mirror of https://gitee.com/bigwinds/arangodb
327 lines
11 KiB
C++
327 lines
11 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2014-2016 ArangoDB GmbH, Cologne, Germany
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/// Copyright 2004-2014 triAGENS GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Michael Hackstein
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGODB_VOCBASE_PATHENUMERATOR_H
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#define ARANGODB_VOCBASE_PATHENUMERATOR_H 1
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#include "Basics/Common.h"
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#include "VocBase/TraverserOptions.h"
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#include <velocypack/Slice.h>
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#include <stack>
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namespace arangodb {
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namespace aql {
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struct AqlValue;
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}
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namespace velocypack {
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class Builder;
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}
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namespace traverser {
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class Traverser;
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struct TraverserOptions;
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struct EnumeratedPath {
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std::vector<arangodb::velocypack::Slice> edges;
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std::vector<arangodb::velocypack::Slice> vertices;
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EnumeratedPath() {}
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};
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class PathEnumerator {
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protected:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief This is the class that knows the details on how to
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/// load the data and how to return data in the expected format
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/// NOTE: This class does not known the traverser.
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//////////////////////////////////////////////////////////////////////////////
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traverser::Traverser* _traverser;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Indicates if we issue next() the first time.
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/// It shall return an empty path in this case.
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//////////////////////////////////////////////////////////////////////////////
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bool _isFirst;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Maximal path length which should be enumerated.
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//////////////////////////////////////////////////////////////////////////////
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TraverserOptions const* _opts;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief List of the last path is used to
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//////////////////////////////////////////////////////////////////////////////
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EnumeratedPath _enumeratedPath;
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/// @brief List which edges have been visited already.
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std::unordered_set<arangodb::velocypack::Slice> _returnedEdges;
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public:
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PathEnumerator(Traverser* traverser, arangodb::velocypack::Slice startVertex,
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TraverserOptions const* opts)
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: _traverser(traverser), _isFirst(true), _opts(opts) {
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TRI_ASSERT(startVertex.isString());
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_enumeratedPath.vertices.push_back(startVertex);
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TRI_ASSERT(_enumeratedPath.vertices.size() == 1);
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}
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virtual ~PathEnumerator() {}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Compute the next Path element from the traversal.
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/// Returns false if there is no next path element.
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/// Only if this is true one can compute the AQL values.
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//////////////////////////////////////////////////////////////////////////////
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virtual bool next() = 0;
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virtual aql::AqlValue lastVertexToAqlValue() = 0;
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virtual aql::AqlValue lastEdgeToAqlValue() = 0;
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virtual aql::AqlValue pathToAqlValue(arangodb::velocypack::Builder&) = 0;
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};
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class DepthFirstEnumerator final : public PathEnumerator {
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private:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief The stack of EdgeCursors to walk through.
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//////////////////////////////////////////////////////////////////////////////
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std::stack<std::unique_ptr<EdgeCursor>> _edgeCursors;
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public:
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DepthFirstEnumerator(Traverser* traverser,
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arangodb::velocypack::Slice startVertex,
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TraverserOptions const* opts)
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: PathEnumerator(traverser, startVertex, opts) {}
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~DepthFirstEnumerator() {
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}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Get the next Path element from the traversal.
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//////////////////////////////////////////////////////////////////////////////
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bool next() override;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Prunes the current path prefix, the next function should not return
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/// any path having this prefix anymore.
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//////////////////////////////////////////////////////////////////////////////
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aql::AqlValue lastVertexToAqlValue() override;
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aql::AqlValue lastEdgeToAqlValue() override;
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aql::AqlValue pathToAqlValue(arangodb::velocypack::Builder& result) override;
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};
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class BreadthFirstEnumerator final : public PathEnumerator {
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private:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief One entry in the schreier vector
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//////////////////////////////////////////////////////////////////////////////
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struct PathStep {
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size_t sourceIdx;
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arangodb::velocypack::Slice edge;
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arangodb::velocypack::Slice vertex;
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private:
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PathStep() {}
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public:
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explicit PathStep(arangodb::velocypack::Slice vertex) : sourceIdx(0), vertex(vertex) {}
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PathStep(size_t sourceIdx, arangodb::velocypack::Slice edge,
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arangodb::velocypack::Slice vertex)
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: sourceIdx(sourceIdx), edge(edge), vertex(vertex) {}
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};
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Struct to hold all information required to get the list of
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/// connected edges
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//////////////////////////////////////////////////////////////////////////////
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struct NextStep {
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size_t sourceIdx;
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private:
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NextStep() = delete;
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public:
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explicit NextStep(size_t sourceIdx)
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: sourceIdx(sourceIdx) {}
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};
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//////////////////////////////////////////////////////////////////////////////
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/// @brief schreier vector to store the visited vertices
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//////////////////////////////////////////////////////////////////////////////
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std::vector<PathStep> _schreier;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Next free index in schreier vector.
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//////////////////////////////////////////////////////////////////////////////
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size_t _schreierIndex;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Position of the last returned value in the schreier vector
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//////////////////////////////////////////////////////////////////////////////
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size_t _lastReturned;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Vector to store where to continue search on next depth
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//////////////////////////////////////////////////////////////////////////////
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std::vector<NextStep> _nextDepth;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Vector storing the position at current search depth
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//////////////////////////////////////////////////////////////////////////////
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std::vector<NextStep> _toSearch;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Vector storing the position at current search depth
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//////////////////////////////////////////////////////////////////////////////
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std::unordered_set<arangodb::velocypack::Slice> _tmpEdges;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Marker for the search depth. Used to abort searching.
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//////////////////////////////////////////////////////////////////////////////
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size_t _currentDepth;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief position in _toSerach. If this is >= _toSearch.size() we are done
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/// with this depth.
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//////////////////////////////////////////////////////////////////////////////
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size_t _toSearchPos;
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public:
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BreadthFirstEnumerator(Traverser* traverser,
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arangodb::velocypack::Slice startVertex,
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TraverserOptions const* opts);
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~BreadthFirstEnumerator() {}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Get the next Path element from the traversal.
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//////////////////////////////////////////////////////////////////////////////
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bool next() override;
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aql::AqlValue lastVertexToAqlValue() override;
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aql::AqlValue lastEdgeToAqlValue() override;
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aql::AqlValue pathToAqlValue(arangodb::velocypack::Builder& result) override;
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private:
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inline size_t getDepth(size_t index) const {
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size_t depth = 0;
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while (index != 0) {
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++depth;
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index = _schreier[index].sourceIdx;
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}
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return depth;
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}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Build the enumerated path for the given index in the schreier
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/// vector.
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//////////////////////////////////////////////////////////////////////////////
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void computeEnumeratedPath(size_t index);
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};
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// @brief Enumerator optimized for neighbors. Does not allow edge access
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class NeighborsEnumerator final : public PathEnumerator {
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std::unordered_set<arangodb::basics::VPackHashedSlice,
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arangodb::basics::VelocyPackHelper::VPackHashedStringHash,
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arangodb::basics::VelocyPackHelper::VPackHashedStringEqual>
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_allFound;
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std::unordered_set<arangodb::basics::VPackHashedSlice,
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arangodb::basics::VelocyPackHelper::VPackHashedStringHash,
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arangodb::basics::VelocyPackHelper::VPackHashedStringEqual>
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_currentDepth;
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std::unordered_set<arangodb::basics::VPackHashedSlice,
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arangodb::basics::VelocyPackHelper::VPackHashedStringHash,
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arangodb::basics::VelocyPackHelper::VPackHashedStringEqual>
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_lastDepth;
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std::unordered_set<arangodb::basics::VPackHashedSlice, arangodb::basics::VelocyPackHelper::VPackHashedStringHash, arangodb::basics::VelocyPackHelper::VPackHashedStringEqual>::iterator _iterator;
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size_t _searchDepth;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Vector storing the position at current search depth
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//////////////////////////////////////////////////////////////////////////////
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std::unordered_set<arangodb::velocypack::Slice> _tmpEdges;
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public:
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NeighborsEnumerator(Traverser* traverser,
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arangodb::velocypack::Slice startVertex,
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TraverserOptions const* opts);
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~NeighborsEnumerator() {
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}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Get the next Path element from the traversal.
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//////////////////////////////////////////////////////////////////////////////
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bool next() override;
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aql::AqlValue lastVertexToAqlValue() override;
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aql::AqlValue lastEdgeToAqlValue() override;
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aql::AqlValue pathToAqlValue(arangodb::velocypack::Builder& result) override;
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};
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} // namespace traverser
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} // namespace arangodb
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#endif
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