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VILLASnode/fpga/include/villas/directed_graph.hpp
Daniel Krebs ba7531ac46 lib/graph: allow stringifying of vertex and edge derived types
This yields nices debug messages and a much nice dump().
2018-01-30 19:16:59 +01:00

271 lines
6.1 KiB
C++

#pragma once
#include <map>
#include <list>
#include <memory>
#include <sstream>
#include <string>
#include <stdexcept>
#include <algorithm>
#include "log.hpp"
namespace villas {
namespace graph {
// use vector indices as identifiers
// forward declarations
class Edge;
class Vertex;
class Vertex {
template<typename VertexType, typename EdgeType>
friend class DirectedGraph;
public:
using Identifier = std::size_t;
friend std::ostream&
operator<< (std::ostream& stream, const Vertex& vertex)
{ return stream << vertex.id; }
bool
operator==(const Vertex& other)
{ return this->id == other.id; }
private:
Identifier id;
// HACK: how to resolve this circular type dependency?
std::list<std::size_t> edges;
};
class Edge {
template<typename VertexType, typename EdgeType>
friend class DirectedGraph;
public:
using Identifier = std::size_t;
friend std::ostream&
operator<< (std::ostream& stream, const Edge& edge)
{ return stream << edge.id; }
bool
operator==(const Edge& other)
{ return this->id == other.id; }
private:
Identifier id;
Vertex::Identifier from;
Vertex::Identifier to;
};
template<typename VertexType = Vertex, typename EdgeType = Edge>
class DirectedGraph {
public:
using VertexIdentifier = Vertex::Identifier;
using EdgeIdentifier = Edge::Identifier;
DirectedGraph(const std::string& name = "DirectedGraph") :
lastVertexId(0), lastEdgeId(0)
{
logger = loggerGetOrCreate(name);
}
std::shared_ptr<VertexType> getVertex(VertexIdentifier vertexId) const
{
if(vertexId < 0 or vertexId >= lastVertexId)
throw std::invalid_argument("vertex doesn't exist");
// cannot use [] operator, because creates non-existing elements
// at() will throw std::out_of_range if element does not exist
return vertices.at(vertexId);
}
std::shared_ptr<EdgeType> getEdge(EdgeIdentifier edgeId) const
{
if(edgeId < 0 or edgeId >= lastEdgeId)
throw std::invalid_argument("edge doesn't exist");
// cannot use [] operator, because creates non-existing elements
// at() will throw std::out_of_range if element does not exist
return edges.at(edgeId);
}
std::size_t getEdgeCount() const
{ return edges.size(); }
std::size_t getVertexCount() const
{ return vertices.size(); }
VertexIdentifier addVertex(std::shared_ptr<VertexType> vertex)
{
vertex->id = lastVertexId++;
logger->debug("New vertex: {}", *vertex);
vertices[vertex->id] = vertex;
return vertex->id;
}
EdgeIdentifier addEdge(std::shared_ptr<EdgeType> edge,
VertexIdentifier fromVertexId,
VertexIdentifier toVertexId)
{
// allocate edge id
edge->id = lastEdgeId++;
// connect it
edge->from = fromVertexId;
edge->to = toVertexId;
logger->debug("New edge {}: {} -> {}", *edge, edge->from, edge->to);
// this is a directed graph, so only push edge to starting vertex
getVertex(edge->from)->edges.push_back(edge->id);
// add new edge to graph
edges[edge->id] = edge;
return edge->id;
}
EdgeIdentifier addDefaultEdge(VertexIdentifier fromVertexId,
VertexIdentifier toVertexId)
{
// create a new edge
std::shared_ptr<EdgeType> edge(new EdgeType);
return addEdge(edge, fromVertexId, toVertexId);
}
void removeEdge(EdgeIdentifier edgeId)
{
auto edge = getEdge(edgeId);
auto startVertex = getVertex(edge->from);
// remove edge only from starting vertex (this is a directed graph)
logger->debug("Remove edge {} from vertex {}", edgeId, edge->from);
startVertex->edges.remove(edgeId);
logger->debug("Remove edge {}", edgeId);
edges.erase(edgeId);
}
void removeVertex(VertexIdentifier vertexId)
{
// delete every edge that start or ends at this vertex
auto it = edges.begin();
while(it != edges.end()) {
auto& [edgeId, edge] = *it;
bool removeEdge = false;
if(edge->to == vertexId) {
logger->debug("Remove edge {} from vertex {}'s edge list",
edgeId, edge->from);
removeEdge = true;
auto startVertex = getVertex(edge->from);
startVertex->edges.remove(edge->id);
}
if((edge->from == vertexId) or removeEdge) {
logger->debug("Remove edge {}", edgeId);
// remove edge from global edge list
it = edges.erase(it);
} else {
++it;
}
}
logger->debug("Remove vertex {}", vertexId);
vertices.erase(vertexId);
}
const std::list<EdgeIdentifier>&
vertexGetEdges(VertexIdentifier vertexId) const
{ return getVertex(vertexId)->edges; }
bool getPath(VertexIdentifier fromVertexId, VertexIdentifier toVertexId,
std::list<EdgeIdentifier>& path)
{
if(fromVertexId == toVertexId) {
// arrived at the destination
return true;
} else {
auto fromVertex = getVertex(fromVertexId);
for(auto& edgeId : fromVertex->edges) {
auto edge = getEdge(edgeId);
// loop detection
bool loop = false;
for(auto& edgeIdInPath : path) {
auto edgeInPath = getEdge(edgeIdInPath);
if(edgeInPath->from == edgeId) {
loop = true;
break;
}
}
if(loop) {
logger->debug("Loop detected via edge {}", edgeId);
continue;
}
// remember the path we're investigating to detect loops
path.push_back(edgeId);
// recursive, depth-first search
if(getPath(edge->to, toVertexId, path)) {
// path found, we're done
return true;
} else {
// tear down path that didn't lead to the destination
path.pop_back();
}
}
}
return false;
}
void dump()
{
logger->info("Vertices:");
for(auto& [vertexId, vertex] : vertices) {
// format connected vertices into a list
std::stringstream ssEdges;
for(auto& edge : vertex->edges) {
ssEdges << getEdge(edge)->to << " ";
}
logger->info(" {} connected to: {}", *vertex, ssEdges.str());
}
logger->info("Edges:");
for(auto& [edgeId, edge] : edges) {
logger->info(" {}: {} -> {}", *edge, edge->from, edge->to);
}
}
private:
VertexIdentifier lastVertexId;
EdgeIdentifier lastEdgeId;
std::map<VertexIdentifier, std::shared_ptr<VertexType>> vertices;
std::map<EdgeIdentifier, std::shared_ptr<EdgeType>> edges;
SpdLogger logger;
};
} // namespacae graph
} // namespace villas