mirror of https://gitee.com/bigwinds/arangodb
393 lines
13 KiB
C++
393 lines
13 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_VOC_BASE_TRAVERSER_H
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#define ARANGOD_VOC_BASE_TRAVERSER_H 1
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#include "Basics/Common.h"
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#include "Basics/Traverser.h"
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#include "Aql/AstNode.h"
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#include "Utils/CollectionNameResolver.h"
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#include "Utils/Transaction.h"
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#include "VocBase/DocumentAccessor.h"
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#include "VocBase/voc-types.h"
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#include <velocypack/Slice.h>
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#include <velocypack/velocypack-aliases.h>
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namespace triagens {
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namespace arango {
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namespace traverser {
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Template for a vertex id. Is simply a pair of cid and key
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/// NOTE: This struct will never free the value asigned to char const* key
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/// The environment has to make sure that the string it points to is
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/// not freed as long as this struct is in use!
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////////////////////////////////////////////////////////////////////////////////
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struct VertexId {
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TRI_voc_cid_t cid;
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char const* key;
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VertexId() : cid(0), key("") {}
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VertexId(TRI_voc_cid_t cid, char const* key) : cid(cid), key(key) {}
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bool operator==(VertexId const& other) const {
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if (cid == other.cid) {
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return strcmp(key, other.key) == 0;
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}
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return false;
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}
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std::string toString(
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triagens::arango::CollectionNameResolver const* resolver) const {
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return resolver->getCollectionNameCluster(cid) + "/" + std::string(key);
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}
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};
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// EdgeId and VertexId are similar here. both have a key and a cid
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typedef VertexId EdgeId;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Helper function to convert an _id string into a VertexId
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////////////////////////////////////////////////////////////////////////////////
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VertexId IdStringToVertexId(
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triagens::arango::CollectionNameResolver const* resolver,
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std::string const& vertex);
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class TraverserExpression {
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public:
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bool isEdgeAccess;
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triagens::aql::AstNodeType comparisonType;
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triagens::aql::AstNode const* varAccess;
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std::unique_ptr<triagens::basics::Json> compareTo;
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TraverserExpression(bool pisEdgeAccess,
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triagens::aql::AstNodeType pcomparisonType,
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triagens::aql::AstNode const* pvarAccess)
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: isEdgeAccess(pisEdgeAccess),
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comparisonType(pcomparisonType),
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varAccess(pvarAccess),
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compareTo(nullptr) {}
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explicit TraverserExpression(VPackSlice const& slice);
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virtual ~TraverserExpression() {
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// no need to destroy varAccess here. Its memory is managed via the
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// _nodeRegister variable in this class
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for (auto& it : _stringRegister) {
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delete it;
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}
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}
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void toJson(triagens::basics::Json& json, TRI_memory_zone_t* zone) const;
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bool matchesCheck(TRI_doc_mptr_t& element,
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TRI_document_collection_t* collection,
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CollectionNameResolver const* resolver) const;
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bool matchesCheck(TRI_json_t const* element) const;
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bool matchesCheck(VPackSlice const& element) const;
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bool matchesCheck(DocumentAccessor& accessor) const;
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protected:
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TraverserExpression()
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: isEdgeAccess(false),
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comparisonType(triagens::aql::NODE_TYPE_ROOT),
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varAccess(nullptr),
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compareTo(nullptr) {}
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private:
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bool recursiveCheck(triagens::aql::AstNode const*, DocumentAccessor&) const;
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// Required when creating this expression without AST
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std::vector<std::unique_ptr<triagens::aql::AstNode const>> _nodeRegister;
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std::vector<std::string*> _stringRegister;
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};
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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 Json
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/// Has the format:
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/// {
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/// vertices: [<vertex-as-json>],
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/// edges: [<edge-as-json>]
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/// }
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////////////////////////////////////////////////////////////////////////////////
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virtual triagens::basics::Json* pathToJson(Transaction*,
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CollectionNameResolver*) = 0;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Builds only the last edge on the path as Json
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////////////////////////////////////////////////////////////////////////////////
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virtual triagens::basics::Json* lastEdgeToJson(Transaction*,
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CollectionNameResolver*) = 0;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Builds only the last vertex as Json
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////////////////////////////////////////////////////////////////////////////////
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virtual triagens::basics::Json* lastVertexToJson(Transaction*,
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CollectionNameResolver*) = 0;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Gets the amount of read documents
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////////////////////////////////////////////////////////////////////////////////
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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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struct TraverserOptions {
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private:
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std::function<bool(const TraversalPath* path)> pruningFunction;
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public:
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TRI_edge_direction_e direction;
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uint64_t minDepth;
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uint64_t maxDepth;
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bool usesPrune;
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TraverserOptions()
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: direction(TRI_EDGE_OUT), minDepth(1), maxDepth(1), usesPrune(false) {}
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void setPruningFunction(
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std::function<bool(TraversalPath const* path)> const& callback) {
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pruningFunction = callback;
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usesPrune = true;
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}
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bool shouldPrunePath(TraversalPath const* path) {
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if (!usesPrune) {
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return false;
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}
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return pruningFunction(path);
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}
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};
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class Traverser {
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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()
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: _readDocuments(0),
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_filteredPaths(0),
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_pruneNext(false),
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_done(true),
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_expressions(nullptr) {}
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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,
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std::unordered_map<size_t, std::vector<TraverserExpression*>> const*
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expressions)
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: _readDocuments(0),
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_filteredPaths(0),
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_pruneNext(false),
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_done(true),
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_opts(opts),
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_expressions(expressions) {}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Destructor
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////////////////////////////////////////////////////////////////////////////////
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virtual ~Traverser() {}
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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(VertexId const& v) = 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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std::unique_ptr<TraversalPath> p(next());
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if (p == nullptr) {
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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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////////////////////////////////////////////////////////////////////////////////
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/// @brief Get the next possible path in the graph.
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////////////////////////////////////////////////////////////////////////////////
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virtual TraversalPath* next() = 0;
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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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size_t tmp = _filteredPaths;
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_filteredPaths = 0;
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return tmp;
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}
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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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size_t tmp = _readDocuments;
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_readDocuments = 0;
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return tmp;
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}
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Prune the current path prefix. Do not evaluate it any further.
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////////////////////////////////////////////////////////////////////////////////
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void prune() { _pruneNext = true; }
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////////////////////////////////////////////////////////////////////////////////
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/// @brief Simple check if there 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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protected:
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////////////////////////////////////////////////////////////////////////////////
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/// @brief counter for all read documents
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////////////////////////////////////////////////////////////////////////////////
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size_t _readDocuments;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief counter for all filtered paths
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////////////////////////////////////////////////////////////////////////////////
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size_t _filteredPaths;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief toggle if this path should be pruned on next step
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////////////////////////////////////////////////////////////////////////////////
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bool _pruneNext;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief indicator if this traversal is done
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////////////////////////////////////////////////////////////////////////////////
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bool _done;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief options for traversal
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////////////////////////////////////////////////////////////////////////////////
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TraverserOptions _opts;
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////////////////////////////////////////////////////////////////////////////////
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/// @brief a vector containing all information for early pruning
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////////////////////////////////////////////////////////////////////////////////
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std::unordered_map<size_t, std::vector<TraverserExpression*>> const*
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_expressions;
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};
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} // traverser
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} // arango
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} // triagens
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namespace std {
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template <>
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struct hash<triagens::arango::traverser::VertexId> {
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public:
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size_t operator()(triagens::arango::traverser::VertexId const& s) const {
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size_t h1 = std::hash<TRI_voc_cid_t>()(s.cid);
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size_t h2 = TRI_FnvHashString(s.key);
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return h1 ^ (h2 << 1);
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}
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};
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template <>
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struct equal_to<triagens::arango::traverser::VertexId> {
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public:
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bool operator()(triagens::arango::traverser::VertexId const& s,
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triagens::arango::traverser::VertexId const& t) const {
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return s.cid == t.cid && strcmp(s.key, t.key) == 0;
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}
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};
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template <>
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struct less<triagens::arango::traverser::VertexId> {
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public:
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bool operator()(triagens::arango::traverser::VertexId const& lhs,
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triagens::arango::traverser::VertexId const& rhs) {
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if (lhs.cid != rhs.cid) {
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return lhs.cid < rhs.cid;
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}
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return strcmp(lhs.key, rhs.key) < 0;
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}
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};
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}
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#endif
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