geos.go

// Package geos provides an interface to GEOS. See https://trac.osgeo.org/geos/.
package geos

// #cgo pkg-config: geos
// #include "go-geos.h"
import "C"

// Version.
const (
	VersionMajor = C.GEOS_VERSION_MAJOR
	VersionMinor = C.GEOS_VERSION_MINOR
	VersionPatch = C.GEOS_VERSION_PATCH
)

// A TypeID is a geometry type id.
type TypeID int

// Geometry type ids.
const (
	TypeIDPoint              TypeID = C.GEOS_POINT
	TypeIDLineString         TypeID = C.GEOS_LINESTRING
	TypeIDLinearRing         TypeID = C.GEOS_LINEARRING
	TypeIDPolygon            TypeID = C.GEOS_POLYGON
	TypeIDMultiPoint         TypeID = C.GEOS_MULTIPOINT
	TypeIDMultiLineString    TypeID = C.GEOS_MULTILINESTRING
	TypeIDMultiPolygon       TypeID = C.GEOS_MULTIPOLYGON
	TypeIDGeometryCollection TypeID = C.GEOS_GEOMETRYCOLLECTION
)

// A BoundaryNodeRule is a boundary node rule.
type RelateBoundaryNodeRule int

// Boundary node rules.
const (
	RelateBoundaryNodeRuleMod2                RelateBoundaryNodeRule = C.GEOSRELATE_BNR_MOD2
	RelateBoundaryNodeRuleOGC                 RelateBoundaryNodeRule = C.GEOSRELATE_BNR_OGC
	RelateBoundaryNodeRuleEndpoint            RelateBoundaryNodeRule = C.GEOSRELATE_BNR_ENDPOINT
	RelateBoundaryNodeRuleMultivalentEndpoint RelateBoundaryNodeRule = C.GEOSRELATE_BNR_MULTIVALENT_ENDPOINT
	RelateBoundaryNodeRuleMonovalentEndpoint  RelateBoundaryNodeRule = C.GEOSRELATE_BNR_MONOVALENT_ENDPOINT
)

type BufCapStyle int

// Buffer cap styles.
const (
	BufCapStyleRound  BufCapStyle = C.GEOSBUF_CAP_ROUND
	BufCapStyleFlat   BufCapStyle = C.GEOSBUF_CAP_FLAT
	BufCapStyleSquare BufCapStyle = C.GEOSBUF_CAP_SQUARE
)

type BufJoinStyle int

// Buffer join styles.
const (
	BufJoinStyleRound BufJoinStyle = C.GEOSBUF_JOIN_ROUND
	BufJoinStyleMitre BufJoinStyle = C.GEOSBUF_JOIN_MITRE
	BufJoinStyleBevel BufJoinStyle = C.GEOSBUF_JOIN_BEVEL
)

// An Error is an error returned by GEOS.
type Error string

func (e Error) Error() string {
	return string(e)
}

var (
	errContextMismatch     = Error("context mismatch")
	errDimensionOutOfRange = Error("dimension out of range")
	errDuplicateValue      = Error("duplicate value")
	errIndexOutOfRange     = Error("index out of range")
)

type PrecisionRule int

// Precision rules.
const (
	PrecisionRuleNone          PrecisionRule = 0
	PrecisionRuleValidOutput   PrecisionRule = C.GEOS_PREC_VALID_OUTPUT
	PrecisionRuleNoTopo        PrecisionRule = C.GEOS_PREC_NO_TOPO
	PrecisionRulePointwise     PrecisionRule = C.GEOS_PREC_NO_TOPO
	PrecisionRuleKeepCollapsed PrecisionRule = C.GEOS_PREC_KEEP_COLLAPSED
)

type MakeValidMethod int

// MakeValidMethods.
const (
	MakeValidLinework  MakeValidMethod = C.GEOS_MAKE_VALID_LINEWORK
	MakeValidStructure MakeValidMethod = C.GEOS_MAKE_VALID_STRUCTURE
)

type MakeValidCollapsed int

// MakeValidMethods.
const (
	MakeValidDiscardCollapsed MakeValidCollapsed = 0
	MakeValidKeepCollapsed    MakeValidCollapsed = 1
)

// VersionCompare returns a negative number if the GEOS version is less than the
// given major.minor.patch version, zero if it is equal, or a positive number
// otherwise.
func VersionCompare(major, minor, patch int) int {
	if majorDelta := VersionMajor - major; majorDelta != 0 {
		return majorDelta
	}
	if minorDelta := VersionMinor - minor; minorDelta != 0 {
		return minorDelta
	}
	return VersionPatch - patch
}