YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

//--------------------------------------------------------------------------------------------------

// Copyright (c) YugaByte, Inc.

//

// This module defines the ResultSet that QL database returns to a query request.

// QLResultSet is a set of rows of data that is returned by a query request.

// - Within our code, we call it "rsrow" instead of row to distinguish between selected-rows and

//   rows of a table in the database.

// - Similarly, we use "rscol" in place of "column".

// - To end users, at a high level interface, we would call them all as rows & columns.

//

// NOTE:

// - This should be merged or shared a super class with ql_rowblock.cc.

// - This will be done in the next diff. We don't do this now to avoid large code modifications.

// - For optimization, columns and rows are serialized (in CQL wire format) directly for return to

//   call. If there is a need to manipulate the rows before return, QLResultSet should be changed to

//   an interface with multiple implementations for different use-cases.

//--------------------------------------------------------------------------------------------------

#ifndef YB_COMMON_QL_RESULTSET_H_

#define YB_COMMON_QL_RESULTSET_H_

#include "yb/common/common_fwd.h"

#include "yb/common/ql_type.h"

namespace yb {

class faststring;

//--------------------------------------------------------------------------------------------------

// A rsrow descriptor represents the metadata of a row in the resultset.

class QLRSRowDesc {

 public:

  class RSColDesc {

   public:

    explicit RSColDesc(const QLRSColDescPB& desc_pb);

    const std::string& name() const {

      return name_;

    }

    const QLType::SharedPtr& ql_type() const {

      return ql_type_;

    }

   private:

    std::string name_;

    QLType::SharedPtr ql_type_;

  };

  explicit QLRSRowDesc(const QLRSRowDescPB& desc_pb);

  virtual ~QLRSRowDesc();

  size_t rscol_count() const {

    return rscol_descs_.size();

  }

  const std::vector<RSColDesc>& rscol_descs() const {

    return rscol_descs_;

  }

 private:

  std::vector<RSColDesc> rscol_descs_;

};

//--------------------------------------------------------------------------------------------------

// A set of rows.

class QLResultSet {

 public:

  typedef std::shared_ptr<QLResultSet> SharedPtr;

  // Constructor and destructor.

  QLResultSet(const QLRSRowDesc* rsrow_desc, faststring* rows_data);

  virtual ~QLResultSet();

  // Allocate a new row at the end of result set.

  void AllocateRow();

  // Append a column to the last row in the result set.

  void AppendColumn(size_t index, const QLValue& value);

  void AppendColumn(size_t index, const QLValuePB& value);

  // Row count

  size_t rsrow_count() const;

 private:

  const QLRSRowDesc* rsrow_desc_ = nullptr;

  faststring* rows_data_ = nullptr;

};

} // namespace yb

#endif // YB_COMMON_QL_RESULTSET_H_