See: Description
| Class | Description | 
|---|---|
| ConversionContext | Conversion context, some rules need this data to convert the nodes. | 
| ExpressionConverter | Extracts expressions (function calls, field accesses) from the resolve query nodes, converts them
 to RexNodes. | 
| QueryStatementConverter | Converts a resolved Zeta SQL query represented by a tree to corresponding Calcite representation. | 
| SqlOperators | A separate SqlOperators table for those functions that do not exist or not compatible with
 Calcite. | 
| UserFunctionDefinitions | Holds user defined function definitions. | 
| UserFunctionDefinitions.Builder | |
| UserFunctionDefinitions.JavaScalarFunction | |
| ZetaSqlScalarFunctionImpl | ZetaSQL-specific extension to  ScalarFunctionImpl. |