public interface AggImplementor
Modifier and Type | Method and Description |
---|---|
java.util.List<java.lang.reflect.Type> |
getStateType(AggContext info)
Returns the types of the intermediate variables used by the aggregate
implementation.
|
void |
implementAdd(AggContext info,
AggAddContext add)
Updates intermediate values to account for the newly added value.
|
void |
implementReset(AggContext info,
AggResetContext reset)
Implements reset of the intermediate variables to the initial state.
|
Expression |
implementResult(AggContext info,
AggResultContext result)
Calculates the resulting value based on the intermediate variables.
|
java.util.List<java.lang.reflect.Type> getStateType(AggContext info)
For instance, for "concatenate to string" this can be
StringBuilder
.
Calcite calls this method before all other implement*
methods.
info
- Aggregate contextvoid implementReset(AggContext info, AggResetContext reset)
AggResetContext.accumulator()
should be used to reference
the state variables.
For instance, to zero the count, use the following code:
reset.currentBlock().add(
Expressions.statement(
Expressions.assign(reset.accumulator().get(0),
Expressions.constant(0)));
info
- Aggregate contextreset
- Reset contextvoid implementAdd(AggContext info, AggAddContext add)
AggResetContext.accumulator()
should be used to reference
the state variables.info
- Aggregate contextadd
- Add contextExpression implementResult(AggContext info, AggResultContext result)
AggResetContext.accumulator()
should be used to reference
the state variables.info
- Aggregate contextresult
- Result contextCopyright © 2012–2019 The Apache Software Foundation. All rights reserved.