mirror of https://gitee.com/bigwinds/arangodb
334 lines
12 KiB
C++
334 lines
12 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 ARANGOD_GRAPH_TRAVERSER_H
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#define ARANGOD_GRAPH_TRAVERSER_H 1
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#include "Aql/AqlValue.h"
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#include "Aql/AstNode.h"
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#include "Basics/Common.h"
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#include "Basics/VelocyPackHelper.h"
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#include "Basics/hashes.h"
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#include "Graph/AttributeWeightShortestPathFinder.h"
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#include "Graph/ConstantWeightShortestPathFinder.h"
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#include "Graph/PathEnumerator.h"
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#include "Graph/ShortestPathFinder.h"
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#include "Transaction/Helpers.h"
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#include "VocBase/voc-types.h"
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#include <velocypack/StringRef.h>
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namespace arangodb {
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namespace transaction {
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class Methods;
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}
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namespace velocypack {
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class Builder;
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class Slice;
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} // namespace velocypack
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namespace aql {
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struct AstNode;
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class Expression;
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class Query;
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} // namespace aql
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namespace graph {
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class BreadthFirstEnumerator;
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class NeighborsEnumerator;
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class TraverserCache;
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} // namespace graph
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namespace traverser {
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struct TraverserOptions;
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class TraversalPath {
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public:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Constructor. This is an abstract only class.
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//////////////////////////////////////////////////////////////////////////////
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TraversalPath() : _readDocuments(0) {}
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virtual ~TraversalPath() {}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Builds the complete path as VelocyPack
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/// Has the format:
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/// {
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/// vertices: [<vertex-as-velocypack>],
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/// edges: [<edge-as-velocypack>]
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/// }
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//////////////////////////////////////////////////////////////////////////////
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virtual void pathToVelocyPack(transaction::Methods*, arangodb::velocypack::Builder&) = 0;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Builds only the last edge on the path as VelocyPack
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//////////////////////////////////////////////////////////////////////////////
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virtual void lastEdgeToVelocyPack(transaction::Methods*,
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arangodb::velocypack::Builder&) = 0;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Builds only the last vertex as VelocyPack
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//////////////////////////////////////////////////////////////////////////////
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virtual aql::AqlValue lastVertexToAqlValue(transaction::Methods*) = 0;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Gets the amount of read documents
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//////////////////////////////////////////////////////////////////////////////
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virtual size_t getReadDocuments() const { return _readDocuments; }
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protected:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Count how many documents have been read
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//////////////////////////////////////////////////////////////////////////////
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size_t _readDocuments;
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};
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class Traverser {
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friend class arangodb::graph::BreadthFirstEnumerator;
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friend class DepthFirstEnumerator;
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friend class arangodb::graph::NeighborsEnumerator;
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#ifdef USE_ENTERPRISE
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friend class SmartDepthFirstPathEnumerator;
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friend class SmartBreadthFirstPathEnumerator;
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#endif
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protected:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Class to read vertices.
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/////////////////////////////////////////////////////////////////////////////
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class VertexGetter {
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public:
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explicit VertexGetter(Traverser* traverser) : _traverser(traverser) {}
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virtual ~VertexGetter() = default;
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virtual bool getVertex(arangodb::velocypack::Slice,
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std::vector<arangodb::velocypack::StringRef>&);
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virtual bool getSingleVertex(arangodb::velocypack::Slice, arangodb::velocypack::StringRef,
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uint64_t, arangodb::velocypack::StringRef&);
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virtual void reset(arangodb::velocypack::StringRef const&);
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protected:
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Traverser* _traverser;
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};
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Class to read vertices. Will return each vertex exactly once!
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/////////////////////////////////////////////////////////////////////////////
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class UniqueVertexGetter final : public VertexGetter {
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public:
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explicit UniqueVertexGetter(Traverser* traverser)
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: VertexGetter(traverser) {}
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~UniqueVertexGetter() = default;
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bool getVertex(arangodb::velocypack::Slice,
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std::vector<arangodb::velocypack::StringRef>&) override;
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bool getSingleVertex(arangodb::velocypack::Slice, arangodb::velocypack::StringRef,
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uint64_t, arangodb::velocypack::StringRef&) override;
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void reset(arangodb::velocypack::StringRef const&) override;
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private:
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std::unordered_set<arangodb::velocypack::StringRef> _returnedVertices;
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};
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public:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Constructor. This is an abstract only class.
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//////////////////////////////////////////////////////////////////////////////
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Traverser(TraverserOptions* opts, transaction::Methods* trx);
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Destructor
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//////////////////////////////////////////////////////////////////////////////
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virtual ~Traverser();
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void done() { _done = true; }
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Reset the traverser to use another start vertex
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//////////////////////////////////////////////////////////////////////////////
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virtual void setStartVertex(std::string const& value) = 0;
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Skip amount many paths of the graph.
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//////////////////////////////////////////////////////////////////////////////
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size_t skip(size_t amount) {
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size_t skipped = 0;
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for (size_t i = 0; i < amount; ++i) {
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if (!next()) {
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_done = true;
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break;
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}
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++skipped;
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}
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return skipped;
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}
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/// @brief Get the next possible path in the graph.
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bool next();
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graph::TraverserCache* traverserCache();
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protected:
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/// @brief Function to load the other sides vertex of an edge
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/// Returns true if the vertex passes filtering conditions
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/// Also appends the _id value of the vertex in the given vector
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virtual bool getVertex(arangodb::velocypack::Slice,
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std::vector<arangodb::velocypack::StringRef>&) = 0;
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/// @brief Function to load the other sides vertex of an edge
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/// Returns true if the vertex passes filtering conditions
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virtual bool getSingleVertex(arangodb::velocypack::Slice edge,
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arangodb::velocypack::StringRef const sourceVertexId,
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uint64_t depth,
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arangodb::velocypack::StringRef& targetVertexId) = 0;
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public:
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Builds only the last vertex as AQLValue
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//////////////////////////////////////////////////////////////////////////////
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aql::AqlValue lastVertexToAqlValue() {
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return _enumerator->lastVertexToAqlValue();
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}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Builds only the last edge as AQLValue
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//////////////////////////////////////////////////////////////////////////////
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aql::AqlValue lastEdgeToAqlValue() {
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return _enumerator->lastEdgeToAqlValue();
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}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Builds the complete path as AQLValue
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/// Has the format:
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/// {
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/// vertices: [<vertex-as-velocypack>],
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/// edges: [<edge-as-velocypack>]
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/// }
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/// NOTE: Will clear the given buffer and will leave the path in it.
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//////////////////////////////////////////////////////////////////////////////
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aql::AqlValue pathToAqlValue(arangodb::velocypack::Builder& builder) {
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return _enumerator->pathToAqlValue(builder);
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}
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Get the number of filtered paths
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//////////////////////////////////////////////////////////////////////////////
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size_t getAndResetFilteredPaths();
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Get the number of documents loaded
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//////////////////////////////////////////////////////////////////////////////
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size_t getAndResetReadDocuments();
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Get the number of HTTP requests made
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//////////////////////////////////////////////////////////////////////////////
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size_t getAndResetHttpRequests();
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TraverserOptions* options() { return _opts; }
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Simple check if there are potentially more paths.
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/// It might return true although there are no more paths available.
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/// If it returns false it is guaranteed that there are no more paths.
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//////////////////////////////////////////////////////////////////////////////
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bool hasMore() { return !_done; }
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bool edgeMatchesConditions(arangodb::velocypack::Slice edge,
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arangodb::velocypack::StringRef vid,
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uint64_t depth, size_t cursorId);
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bool vertexMatchesConditions(arangodb::velocypack::StringRef vid, uint64_t depth);
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void allowOptimizedNeighbors();
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transaction::Methods* trx() const { return _trx; }
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//////////////////////////////////////////////////////////////////////////////
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/// @brief Destroy DBServer Traverser Engines
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//////////////////////////////////////////////////////////////////////////////
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virtual void destroyEngines() = 0;
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protected:
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/// @brief Outer top level transaction
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transaction::Methods* _trx;
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/// @brief internal cursor to enumerate the paths of a graph
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std::unique_ptr<traverser::PathEnumerator> _enumerator;
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/// @brief internal getter to extract an edge
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std::unique_ptr<VertexGetter> _vertexGetter;
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/// @brief Builder for the start value slice. Leased from transaction
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velocypack::Builder _startIdBuilder;
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/// @brief indicator if this traversal is done
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bool _done;
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/// @brief options for traversal
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TraverserOptions* _opts;
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bool _canUseOptimizedNeighbors;
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/// @brief Function to fetch the real data of a vertex into an AQLValue
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virtual aql::AqlValue fetchVertexData(arangodb::velocypack::StringRef vid) = 0;
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/// @brief Function to add the real data of a vertex into a velocypack builder
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virtual void addVertexToVelocyPack(arangodb::velocypack::StringRef vid,
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arangodb::velocypack::Builder&) = 0;
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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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