CMake/Source/cmComputeComponentGraph.h

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Simplify CMake per-source license notices Per-source copyright/license notice headers that spell out copyright holder names and years are hard to maintain and often out-of-date or plain wrong. Precise contributor information is already maintained automatically by the version control tool. Ultimately it is the receiver of a file who is responsible for determining its licensing status, and per-source notices are merely a convenience. Therefore it is simpler and more accurate for each source to have a generic notice of the license name and references to more detailed information on copyright holders and full license terms. Our `Copyright.txt` file now contains a list of Contributors whose names appeared source-level copyright notices. It also references version control history for more precise information. Therefore we no longer need to spell out the list of Contributors in each source file notice. Replace CMake per-source copyright/license notice headers with a short description of the license and links to `Copyright.txt` and online information available from "https://cmake.org/licensing". The online URL also handles cases of modules being copied out of our source into other projects, so we can drop our notices about replacing links with full license text. Run the `Utilities/Scripts/filter-notices.bash` script to perform the majority of the replacements mechanically. Manually fix up shebang lines and trailing newlines in a few files. Manually update the notices in a few files that the script does not handle.
2016-09-27 22:01:08 +03:00
/* Distributed under the OSI-approved BSD 3-Clause License. See accompanying
file Copyright.txt or https://cmake.org/licensing for details. */
#ifndef cmComputeComponentGraph_h
#define cmComputeComponentGraph_h
#include <cmConfigure.h> // IWYU pragma: keep
#include "cmGraphAdjacencyList.h"
#include <stack>
#include <vector>
/** \class cmComputeComponentGraph
* \brief Analyze a graph to determine strongly connected components.
*
* Convert a directed graph into a directed acyclic graph whose nodes
* correspond to strongly connected components of the original graph.
*
* We use Tarjan's algorithm to enumerate the components efficiently.
* An advantage of this approach is that the components are identified
* in a topologically sorted order.
*/
class cmComputeComponentGraph
{
public:
// Represent the graph with an adjacency list.
typedef cmGraphNodeList NodeList;
typedef cmGraphEdgeList EdgeList;
typedef cmGraphAdjacencyList Graph;
cmComputeComponentGraph(Graph const& input);
~cmComputeComponentGraph();
/** Get the adjacency list of the component graph. */
Graph const& GetComponentGraph() const { return this->ComponentGraph; }
EdgeList const& GetComponentGraphEdges(int c) const
{
return this->ComponentGraph[c];
}
/** Get map from component index to original node indices. */
std::vector<NodeList> const& GetComponents() const
{
return this->Components;
}
NodeList const& GetComponent(int c) const { return this->Components[c]; }
/** Get map from original node index to component index. */
std::vector<int> const& GetComponentMap() const
{
return this->TarjanComponents;
}
private:
void TransferEdges();
Graph const& InputGraph;
Graph ComponentGraph;
// Tarjan's algorithm.
struct TarjanEntry
{
int Root;
int VisitIndex;
};
std::vector<int> TarjanVisited;
std::vector<int> TarjanComponents;
std::vector<TarjanEntry> TarjanEntries;
std::vector<NodeList> Components;
std::stack<int> TarjanStack;
int TarjanWalkId;
int TarjanIndex;
void Tarjan();
void TarjanVisit(int i);
// Connected components.
};
#endif