A string of connected line segments. More...

#include <geometries.h>

Inheritance diagram for gis::Linestring:

Public Member Functions
Geometry_type	type () const override
	Gets the geometry type of the object. More...

bool	accept (Geometry_visitor *v) override=0
	Applies a hierarchical visitor to this geometry. More...

bool	is_empty () const override
	Check if this is an empty geometry. More...

Linestring *	clone () const override=0

virtual void	push_back (const Point &pt)=0
	Adds a point to the end of the linestring. More...

virtual void	push_back (Point &&pt)=0

virtual void	pop_front ()=0
	Removes a point from the front of the linestring. More...

virtual bool	empty () const =0
	Checks if the linestring is empty. More...

virtual std::size_t	size () const =0
	Returns the size of (number of points in) the linestring. More...

virtual void	clear () noexcept=0
	Removes all points from the linestring. More...

virtual Point &	back ()=0
	Returns the last point of the linestring. More...

virtual const Point &	back () const =0

virtual Point &	front ()=0
	Returns the first point of the linestring. More...

virtual const Point &	front () const =0

virtual Point &	operator[] (std::size_t i)=0

virtual const Point &	operator[] (std::size_t i) const =0

Public Member Functions inherited from gis::Geometry
	Geometry ()=default

virtual	~Geometry ()=default

	Geometry (const Geometry &)=default

Geometry &	operator= (const Geometry &)=default

virtual Coordinate_system	coordinate_system () const =0
	Gets the coordinate system. More...

Static Public Member Functions
static Linestring *	create_linestring (Coordinate_system coordinate_system)
	Creates a subclass of Linestring from a Coordinate_system. More...

Detailed Description

A string of connected line segments.

Linestring is an instantiable type in SQL.

According to the SFA-CA, linestrings have a linear interpolation between points. In MySQL, a linestring represents the geodesic. On a plane, this is linear interpolation, but on an ellipsoid, it's the shortest path along the ellipsoid surface.

Member Function Documentation

◆ accept()

bool gis::Linestring::accept ( Geometry_visitor * v )

overridepure virtual

Applies a hierarchical visitor to this geometry.

See also: gis::Geometry_visitor

Parameters

v	A hierarchical visitor.

Return values

true	The execution was aborted by the visitor.
false	The execution completed.

Implements gis::Curve.

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, gis::Geographic_linearring, and gis::Linearring.

◆ back() [1/2]

virtual const Point & gis::Linestring::back ( ) const

pure virtual

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ back() [2/2]

virtual Point & gis::Linestring::back ( )

pure virtual

Returns the last point of the linestring.

Returns: Last point of linestring

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ clear()

virtual void gis::Linestring::clear ( )

pure virtualnoexcept

Removes all points from the linestring.

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ clone()

Linestring * gis::Linestring::clone ( ) const

overridepure virtual

Implements gis::Geometry.

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ create_linestring()

Linestring * gis::Linestring::create_linestring ( Coordinate_system coordinate_system )

static

Creates a subclass of Linestring from a Coordinate_system.

Parameters

[in] coordinate_system Coordinate system to create a Linestring for.

Returns: A pointer to a Linestring that caller must free when it is done with it.

◆ empty()

virtual bool gis::Linestring::empty ( ) const

pure virtual

Checks if the linestring is empty.

Here, the definition of empty is that the linestring does not contain any points. An invalid linestring with only one coordinate is not empty.

Return values

true	The linestring is empty.
false	The linestring is not empty.

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ front() [1/2]

virtual const Point & gis::Linestring::front ( ) const

pure virtual

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ front() [2/2]

virtual Point & gis::Linestring::front ( )

pure virtual

Returns the first point of the linestring.

Returns: First point of linestring

Implemented in gis::Cartesian_linestring, gis::Geographic_linestring, gis::Cartesian_linearring, and gis::Geographic_linearring.

◆ is_empty()

bool gis::Linestring::is_empty ( ) const

inlineoverridevirtual

Check if this is an empty geometry.

The definition of empty geometries is the one in SFA-CA (OGC 06-103r4, Sect. 6.1.2.2), i.e., an empty point set.

Note: This is different from the function "empty", which returns true if a geometry contains no subgeometries. E.g., a geometry collection may contain another geometry collection which is empty. In this case, the "empty" function would return false on the outermost geometry collection, while "is_empty" would return true.

Return values