The OGRGNMWrappedResultLayer class for search paths queries results. More...

#include <gnm.h>

Inheritance diagram for OGRGNMWrappedResultLayer:

Public Member Functions
	OGRGNMWrappedResultLayer (GDALDataset poDS, OGRLayer poLayer)
	Constructor.

virtual void	ResetReading () override
	Reset feature reading to start on the first feature. More...

virtual OGRFeature *	GetNextFeature () override
	Fetch the next available feature from this layer. More...

virtual OGRErr	SetNextByIndex (GIntBig nIndex) override
	Move read cursor to the nIndex'th feature in the current resultset. More...

virtual OGRFeature *	GetFeature (GIntBig nFID) override
	Fetch a feature by its identifier. More...

virtual OGRFeatureDefn *	GetLayerDefn () override
	Fetch the schema information for this layer. More...

virtual GIntBig	GetFeatureCount (int bForce=TRUE) override
	Fetch the feature count in this layer. More...

virtual int	TestCapability (const char *pszCap) override
	Test if this layer supported the named capability. More...

virtual OGRErr	CreateField (OGRFieldDefn *poField, int bApproxOK=TRUE) override
	Create a new field on a layer. More...

virtual OGRErr	CreateGeomField (OGRGeomFieldDefn *poField, int bApproxOK=TRUE) override
	Create a new geometry field on a layer. More...

virtual const char *	GetFIDColumn () override
	This method returns the name of the underlying database column being used as the FID column, or "" if not supported. More...

virtual const char *	GetGeometryColumn () override
	This method returns the name of the underlying database column being used as the geometry column, or "" if not supported. More...

virtual OGRSpatialReference *	GetSpatialRef () override
	Fetch the spatial reference system for this layer. More...

virtual OGRErr	InsertFeature (OGRFeature *poFeature, const CPLString &soLayerName, int nPathNo, bool bIsEdge)
	Undocumented.

Public Member Functions inherited from OGRLayer
FeatureIterator	begin ()
	Return begin of feature iterator. More...

FeatureIterator	end ()
	Return end of feature iterator. More...

virtual OGRGeometry *	GetSpatialFilter ()
	This method returns the current spatial filter for this layer. More...

virtual void	SetSpatialFilter (OGRGeometry *)
	Set a new spatial filter. More...

virtual void	SetSpatialFilterRect (double dfMinX, double dfMinY, double dfMaxX, double dfMaxY)
	Set a new rectangular spatial filter. More...

virtual void	SetSpatialFilter (int iGeomField, OGRGeometry *)
	Set a new spatial filter. More...

virtual void	SetSpatialFilterRect (int iGeomField, double dfMinX, double dfMinY, double dfMaxX, double dfMaxY)
	Set a new rectangular spatial filter. More...

virtual OGRErr	SetAttributeFilter (const char *)
	Set a new attribute query. More...

OGRErr	SetFeature (OGRFeature *poFeature) CPL_WARN_UNUSED_RESULT
	Rewrite an existing feature. More...

OGRErr	CreateFeature (OGRFeature *poFeature) CPL_WARN_UNUSED_RESULT
	Create and write a new feature within a layer. More...

virtual OGRErr	DeleteFeature (GIntBig nFID) CPL_WARN_UNUSED_RESULT
	Delete feature from layer. More...

virtual const char *	GetName ()
	Return the layer name. More...

virtual OGRwkbGeometryType	GetGeomType ()
	Return the layer geometry type. More...

virtual int	FindFieldIndex (const char *pszFieldName, int bExactMatch)
	Find the index of field in the layer. More...

virtual OGRErr	GetExtent (OGREnvelope *psExtent, int bForce=TRUE) CPL_WARN_UNUSED_RESULT
	Fetch the extent of this layer. More...

virtual OGRErr	GetExtent (int iGeomField, OGREnvelope *psExtent, int bForce=TRUE) CPL_WARN_UNUSED_RESULT
	Fetch the extent of this layer, on the specified geometry field. More...

virtual OGRErr	DeleteField (int iField)
	Delete an existing field on a layer. More...

virtual OGRErr	ReorderFields (int *panMap)
	Reorder all the fields of a layer. More...

virtual OGRErr	AlterFieldDefn (int iField, OGRFieldDefn *poNewFieldDefn, int nFlagsIn)
	Alter the definition of an existing field on a layer. More...

virtual OGRErr	SyncToDisk ()
	Flush pending changes to disk. More...

virtual OGRStyleTable *	GetStyleTable ()
	Returns layer style table. More...

virtual void	SetStyleTableDirectly (OGRStyleTable *poStyleTable)
	Set layer style table. More...

virtual void	SetStyleTable (OGRStyleTable *poStyleTable)
	Set layer style table. More...

virtual OGRErr	StartTransaction () CPL_WARN_UNUSED_RESULT
	For datasources which support transactions, StartTransaction creates a transaction. More...

virtual OGRErr	CommitTransaction () CPL_WARN_UNUSED_RESULT
	For datasources which support transactions, CommitTransaction commits a transaction. More...

virtual OGRErr	RollbackTransaction ()
	For datasources which support transactions, RollbackTransaction will roll back a datasource to its state before the start of the current transaction. More...

virtual OGRErr	SetIgnoredFields (const char **papszFields)
	Set which fields can be omitted when retrieving features from the layer. More...

OGRErr	Intersection (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions=nullptr, GDALProgressFunc pfnProgress=nullptr, void pProgressArg=nullptr)
	Intersection of two layers. More...

OGRErr	Union (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions=nullptr, GDALProgressFunc pfnProgress=nullptr, void pProgressArg=nullptr)
	Union of two layers. More...

OGRErr	SymDifference (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions, GDALProgressFunc pfnProgress, void pProgressArg)
	Symmetrical difference of two layers. More...

OGRErr	Identity (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions=nullptr, GDALProgressFunc pfnProgress=nullptr, void pProgressArg=nullptr)
	Identify the features of this layer with the ones from the identity layer. More...

OGRErr	Update (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions=nullptr, GDALProgressFunc pfnProgress=nullptr, void pProgressArg=nullptr)
	Update this layer with features from the update layer. More...

OGRErr	Clip (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions=nullptr, GDALProgressFunc pfnProgress=nullptr, void pProgressArg=nullptr)
	Clip off areas that are not covered by the method layer. More...

OGRErr	Erase (OGRLayer pLayerMethod, OGRLayer pLayerResult, char *papszOptions=nullptr, GDALProgressFunc pfnProgress=nullptr, void pProgressArg=nullptr)
	Remove areas that are covered by the method layer. More...

int	Reference ()
	Increment layer reference count. More...

int	Dereference ()
	Decrement layer reference count. More...

int	GetRefCount () const
	Fetch reference count. More...

OGRErr	ReorderField (int iOldFieldPos, int iNewFieldPos)
	Reorder an existing field on a layer. More...

Public Member Functions inherited from GDALMajorObject
int	GetMOFlags () const
	Returns the GMO_ flags. More...

void	SetMOFlags (int nFlagsIn)
	Assign GMO_flags. More...

virtual const char *	GetDescription () const
	Fetch object description. More...

virtual void	SetDescription (const char *)
	Set object description. More...

virtual char **	GetMetadataDomainList ()
	Fetch list of metadata domains. More...

virtual char **	GetMetadata (const char *pszDomain="")
	Fetch metadata. More...

virtual CPLErr	SetMetadata (char *papszMetadata, const char pszDomain="")
	Set metadata. More...

virtual const char *	GetMetadataItem (const char pszName, const char pszDomain="")
	Fetch single metadata item. More...

virtual CPLErr	SetMetadataItem (const char pszName, const char pszValue, const char *pszDomain="")
	Set single metadata item. More...

Protected Member Functions
virtual OGRErr	ISetFeature (OGRFeature *poFeature) override
	Rewrite an existing feature. More...

virtual OGRErr	ICreateFeature (OGRFeature *poFeature) override
	Create and write a new feature within a layer. More...

Protected Member Functions inherited from GDALMajorObject
char **	BuildMetadataDomainList (char **papszList, int bCheckNonEmpty,...) CPL_NULL_TERMINATED
	Helper function for custom implementations of GetMetadataDomainList() More...

Additional Inherited Members
Static Public Member Functions inherited from OGRLayer
static OGRLayerH	ToHandle (OGRLayer *poLayer)
	Convert a OGRLayer* to a OGRLayerH. More...

static OGRLayer *	FromHandle (OGRLayerH hLayer)
	Convert a OGRLayerH to a OGRLayer*. More...

Static Public Member Functions inherited from GDALMajorObject
static GDALMajorObjectH	ToHandle (GDALMajorObject *poMajorObject)
	Convert a GDALMajorObject* to a GDALMajorObjectH. More...

static GDALMajorObject *	FromHandle (GDALMajorObjectH hMajorObject)
	Convert a GDALMajorObjectH to a GDALMajorObject*. More...

Detailed Description

The OGRGNMWrappedResultLayer class for search paths queries results.

Since: GDAL 2.1

Member Function Documentation

◆ CreateField()

OGRErr OGRGNMWrappedResultLayer::CreateField	(	OGRFieldDefn *	poField,
		int	bApproxOK = `TRUE`
	)

overridevirtual

Create a new field on a layer.

You must use this to create new fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the new field. Applications should never modify the OGRFeatureDefn used by a layer directly.

This method should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this method. You can query a layer to check if it supports it with the OLCCreateField capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

Drivers may or may not support not-null constraints. If they support creating fields with not-null constraints, this is generally before creating any feature to the layer.

This function is the same as the C function OGR_L_CreateField().

Parameters

poField	field definition to write to disk.
bApproxOK	If TRUE, the field may be created in a slightly different form depending on the limitations of the format driver.

Returns: OGRERR_NONE on success.

Reimplemented from OGRLayer.

◆ CreateGeomField()

OGRErr OGRGNMWrappedResultLayer::CreateGeomField	(	OGRGeomFieldDefn *	poField,
		int	bApproxOK = `TRUE`
	)

overridevirtual

Create a new geometry field on a layer.

You must use this to create new geometry fields on a real layer. Internally the OGRFeatureDefn for the layer will be updated to reflect the new field. Applications should never modify the OGRFeatureDefn used by a layer directly.

This method should not be called while there are feature objects in existence that were obtained or created with the previous layer definition.

Not all drivers support this method. You can query a layer to check if it supports it with the OLCCreateGeomField capability. Some drivers may only support this method while there are still no features in the layer. When it is supported, the existing features of the backing file/database should be updated accordingly.

Drivers may or may not support not-null constraints. If they support creating fields with not-null constraints, this is generally before creating any feature to the layer.

This function is the same as the C function OGR_L_CreateGeomField().

Parameters

poField	geometry field definition to write to disk.
bApproxOK	If TRUE, the field may be created in a slightly different form depending on the limitations of the format driver.

Returns: OGRERR_NONE on success.

Since: OGR 1.11

Reimplemented from OGRLayer.

◆ GetFeature()

OGRFeature * OGRGNMWrappedResultLayer::GetFeature ( GIntBig nFID )

overridevirtual

Fetch a feature by its identifier.

This function will attempt to read the identified feature. The nFID value cannot be OGRNullFID. Success or failure of this operation is unaffected by the spatial or attribute filters (and specialized implementations in drivers should make sure that they do not take into account spatial or attribute filters).

If this method returns a non-NULL feature, it is guaranteed that its feature id (OGRFeature::GetFID()) will be the same as nFID.

Use OGRLayer::TestCapability(OLCRandomRead) to establish if this layer supports efficient random access reading via GetFeature(); however, the call should always work if the feature exists as a fallback implementation just scans all the features in the layer looking for the desired feature.

Sequential reads (with GetNextFeature()) are generally considered interrupted by a GetFeature() call.

The returned feature should be free with OGRFeature::DestroyFeature().

This method is the same as the C function OGR_L_GetFeature().

Parameters

nFID	the feature id of the feature to read.

Returns: a feature now owned by the caller, or NULL on failure.

Reimplemented from OGRLayer.

◆ GetFeatureCount()

GIntBig OGRGNMWrappedResultLayer::GetFeatureCount ( int bForce = TRUE )

overridevirtual

Fetch the feature count in this layer.

Returns the number of features in the layer. For dynamic databases the count may not be exact. If bForce is FALSE, and it would be expensive to establish the feature count a value of -1 may be returned indicating that the count isn't know. If bForce is TRUE some implementations will actually scan the entire layer once to count objects.

The returned count takes the spatial filter into account.

Note that some implementations of this method may alter the read cursor of the layer.

This method is the same as the C function OGR_L_GetFeatureCount().

Note: since GDAL 2.0, this method returns a GIntBig (previously a int)

Parameters

bForce Flag indicating whether the count should be computed even if it is expensive.

Returns: feature count, -1 if count not known.

Reimplemented from OGRLayer.

◆ GetFIDColumn()

const char * OGRGNMWrappedResultLayer::GetFIDColumn ( )

overridevirtual

This method returns the name of the underlying database column being used as the FID column, or "" if not supported.

This method is the same as the C function OGR_L_GetFIDColumn().

Returns: fid column name.

Reimplemented from OGRLayer.

◆ GetGeometryColumn()

const char * OGRGNMWrappedResultLayer::GetGeometryColumn ( )

overridevirtual

This method returns the name of the underlying database column being used as the geometry column, or "" if not supported.

For layers with multiple geometry fields, this method only returns the name of the first geometry column. For other columns, use GetLayerDefn()->OGRFeatureDefn::GetGeomFieldDefn(i)->GetNameRef().

This method is the same as the C function OGR_L_GetGeometryColumn().

Returns: geometry column name.

Reimplemented from OGRLayer.

◆ GetLayerDefn()

OGRFeatureDefn * OGRGNMWrappedResultLayer::GetLayerDefn ( )

overridevirtual

Fetch the schema information for this layer.

The returned OGRFeatureDefn is owned by the OGRLayer, and should not be modified or freed by the application. It encapsulates the attribute schema of the features of the layer.

This method is the same as the C function OGR_L_GetLayerDefn().

Returns: feature definition.

Implements OGRLayer.

◆ GetNextFeature()

OGRFeature * OGRGNMWrappedResultLayer::GetNextFeature ( )

overridevirtual

Fetch the next available feature from this layer.

The returned feature becomes the responsibility of the caller to delete with OGRFeature::DestroyFeature(). It is critical that all features associated with an OGRLayer (more specifically an OGRFeatureDefn) be deleted before that layer/datasource is deleted.

Only features matching the current spatial filter (set with SetSpatialFilter()) will be returned.

This method implements sequential access to the features of a layer. The ResetReading() method can be used to start at the beginning again.

Features returned by GetNextFeature() may or may not be affected by concurrent modifications depending on drivers. A guaranteed way of seeing modifications in effect is to call ResetReading() on layers where GetNextFeature() has been called, before reading again. Structural changes in layers (field addition, deletion, ...) when a read is in progress may or may not be possible depending on drivers. If a transaction is committed/aborted, the current sequential reading may or may not be valid after that operation and a call to ResetReading() might be needed.

This method is the same as the C function OGR_L_GetNextFeature().

Returns: a feature, or NULL if no more features are available.

Implements OGRLayer.

◆ GetSpatialRef()

OGRSpatialReference * OGRGNMWrappedResultLayer::GetSpatialRef ( )

overridevirtual

Fetch the spatial reference system for this layer.

The returned object is owned by the OGRLayer and should not be modified or freed by the application.

Starting with OGR 1.11, several geometry fields can be associated to a feature definition. Each geometry field can have its own spatial reference system, which is returned by OGRGeomFieldDefn::GetSpatialRef(). OGRLayer::GetSpatialRef() is equivalent to GetLayerDefn()->OGRFeatureDefn::GetGeomFieldDefn(0)->GetSpatialRef()

This method is the same as the C function OGR_L_GetSpatialRef().

Returns: spatial reference, or NULL if there isn't one.

Reimplemented from OGRLayer.

◆ ICreateFeature()

OGRErr OGRGNMWrappedResultLayer::ICreateFeature ( OGRFeature * poFeature )

overrideprotectedvirtual

Create and write a new feature within a layer.

This method is implemented by drivers and not called directly. User code should use CreateFeature() instead.

The passed feature is written to the layer as a new feature, rather than overwriting an existing one. If the feature has a feature id other than OGRNullFID, then the native implementation may use that as the feature id of the new feature, but not necessarily. Upon successful return the passed feature will have been updated with the new feature id.

Parameters

poFeature the feature to write to disk.

Returns: OGRERR_NONE on success.

Since: GDAL 2.0

Reimplemented from OGRLayer.

◆ ISetFeature()

OGRErr OGRGNMWrappedResultLayer::ISetFeature ( OGRFeature * poFeature )

overrideprotectedvirtual

Rewrite an existing feature.

This method is implemented by drivers and not called directly. User code should use SetFeature() instead.

This method will write a feature to the layer, based on the feature id within the OGRFeature.

Parameters

poFeature the feature to write.

Returns: OGRERR_NONE if the operation works, otherwise an appropriate error code (e.g OGRERR_NON_EXISTING_FEATURE if the feature does not exist).

Since: GDAL 2.0

Reimplemented from OGRLayer.

◆ ResetReading()

void OGRGNMWrappedResultLayer::ResetReading ( )

overridevirtual

Reset feature reading to start on the first feature.

This affects GetNextFeature().

This method is the same as the C function OGR_L_ResetReading().

Implements OGRLayer.

◆ SetNextByIndex()

OGRErr OGRGNMWrappedResultLayer::SetNextByIndex ( GIntBig nIndex )

overridevirtual

Move read cursor to the nIndex'th feature in the current resultset.

This method allows positioning of a layer such that the GetNextFeature() call will read the requested feature, where nIndex is an absolute index into the current result set. So, setting it to 3 would mean the next feature read with GetNextFeature() would have been the 4th feature to have been read if sequential reading took place from the beginning of the layer, including accounting for spatial and attribute filters.

Only in rare circumstances is SetNextByIndex() efficiently implemented. In all other cases the default implementation which calls ResetReading() and then calls GetNextFeature() nIndex times is used. To determine if fast seeking is available on the current layer use the TestCapability() method with a value of OLCFastSetNextByIndex.

This method is the same as the C function OGR_L_SetNextByIndex().

Parameters

nIndex the index indicating how many steps into the result set to seek.

Returns: OGRERR_NONE on success or an error code.

Reimplemented from OGRLayer.

◆ TestCapability()

int OGRGNMWrappedResultLayer::TestCapability ( const char * pszCap )

overridevirtual

Test if this layer supported the named capability.

The capability codes that can be tested are represented as strings, but #defined constants exists to ensure correct spelling. Specific layer types may implement class specific capabilities, but this can't generally be discovered by the caller.

OLCRandomRead / "RandomRead": TRUE if the GetFeature() method is implemented in an optimized way for this layer, as opposed to the default implementation using ResetReading() and GetNextFeature() to find the requested feature id.
OLCSequentialWrite / "SequentialWrite": TRUE if the CreateFeature() method works for this layer. Note this means that this particular layer is writable. The same OGRLayer class may returned FALSE for other layer instances that are effectively read-only.
OLCRandomWrite / "RandomWrite": TRUE if the SetFeature() method is operational on this layer. Note this means that this particular layer is writable. The same OGRLayer class may returned FALSE for other layer instances that are effectively read-only.
OLCFastSpatialFilter / "FastSpatialFilter": TRUE if this layer implements spatial filtering efficiently. Layers that effectively read all features, and test them with the OGRFeature intersection methods should return FALSE. This can be used as a clue by the application whether it should build and maintain its own spatial index for features in this layer.
OLCFastFeatureCount / "FastFeatureCount": TRUE if this layer can return a feature count (via GetFeatureCount()) efficiently. i.e. without counting the features. In some cases this will return TRUE until a spatial filter is installed after which it will return FALSE.
OLCFastGetExtent / "FastGetExtent": TRUE if this layer can return its data extent (via GetExtent()) efficiently, i.e. without scanning all the features. In some cases this will return TRUE until a spatial filter is installed after which it will return FALSE.
OLCFastSetNextByIndex / "FastSetNextByIndex": TRUE if this layer can perform the SetNextByIndex() call efficiently, otherwise FALSE.
OLCCreateField / "CreateField": TRUE if this layer can create new fields on the current layer using CreateField(), otherwise FALSE.
OLCCreateGeomField / "CreateGeomField": (GDAL >= 1.11) TRUE if this layer can create new geometry fields on the current layer using CreateGeomField(), otherwise FALSE.
OLCDeleteField / "DeleteField": TRUE if this layer can delete existing fields on the current layer using DeleteField(), otherwise FALSE.
OLCReorderFields / "ReorderFields": TRUE if this layer can reorder existing fields on the current layer using ReorderField() or ReorderFields(), otherwise FALSE.
OLCAlterFieldDefn / "AlterFieldDefn": TRUE if this layer can alter the definition of an existing field on the current layer using AlterFieldDefn(), otherwise FALSE.
OLCDeleteFeature / "DeleteFeature": TRUE if the DeleteFeature() method is supported on this layer, otherwise FALSE.
OLCStringsAsUTF8 / "StringsAsUTF8": TRUE if values of OFTString fields are assured to be in UTF-8 format. If FALSE the encoding of fields is uncertain, though it might still be UTF-8.
OLCTransactions / "Transactions": TRUE if the StartTransaction(), CommitTransaction() and RollbackTransaction() methods work in a meaningful way, otherwise FALSE.
OLCIgnoreFields / "IgnoreFields": TRUE if fields, geometry and style will be omitted when fetching features as set by SetIgnoredFields() method.
OLCCurveGeometries / "CurveGeometries": TRUE if this layer supports writing curve geometries or may return such geometries. (GDAL 2.0).

This method is the same as the C function OGR_L_TestCapability().

Parameters

pszCap the name of the capability to test.

Returns: TRUE if the layer has the requested capability, or FALSE otherwise. OGRLayers will return FALSE for any unrecognized capabilities.

Implements OGRLayer.

The documentation for this class was generated from the following files:

gnm.h
gnmresultlayer.cpp

Public Member Functions

Protected Member Functions

Additional Inherited Members

Detailed Description

Member Function Documentation

◆ CreateField()

◆ CreateGeomField()

◆ GetFeature()

◆ GetFeatureCount()

◆ GetFIDColumn()

◆ GetGeometryColumn()

◆ GetLayerDefn()

◆ GetNextFeature()

◆ GetSpatialRef()

◆ ICreateFeature()

◆ ISetFeature()

◆ ResetReading()

◆ SetNextByIndex()

◆ TestCapability()