ch.ethz.mxquery.query.optimizer
Class ExpressionSplitter

java.lang.Object
  ch.ethz.mxquery.query.optimizer.ExpressionSplitter

public final class ExpressionSplitter
extends java.lang.Object

This is an optimization class for the WindowIndexIterator. It helps to split a expression into disjunction terms and finds max index patterns. In the near future maybe this can replaced by a query rewriter.

Constructor Summary

ExpressionSplitter(java.util.List startVars, java.util.List endVars)

Method Summary

static ValueLiteral	createValueTerm(XDMIterator iter, java.util.List startVars, java.util.List endVars) Helper calls to create a new value term from an iterator and analyze the dependencies
DTerm	splitExpression(XDMIterator expr) Splits an Iterator tree into disjunction terms and sorts them regarding to the variable dependencies

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionSplitter

public ExpressionSplitter(java.util.List startVars,
                          java.util.List endVars)

Parameters:

startVars - List of variables

endVars - List of variables

Method Detail

splitExpression

public DTerm splitExpression(XDMIterator expr)

Splits an Iterator tree into disjunction terms and sorts them regarding to the variable dependencies

Parameters:

expr -

Returns:

the DTerm containing the expression

createValueTerm

public static ValueLiteral createValueTerm(XDMIterator iter,
                                           java.util.List startVars,
                                           java.util.List endVars)

Helper calls to create a new value term from an iterator and analyze the dependencies

Parameters:

iter -

startVars -

endVars -

Returns:

the value literal for the iterator