uk.ac.bbk.dcs.automed.qproc.iql
Class IQLUtility

java.lang.Object
  uk.ac.bbk.dcs.automed.qproc.iql.IQLUtility

public class IQLUtility
extends java.lang.Object

Provides a number of static methods that simplify IQL expressions.

Author:

Lucas Zamboulis

Field Summary

protected static java.util.logging.Logger

logger

Constructor Summary

IQLUtility()

Method Summary

static float	getCompDistributionMetric(Cell root)
static Cell	getDefaultQuery(int rangeSemantics)
static java.util.Collection	getSchemes(Cell root, java.util.Collection col)
static boolean	processFlatmapRange(Cell c) Performs in a top-down manner the following simplification:
static boolean	processRangeArgs(Cell c)
static boolean	processRangeInGen(Cell c) Performs in a top-down manner the following simplification:
static boolean	processRangeRange(Cell c) Performs in a bottom-up manner the following simplifications:
static boolean	simplifyBasedOnEquijoins(Cell root) Traverses query and replaces certain comprehensions with [].
static boolean	simplifyBasedOnQualifiers(Cell c) Performs in a bottom-up manner the following simplifications:
static void	simplifyRange(Cell c)
static boolean	simplifyUnionIntersect(Cell c) Simplifies the input query so that union Void Void returns Void and intersect Any Any returns Any

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static java.util.logging.Logger logger

Constructor Detail

IQLUtility

public IQLUtility()

Method Detail

simplifyRange

public static void simplifyRange(Cell c)

processRangeArgs

public static boolean processRangeArgs(Cell c)

processRangeRange

public static boolean processRangeRange(Cell c)

Performs in a bottom-up manner the following simplifications:

• Range Void (Range e1 e2) = Range e1 e2
• Range (Range e1 e2) Any = Range e1 e2

Parameters:

c - the root of the expression to be simplified

Returns:

true if a simplification occurred

processFlatmapRange

public static boolean processFlatmapRange(Cell c)

Performs in a top-down manner the following simplification:

• flatmap f (Range e1 e2) = Range (flatmap f e1) (flatmap f e2)

Parameters:

c - the root of the expression to be simplified

Returns:

true if a simplification occurred

processRangeInGen

public static boolean processRangeInGen(Cell c)

Performs in a top-down manner the following simplification:

• [h|Q;p<-(Range e1 e2);Q']=Range [h|Q;p<-e1;Q'] [h|Q;p<-e2;Q']

Parameters:

c - the root of the expression to be simplified

Returns:

true if a simplification occurred

simplifyBasedOnQualifiers

public static boolean simplifyBasedOnQualifiers(Cell c)

Performs in a bottom-up manner the following simplifications:

• [e|Q;p<-[];Q']=[]
• [e|Q;p<-Void;Q']=Void
• [e|Q;p<-Any;Q']=Any
• [e|Q;False;Q']=[]

Parameters:

c - the root of the expression to be simplified

Returns:

true if a simplification occurred

simplifyBasedOnEquijoins

public static boolean simplifyBasedOnEquijoins(Cell root)
                                        throws IQLException

Traverses query and replaces certain comprehensions with []. These comprehensions contain a join Traverse top-to-bottom - more efficient if top comprehension becomes [] right away.

Parameters:

root - root of the comprehension

Returns:

true if a simplification occurred

Throws:

IQLException

getCompDistributionMetric

public static float getCompDistributionMetric(Cell root)

Parameters:

root - the root of an IQL query

Returns:

the ratio a/b, where b is the number of schemes in the IQL query and a is the number of schemes in the query that the uk.ac.bbk.dcs.automed.qproc.optimise.ComprehensionDistributor would create - does NOT consider filters containing comprehensions (returns -1 if IQL query has no generators in the first place)

getSchemes

public static java.util.Collection getSchemes(Cell root,
                                              java.util.Collection col)

simplifyUnionIntersect

public static boolean simplifyUnionIntersect(Cell c)

Simplifies the input query so that union Void Void returns Void and intersect Any Any returns Any

Parameters:

c - the root of the input query

getDefaultQuery

public static Cell getDefaultQuery(int rangeSemantics)