.. _program_listing_file__tmp_ws_src_warehouse_ros_sqlite_include_warehouse_ros_sqlite_impl_variant.hpp:

Program Listing for File variant.hpp
====================================

|exhale_lsh| :ref:`Return to documentation for file <file__tmp_ws_src_warehouse_ros_sqlite_include_warehouse_ros_sqlite_impl_variant.hpp>` (``/tmp/ws/src/warehouse_ros_sqlite/include/warehouse_ros_sqlite/impl/variant.hpp``)

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.. code-block:: cpp

   // Copyright 2020 Bjarne von Horn
   //
   // Redistribution and use in source and binary forms, with or without
   // modification, are permitted provided that the following conditions are met:
   //
   //    * Redistributions of source code must retain the above copyright
   //      notice, this list of conditions and the following disclaimer.
   //
   //    * Redistributions in binary form must reproduce the above copyright
   //      notice, this list of conditions and the following disclaimer in the
   //      documentation and/or other materials provided with the distribution.
   //
   //    * Neither the name of the copyright holder nor the names of its
   //      contributors may be used to endorse or promote products derived from
   //      this software without specific prior written permission.
   //
   // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
   // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   // POSSIBILITY OF SUCH DAMAGE.
   
   // SPDX-License-Identifier: BSD-3-Clause
   
   #ifndef WAREHOUSE_ROS_SQLITE__IMPL__VARIANT_HPP_
   #define WAREHOUSE_ROS_SQLITE__IMPL__VARIANT_HPP_
   
   #include <sqlite3.h>
   
   #include <boost/variant.hpp>
   
   #include <warehouse_ros_sqlite/utils.hpp>
   #include <warehouse_ros_sqlite/exceptions.hpp>
   
   #include <string>
   #include <sstream>
   #include <utility>
   
   namespace warehouse_ros_sqlite
   {
   class BindVisitor : boost::static_visitor<int>
   {
     sqlite3_stmt * stmt_;
     int idx_;
   
   public:
     explicit BindVisitor(sqlite3_stmt * stmt, int start_idx = 1)
     : stmt_(stmt), idx_(start_idx)
     {
     }
     int operator()(int i)
     {
       return sqlite3_bind_int64(stmt_, idx_++, i);
     }
     int operator()(double d)
     {
       return sqlite3_bind_double(stmt_, idx_++, d);
     }
     int operator()(const std::string & s)
     {
       return sqlite3_bind_blob64(stmt_, idx_++, s.data(), s.size(), SQLITE_STATIC);
     }
     int operator()(NullValue /* unused */)
     {
       return sqlite3_bind_null(stmt_, idx_++);
     }
     int getTotalBinds() const
     {
       return idx_ - 1;
     }
   };
   
   class EnsureColumnVisitor : boost::static_visitor<>
   {
     sqlite3 * db_;
     std::string unescaped_tablename_;
     schema::escaped_tablename escaped_tablename_;
     std::string unescaped_colname_;
     bool columnExists()
     {
       const std::string colname(schema::METADATA_COLUMN_PREFIX + unescaped_colname_);
       return sqlite3_table_column_metadata(
         db_, schema::DB_NAME, unescaped_tablename_.c_str(), colname.c_str(), nullptr,
         nullptr, nullptr, nullptr, nullptr) == SQLITE_OK;
     }
     void addColumn(const char * datatype)
     {
       std::ostringstream query_builder;
       query_builder << "ALTER TABLE " << escaped_tablename_ << " ADD " <<
         schema::escape_columnname_with_prefix(unescaped_colname_) << " " << datatype << ";";
       if (sqlite3_exec(db_, query_builder.str().c_str(), nullptr, nullptr, nullptr) != SQLITE_OK) {
         throw InternalError("could not create column", db_);
       }
     }
   
   public:
     EnsureColumnVisitor(sqlite3 * db, const std::string & unescaped_tablename)
     : db_(db),
       unescaped_tablename_(unescaped_tablename),
       escaped_tablename_(schema::escape_identifier(unescaped_tablename))
     {
     }
     void operator()(int /*unused*/)  // NOLINT
     {
       if (!columnExists()) {
         addColumn("INTEGER");
       }
     }
     void operator()(double /*unused*/)  // NOLINT
     {
       if (!columnExists()) {
         addColumn("FLOAT");
       }
     }
     void operator()(const std::string & /*unused*/)
     {
       if (!columnExists()) {
         addColumn("BLOB");
       }
     }
     void operator()(NullValue /* unused */)
     {
       if (!columnExists()) {
         throw std::runtime_error("not implemented");
       }
     }
     EnsureColumnVisitor & setColumnName(const std::string & unescaped_column)
     {
       unescaped_colname_ = unescaped_column;
       return *this;
     }
   };
   
   namespace detail
   {
   template<typename R, typename T>
   struct NullValueGet
   {
     static R get(T /* unused */)
     {
       throw boost::bad_get();
     }
   };
   
   template<typename R>
   struct NullValueGet<R, typename std::enable_if<!std::is_same<R, NullValue>::value, R>::type>
   {
     static R get(R r)
     {
       return std::forward<R>(r);
     }
   };
   
   template<typename R>
   struct NullValueGet<R, NullValue>
   {
     static R get(NullValue /* unused */)
     {
       return R();
     }
   };
   
   }  // namespace detail
   
   template<typename R>
   struct NullValueVisitor : boost::static_visitor<R>
   {
     template<typename T>
     R operator()(T t) const
     {
       return detail::NullValueGet<R, T>::get(std::forward<T>(t));
     }
   };
   }  // namespace warehouse_ros_sqlite
   
   #endif  // WAREHOUSE_ROS_SQLITE__IMPL__VARIANT_HPP_