text: // Licensed to the Apache Software Foundation (ASF) under one
  // or more contributor license agreements.  See the LICENSE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The ASF licenses this file
  // to you 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.
  
  #pragma once
  
  #include <set>
  
  #include "store/graph.h"
  
  class GraphStoreSet : public GraphStore
  {
  public:
    void add_edge(const std::string& subject,
                  const std::string& predicate,
                  const std::string& object,
                  const std::string& label) final;
    void delete_edge(const std::string& subject,
                     const std::string& predicate,
                     const std::string& object,
                     const std::string& label) final;
  
  private:
    struct Edge {
      std::string subject;
      std::string predicate;
      std::string object;
      std::string label;
  
      bool operator<(const Edge& edge) const
      {
        return std::make_tuple(subject, predicate, object, label) <
               std::make_tuple(edge.subject, edge.predicate, edge.subject,
                               edge.label);
      }
    };
  
    std::set<Edge> edges;
  };
  