GDAL
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Public Member Functions | |
OGRErr | Compile (OGRFeatureDefn *, const char *, int bCheck=TRUE, swq_custom_func_registrar *poCustomFuncRegistrar=NULL) |
int | Evaluate (OGRFeature *) |
GIntBig * | EvaluateAgainstIndices (OGRLayer *, OGRErr *) |
int | CanUseIndex (OGRLayer *) |
char ** | GetUsedFields () |
Returns lists of fields in expression. More... | |
void * | GetSWQExpr () |
char ** OGRFeatureQuery::GetUsedFields | ( | ) |
Returns lists of fields in expression.
All attribute fields are used in the expression of this feature query are returned as a StringList of field names. This function would primarily be used within drivers to recognise special case conditions depending only on attribute fields that can be very efficiently fetched.
NOTE: If any fields in the expression are from tables other than the primary table then NULL is returned indicating an error. In succesful use, no non-empty expression should return an empty list.