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Extract toposort into a free function

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This commit is contained in:
Alexander Karatarakis 2017-04-11 14:44:14 -07:00
parent cfbfa0d813
commit d7466d98bb
1 changed files with 48 additions and 34 deletions
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82
toolsrc/include/vcpkg_Graphs.h
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@ -17,39 +17,55 @@ namespace vcpkg::Graphs
FULLY_EXPLORED
};
template <class V, class Func>
static void topological_sort_internal(V vertex,
ExplorationStatus& status,
const Func adjacency_list_provider,
std::unordered_map<V, ExplorationStatus>& exploration_status,
std::vector<V>& sorted)
{
status = ExplorationStatus::PARTIALLY_EXPLORED;
auto neighbours = adjacency_list_provider(vertex);
for (V neighbour : neighbours)
{
ExplorationStatus& neighbour_status = exploration_status[neighbour];
if (neighbour_status == ExplorationStatus::NOT_EXPLORED)
{
topological_sort_internal(neighbour, neighbour_status, adjacency_list_provider, exploration_status, sorted);
}
else if (neighbour_status == ExplorationStatus::PARTIALLY_EXPLORED)
{
throw std::runtime_error("cycle in graph");
}
}
status = ExplorationStatus::FULLY_EXPLORED;
sorted.push_back(vertex);
}
template <class V, class Func>
std::vector<V> topological_sort(const std::vector<V>& starting_vertices, const Func adjacency_list_provider)
{
std::vector<V> sorted;
std::unordered_map<V, ExplorationStatus> exploration_status;
for (auto& vertex : starting_vertices)
{
ExplorationStatus& status = exploration_status[vertex];
if (status == ExplorationStatus::NOT_EXPLORED)
{
topological_sort_internal(vertex, status, adjacency_list_provider, exploration_status, sorted);
}
}
return sorted;
}
template <class V>
class Graph
{
template <class Func>
static void topological_sort_internal(V vertex,
ExplorationStatus& status,
const Func adjacency_list_provider,
std::unordered_map<V, ExplorationStatus>& exploration_status,
std::vector<V>& sorted)
{
status = ExplorationStatus::PARTIALLY_EXPLORED;
auto neighbours = adjacency_list_provider(vertex);
for (V neighbour : neighbours)
{
ExplorationStatus& neighbour_status = exploration_status[neighbour];
if (neighbour_status == ExplorationStatus::NOT_EXPLORED)
{
topological_sort_internal(neighbour, neighbour_status, adjacency_list_provider, exploration_status, sorted);
}
else if (neighbour_status == ExplorationStatus::PARTIALLY_EXPLORED)
{
throw std::runtime_error("cycle in graph");
}
}
status = ExplorationStatus::FULLY_EXPLORED;
sorted.push_back(vertex);
}
public:
void add_vertex(V v)
{
this->vertices[v];
@ -88,11 +104,9 @@ namespace vcpkg::Graphs
ExplorationStatus& status = exploration_status[vertex];
if (status == ExplorationStatus::NOT_EXPLORED)
{
topological_sort_internal(vertex,
status,
[this](const V& v) { return this->vertices.at(v); },
exploration_status,
sorted);
topological_sort_internal(vertex, status,
[this](const V& v) { return this->vertices.at(v); },
exploration_status, sorted);
}
}
}