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OGRGNMWrappedResultLayer Class Reference

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

#include <gnm.h>

Inheritance diagram for OGRGNMWrappedResultLayer:
OGRLayer GDALMajorObject

Public Member Functions

 OGRGNMWrappedResultLayer (GDALDataset *poDS, OGRLayer *poLayer)
 Constructor.
 
virtual void ResetReading () CPL_OVERRIDE
 Reset feature reading to start on the first feature. More...
 
virtual OGRFeatureGetNextFeature () CPL_OVERRIDE
 Fetch the next available feature from this layer. More...
 
virtual OGRErr SetNextByIndex (GIntBig nIndex) CPL_OVERRIDE
 Move read cursor to the nIndex'th feature in the current resultset. More...
 
virtual OGRFeatureGetFeature (GIntBig nFID) CPL_OVERRIDE
 Fetch a feature by its identifier. More...
 
virtual OGRFeatureDefnGetLayerDefn () CPL_OVERRIDE
 Fetch the schema information for this layer. More...
 
virtual GIntBig GetFeatureCount (int bForce=TRUE) CPL_OVERRIDE
 Fetch the feature count in this layer. More...
 
virtual int TestCapability (const char *pszCap) CPL_OVERRIDE
 Test if this layer supported the named capability. More...
 
virtual OGRErr CreateField (OGRFieldDefn *poField, int bApproxOK=TRUE) CPL_OVERRIDE
 Create a new field on a layer. More...
 
virtual OGRErr CreateGeomField (OGRGeomFieldDefn *poField, int bApproxOK=TRUE) CPL_OVERRIDE
 Create a new geometry field on a layer. More...
 
virtual const char * GetFIDColumn () CPL_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 () CPL_OVERRIDE
 This method returns the name of the underlying database column being used as the geometry column, or "" if not supported. More...
 
virtual OGRSpatialReferenceGetSpatialRef () CPL_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
virtual OGRGeometryGetSpatialFilter ()
 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 OGRStyleTableGetStyleTable ()
 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=NULL, GDALProgressFunc pfnProgress=NULL, void *pProgressArg=NULL)
 Intersection of two layers. More...
 
OGRErr Union (OGRLayer *pLayerMethod, OGRLayer *pLayerResult, char **papszOptions=NULL, GDALProgressFunc pfnProgress=NULL, void *pProgressArg=NULL)
 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=NULL, GDALProgressFunc pfnProgress=NULL, void *pProgressArg=NULL)
 Identify the features of this layer with the ones from the identity layer. More...
 
OGRErr Update (OGRLayer *pLayerMethod, OGRLayer *pLayerResult, char **papszOptions=NULL, GDALProgressFunc pfnProgress=NULL, void *pProgressArg=NULL)
 Update this layer with features from the update layer. More...
 
OGRErr Clip (OGRLayer *pLayerMethod, OGRLayer *pLayerResult, char **papszOptions=NULL, GDALProgressFunc pfnProgress=NULL, void *pProgressArg=NULL)
 Clip off areas that are not covered by the method layer. More...
 
OGRErr Erase (OGRLayer *pLayerMethod, OGRLayer *pLayerResult, char **papszOptions=NULL, GDALProgressFunc pfnProgress=NULL, void *pProgressArg=NULL)
 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) CPL_OVERRIDE
 Rewrite an existing feature. More...
 
virtual OGRErr ICreateFeature (OGRFeature *poFeature) CPL_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...
 

Detailed Description

The OGRGNMWrappedResultLayer class for search paths queries results.

Since
GDAL 2.1

Member Function Documentation

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

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
poFieldfield definition to write to disk.
bApproxOKIf 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.

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

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
poFieldgeometry field definition to write to disk.
bApproxOKIf 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.

OGRFeature * OGRGNMWrappedResultLayer::GetFeature ( GIntBig  nFID)
virtual

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
nFIDthe feature id of the feature to read.
Returns
a feature now owned by the caller, or NULL on failure.

Reimplemented from OGRLayer.

GIntBig OGRGNMWrappedResultLayer::GetFeatureCount ( int  bForce = TRUE)
virtual

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
bForceFlag indicating whether the count should be computed even if it is expensive.
Returns
feature count, -1 if count not known.

Reimplemented from OGRLayer.

const char * OGRGNMWrappedResultLayer::GetFIDColumn ( )
virtual

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.

const char * OGRGNMWrappedResultLayer::GetGeometryColumn ( )
virtual

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.

OGRFeatureDefn * OGRGNMWrappedResultLayer::GetLayerDefn ( )
virtual

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.

OGRFeature * OGRGNMWrappedResultLayer::GetNextFeature ( )
virtual

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.

OGRSpatialReference * OGRGNMWrappedResultLayer::GetSpatialRef ( )
virtual

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.

OGRErr OGRGNMWrappedResultLayer::ICreateFeature ( OGRFeature poFeature)
protectedvirtual

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
poFeaturethe feature to write to disk.
Returns
OGRERR_NONE on success.
Since
GDAL 2.0

Reimplemented from OGRLayer.

OGRErr OGRGNMWrappedResultLayer::ISetFeature ( OGRFeature poFeature)
protectedvirtual

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
poFeaturethe 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.

void OGRGNMWrappedResultLayer::ResetReading ( )
virtual

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.

OGRErr OGRGNMWrappedResultLayer::SetNextByIndex ( GIntBig  nIndex)
virtual

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
nIndexthe index indicating how many steps into the result set to seek.
Returns
OGRERR_NONE on success or an error code.

Reimplemented from OGRLayer.

int OGRGNMWrappedResultLayer::TestCapability ( const char *  pszCap)
virtual

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
pszCapthe 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:

Generated for GDAL by doxygen 1.8.8.