Obtain the names of available layers from a GDAL vector source.
Usage
vapour_layer_names(dsource, sql = "")
Arguments
dsource
data source name (path to file, connection string, URL)
sql
if not empty this is executed against the data source (layer will be ignored)
Value
character vector of layer names
Details
Some vector sources have multiple layers while many have only one. Shapefiles
for example have only one, and the single layer gets the file name with no path
and no extension. GDAL provides a quirk for shapefiles in that a directory may
act as a data source, and any shapefile in that directory acts like a layer of that
data source. This is a little like the one-or-many sleight that exists for raster
data sources with subdatasets (there's no way to virtualize single rasters into
a data source with multiple subdatasets, oh except by using VRT....)