org.eigenbase.rel.rules
Class ReduceDecimalsRule

java.lang.Object
  org.eigenbase.relopt.RelOptRule
      org.eigenbase.rel.rules.ReduceDecimalsRule

public class ReduceDecimalsRule
extends RelOptRule

ReduceDecimalsRule is a rule which reduces decimal operations (such as casts or arithmetic) into operations involving more primitive types (such as longs and doubles). The rule allows eigenbase implementations to deal with decimals in a consistent manner, while saving the effort of implementing them.

The rule can be applied to a CalcRel with a program for which RexUtil.requiresDecimalExpansion(org.eigenbase.rex.RexNode, boolean) returns true. The rule relies on a RexShuttle to walk over relational expressions and replace them.

While decimals are generally not implemented by the eigenbase runtime, the rule is optionally applied, in order to support the situation in which we would like to push down decimal operations to an external database.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/ReduceDecimalsRule.java#3 $

Author:

jpham

Nested Class Summary

private class	ReduceDecimalsRule.BinaryArithmeticExpander Expands a decimal arithmetic expression
private class	ReduceDecimalsRule.CaseExpander Expander that rewrites case expressions, in place.
private class	ReduceDecimalsRule.CastArgAsDoubleExpander An expander which casts decimal arguments as doubles
private class	ReduceDecimalsRule.CastArgAsReturnExpander An expander which casts decimal arguments as call return type
private class	ReduceDecimalsRule.CastArgAsTypeExpander An expander which casts decimal arguments as another type
private class	ReduceDecimalsRule.CastExpander Expands a decimal cast expression
private class	ReduceDecimalsRule.CeilExpander Expander that rewrites ceiling(decimal) expressions:
class	ReduceDecimalsRule.DecimalShuttle A shuttle which converts decimal expressions to expressions based on longs.
private class	ReduceDecimalsRule.ExpanderMap Maps a RexCall to a RexExpander
private class	ReduceDecimalsRule.FloorExpander Expander that rewrites floor(decimal) expressions:
private class	ReduceDecimalsRule.PassThroughExpander An expander that substitutes decimals with their integer representations.
private class	ReduceDecimalsRule.ReinterpretExpander This expander simplifies reinterpret calls.
class	ReduceDecimalsRule.RexExpander Rewrites a decimal expression for a specific set of SqlOperator's.

Field Summary

static ReduceDecimalsRule

instance

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

ReduceDecimalsRule() Creates a ReduceDecimalsRule.

Method Summary

CallingConvention	getOutConvention() Returns the calling convention of the result of firing this rule, null if not known.
void	onMatch(RelOptRuleCall call) Receives notification about a rule match.

Methods inherited from class org.eigenbase.relopt.RelOptRule

convert, equals, equals, getOperand, getOperands, getOutTrait, hashCode, matches, mergeTraitsAndConvert, mergeTraitsAndConvert, toString

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

instance

public static final ReduceDecimalsRule instance

Constructor Detail

ReduceDecimalsRule

private ReduceDecimalsRule()

Creates a ReduceDecimalsRule.

Method Detail

getOutConvention

public CallingConvention getOutConvention()

Description copied from class: RelOptRule

Returns the calling convention of the result of firing this rule, null if not known.

Overrides:

getOutConvention in class RelOptRule

onMatch

public void onMatch(RelOptRuleCall call)

Description copied from class: RelOptRule

Receives notification about a rule match. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.

Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back RelOptRuleCall.transformTo(org.eigenbase.rel.RelNode) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)