net.sf.farrago.fennel.calc
Class CalcRexImplementorTableImpl.HistogramAggRexImplementor

java.lang.Object
  net.sf.farrago.fennel.calc.CalcRexImplementorTableImpl.AbstractCalcRexAggImplementor
      net.sf.farrago.fennel.calc.CalcRexImplementorTableImpl.HistogramAggRexImplementor

All Implemented Interfaces:

CalcRexAggImplementor

Enclosing class:

CalcRexImplementorTableImpl

private static class CalcRexImplementorTableImpl.HistogramAggRexImplementor
extends CalcRexImplementorTableImpl.AbstractCalcRexAggImplementor

Implementation of the $HISTOGRAM aggregate function (SqlStdOperatorTable.histogramAggFunction, which helps implement MIN, MAX, FIRST_VALUE, LAST_VALUE in a windowed aggregation scenario.

See Also:

CalcRexImplementorTableImpl.HistogramResultRexImplementor

Constructor Summary

CalcRexImplementorTableImpl.HistogramAggRexImplementor()

Method Summary

void	implementAdd(RexCall call, CalcReg accumulatorRegister, RexToCalcTranslator translator) Generates instructions to add a new value to an aggregation.
void	implementDrop(RexCall call, CalcReg accumulatorRegister, RexToCalcTranslator translator) Generates instructions to implement this call, and returns the register which holds the result.
void	implementInitialize(RexCall call, CalcReg accumulatorRegister, RexToCalcTranslator translator) Generates instructions to initialize an accumulator for a call to this aggregate function, and returns the register which holds the accumulator.

Methods inherited from class net.sf.farrago.fennel.calc.CalcRexImplementorTableImpl.AbstractCalcRexAggImplementor

canImplement, implementInitAdd

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CalcRexImplementorTableImpl.HistogramAggRexImplementor

public CalcRexImplementorTableImpl.HistogramAggRexImplementor()

Method Detail

implementInitialize

public void implementInitialize(RexCall call,
                                CalcReg accumulatorRegister,
                                RexToCalcTranslator translator)

Description copied from interface: CalcRexAggImplementor

Generates instructions to initialize an accumulator for a call to this aggregate function, and returns the register which holds the accumulator.

For example, for SUM(x), this method generates O s8; V 0; T; MOVE O0, C0; and returns the O0 register.

Parameters:

call - The call to the aggregate function to be implemented

accumulatorRegister - The accumulator register to be populated

translator - Calculator code generator

implementAdd

public void implementAdd(RexCall call,
                         CalcReg accumulatorRegister,
                         RexToCalcTranslator translator)

Description copied from interface: CalcRexAggImplementor

Generates instructions to add a new value to an aggregation.

For example, for SUM(x), this method generates I s8; O s8; T; ADD O0, I0;.

Parameters:

call - The call to the aggregate function to be implemented

accumulatorRegister - The accumulator register

translator - Calculator code generator

implementDrop

public void implementDrop(RexCall call,
                          CalcReg accumulatorRegister,
                          RexToCalcTranslator translator)

Description copied from interface: CalcRexAggImplementor

Generates instructions to implement this call, and returns the register which holds the result.

For example, for SUM(x), this method generates I s8; O s8; T; SUB O0, I0;

Parameters:

call - The call to the aggregate function to be implemented.

accumulatorRegister - The accumulator register

translator - Calculator code generator