saffron
Class BuiltinAggregation.MinMax

java.lang.Object
  |
  +--saffron.BuiltinAggregation
        |
        +--saffron.BuiltinAggregation.MinMax

All Implemented Interfaces:

Aggregation

Enclosing class:

BuiltinAggregation

static class BuiltinAggregation.MinMax

extends BuiltinAggregation

MinMax implements the "min" and "max" aggregator functions, returning the returns the smallest/largest of the values which go into it. There are 3 forms:

sum(primitive type)

values are compared using <

sum(Comparable)

values are compared using Comparable.compareTo(java.lang.Object)

sum(Comparator, Object)

the Comparator.compare(java.lang.Object, java.lang.Object) method of the comparator is used to compare pairs of objects. The comparator is a startup argument, and must therefore be constant for the duration of the aggregation.

Nested Class Summary

Nested classes inherited from class saffron.BuiltinAggregation

BuiltinAggregation.Count, BuiltinAggregation.MinMax, BuiltinAggregation.Sum

Field Summary

private OJClass[]	argTypes
private boolean	isMin
private int	kind
(package private) static int	MINMAX_COMPARABLE
(package private) static int	MINMAX_COMPARATOR
(package private) static int	MINMAX_INVALID
(package private) static int	MINMAX_PRIMITIVE

Constructor Summary

(package private)

BuiltinAggregation.MinMax(OJClass[] argTypes, boolean isMin)

Method Summary

boolean	canMerge() Whether this aggregation can merge together two accumulators.
(package private) static int	getKind(OJClass[] argTypes)
(package private) String	getName()
OJClass[]	getParameterTypes()
OJClass	getReturnType()
OJClass[]	getStartParameterTypes()
void	implementNext(Implementor implementor, Rel rel, Expression accumulator, int[] args) Generates (into the current statement list, gleaned by calling implementor's Implementor.getStatementList() method) the piece of code which gets called each time an extra row is seen.
Expression	implementResult(Expression accumulator) Generates the expression which gets called when a total is complete.
Expression	implementStart(Implementor implementor, Rel rel, int[] args) Generates the expression which gets called when a new total is created.

Methods inherited from class saffron.BuiltinAggregation

count, count, count, count, create, implementMerge, implementStartAndNext, lookup, max, max, max, min, min, min, sum, sum

Methods inherited from class java.lang.Object

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

Field Detail

argTypes

private OJClass[] argTypes

isMin

private boolean isMin

kind

private int kind

MINMAX_INVALID

static final int MINMAX_INVALID

See Also:

Constant Field Values

MINMAX_PRIMITIVE

static final int MINMAX_PRIMITIVE

See Also:

Constant Field Values

MINMAX_COMPARABLE

static final int MINMAX_COMPARABLE

See Also:

Constant Field Values

MINMAX_COMPARATOR

static final int MINMAX_COMPARATOR

See Also:

Constant Field Values

Constructor Detail

BuiltinAggregation.MinMax

BuiltinAggregation.MinMax(OJClass[] argTypes,
                          boolean isMin)

Method Detail

getKind

static int getKind(OJClass[] argTypes)

getName

String getName()

Specified by:

getName in class BuiltinAggregation

canMerge

public boolean canMerge()

Description copied from interface: Aggregation

Whether this aggregation can merge together two accumulators. count can (you just add the accumulators); avg and Nth cannot.

Specified by:

canMerge in interface Aggregation

Overrides:

canMerge in class BuiltinAggregation

getReturnType

public OJClass getReturnType()

getStartParameterTypes

public OJClass[] getStartParameterTypes()

getParameterTypes

public OJClass[] getParameterTypes()

implementStart

public Expression implementStart(Implementor implementor,
                                 Rel rel,
                                 int[] args)

Description copied from interface: Aggregation

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).

implementNext

public void implementNext(Implementor implementor,
                          Rel rel,
                          Expression accumulator,
                          int[] args)

Description copied from interface: Aggregation

Generates (into the current statement list, gleaned by calling implementor's Implementor.getStatementList() method) the piece of code which gets called each time an extra row is seen. For sum(x), this looks like ((saffron.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

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

implementResult

public Expression implementResult(Expression accumulator)

Description copied from interface: Aggregation

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