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arangodb/arangod/Aql/ShortestPathBlock.h

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C++

////////////////////////////////////////////////////////////////////////////////
/// DISCLAIMER
///
/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Michael Hackstein
////////////////////////////////////////////////////////////////////////////////
#ifndef ARANGOD_AQL_SHORTEST_PATH_BLOCK_H
#define ARANGOD_AQL_SHORTEST_PATH_BLOCK_H 1
#include "Aql/ExecutionBlock.h"
#include "Aql/ShortestPathNode.h"
#include "Graph/ShortestPathOptions.h"
namespace arangodb {
class ManagedDocumentResult;
namespace graph {
class ShortestPathFinder;
class ShortestPathResult;
}
namespace aql {
class ShortestPathNode;
class ShortestPathBlock final : public ExecutionBlock {
public:
ShortestPathBlock(ExecutionEngine* engine, ShortestPathNode const* ep);
/// @brief initializeCursor
std::pair<ExecutionState, Result> initializeCursor(AqlItemBlock* items, size_t pos) override;
std::pair<ExecutionState, Result> shutdown(int errorCode) override;
/// @brief getSome
std::pair<ExecutionState, std::unique_ptr<AqlItemBlock>> getSome(
size_t atMost) override final;
// skip atMost documents, returns the number actually skipped . . .
// will only return less than atMost if there aren't atMost many
// things to skip overall.
std::pair<ExecutionState, size_t> skipSome(size_t atMost) override final;
private:
/// @brief Compute the next shortest path
bool nextPath(AqlItemBlock const*);
/// @brief Checks if we output the vertex
bool usesVertexOutput() { return _vertexVar != nullptr; }
/// @brief Checks if we output the edge
bool usesEdgeOutput() { return _edgeVar != nullptr; }
/// SECTION private Variables
/// @brief Variable for the vertex output
Variable const* _vertexVar;
/// @brief Register for the vertex output
RegisterId _vertexReg;
/// @brief Variable for the edge output
Variable const* _edgeVar;
/// @brief Register for the edge output
RegisterId _edgeReg;
/// @brief options to compute the shortest path
graph::ShortestPathOptions* _opts;
/// @brief position in the current path
size_t _posInPath;
/// @brief length of the current path
size_t _pathLength;
/// @brief current computed path.
std::unique_ptr<graph::ShortestPathResult> _path;
/// @brief the shortest path finder.
std::unique_ptr<arangodb::graph::ShortestPathFinder> _finder;
/// @brief The information to get the starting point, when a register id is
/// used
arangodb::aql::RegisterId _startReg;
/// @brief Keep a copy of the start vertex id-string. Can be freed if this
/// start vertex is not in use any more.
std::string _startVertexId;
/// @brief Indicator if we use a register for start input variable.
/// Invariant: _useStartRegister == true <=> _startReg != undefined
bool _useStartRegister;
/// @brief The information to get the starting point, when a register id is
/// used
arangodb::aql::RegisterId _targetReg;
/// @brief Keep a copy of the target vertex id-string. Can be freed if this
/// start vertex is not in use any more.
std::string _targetVertexId;
/// @brief Indicator if we use a register for target input variable.
/// Invariant: _useTargetRegister == true <=> _targetReg != undefined
bool _useTargetRegister;
/// @brief Indicator if we have used both constant input parameter for
/// computation
/// We use it to check if we are done with enumerating.
bool _usedConstant;
/// @brief Traverser Engines
std::unordered_map<ServerID, traverser::TraverserEngineID> const* _engines;
};
} // namespace arangodb::aql
} // namespace arangodb
#endif