text: /**
   *    Copyright (C) 2013-2014 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #pragma once
  
  #include <memory>
  #include <vector>
  
  #include "mongo/db/exec/plan_stage.h"
  #include "mongo/db/exec/working_set.h"
  #include "mongo/db/fts/fts_query_impl.h"
  #include "mongo/db/fts/fts_spec.h"
  #include "mongo/db/fts/fts_util.h"
  #include "mongo/db/index/index_descriptor.h"
  
  namespace mongo {
  
  using std::unique_ptr;
  using std::vector;
  
  using fts::FTSQueryImpl;
  using fts::FTSSpec;
  
  class OperationContext;
  
  struct TextStageParams {
      TextStageParams(const FTSSpec& s) : spec(s) {}
  
      // Text index descriptor.  IndexCatalog owns this.
      IndexDescriptor* index;
  
      // Index spec.
      FTSSpec spec;
  
      // Index keys that precede the "text" index key.
      BSONObj indexPrefix;
  
      // The text query.
      FTSQueryImpl query;
  };
  
  /**
   * Implements a blocking stage that returns text search results.
   *
   * Output type: LOC_AND_OBJ.
   */
  class TextStage final : public PlanStage {
  public:
      TextStage(OperationContext* txn,
                const TextStageParams& params,
                WorkingSet* ws,
                const MatchExpression* filter);
  
  
      StageState doWork(WorkingSetID* out) final;
      bool isEOF() final;
  
      StageType stageType() const final {
          return STAGE_TEXT;
      }
  
      std::unique_ptr<PlanStageStats> getStats();
  
      const SpecificStats* getSpecificStats() const final;
  
      static const char* kStageType;
  
  private:
      /**
       * Helper method to built the query execution plan for the text stage.
       */
      unique_ptr<PlanStage> buildTextTree(OperationContext* txn,
                                          WorkingSet* ws,
                                          const MatchExpression* filter) const;
  
      // Parameters of this text stage.
      TextStageParams _params;
  
      // Stats.
      TextStats _specificStats;
  };
  
  }  // namespace mongo
  