mapnik/utils/pgsql2sqlite/sqlite.hpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2021 Artem Pavlenko
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 *****************************************************************************/

#include <mapnik/util/noncopyable.hpp>
#include <mapnik/util/variant.hpp>
// boost
#include <memory>

#include <mapnik/warning.hpp>
MAPNIK_DISABLE_WARNING_PUSH
#include <mapnik/warning_ignore.hpp>
#include <sqlite3.h>
MAPNIK_DISABLE_WARNING_POP

//stl
#ifdef MAPNIK_DEBUG
#include <cassert>
#endif

#include <iostream>
#include <string>
#include <vector>

namespace mapnik {  namespace sqlite {

    class database : private util::noncopyable
    {
        friend class prepared_statement;

        struct database_closer
        {
            void operator () (sqlite3 * db)
            {
#ifdef MAPNIK_DEBUG
                std::cerr << "close database " << db << "\n";
#endif
                sqlite3_close(db);
            }
        };

        using sqlite_db = std::shared_ptr<sqlite3>;
        sqlite_db db_;

    public:
        database(std::string const& name);
        ~database();
        bool execute(std::string const& sql);
    };

    struct null_type {};
    struct blob
    {
        blob(const char* buf, unsigned size)
            : buf_(buf), size_(size) {}

        const char * buf_;
        unsigned size_;
    };

    using value_type = mapnik::util::variant<int,double,std::string, blob,null_type>;
    using record_type = std::vector<value_type>;

    class prepared_statement : util::noncopyable
    {
        struct binder
        {
            binder(sqlite3_stmt * stmt, unsigned index)
                : stmt_(stmt), index_(index) {}

            bool operator() (null_type )
            {
                if (sqlite3_bind_null(stmt_, index_) != SQLITE_OK)
                {
                    std::cerr << "cannot bind nullptr\n";
                    return false;
                }
                return true;
            }

            bool operator() (int val)
            {
                if (sqlite3_bind_int(stmt_, index_ , val ) != SQLITE_OK)
                {
                    std::cerr << "cannot bind " << val << "\n";
                    return false;
                }
                return true;
            }

            bool operator() (double val)
            {
                if (sqlite3_bind_double(stmt_, index_ , val ) != SQLITE_OK)
                {
                    std::cerr << "cannot bind " << val << "\n";
                    return false;
                }
                return true;
            }

            bool operator() (std::string const& val)
            {
                if (sqlite3_bind_text(stmt_, index_, val.c_str(), val.length(), SQLITE_STATIC) != SQLITE_OK)
                {
                    std::cerr << "cannot bind " << val << "\n";
                    return false;
                }
                return true;
            }

            bool operator() (blob const& val)
            {
                if (sqlite3_bind_blob(stmt_, index_, val.buf_, val.size_, SQLITE_STATIC) != SQLITE_OK)
                {
                    std::cerr << "cannot bind BLOB\n";
                    return false;
                }
                return true;
            }

            sqlite3_stmt * stmt_;
            unsigned index_;
        };
    public:
        prepared_statement(database & db, std::string const& sql)
            : db_(db.db_.get()), stmt_(0)
        {
            const char * tail;
            //char * err_msg;
            int res = sqlite3_prepare_v2(db_, sql.c_str(),-1, &stmt_,&tail);
            if (res != SQLITE_OK)
            {
                std::cerr << "ERR:"<< res << "\n";
                throw;
            }
        }

        ~prepared_statement()
        {
            int res = sqlite3_finalize(stmt_);
            if (res != SQLITE_OK)
            {
                std::cerr << "ERR:" << res << "\n";
            }
        }

        bool insert_record(record_type const& rec) const
        {
#ifdef MAPNIK_DEBUG
            assert( unsigned(sqlite3_bind_parameter_count(stmt_)) == rec.size());
#endif
            record_type::const_iterator itr = rec.begin();
            record_type::const_iterator end = rec.end();
            int count = 1;
            for (; itr!=end;++itr)
            {
                binder op(stmt_,count++);
                if (!util::apply_visitor(op,*itr))
                {
                    return false;
                }
            }

            sqlite3_step(stmt_);
            sqlite3_reset(stmt_);

            return true;
        }

    private:
        sqlite3 * db_;
        sqlite3_stmt * stmt_;
    };
    }
}