graph() : numedges_(0) {}
///
typedef std::vector<int> EdgePath;
/// \return a vector of the vertices from which "to" can be reached
EdgePath const getReachableTo(int to, bool clear_visited);
/// \return a vector of the reachable vertices, avoiding all "excludes"
EdgePath const getReachable(int from, bool only_viewable,
bool clear_visited, std::set<int> excludes = std::set<int>());
/// can "from" be reached from "to"?
bool isReachable(int from, int to);
/// find a path from "from" to "to". always returns one of the
/// shortest such paths.
EdgePath const getPath(int from, int to);
/// called repeatedly to build the graph
void addEdge(int from, int to);
/// reset the internal data structures
void init(int size);
private:
///
bool bfs_init(int, bool clear_visited, std::queue<int> & Q);
/// these represent the arrows connecting the nodes of the graph.
/// this is the basic representation of the graph: as a bunch of
/// arrows.
struct Arrow {
///
Arrow(int f, int t, int i):
from(f), to(t), id(i) {}
/// the vertex at the tail of the arrow
int from;
/// the vertex at the head
int to;
/// an id for this arrow, e.g., for use in describing paths
/// through the graph
int id;
};
/// a container for the arrows
/// we use a list because we want pointers to the arrows,
/// and a vector might invalidate them
typedef std::list<Arrow> Arrows;
Arrows arrows_;
/// Represents a vertex of the graph. Note that we could recover
/// the in_arrows and out_arrows from the Arrows, so these are in
/// effect a kind of cache.
struct Vertex {
/// arrows that point at this one
std::vector<Arrow *> in_arrows;
/// arrows out from here
std::vector<Arrow *> out_arrows;
/// used in the search routines
bool visited;
};
/// a container for the vertices
/// the index into the vector functions as the identifier by which
/// these are referenced in the Arrow struct
/// the code making use of the Graph must keep track of the relation
/// between these indices and the objects they represent. (in the case
/// of Format, this is easy, since the Format objects already have ints
/// as identifiers.)
std::vector<Vertex> vertices_;
/// a counter that we use to assign id's to the arrows
/// FIXME This technique assumes a correspondence between the
/// ids of the arrows and ids associated with Converters that
/// seems kind of fragile. Perhaps a better solution would be
/// to pass the ids as we create the arrows.
int numedges_;
};
} // namespace lyx
#endif //GRAPH_H