wkb.hpp

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#ifndef OSMIUM_GEOM_WKB_HPP
#define OSMIUM_GEOM_WKB_HPP
 
/*
 
This file is part of Osmium (https://osmcode.org/libosmium).
 
Copyright 2013-2023 Jochen Topf <jochen@topf.org> and others (see README).
 
Boost Software License - Version 1.0 - August 17th, 2003
 
Permission is hereby granted, free of charge, to any person or organization
obtaining a copy of the software and accompanying documentation covered by
this license (the "Software") to use, reproduce, display, distribute,
execute, and transmit the Software, and to prepare derivative works of the
Software, and to permit third-parties to whom the Software is furnished to
do so, all subject to the following:
 
The copyright notices in the Software and this entire statement, including
the above license grant, this restriction and the following disclaimer,
must be included in all copies of the Software, in whole or in part, and
all derivative works of the Software, unless such copies or derivative
works are solely in the form of machine-executable object code generated by
a source language processor.
 
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.
 
*/
 
#include <osmium/geom/coordinates.hpp>
#include <osmium/geom/factory.hpp>
#include <osmium/util/endian.hpp>
 
#include <algorithm>
#include <cstddef>
#include <cstdint>
#include <string>
 
namespace osmium {
 
    namespace geom {
 
        enum class wkb_type : bool {
            wkb  = false,
            ewkb = true
        }; // enum class wkb_type
 
        enum class out_type : bool {
            binary = false,
            hex    = true
        }; // enum class out_type
 
        namespace detail {
 
            template <typename T>
            inline void str_push(std::string& str, T data) {
                str.append(reinterpret_cast<const char*>(&data), sizeof(T));
            }
 
            inline std::string convert_to_hex(const std::string& str) {
                static const char* lookup_hex = "0123456789ABCDEF";
                std::string out;
                out.reserve(str.size() * 2);
 
                for (const char c : str) {
                    out += lookup_hex[(static_cast<unsigned int>(c) >> 4U) & 0xfU];
                    out += lookup_hex[ static_cast<unsigned int>(c)        & 0xfU];
                }
 
                return out;
            }
 
            class WKBFactoryImpl {
 
                enum wkbGeometryType : uint32_t {
                    wkbPoint               = 1,
                    wkbLineString          = 2,
                    wkbPolygon             = 3,
                    wkbMultiPoint          = 4,
                    wkbMultiLineString     = 5,
                    wkbMultiPolygon        = 6,
                    wkbGeometryCollection  = 7,
 
                    // SRID-presence flag (EWKB)
                    wkbSRID                = 0x20000000
                }; // enum wkbGeometryType
 
                enum class wkb_byte_order_type : uint8_t {
                    XDR = 0,         // Big Endian
                    NDR = 1          // Little Endian
                }; // enum class wkb_byte_order_type
 
                std::string m_data;
                uint32_t m_points = 0;
                int m_srid;
                wkb_type m_wkb_type;
                out_type m_out_type;
 
                std::size_t m_linestring_size_offset = 0;
                std::size_t m_polygons = 0;
                std::size_t m_rings = 0;
                std::size_t m_multipolygon_size_offset = 0;
                std::size_t m_polygon_size_offset = 0;
                std::size_t m_ring_size_offset = 0;
 
                std::size_t header(std::string& str, wkbGeometryType type, bool add_length) const {
#if __BYTE_ORDER == __LITTLE_ENDIAN
                    str_push(str, wkb_byte_order_type::NDR);
#else
                    str_push(str, wkb_byte_order_type::XDR);
#endif
                    if (m_wkb_type == wkb_type::ewkb) {
                        str_push(str, type | wkbSRID);
                        str_push(str, m_srid);
                    } else {
                        str_push(str, type);
                    }
                    const std::size_t offset = str.size();
                    if (add_length) {
                        str_push(str, static_cast<uint32_t>(0));
                    }
                    return offset;
                }
 
                void set_size(const std::size_t offset, const std::size_t size) {
                    if (size > std::numeric_limits<uint32_t>::max()) {
                        throw geometry_error{"Too many points in geometry"};
                    }
                    const auto s = static_cast<uint32_t>(size);
                    std::copy_n(reinterpret_cast<const char*>(&s), sizeof(uint32_t), &m_data[offset]);
                }
 
            public:
 
                using point_type        = std::string;
                using linestring_type   = std::string;
                using polygon_type      = std::string;
                using multipolygon_type = std::string;
                using ring_type         = std::string;
 
                explicit WKBFactoryImpl(int srid, wkb_type wtype = wkb_type::wkb, out_type otype = out_type::binary) :
                    m_srid(srid),
                    m_wkb_type(wtype),
                    m_out_type(otype) {
                }
 
                /* Point */
 
                point_type make_point(const osmium::geom::Coordinates& xy) const {
                    std::string data;
                    header(data, wkbPoint, false);
                    str_push(data, xy.x);
                    str_push(data, xy.y);
 
                    if (m_out_type == out_type::hex) {
                        return convert_to_hex(data);
                    }
 
                    return data;
                }
 
                /* LineString */
 
                void linestring_start() {
                    m_data.clear();
                    m_linestring_size_offset = header(m_data, wkbLineString, true);
                }
 
                void linestring_add_location(const osmium::geom::Coordinates& xy) {
                    str_push(m_data, xy.x);
                    str_push(m_data, xy.y);
                }
 
                linestring_type linestring_finish(std::size_t num_points) {
                    set_size(m_linestring_size_offset, num_points);
                    std::string data;
 
                    using std::swap;
                    swap(data, m_data);
 
                    if (m_out_type == out_type::hex) {
                        return convert_to_hex(data);
                    }
 
                    return data;
                }
 
                /* Polygon */
 
                void polygon_start() {
                    m_data.clear();
                    set_size(header(m_data, wkbPolygon, true), 1);
                    m_ring_size_offset = m_data.size();
                    str_push(m_data, static_cast<uint32_t>(0));
                }
 
                void polygon_add_location(const osmium::geom::Coordinates& xy) {
                    str_push(m_data, xy.x);
                    str_push(m_data, xy.y);
                }
 
                polygon_type polygon_finish(std::size_t num_points) {
                    set_size(m_ring_size_offset, num_points);
                    std::string data;
 
                    using std::swap;
                    swap(data, m_data);
 
                    if (m_out_type == out_type::hex) {
                        return convert_to_hex(data);
                    }
 
                    return data;
                }
 
                /* MultiPolygon */
 
                void multipolygon_start() {
                    m_data.clear();
                    m_polygons = 0;
                    m_multipolygon_size_offset = header(m_data, wkbMultiPolygon, true);
                }
 
                void multipolygon_polygon_start() {
                    ++m_polygons;
                    m_rings = 0;
                    m_polygon_size_offset = header(m_data, wkbPolygon, true);
                }
 
                void multipolygon_polygon_finish() {
                    set_size(m_polygon_size_offset, m_rings);
                }
 
                void multipolygon_outer_ring_start() {
                    ++m_rings;
                    m_points = 0;
                    m_ring_size_offset = m_data.size();
                    str_push(m_data, static_cast<uint32_t>(0));
                }
 
                void multipolygon_outer_ring_finish() {
                    set_size(m_ring_size_offset, m_points);
                }
 
                void multipolygon_inner_ring_start() {
                    ++m_rings;
                    m_points = 0;
                    m_ring_size_offset = m_data.size();
                    str_push(m_data, static_cast<uint32_t>(0));
                }
 
                void multipolygon_inner_ring_finish() {
                    set_size(m_ring_size_offset, m_points);
                }
 
                void multipolygon_add_location(const osmium::geom::Coordinates& xy) {
                    str_push(m_data, xy.x);
                    str_push(m_data, xy.y);
                    ++m_points;
                }
 
                multipolygon_type multipolygon_finish() {
                    set_size(m_multipolygon_size_offset, m_polygons);
                    std::string data;
 
                    using std::swap;
                    swap(data, m_data);
 
                    if (m_out_type == out_type::hex) {
                        return convert_to_hex(data);
                    }
 
                    return data;
                }
 
            }; // class WKBFactoryImpl
 
        } // namespace detail
 
        template <typename TProjection = IdentityProjection>
        using WKBFactory = GeometryFactory<osmium::geom::detail::WKBFactoryImpl, TProjection>;
 
    } // namespace geom
 
} // namespace osmium
 
#endif // OSMIUM_GEOM_WKB_HPP