Class WktShapeParser

An extensible parser for Well Known Text (WKT). The shapes supported by this class are:

'EMPTY' is supported. Specifying 'Z', 'M', or any other dimensionality in the WKT is effectively ignored. Thus, you can specify any number of numbers in the coordinate points but only the first two take effect. The docs for the parse___Shape methods further describe these shapes, or you

Most users of this class will call just one method: Parse(String), or ParseIfSupported(String) to not fail if it isn't parse-able.

To support more shapes, extend this class and override ParseShapeByType(WktShapeParser.State, String). It's also possible to delegate to a WKTParser by also delegating NewState(String).

Note, instances of this base class are threadsafe.

Inheritance
System.Object
WktShapeParser
Inherited Members
System.Object.Equals(System.Object)
System.Object.Equals(System.Object, System.Object)
System.Object.GetHashCode()
System.Object.GetType()
System.Object.MemberwiseClone()
System.Object.ReferenceEquals(System.Object, System.Object)
System.Object.ToString()
Assembly: Spatial4n.dll
Syntax
[Serializable]
public class WktShapeParser

Constructors

Name Description
WktShapeParser(SpatialContext, SpatialContextFactory)

This constructor is required by MakeWktShapeParser(SpatialContext).

Fields

Name Description
m_ctx

Properties

Name Description
Ctx

Methods

Name Description
NewState(String)

(internal) Creates a new State with the given String. It's only called by ParseIfSupported(String). This is an extension point for subclassing.
NormDist(Double)

Called to normalize a value that isn't X or Y. X & Y or normalized via NormX(Double) & NormY(Double).
Parse(String)

Parses the wktString, returning the defined IShape.
ParseBufferShape(WktShapeParser.State)

Parses the BUFFER operation applied to a parsed shape.

  '(' shape ',' number ')'

Whereas 'number' is the distance to buffer the shape by.
ParseEnvelopeShape(WktShapeParser.State)

Parses an ENVELOPE (aka Rectangle) shape from the raw string. The values are normalized.

Source: OGC "Catalogue Services Specification", the "CQL" (Common Query Language) sub-spec. Note the inconsistent order of the min & max values between x & y!

  '(' x1 ',' x2 ',' y2 ',' y1 ')'
ParseGeometryCollectionShape(WktShapeParser.State)

Parses a GEOMETRYCOLLECTION shape from the raw string.

  '(' shape (',' shape )* ')'
ParseIfSupported(String)

Parses the wktString, returning the defined IShape. If it can't because the shape name is unknown or an empty or blank string was passed, then it returns null. If the WKT starts with a supported shape but contains an inner unsupported shape then it will result in a ParseException.
ParseLineStringShape(WktShapeParser.State)

Parses a LINESTRING shape from the raw string -- an ordered sequence of points.

  coordinateSequence
ParseMultiLineStringShape(WktShapeParser.State)

Parses a MULTILINESTRING shape from the raw string -- a collection of line strings.

  '(' coordinateSequence (',' coordinateSequence )* ')'
ParseMultiPointShape(WktShapeParser.State)

Parses a MULTIPOINT shape from the raw string -- a collection of points.

  '(' coordinate (',' coordinate )* ')'

Furthermore, coordinate can optionally be wrapped in parenthesis.
ParsePointShape(WktShapeParser.State)

Parses a POINT shape from the raw string.

  '(' coordinate ')'
ParseShapeByType(WktShapeParser.State, String)

(internal) Parses the remainder of a shape definition following the shape's name given as shapeType already consumed via NextWord(). If it's able to parse the shape, offset should be advanced beyond it (e.g. to the ',' or ')' or EOF in general). The default implementation checks the name against some predefined names and calls corresponding parse methods to handle the rest. Overriding this method is an excellent extension point for additional shape types. Or, use this class by delegation to this method.

When writing a parse method that reacts to a specific shape type, remember to handle the dimension and EMPTY token via NextIfEmptyAndSkipZM().

Point(WktShapeParser.State)

Reads a raw Point (AKA Coordinate) from the current position. Only the first 2 numbers are used. The values are normalized.

  number number number*
PointList(WktShapeParser.State)

Reads a list of Points (AKA CoordinateSequence) from the current position.

  '(' coordinate (',' coordinate )* ')'
Shape(WktShapeParser.State)

Reads a shape from the current position, starting with the name of the shape. It calls ParseShapeByType(WktShapeParser.State, String) and throws an exception if the shape wasn't supported.

Extension Methods