82 lines
3 KiB
C++
82 lines
3 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) 2014 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 <mapnik/feature.hpp>
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#include <mapnik/feature_factory.hpp>
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#include <mapnik/json/geometry_grammar.hpp>
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#include <mapnik/json/feature_grammar.hpp>
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#include <mapnik/utils.hpp>
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// stl
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#include <string>
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#include <vector>
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#include <deque>
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#include "large_geojson_featureset.hpp"
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large_geojson_featureset::large_geojson_featureset(std::string const& filename,
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array_type && index_array)
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:
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#ifdef _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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index_array_(std::move(index_array)),
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index_itr_(index_array_.begin()),
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index_end_(index_array_.end()),
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ctx_(std::make_shared<mapnik::context_type>())
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{
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if (!file_) throw std::runtime_error("Can't open " + filename);
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}
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large_geojson_featureset::~large_geojson_featureset() {}
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mapnik::feature_ptr large_geojson_featureset::next()
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{
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if (index_itr_ != index_end_)
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{
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geojson_datasource::item_type const& item = *index_itr_++;
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std::size_t file_offset = item.second.first;
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std::size_t size = item.second.second;
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std::fseek(file_.get(), file_offset, SEEK_SET);
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std::vector<char> json;
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json.resize(size);
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std::fread(json.data(), size, 1, file_.get());
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using chr_iterator_type = char const*;
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chr_iterator_type start = json.data();
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chr_iterator_type end = start + json.size();
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static const mapnik::transcoder tr("utf8");
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static const mapnik::json::feature_grammar<chr_iterator_type,mapnik::feature_impl> grammar(tr);
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using namespace boost::spirit;
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ascii::space_type space;
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mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx_,1));
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if (!qi::phrase_parse(start, end, (grammar)(boost::phoenix::ref(*feature)), space))
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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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return feature;
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}
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return mapnik::feature_ptr();
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}
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