org.apache.calcite.rel.metadata

Class RelMdPredicates.JoinConditionBasedPredicateInference.ExprsItr

java.lang.Object

org.apache.calcite.rel.metadata.RelMdPredicates.JoinConditionBasedPredicateInference.ExprsItr

All Implemented Interfaces:

Iterator<Mapping>

Enclosing class:

RelMdPredicates.JoinConditionBasedPredicateInference

class RelMdPredicates.JoinConditionBasedPredicateInference.ExprsItr
extends Object
implements Iterator<Mapping>

Given an expression returns all the possible substitutions.

For example, for an expression 'a + b + c' and the following equivalences:

 a : {a, b}
 b : {a, b}
 c : {c, e}
 

The following Mappings will be returned:

 {a → a, b → a, c → c}
 {a → a, b → a, c → e}
 {a → a, b → b, c → c}
 {a → a, b → b, c → e}
 {a → b, b → a, c → c}
 {a → b, b → a, c → e}
 {a → b, b → b, c → c}
 {a → b, b → b, c → e}
 

which imply the following inferences:

 a + a + c
 a + a + e
 a + b + c
 a + b + e
 b + a + c
 b + a + e
 b + b + c
 b + b + e
 

Field Summary

Fields

Modifier and Type	Field and Description
(package private) int[]	columns
(package private) BitSet[]	columnSets
(package private) boolean	firstCall
(package private) int[]	iterationIdx
(package private) Mapping	nextMapping

Constructor Summary

Constructors

Constructor and Description
ExprsItr(ImmutableBitSet fields)

Method Summary

Modifier and Type	Method and Description
private void	computeNextMapping(int level)
boolean	hasNext()
private void	initializeMapping()
Mapping	next()
void	remove()

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Iterator

forEachRemaining

Field Detail

columns

final int[] columns

columnSets

final BitSet[] columnSets

iterationIdx

final int[] iterationIdx

nextMapping

Mapping nextMapping

firstCall

boolean firstCall

Constructor Detail

ExprsItr

ExprsItr(ImmutableBitSet fields)

Method Detail

hasNext

public boolean hasNext()

Specified by:

hasNext in interface Iterator<Mapping>

next

public Mapping next()

Specified by:

next in interface Iterator<Mapping>

remove

public void remove()

Specified by:

remove in interface Iterator<Mapping>

computeNextMapping

private void computeNextMapping(int level)

initializeMapping

private void initializeMapping()