org.eigenbase.oj.rex
Class OJRexImplementorTableImpl.OJMinMaxAggImplementor

java.lang.Object
  org.eigenbase.oj.rex.OJRexImplementorTableImpl.OJBasicAggImplementor
      org.eigenbase.oj.rex.OJRexImplementorTableImpl.OJMinMaxAggImplementor

All Implemented Interfaces:

OJAggImplementor

Enclosing class:

OJRexImplementorTableImpl

public static class OJRexImplementorTableImpl.OJMinMaxAggImplementor
extends OJRexImplementorTableImpl.OJBasicAggImplementor

Constructor Summary

OJRexImplementorTableImpl.OJMinMaxAggImplementor()

Method Summary

boolean	canMerge() Returns whether this aggregation can merge together two accumulators.
void	implementNext(JavaRelImplementor implementor, JavaRel rel, Expression accumulator, AggregateCall call) Generates (into the current statement list, gleaned by calling implementor's JavaRelImplementor.getStatementList() method) the piece of code which gets called each time an extra row is seen.
Expression	implementResult(JavaRelImplementor implementor, Expression accumulator, AggregateCall call) Generates the expression which gets called when a total is complete.
Expression	implementStart(JavaRelImplementor implementor, JavaRel rel, AggregateCall call) Generates the expression which gets called when a new total is created.

Methods inherited from class org.eigenbase.oj.rex.OJRexImplementorTableImpl.OJBasicAggImplementor

implementMerge, implementStartAndNext

Methods inherited from class java.lang.Object

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

Constructor Detail

OJRexImplementorTableImpl.OJMinMaxAggImplementor

public OJRexImplementorTableImpl.OJMinMaxAggImplementor()

Method Detail

canMerge

public boolean canMerge()

Description copied from interface: OJAggImplementor

Returns whether this aggregation can merge together two accumulators.

For example, COUNT can (you just add the accumulators); AVG and MEDIAN cannot.

Specified by:

canMerge in interface OJAggImplementor

Overrides:

canMerge in class OJRexImplementorTableImpl.OJBasicAggImplementor

Returns:

whether this aggregation can merge together two accumulators

implementNext

public void implementNext(JavaRelImplementor implementor,
                          JavaRel rel,
                          Expression accumulator,
                          AggregateCall call)

Description copied from interface: OJAggImplementor

Generates (into the current statement list, gleaned by calling implementor's JavaRelImplementor.getStatementList() method) the piece of code which gets called each time an extra row is seen. For sum(x), this looks like ((org.eigenbase.runtime.Holder.int_Holder) accumulator).value += x.

Parameters:

implementor - a callback object which knows how to generate things

rel - the relational expression which is generating this code

accumulator - the expression which holds the total

call - the ordinals of the fields of the child row which are arguments to this aggregation

implementResult

public Expression implementResult(JavaRelImplementor implementor,
                                  Expression accumulator,
                                  AggregateCall call)

Description copied from interface: OJAggImplementor

Generates the expression which gets called when a total is complete. For sum(x), this looks like ((saffron.runtime.Holder.int_Holder) accumulator).value.

implementStart

public Expression implementStart(JavaRelImplementor implementor,
                                 JavaRel rel,
                                 AggregateCall call)

Description copied from interface: OJAggImplementor

Generates the expression which gets called when a new total is created. For sum(x), this looks like new saffron.runtime.Holder.int_Holder(0).