/
geojson_datasource.cpp
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/
geojson_datasource.cpp
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/*****************************************************************************
*
* This file is part of Mapnik (c++ mapping toolkit)
*
* Copyright (C) 2014 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 "geojson_datasource.hpp"
#include "geojson_featureset.hpp"
#include "large_geojson_featureset.hpp"
#include <fstream>
#include <algorithm>
// boost
#include <boost/algorithm/string.hpp>
#include <boost/spirit/include/qi.hpp>
// mapnik
#include <mapnik/boolean.hpp>
#include <mapnik/unicode.hpp>
#include <mapnik/utils.hpp>
#include <mapnik/feature.hpp>
#include <mapnik/feature_factory.hpp>
#include <mapnik/feature_kv_iterator.hpp>
#include <mapnik/value_types.hpp>
#include <mapnik/box2d.hpp>
#include <mapnik/debug.hpp>
#include <mapnik/proj_transform.hpp>
#include <mapnik/projection.hpp>
#include <mapnik/util/variant.hpp>
#include <mapnik/util/file_io.hpp>
#include <mapnik/util/geometry_to_ds_type.hpp>
#include <mapnik/make_unique.hpp>
#include <mapnik/json/feature_collection_grammar.hpp>
#include <mapnik/json/extract_bounding_box_grammar_impl.hpp>
#include <mapnik/util/boost_geometry_adapters.hpp> // boost.geometry - register box2d<double>
#if defined(SHAPE_MEMORY_MAPPED_FILE)
#include <boost/interprocess/mapped_region.hpp>
#include <mapnik/mapped_memory_cache.hpp>
#endif
using mapnik::datasource;
using mapnik::parameters;
DATASOURCE_PLUGIN(geojson_datasource)
struct attr_value_converter
{
mapnik::eAttributeType operator() (mapnik::value_integer) const
{
return mapnik::Integer;
}
mapnik::eAttributeType operator() (double) const
{
return mapnik::Double;
}
mapnik::eAttributeType operator() (float) const
{
return mapnik::Double;
}
mapnik::eAttributeType operator() (bool) const
{
return mapnik::Boolean;
}
mapnik::eAttributeType operator() (std::string const& ) const
{
return mapnik::String;
}
mapnik::eAttributeType operator() (mapnik::value_unicode_string const&) const
{
return mapnik::String;
}
mapnik::eAttributeType operator() (mapnik::value_null const& ) const
{
return mapnik::String;
}
};
geojson_datasource::geojson_datasource(parameters const& params)
: datasource(params),
type_(datasource::Vector),
desc_(geojson_datasource::name(),
*params.get<std::string>("encoding","utf-8")),
filename_(),
inline_string_(),
extent_(),
features_(),
tree_(nullptr)
{
boost::optional<std::string> inline_string = params.get<std::string>("inline");
if (inline_string)
{
inline_string_ = *inline_string;
}
else
{
boost::optional<std::string> file = params.get<std::string>("file");
if (!file) throw mapnik::datasource_exception("GeoJSON Plugin: missing <file> parameter");
boost::optional<std::string> base = params.get<std::string>("base");
if (base)
filename_ = *base + "/" + *file;
else
filename_ = *file;
}
if (!inline_string_.empty())
{
char const* start = inline_string_.c_str();
char const* end = start + inline_string_.size();
parse_geojson(start, end);
}
else
{
cache_features_ = *params.get<mapnik::boolean_type>("cache_features", true);
#if !defined(SHAPE_MEMORY_MAPPED_FILE)
mapnik::util::file file(filename_);
if (!file.open())
{
throw mapnik::datasource_exception("GeoJSON Plugin: could not open: '" + filename_ + "'");
}
std::string file_buffer;
file_buffer.resize(file.size());
std::fread(&file_buffer[0], file.size(), 1, file.get());
char const* start = file_buffer.c_str();
char const* end = start + file_buffer.length();
if (cache_features_)
{
parse_geojson(start, end);
}
else
{
initialise_index(start, end);
}
#else
boost::optional<mapnik::mapped_region_ptr> mapped_region =
mapnik::mapped_memory_cache::instance().find(filename_, false);
if (!mapped_region)
{
throw std::runtime_error("could not get file mapping for "+ filename_);
}
char const* start = reinterpret_cast<char const*>((*mapped_region)->get_address());
char const* end = start + (*mapped_region)->get_size();
if (cache_features_)
{
parse_geojson(start, end);
}
else
{
initialise_index(start, end);
}
#endif
}
}
namespace {
using base_iterator_type = char const*;
const mapnik::transcoder geojson_datasource_static_tr("utf8");
const mapnik::json::feature_collection_grammar<base_iterator_type,mapnik::feature_impl> geojson_datasource_static_fc_grammar(geojson_datasource_static_tr);
const mapnik::json::feature_grammar<base_iterator_type, mapnik::feature_impl> geojson_datasource_static_feature_grammar(geojson_datasource_static_tr);
const mapnik::json::extract_bounding_box_grammar<base_iterator_type> geojson_datasource_static_bbox_grammar;
}
template <typename Iterator>
void geojson_datasource::initialise_index(Iterator start, Iterator end)
{
mapnik::json::boxes boxes;
boost::spirit::ascii::space_type space;
Iterator itr = start;
if (!boost::spirit::qi::phrase_parse(itr, end, (geojson_datasource_static_bbox_grammar)(boost::phoenix::ref(boxes)) , space))
{
throw mapnik::datasource_exception("GeoJSON Plugin: could not parse: '" + filename_ + "'");
}
// bulk insert initialise r-tree
tree_ = std::make_unique<spatial_index_type>(boxes);
// calculate total extent
for (auto const& item : boxes)
{
auto const& box = std::get<0>(item);
auto const& geometry_index = std::get<1>(item);
if (!extent_.valid())
{
extent_ = box;
// parse first feature to extract attributes schema.
// NOTE: this doesn't yield correct answer for geoJSON in general, just an indication
Iterator itr = start + geometry_index.first;
Iterator end = itr + geometry_index.second;
mapnik::context_ptr ctx = std::make_shared<mapnik::context_type>();
mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx,1));
boost::spirit::ascii::space_type space;
if (!boost::spirit::qi::phrase_parse(itr, end, (geojson_datasource_static_feature_grammar)(boost::phoenix::ref(*feature)), space))
{
throw std::runtime_error("Failed to parse geojson feature");
}
for ( auto const& kv : *feature)
{
desc_.add_descriptor(mapnik::attribute_descriptor(std::get<0>(kv),
mapnik::util::apply_visitor(attr_value_converter(),
std::get<1>(kv))));
}
}
else
{
extent_.expand_to_include(box);
}
}
}
template <typename Iterator>
void geojson_datasource::parse_geojson(Iterator start, Iterator end)
{
boost::spirit::ascii::space_type space;
mapnik::context_ptr ctx = std::make_shared<mapnik::context_type>();
std::size_t start_id = 1;
mapnik::json::default_feature_callback callback(features_);
bool result = boost::spirit::qi::phrase_parse(start, end, (geojson_datasource_static_fc_grammar)
(boost::phoenix::ref(ctx),boost::phoenix::ref(start_id), boost::phoenix::ref(callback)),
space);
if (!result)
{
if (!inline_string_.empty()) throw mapnik::datasource_exception("geojson_datasource: Failed parse GeoJSON file from in-memory string");
else throw mapnik::datasource_exception("geojson_datasource: Failed parse GeoJSON file '" + filename_ + "'");
}
using values_container = std::vector< std::pair<box_type, std::pair<std::size_t, std::size_t>>>;
values_container values;
values.reserve(features_.size());
std::size_t geometry_index = 0;
for (mapnik::feature_ptr const& f : features_)
{
mapnik::box2d<double> box = f->envelope();
if (box.valid())
{
if (geometry_index == 0)
{
extent_ = box;
for ( auto const& kv : *f)
{
desc_.add_descriptor(mapnik::attribute_descriptor(std::get<0>(kv),
mapnik::util::apply_visitor(attr_value_converter(),
std::get<1>(kv))));
}
}
else
{
extent_.expand_to_include(box);
}
}
values.emplace_back(box, std::make_pair(geometry_index,0));
++geometry_index;
}
// packing algorithm
tree_ = std::make_unique<spatial_index_type>(values);
}
geojson_datasource::~geojson_datasource() { }
const char * geojson_datasource::name()
{
return "geojson";
}
mapnik::datasource::datasource_t geojson_datasource::type() const
{
return type_;
}
mapnik::box2d<double> geojson_datasource::envelope() const
{
return extent_;
}
mapnik::layer_descriptor geojson_datasource::get_descriptor() const
{
return desc_;
}
boost::optional<mapnik::datasource_geometry_t> geojson_datasource::get_geometry_type() const
{
boost::optional<mapnik::datasource_geometry_t> result;
int multi_type = 0;
if (cache_features_)
{
unsigned num_features = features_.size();
for (unsigned i = 0; i < num_features && i < 5; ++i)
{
result = mapnik::util::to_ds_type(features_[i]->get_geometry());
if (result)
{
int type = static_cast<int>(*result);
if (multi_type > 0 && multi_type != type)
{
result.reset(mapnik::datasource_geometry_t::Collection);
return result;
}
multi_type = type;
}
}
}
else
{
mapnik::util::file file(filename_);
if (!file.open())
{
throw mapnik::datasource_exception("GeoJSON Plugin: could not open: '" + filename_ + "'");
}
auto itr = tree_->qbegin(boost::geometry::index::intersects(extent_));
auto end = tree_->qend();
mapnik::context_ptr ctx = std::make_shared<mapnik::context_type>();
for (std::size_t count = 0; itr !=end && count < 5; ++itr,++count)
{
geojson_datasource::item_type const& item = *itr;
std::size_t file_offset = item.second.first;
std::size_t size = item.second.second;
std::fseek(file.get(), file_offset, SEEK_SET);
std::vector<char> json;
json.resize(size);
std::fread(json.data(), size, 1, file.get());
using chr_iterator_type = char const*;
chr_iterator_type start = json.data();
chr_iterator_type end = start + json.size();
using namespace boost::spirit;
ascii::space_type space;
mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx,1));
if (!qi::phrase_parse(start, end, (geojson_datasource_static_feature_grammar)(boost::phoenix::ref(*feature)), space))
{
throw std::runtime_error("Failed to parse geojson feature");
}
result = mapnik::util::to_ds_type(feature->get_geometry());
if (result)
{
int type = static_cast<int>(*result);
if (multi_type > 0 && multi_type != type)
{
result.reset(mapnik::datasource_geometry_t::Collection);
return result;
}
multi_type = type;
}
}
}
return result;
}
mapnik::featureset_ptr geojson_datasource::features(mapnik::query const& q) const
{
// if the query box intersects our world extent then query for features
mapnik::box2d<double> const& box = q.get_bbox();
if (extent_.intersects(box))
{
geojson_featureset::array_type index_array;
if (tree_)
{
tree_->query(boost::geometry::index::intersects(box),std::back_inserter(index_array));
if (cache_features_)
{
return std::make_shared<geojson_featureset>(features_, std::move(index_array));
}
else
{
std::sort(index_array.begin(),index_array.end(),
[] (item_type const& item0, item_type const& item1)
{
return item0.second.first < item1.second.first;
});
return std::make_shared<large_geojson_featureset>(filename_, std::move(index_array));
}
}
}
// otherwise return an empty featureset pointer
return mapnik::featureset_ptr();
}
mapnik::featureset_ptr geojson_datasource::features_at_point(mapnik::coord2d const& pt, double tol) const
{
mapnik::box2d<double> query_bbox(pt, pt);
query_bbox.pad(tol);
mapnik::query q(query_bbox);
std::vector<mapnik::attribute_descriptor> const& desc = desc_.get_descriptors();
std::vector<mapnik::attribute_descriptor>::const_iterator itr = desc.begin();
std::vector<mapnik::attribute_descriptor>::const_iterator end = desc.end();
for ( ;itr!=end;++itr)
{
q.add_property_name(itr->get_name());
}
return features(q);
}