Add &str function in the expression base
Prepare the SQL equivalent function for &str (i.e., the string cast
function).
Implement SPARQL STR function in the query parser handler.
Specify the return type to its proper class.
Minor refactor for readability.
Method renamed.
Code tidy.
Refactor the SqlDeparser to make it decouple from formatting utils.
Make as a final class.
Remove unsupported type from the mapping.
Remove unused class.
Code tidy.
Code tidy.
Add method interface to get the column type.
Reimplement datatype-override RDF literal in the parsers.
Implement CAST function in SQL dialects.
Separate the SQL select list handler to a different visitor class.
Remove unused method. The SQL column class should be a read-only object.
Code tidy.
Rename exception class.