net.sf.saffron.rel
Class RemoveTrivialProjectRule

java.lang.Object
  |
  +--net.sf.saffron.opt.VolcanoRule
        |
        +--net.sf.saffron.rel.RemoveTrivialProjectRule

public class RemoveTrivialProjectRule

extends VolcanoRule

Rule which, given a ProjectRel node which merely returns its input, converts the node into its child.

For example, ProjectRel(ArrayReader(a), {$input0}) becomes ArrayReader(a).

Field Summary

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

description, planner

Constructor Summary

RemoveTrivialProjectRule()

Method Summary

private static boolean	isIdentity(RexNode[] exps, int fieldCount)
void	onMatch(VolcanoRuleCall call) This method is called every time the rule matches.

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

convert, getOutConvention, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

RemoveTrivialProjectRule

public RemoveTrivialProjectRule()

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

isIdentity

private static boolean isIdentity(RexNode[] exps,
                                  int fieldCount)