mapnik/plugins/input/csv/csv_featureset.cpp

/*****************************************************************************
 *
 * This file is part of Mapnik (c++ mapping toolkit)
 *
 * Copyright (C) 2024 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
 *
 *****************************************************************************/

// mapnik
#include "csv_featureset.hpp"
#include <mapnik/debug.hpp>
#include <mapnik/feature.hpp>
#include <mapnik/feature_factory.hpp>
#include <mapnik/util/utf_conv_win.hpp>
// stl
#include <string>
#include <vector>
#include <deque>

csv_featureset::csv_featureset(std::string const& filename,
                               locator_type const& locator,
                               char separator,
                               char quote,
                               std::vector<std::string> const& headers,
                               mapnik::context_ptr const& ctx,
                               array_type&& index_array)
    :
#if defined(MAPNIK_MEMORY_MAPPED_FILE)
//
#elif defined(_WIN32)
    file_(_wfopen(mapnik::utf8_to_utf16(filename).c_str(), L"rb"), std::fclose)
    ,
#else
    file_(std::fopen(filename.c_str(), "rb"), std::fclose)
    ,
#endif
    separator_(separator)
    , quote_(quote)
    , headers_(headers)
    , index_array_(std::move(index_array))
    , index_itr_(index_array_.begin())
    , index_end_(index_array_.end())
    , ctx_(ctx)
    , locator_(locator)
    , tr_("utf8")
{
#if defined(MAPNIK_MEMORY_MAPPED_FILE)
    const auto memory = mapnik::mapped_memory_cache::instance().find(filename, true);
    if (memory.has_value())
    {
        mapped_region_ = *memory;
    }
    else
    {
        throw std::runtime_error("could not create file mapping for " + filename);
    }
#else
    if (!file_)
        throw std::runtime_error("Can't open " + filename);
#endif
}

csv_featureset::~csv_featureset() {}

mapnik::feature_ptr csv_featureset::parse_feature(char const* beg, char const* end)
{
    auto values = csv_utils::parse_line(beg, end, separator_, quote_, headers_.size());
    auto geom = csv_utils::extract_geometry(values, locator_);
    if (!geom.is<mapnik::geometry::geometry_empty>())
    {
        mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx_, ++feature_id_));
        feature->set_geometry(std::move(geom));
        csv_utils::process_properties(*feature, headers_, values, locator_, tr_);
        return feature;
    }
    return mapnik::feature_ptr();
}

mapnik::feature_ptr csv_featureset::next()
{
    if (index_itr_ != index_end_)
    {
        csv_datasource::item_type const& item = *index_itr_++;
        std::uint64_t file_offset = item.second.first;
        std::uint64_t size = item.second.second;
#if defined(MAPNIK_MEMORY_MAPPED_FILE)
        char const* start = (char const*)mapped_region_->get_address() + file_offset;
        char const* end = start + size;
#else
        std::fseek(file_.get(), file_offset, SEEK_SET);
        std::vector<char> record;
        record.resize(size);
        if (std::fread(record.data(), size, 1, file_.get()) != 1)
        {
            return mapnik::feature_ptr();
        }
        auto const* start = record.data();
        auto const* end = start + record.size();
#endif
        return parse_feature(start, end);
    }
    return mapnik::feature_ptr();
}