Package org.apache.vxquery.compiler.rewriter.rules

Class RemoveRedundantCastExpressionsRule

java.lang.Object

org.apache.vxquery.compiler.rewriter.rules.AbstractRemoveRedundantTypeExpressionsRule

org.apache.vxquery.compiler.rewriter.rules.RemoveRedundantCastExpressionsRule

All Implemented Interfaces:

org.apache.hyracks.algebricks.core.rewriter.base.IAlgebraicRewriteRule

public class RemoveRedundantCastExpressionsRule
extends AbstractRemoveRedundantTypeExpressionsRule

The rule searches for where the xquery cast function is used. When the expression's return type matches the treat expression type, the cast is removed.

 Before
 
   plan__parent
   %OPERATOR( $v1 : cast( \@input_expression, \@type_expression ) )
   plan__child
   
   Where treat \@type_expression is the same as the return type of \@input_expression.
   
 After 
 
   plan__parent
   %OPERATOR( $v1 : \@input_expression )
   plan__child
 

Author:

prestonc

Constructor Summary

Constructors

Constructor	Description
RemoveRedundantCastExpressionsRule()

Method Summary

Modifier and Type	Method	Description
protected org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier	getSearchFunction()
boolean	matchesAllInstancesOf(SequenceType sTypeArg, SequenceType sTypeOutput)

Methods inherited from class org.apache.vxquery.compiler.rewriter.rules.AbstractRemoveRedundantTypeExpressionsRule

hasTypeArgument, rewritePost, rewritePre

Methods inherited from class java.lang.Object

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

Constructor Detail

RemoveRedundantCastExpressionsRule

public RemoveRedundantCastExpressionsRule()

Method Detail

getSearchFunction

protected org.apache.hyracks.algebricks.core.algebra.functions.FunctionIdentifier getSearchFunction()

Specified by:

getSearchFunction in class AbstractRemoveRedundantTypeExpressionsRule

matchesAllInstancesOf

public boolean matchesAllInstancesOf(SequenceType sTypeArg,
                                     SequenceType sTypeOutput)

Specified by:

matchesAllInstancesOf in class AbstractRemoveRedundantTypeExpressionsRule