net.sf.saffron.opt
Class AbstractConverter.ExpandConversionRule

java.lang.Object
  |
  +--net.sf.saffron.opt.VolcanoRule
        |
        +--net.sf.saffron.opt.AbstractConverter.ExpandConversionRule

Enclosing class:

AbstractConverter

public static class AbstractConverter.ExpandConversionRule

extends VolcanoRule

Rule which converts an AbstractConverter into a chain of converters from the source relation to the target calling convention.

The chain produced is mimimal: we have previously built the transitive closure of the graph of conversions, so we choose the shortest chain.

Unlike the AbstractConverter they are replacing, these converters are guaranteed to be able to convert any relation of their calling convention. Furthermore, because they introduce subsets of other calling conventions along the way, these subsets may spawn more efficient conversions which are not generally applicable.

AbstractConverters can be messy, so they restrain themselves: they don't fire if the target subset already has an implementation (with less than infinite cost).

Field Summary

Fields inherited from class net.sf.saffron.opt.VolcanoRule

description, operand, operands, planner

Constructor Summary

AbstractConverter.ExpandConversionRule()

Method Summary

void	onMatch(VolcanoRuleCall call) This method is called every time the rule matches.

Methods inherited from class net.sf.saffron.opt.VolcanoRule

convert, getOutConvention, getPlanner, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractConverter.ExpandConversionRule

public AbstractConverter.ExpandConversionRule()

Method Detail

onMatch

public void onMatch(VolcanoRuleCall call)

Description copied from class: VolcanoRule

This method is called every time the rule matches. 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 VolcanoRuleCall.transformTo(net.sf.saffron.rel.SaffronRel) to register the expression.

Specified by:

onMatch in class VolcanoRule