107 lines
4 KiB
C++
107 lines
4 KiB
C++
/*****************************************************************************
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*
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* This file is part of Mapnik (c++ mapping toolkit)
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*
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* Copyright (C) 2021 Artem Pavlenko
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*****************************************************************************/
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// mapnik
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#include "geojson_index_featureset.hpp"
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#include <mapnik/feature.hpp>
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#include <mapnik/feature_factory.hpp>
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#include <mapnik/json/feature_grammar.hpp>
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#include <mapnik/util/utf_conv_win.hpp>
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#include <mapnik/util/spatial_index.hpp>
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#include <mapnik/geometry_is_empty.hpp>
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// stl
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#include <string>
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#include <vector>
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#include <fstream>
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geojson_index_featureset::geojson_index_featureset(std::string const& filename, mapnik::filter_in_box const& filter)
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:
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#if defined(MAPNIK_MEMORY_MAPPED_FILE)
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//
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#elif defined _WINDOWS
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file_(_wfopen(mapnik::utf8_to_utf16(filename).c_str(), L"rb"), std::fclose),
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#else
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file_(std::fopen(filename.c_str(),"rb"), std::fclose),
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#endif
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ctx_(std::make_shared<mapnik::context_type>())
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{
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#if defined (MAPNIK_MEMORY_MAPPED_FILE)
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boost::optional<mapnik::mapped_region_ptr> memory =
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mapnik::mapped_memory_cache::instance().find(filename, true);
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if (memory)
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{
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mapped_region_ = *memory;
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}
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else
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{
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throw std::runtime_error("could not create file mapping for " + filename);
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}
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#else
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if (!file_) throw std::runtime_error("Can't open " + filename);
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#endif
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std::string indexname = filename + ".index";
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std::ifstream index(indexname.c_str(), std::ios::binary);
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if (!index) throw mapnik::datasource_exception("GeoJSON Plugin: can't open index file " + indexname);
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mapnik::util::spatial_index<value_type,
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mapnik::filter_in_box,
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std::ifstream>::query(filter, index, positions_);
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std::sort(positions_.begin(), positions_.end(),
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[](value_type const& lhs, value_type const& rhs) { return lhs.first < rhs.first;});
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itr_ = positions_.begin();
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}
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geojson_index_featureset::~geojson_index_featureset() {}
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mapnik::feature_ptr geojson_index_featureset::next()
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{
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while( itr_ != positions_.end())
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{
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auto pos = *itr_++;
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#if defined(MAPNIK_MEMORY_MAPPED_FILE)
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char const* start = (char const*)mapped_region_->get_address() + pos.first;
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char const* end = start + pos.second;
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#else
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std::fseek(file_.get(), pos.first, SEEK_SET);
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std::vector<char> record;
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record.resize(pos.second);
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std::fread(record.data(), pos.second, 1, file_.get());
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auto const* start = record.data();
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auto const* end = start + record.size();
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#endif
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static const mapnik::transcoder tr("utf8");
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static const mapnik::json::feature_grammar<char const*, mapnik::feature_impl> grammar(tr);
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using namespace boost::spirit;
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standard::space_type space;
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mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx_, feature_id_++));
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if (!qi::phrase_parse(start, end, (grammar)(boost::phoenix::ref(*feature)), space) || start != end)
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{
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throw std::runtime_error("Failed to parse GeoJSON feature");
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}
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// skip empty geometries
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if (mapnik::geometry::is_empty(feature->get_geometry()))
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continue;
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return feature;
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}
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return mapnik::feature_ptr();
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}
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