112 lines
4.1 KiB
C++
112 lines
4.1 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/util/utf_conv_win.hpp>
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#include <mapnik/util/conversions.hpp>
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#include <mapnik/geometry/is_empty.hpp>
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#include <mapnik/json/parse_feature.hpp>
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#include <mapnik/json/json_grammar_config.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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#include <algorithm>
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geojson_index_featureset::geojson_index_featureset(std::string const& filename,
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mapnik::bounding_box_filter<float> 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(_WIN32)
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file_(_wfopen(mapnik::utf8_to_utf16(filename).c_str(), L"rb"), std::fclose)
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,
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#else
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file_(std::fopen(filename.c_str(), "rb"), std::fclose)
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,
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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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const auto memory = mapnik::mapped_memory_cache::instance().find(filename, true);
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if (memory.has_value())
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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_)
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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)
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throw mapnik::datasource_exception("GeoJSON Plugin: can't open index file " + indexname);
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mapnik::util::spatial_index<value_type, mapnik::bounding_box_filter<float>, std::ifstream, mapnik::box2d<float>>::
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query(filter, index, positions_);
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positions_.erase(std::remove_if(positions_.begin(),
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positions_.end(),
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[&](value_type const& pos) { return !pos.box.intersects(filter.box_); }),
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positions_.end());
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std::sort(positions_.begin(), positions_.end(), [](value_type const& lhs, value_type const& rhs) {
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return lhs.off < rhs.off;
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});
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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 = static_cast<char const*>(mapped_region_->get_address()) + pos.off;
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char const* end = start + pos.size;
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#else
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std::fseek(file_.get(), pos.off, SEEK_SET);
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std::vector<char> record;
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record.resize(pos.size);
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auto count = std::fread(record.data(), pos.size, 1, file_.get());
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auto const* start = record.data();
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auto const* end = (count == 1) ? start + record.size() : start;
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#endif
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static const mapnik::transcoder tr("utf8");
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mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx_, feature_id_++));
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using mapnik::json::grammar::iterator_type;
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mapnik::json::parse_feature(start, end, *feature, tr); // throw on failure
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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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