Package org.geotools.filter.visitor

Class SimplifyingFilterVisitor

Object

DuplicatingFilterVisitor

SimplifyingFilterVisitor

All Implemented Interfaces:

ExpressionVisitor, FilterVisitor

public class SimplifyingFilterVisitor
extends DuplicatingFilterVisitor

Takes a filter and returns a simplified, equivalent one. At the moment the filter:

• simplifies out Filter.INCLUDE and Filter.EXCLUDE in logical expressions
• removes double logic negations
• deal with FID filter validation removing invalid fids
• optimize out all non volatile functions that do not happen to use attributes, replacing them with literals

FID filter validation is meant to wipe out non valid feature ids from Id filters. This is so in order to avoid sending feature ids down to DataStores that are not valid as per the specific FeatureType fid structure. Since this is structure is usually DataStore specific, some times being a strategy based on how the feature type primary key is generated, fid validation is abstracted out to the SimplifyingFilterVisitor.FIDValidator interface so when a DataStore is about to send a query down to the backend it van provide this visitor with a validator specific for the feature type fid structure being queried.

By default all feature ids are valid. DataStores that want non valid fids to be wiped out should set a SimplifyingFilterVisitor.FIDValidator through the setFIDValidator(FIDValidator) method.

Since:

2.5.x

Author:

Andrea Aime - OpenGeo, Gabriel Roldan (OpenGeo)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	SimplifyingFilterVisitor.FIDValidator	Defines a simple means of assessing whether a feature id in an Id filter is structurally valid and hence can be send down to the backend with confidence it will not cause trouble, the most common one being filtering by pk number even if the type name prefix does not match.
static class	SimplifyingFilterVisitor.RegExFIDValidator	A FID validator that matches the fids with a given regular expression to determine the fid's validity.
static class	SimplifyingFilterVisitor.TypeNameDotNumberFidValidator	A convenient fid validator for the common case of a feature id being a composition of a <typename>.<number>

Field Summary

Fields

Modifier and Type	Field	Description
static final SimplifyingFilterVisitor.FIDValidator	ANY_FID_VALID	A 'null-object' fid validator that assumes any feature id in an Id filter is valid
protected FeatureType	featureType

Fields inherited from class DuplicatingFilterVisitor

ff

Constructor Summary

Constructors

Constructor	Description
SimplifyingFilterVisitor()

Method Summary

Modifier and Type	Method	Description
protected List<Filter>	basicAndSimplification(List<Filter> filters)
protected List<Filter>	basicOrSimplification(List<Filter> filters)
protected <T extends BinaryLogicOperator> List<Filter>	collect(T filter, Class<T> type, Object extraData, List<Filter> collected)
protected List<Filter>	extraAndSimplification(Object extraData, List<Filter> filters)
protected List<Filter>	extraOrSimplification(Object extraData, List<Filter> filters)
protected boolean	isConstant(Expression ex)
boolean	isRangeSimplicationEnabled()
protected boolean	isSimpleFeature()	Returns true if the target feature type is a simple feature one
protected boolean	isVolatileFunction(Function function)	Checks if a function is volatile in this context.
void	setFeatureType(FeatureType featureType)
void	setFIDValidator(SimplifyingFilterVisitor.FIDValidator validator)
void	setRangeSimplicationEnabled(boolean rangeSimplicationEnabled)	Enables/disable range simplification.
static Filter	simplify(Filter filter)	Tries to simplify the filter if it's not already a simple one.
static Filter	simplify(Filter filter, FeatureType featureType)	Tries to simplify the filter if it's not already a simple one
Object	visit(And filter, Object extraData)
Object	visit(Add expression, Object extraData)
Object	visit(Divide expression, Object extraData)
Object	visit(Function function, Object extraData)
Object	visit(Multiply expression, Object extraData)
Object	visit(Subtract expression, Object extraData)
Object	visit(Id filter, Object extraData)	Uses the current SimplifyingFilterVisitor.FIDValidator to wipe out illegal feature ids from the returned filters.
Object	visit(Not filter, Object extraData)
Object	visit(Or filter, Object extraData)
Object	visit(PropertyIsBetween filter, Object extraData)
Object	visit(PropertyIsEqualTo filter, Object extraData)
Object	visit(PropertyIsGreaterThanOrEqualTo filter, Object extraData)
Object	visit(PropertyIsGreaterThan filter, Object extraData)
Object	visit(PropertyIsLessThanOrEqualTo filter, Object extraData)
Object	visit(PropertyIsLessThan filter, Object extraData)
Object	visit(PropertyIsLike filter, Object extraData)
Object	visit(PropertyIsNil filter, Object extraData)
Object	visit(PropertyIsNotEqualTo filter, Object extraData)
Object	visit(PropertyIsNull filter, Object extraData)

Methods inherited from class DuplicatingFilterVisitor

getFactory, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visit, visitNullFilter

Methods inherited from class Object

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

Field Details

ANY_FID_VALID

public static final SimplifyingFilterVisitor.FIDValidator ANY_FID_VALID

A 'null-object' fid validator that assumes any feature id in an Id filter is valid

featureType

protected FeatureType featureType

Constructor Details

SimplifyingFilterVisitor

public SimplifyingFilterVisitor()

Method Details

setFIDValidator

public void setFIDValidator(SimplifyingFilterVisitor.FIDValidator validator)

setFeatureType

public void setFeatureType(FeatureType featureType)

visit

public Object visit(And filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

basicAndSimplification

protected List<Filter> basicAndSimplification(List<Filter> filters)

collect

protected <T extends BinaryLogicOperator>
List<Filter> collect(T filter,
 Class<T> type,
 Object extraData,
 List<Filter> collected)

visit

public Object visit(Or filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

basicOrSimplification

protected List<Filter> basicOrSimplification(List<Filter> filters)

extraAndSimplification

protected List<Filter> extraAndSimplification(Object extraData,
 List<Filter> filters)

extraOrSimplification

protected List<Filter> extraOrSimplification(Object extraData,
 List<Filter> filters)

visit

public Object visit(Id filter,
 Object extraData)

Uses the current SimplifyingFilterVisitor.FIDValidator to wipe out illegal feature ids from the returned filters.

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

Returns:

a filter containing only valid fids as per the current SimplifyingFilterVisitor.FIDValidator, may be Filter.EXCLUDE if none matches or the filter is already empty

visit

public Object visit(Not filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

isSimpleFeature

protected boolean isSimpleFeature()

Returns true if the target feature type is a simple feature one

visit

public Object visit(Function function,
 Object extraData)

Specified by:

visit in interface ExpressionVisitor

Overrides:

visit in class DuplicatingFilterVisitor

isVolatileFunction

protected boolean isVolatileFunction(Function function)

Checks if a function is volatile in this context. By default it checks if the function implements the VolatileFunction interface, subclasses can override

simplify

public static Filter simplify(Filter filter)

Tries to simplify the filter if it's not already a simple one.

simplify

public static Filter simplify(Filter filter,
 FeatureType featureType)

Tries to simplify the filter if it's not already a simple one

isConstant

protected boolean isConstant(Expression ex)

visit

public Object visit(PropertyIsBetween filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsEqualTo filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsNotEqualTo filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsGreaterThan filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsGreaterThanOrEqualTo filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsLessThan filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsLessThanOrEqualTo filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsLike filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsNil filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(PropertyIsNull filter,
 Object extraData)

Specified by:

visit in interface FilterVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(Add expression,
 Object extraData)

Specified by:

visit in interface ExpressionVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(Divide expression,
 Object extraData)

Specified by:

visit in interface ExpressionVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(Subtract expression,
 Object extraData)

Specified by:

visit in interface ExpressionVisitor

Overrides:

visit in class DuplicatingFilterVisitor

visit

public Object visit(Multiply expression,
 Object extraData)

Specified by:

visit in interface ExpressionVisitor

Overrides:

visit in class DuplicatingFilterVisitor

isRangeSimplicationEnabled

public boolean isRangeSimplicationEnabled()

setRangeSimplicationEnabled

public void setRangeSimplicationEnabled(boolean rangeSimplicationEnabled)

Enables/disable range simplification. Range simplification can figure out that the logic combination of multiple ranges against the same property can be turned into a single range, a INCLUDE, or a EXCLUDE, but it requires the range boundaries to be of the same type as the