तृतीय-पक्ष पुस्तकालयों के बिना WKB प्रारूप को पार्स करना

namespace ml { struct point_d { double x; double y; }; inline std::ostream & operator << (std::ostream &s, point_d const &p) { return s << px << ", " << py; } inline double distance(point_d const &p1, point_d const &p2) { double dx = (p1.x-p2.x); double dy = (p1.y-p2.y); return sqrt(dx*dx+dy*dy); } struct rect_d { point_d min; point_d max; static rect_d void_rect() { return rect_d(std::numeric_limits<T>::max(),std::numeric_limits<T>::max(), -std::numeric_limits<T>::max(),-std::numeric_limits<T>::max()); } bool empty() const { return (*this == rect_d::void_rect() || (width()==0 && height()==0)); } inline double height() const { return fabs(max.y-min.y); } inline double width() const { return fabs(max.x-min.x); } rect_d & extend(const rect_d &r) { if(r.empty()) return *this; min.x = std::min(min.x,std::min(r.min.x,r.max.x)); min.y = std::min(min.y,std::min(r.min.y,r.max.y)); max.x = std::max(max.x,std::max(r.min.x,r.max.x)); max.y = std::max(max.y,std::max(r.min.y,r.max.y)); return *this; } template< typename C > rect_d & bounds( C begin, C end) { for(; begin != end; ++begin) { min.x = std::min(min.x,begin->x); min.y = std::min(min.y,begin->y); max.x = std::max(max.x,begin->x); max.y = std::max(max.y,begin->y); } return *this; } }; inline std::ostream & operator << (std::ostream &s,const rect_d &r) { return s << '[' << r.min << ',' << r.max << ']'; } } // namespace ml 

 namespace ml { class wkb { char const * m_data; public: enum type_e{ wkb_point = 1, wkb_line_string = 2, wkb_polygon = 3, wkb_multi_point = 4, wkb_multi_line_string = 5, wkb_multi_polygon = 6, wkb_geometry_collection = 7 }; static char const *type_to_text(type_e type) { switch (type) { case wkb_point: return "wkb_point"; case wkb_line_string: return "wkb_line_string"; case wkb_polygon: return "wkb_polygon"; case wkb_multi_point: return "wkb_multi_point"; case wkb_multi_line_string: return "wkb_multi_line_string"; case wkb_multi_polygon: return "wkb_multi_polygon"; case wkb_geometry_collection: return "wkb_geometry_collection"; default: return "unknown"; } } typedef container<ml::point_d> line; wkb(char const *data) : m_data(data) {} wkb & operator = (wkb const &d) { m_data = d.m_data; return *this; } inline char byte_order() const { return m_data[0]; } inline type_e type() const { return (type_e)*(int*)&m_data[1]; } inline int size() const { return *(int*)&m_data[5]; } line linestring() const { return line((line::value_type*)&m_data[9], size()); } ml::point_d const & point() const { return *(ml::point_d*)&m_data[5]; } wkb linestring(size_t index) const { size_t offset = 9; for(size_t i=0; i<size(); ++i) { wkb l(&m_data[offset]); if (i == index) return l; offset += 9 + 16 * l.size(); } return wkb(0); } line ring(size_t index) const { size_t offset = 9; for(size_t i=0; i<size(); ++i) { int point_count = *(int*)&m_data[offset]; if(i == index) return line((line::value_type*)&m_data[offset+4], point_count); offset = offset + 4 + 16*point_count; } return line(NULL,(size_t)0); } wkb polygon(size_t index) const { size_t offset = 9; for(size_t i=0; i<this->size(); ++i) { wkb o(&m_data[offset]); if(i == index) return o; for(size_t j=0; j<o.size(); ++j) offset += o.ring(j).size() * 16 + 4; offset += 9; } return wkb(0); } ml::rect_d bounds() const { ml::rect_d r(ml::rect_d::void_rect()); switch (type()) { case wkb_polygon: { for(size_t i=0; i < size(); ++i) { line l = ring(i); r.bounds(l.begin(),l.end()); } } break; case wkb_multi_polygon: { for(size_t i=0; i < size(); ++i) { r.extend(polygon(i).bounds()); } } break; case wkb_point: { r.min.x = r.max.x = *(double*)&m_data[5]; r.min.y = r.max.y = *(double*)&m_data[13]; } break; case wkb_line_string: { line l = linestring(); r.bounds(l.begin(),l.end()); } break; case wkb_multi_line_string: { for(size_t i=0; i < size(); ++i) { r.extend(linestring(i).bounds()); } } break; default: break; } return r; } }; } // namespace ml 

  line linestring() const { return line((line::value_type*)(m_data+9), size()); } ml::point_d const & point() const { return *(ml::point_d*)(m_data+5); } wkb linestring(size_t index) const { assert(index>=0 && index<m_size); const char *ptr = m_data+9; while (index--) { ptr += 9 + (*(unsigned int*)(ptr+5) * 16); } return wkb(ptr); } wkb polygon(size_t index) const { assert(index>=0 && index<m_size); const char *ptr = m_data+9; while (index--) { ptr = end_of_polygon(ptr); } return wkb(ptr); } line ring(size_t index) const { assert(index>=0 && index<m_size); const char *ptr = m_data+9; while (index--) { ptr = end_of_ring(ptr); } return line((line::value_type*)(ptr+4),(line::value_type*)end_of_ring(ptr)); } 

 template< typename T > T & apply( T & func) const { switch (type()) { case wkb_polygon: { const char * ptr = m_data+9; for(size_t i=0; i<m_size; ++i) { ml::point_d *begin = (ml::point_d*)(ptr+4); ml::point_d *end = begin + *(unsigned int *)(ptr); ptr = (const char *)end; func(begin,end); } } break; case wkb_multi_polygon: { const char * ptr = m_data+9; for(size_t i=0; i<m_size; ++i) { for (size_t sz = *(unsigned int*)((ptr+=9)-4);sz--;) { ml::point_d *begin = (ml::point_d*)(ptr+4); ml::point_d *end = begin + *(unsigned int *)(ptr); ptr = (const char *)end; func(begin,end); } } } break; case wkb_point: { ml::point_d *begin = (ml::point_d*)(m_data+5); ml::point_d *end = begin + 1; func(begin,end); } break; case wkb_line_string: { ml::point_d *begin = (ml::point_d*)(m_data+9); ml::point_d *end = begin + size(); func(begin,end); } break; case wkb_multi_line_string: { const char * ptr = m_data+9; for(size_t i=0; i<m_size; ++i) { ml::point_d *begin = (ml::point_d*)(ptr+9); ml::point_d *end = begin + *(unsigned int *)(ptr+5); ptr = (const char *)end; func(begin,end); } } break; default: break; } return func; } 

 std::string ml::wkb::to_geo_json() const { struct point_formatter { std::stringstream &ss; unsigned int counter; bool parts; point_formatter(std::stringstream &s) : ss(s),counter(0), parts(false) {} void operator() (ml::point_d const *begin, ml::point_d const *end) { if (parts) ss << (counter ? ",[" : "["); ss << "[" << begin->x << "," << begin->y << "]"; for(++begin;begin != end;++begin){ ss << ",[" << begin->x << "," << begin->y << "]"; } if (parts) ss << "]"; ++counter; } point_formatter & make_parts(bool p) {parts = p; counter = 0; return *this;} }; std::stringstream ss; point_formatter fmt(ss); ss << std::fixed << std::showpoint << std::setprecision(6); ss << "{"; switch(type()) { case wkb_point: { ss << "\"type\":\"Point\",\"coordinates\":"; apply(fmt); } break; case wkb_line_string: { ss << "\"type\":\"LineString\",\"coordinates\": ["; apply(fmt); ss << "]"; } break; case wkb_multi_line_string: { ss << "\"type\":\"MultiLineString\",\"coordinates\": ["; apply(fmt.make_parts(true)); ss << "]"; } break; case wkb_polygon: { ss << "\"type\":\"Polygon\",\"coordinates\": ["; apply(fmt.make_parts(true)); ss << "]"; } break; case wkb_multi_polygon: { ss << "\"type\":\"MultiPolygon\",\"coordinates\": ["; for(size_t i=0; i < size(); ++i) { ss << (i ? ",[" : "["); polygon(i).apply(fmt.make_parts(true)); ss << "]"; } ss << "]"; } break; default: break; } ss << "}"; return ss.str(); }