Added ability to Query if SRID is available

Cleaned up a bit
Added Availableconversions and IsKnownConversionSRID
to enable ability to check if an SRID is usable with
proj for conversion.

Convert.go

@@ -33,9 +33,6 @@ const (
 	WGS84                                = EPSG4326
 )
 
-// ensure only one person is updating our cache of converters at a time
-var cacheLock = sync.Mutex{}
-
 // Convert performs a conversion from a 4326 coordinate system (lon/lat
 // degrees, 2D) to the given projected system (x/y meters, 2D).
 //
@@ -80,7 +77,9 @@ func Inverse(src EPSGCode, input []float64) ([]float64, error) {
 // CustomProjection provides write-only access to the internal projection list
 // so that projections may be added without having to modify the library code.
 func CustomProjection(code EPSGCode, str string) {
+	projStringLock.Lock()
 	projStrings[code] = str
+	projStringLock.Unlock()
 }
 
 //---------------------------------------------------------------------------
@@ -94,19 +93,48 @@ type conversion struct {
 	converter  core.IConvertLPToXY
 }
 
-var conversions = map[EPSGCode]*conversion{}
+var (
+	// cacheLock ensure only one person is updating our cache of converters at a time
+	cacheLock   = sync.Mutex{}
+	conversions = map[EPSGCode]*conversion{}
+
+	projStringLock = sync.RWMutex{}
+	projStrings    = map[EPSGCode]string{
+		EPSG3395: "+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +datum=WGS84",                            // TODO: support +units=m +no_defs
+		EPSG3857: "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0", // TODO: support +units=m +nadgrids=@null +wktext +no_defs
+		EPSG4087: "+proj=eqc +lat_ts=0 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +datum=WGS84",               // TODO: support +units=m +no_defs
+	}
+)
+
+// AvailableConversions  returns a list of conversion that the system knows about
+func AvailableConversions() (ret []EPSGCode) {
+	projStringLock.RLock()
+	defer projStringLock.RUnlock()
+	if len(projStrings) == 0 {
+		return nil
+	}
+	ret = make([]EPSGCode, 0, len(projStrings))
+	for k := range projStrings {
+		ret = append(ret, k)
+	}
+	return ret
+}
 
-var projStrings = map[EPSGCode]string{
-	EPSG3395: "+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +datum=WGS84",                            // TODO: support +units=m +no_defs
-	EPSG3857: "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0", // TODO: support +units=m +nadgrids=@null +wktext +no_defs
-	EPSG4087: "+proj=eqc +lat_ts=0 +lat_0=0 +lon_0=0 +x_0=0 +y_0=0 +datum=WGS84",               // TODO: support +units=m +no_defs
+// IsKnownConversionSRID returns if we know about the conversion
+func IsKnownConversionSRID(srid EPSGCode) bool {
+	projStringLock.RLock()
+	defer projStringLock.RUnlock()
+	_, ok := projStrings[srid]
+	return ok
 }
 
 // newConversion creates a conversion object for the destination systems. If
 // such a conversion already exists in the cache, use that.
 func newConversion(dest EPSGCode) (*conversion, error) {
 
+	projStringLock.RLock()
 	str, ok := projStrings[dest]
+	projStringLock.RUnlock()
 	if !ok {
 		return nil, fmt.Errorf("epsg code is not a supported projection")
 	}

cmd/proj/proj.go

@@ -35,9 +35,9 @@ func Main(inS io.Reader, outS io.Writer, args []string) error {
 
 	// unverbosify all the things
 	merror.ShowSource = false
-	mlog.DebugEnabled = false
-	mlog.InfoEnabled = false
-	mlog.ErrorEnabled = false
+	mlog.DisableDebug()
+	mlog.DisableInfo()
+	mlog.DisableError()
 
 	cli := flag.NewFlagSet(args[0], flag.ContinueOnError)
 	cli.SetOutput(outS)
@@ -67,9 +67,9 @@ func Main(inS io.Reader, outS io.Writer, args []string) error {
 		}
 
 		merror.ShowSource = true
-		mlog.DebugEnabled = true
-		mlog.InfoEnabled = true
-		mlog.ErrorEnabled = true
+		mlog.EnableDebug()
+		mlog.EnableInfo()
+		mlog.EnableError()
 	}
 
 	// handle "-epsg" usage, using the Convert API

core/ConvertLPToXY.go

@@ -243,27 +243,29 @@ func (op *ConvertLPToXY) inverseFinalize(coo *CoordLP) (*CoordLP, error) {
 
 	sys := op.System
 
-	if sys.Left == IOUnitsAngular {
-
-		if sys.Right != IOUnitsAngular {
-			/* Distance from central meridian, taking system zero meridian into account */
-			coo.Lam = coo.Lam + sys.FromGreenwich + sys.Lam0
+	// if left is not in radians return the value as is.
+	if sys.Left != IOUnitsAngular {
+		return coo, nil
+	}
 
-			/* adjust longitude to central meridian */
-			if !sys.Over {
-				coo.Lam = support.Adjlon(coo.Lam)
-			}
+	if sys.Right != IOUnitsAngular {
+		/* Distance from central meridian, taking system zero meridian into account */
+		coo.Lam = coo.Lam + sys.FromGreenwich + sys.Lam0
 
-			if coo.Lam == math.MaxFloat64 {
-				return coo, nil
-			}
+		/* adjust longitude to central meridian */
+		if !sys.Over {
+			coo.Lam = support.Adjlon(coo.Lam)
 		}
 
-		/* If input latitude was geocentrical, convert back to geocentrical */
-		if sys.Geoc {
-			coo = GeocentricLatitude(sys, DirectionForward, coo)
+		if coo.Lam == math.MaxFloat64 {
+			return coo, nil
 		}
 	}
 
+	/* If input latitude was geocentrical, convert back to geocentrical */
+	if sys.Geoc {
+		coo = GeocentricLatitude(sys, DirectionForward, coo)
+	}
+
 	return coo, nil
 }

core/OperationDescription.go

@@ -8,6 +8,8 @@
 package core
 
 import (
+	"fmt"
+
 	"github.com/go-spatial/proj/merror"
 )
 
@@ -58,7 +60,7 @@ func RegisterConvertLPToXY(
 
 	_, ok := OperationDescriptionTable[id]
 	if ok {
-		panic(99)
+		panic(fmt.Sprintf("duplicate operation description id '%s' : %s", id, description))
 	}
 	OperationDescriptionTable[id] = pi
 }
@@ -73,7 +75,7 @@ func (desc *OperationDescription) CreateOperation(sys *System) (IOperation, erro
 	return nil, merror.New(merror.NotYetSupported)
 }
 
-// IsConvertLPToXY returns true iff the operation can be casted to an IConvertLPToXY
+// IsConvertLPToXY returns true iff the operation can be cast to an IConvertLPToXY
 func (desc *OperationDescription) IsConvertLPToXY() bool {
 	return desc.OperationType == OperationTypeConversion &&
 		desc.InputType == CoordTypeLP &&

core/OperationDescription_test.go

@@ -11,13 +11,12 @@ import (
 	"testing"
 
 	"github.com/go-spatial/proj/core"
-
-	"github.com/stretchr/testify/assert"
 )
 
 func TestOperationDescription(t *testing.T) {
-	assert := assert.New(t)
 
 	opDesc := core.OperationDescriptionTable["utm"]
-	assert.NotNil(opDesc)
+	if opDesc == nil {
+		t.Errorf("operaton description table for utm is nil")
+	}
 }

core/System.go

@@ -23,10 +23,10 @@ type DatumType int
 // All the DatumType constants (taken directly from the C)
 const (
 	DatumTypeUnknown   DatumType = 0
-	DatumType3Param              = 1
-	DatumType7Param              = 2
-	DatumTypeGridShift           = 3
-	DatumTypeWGS84               = 4 /* WGS84 (or anything considered equivalent) */
+	DatumType3Param    DatumType = 1
+	DatumType7Param    DatumType = 2
+	DatumTypeGridShift DatumType = 3
+	DatumTypeWGS84     DatumType = 4 /* WGS84 (or anything considered equivalent) */
 )
 
 // IOUnitsType is the enum for the types of input/output units we support
@@ -35,10 +35,10 @@ type IOUnitsType int
 // All the IOUnitsType constants
 const (
 	IOUnitsWhatever  IOUnitsType = 0 /* Doesn't matter (or depends on pipeline neighbours) */
-	IOUnitsClassic               = 1 /* Scaled meters (right), projected system */
-	IOUnitsProjected             = 2 /* Meters, projected system */
-	IOUnitsCartesian             = 3 /* Meters, 3D cartesian system */
-	IOUnitsAngular               = 4 /* Radians */
+	IOUnitsClassic   IOUnitsType = 1 /* Scaled meters (right), projected system */
+	IOUnitsProjected IOUnitsType = 2 /* Meters, projected system */
+	IOUnitsCartesian IOUnitsType = 3 /* Meters, 3D cartesian system */
+	IOUnitsAngular   IOUnitsType = 4 /* Radians */
 )
 
 // DirectionType is the enum for the operation's direction
@@ -47,8 +47,8 @@ type DirectionType int
 // All the DirectionType constants
 const (
 	DirectionForward  DirectionType = 1  /* Forward    */
-	DirectionIdentity               = 0  /* Do nothing */
-	DirectionInverse                = -1 /* Inverse    */
+	DirectionIdentity DirectionType = 0  /* Do nothing */
+	DirectionInverse  DirectionType = -1 /* Inverse    */
 )
 
 const epsLat = 1.0e-12