Class AbstractConverter.ExpandConversionRule

Enclosing class:

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
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


public AbstractConverter.ExpandConversionRule()
Method Detail


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