org.geotools.filter

Class Capabilities

Object

Capabilities

public class Capabilities
extends Object

Allows for easier interaction with FilterCapabilities.

This class provides some out of the box FilterCapabilities constants that you can quickly use to describe the encoding abilities of your service.

This class behaves similar to Citations in that the constants are to be considered immutable, methods have been provided to assist in composing your own set of FilterCapabilities.

Example:

 Capabilities capabilities = new Capabilities();
 capabilities.addAll( Capabilities.LOGICAL );
 capabilities.addAll( Capabilities.SIMPLE_COMPARISONS );
 

You can use the Capabilities class at runtime to check existing filters to see if they are fully supported:

 if( fullySupports( filter )) {
     // do something
 }
 

Right now the class gives no indication as to what part of the provided filter was in error.

Author:

Jody Garnett

Field Summary

Fields

Modifier and Type	Field and Description
static Capabilities	LOGICAL Support for logical types AND, OR and NOT
static Capabilities	LOGICAL_OPENGIS
static Capabilities	SIMPLE_COMPARISONS Capabilities representing the simple comparisions.
static Capabilities	SIMPLE_COMPARISONS_OPENGIS

Constructor Summary

Constructors

Constructor and Description
Capabilities()
Capabilities(FilterCapabilities contents)

Method Summary

Modifier and Type	Method and Description
void	addAll(Capabilities copy)
void	addAll(FilterCapabilities copy)
void	addName(String name) Adds support for the provided name.
void	addName(String name, int argumentCount) Will add support for a function with the provided number of arguments This method will have no effect if the function is already listed.
void	addName(String name, String... argumentNames) Document support for the provided function.
void	addType(Class type) Adds a new support type to capabilities.
boolean	fullySupports(Expression expression) Determines if the expression and all its sub expressions is supported.
boolean	fullySupports(Filter filter) Determines if the filter and all its sub filters and expressions are supported.
FilterCapabilitiesImpl	getContents() Returns the internal FilterCapabilities data structure used for checking.
boolean	supports(Filter filter) Determines if specific filter passed in is supported.
String	toOperationName(Class filterType) Figure out the OperationName for the provided filterType.
String	toOperationName(Filter filter) Quickly look at the filter and determine the OperationName we need to check for in the FilterCapabilities data structure.

Methods inherited from class Object

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

Field Detail

LOGICAL

public static Capabilities LOGICAL

Support for logical types AND, OR and NOT

LOGICAL_OPENGIS

public static Capabilities LOGICAL_OPENGIS

SIMPLE_COMPARISONS

public static Capabilities SIMPLE_COMPARISONS

Capabilities representing the simple comparisions.

SIMPLE_COMPARISONS_OPENGIS

public static Capabilities SIMPLE_COMPARISONS_OPENGIS

Constructor Detail

Capabilities

public Capabilities()

Capabilities

public Capabilities(FilterCapabilities contents)

Method Detail

getContents

public FilterCapabilitiesImpl getContents()

Returns the internal FilterCapabilities data structure used for checking.

Returns:

FilterCapabilities

addType

public void addType(Class type)

Adds a new support type to capabilities.

This is the same as:addName( toOperationName( type ) )

Parameters:

type - the Class that indicates the new support.

addName

public void addName(String name)

Adds support for the provided name.

If this is a known name (avaialble as part of opengis interface) it will be grouped into:

• Spatial Operators: Will added a SpatialOperator into the mix with Point, LineString, Polygon as the supported geometry operands (based on the assumption of JTS)
• Comparison Operators:
• Arithmetic Operators: will cause hassimpleArithmetic to be true
• Other: will be treated as a no argument function call

This method will have no effect if the operator is already known.

Examples:

 capabilities.addName("Beyond"); // will enabled Beyond Filter
 capabilities.addName("NullCheck"); // will enable PropertyIsNull Filter
 capabilities.addName("SUB"); // will enabled hasSimpleArithmetic
 capabilities.addName("PI"); // add a no argument function called PI()
 

Parameters:

name - FilterCapabilities Operand name such as "BBOX", "Like" or "MUL"

addName

public void addName(String name,
                    int argumentCount)

Will add support for a function with the provided number of arguments

This method will have no effect if the function is already listed.

Example:capabilities.addName( "Length", 1 )

addName

public void addName(String name,
                    String... argumentNames)

Document support for the provided function.

This method will have no effect if the function is already listed.

Example:capabilities.addName( "Min", "value1", "value2" )

supports

public boolean supports(Filter filter)

Determines if specific filter passed in is supported.

Parameters:

filter - The Filter to be tested.

Returns:

true if supported, false otherwise.

See Also:

IsSupportedFilterVisitor

fullySupports

public boolean fullySupports(Filter filter)

Determines if the filter and all its sub filters and expressions are supported.

Is most important for logic filters, as they are the only ones with subFilters. The geoapi FilterVisitor and ExpressionVisitors allow for the handling of null, even so care should be taken to use Filter.INCLUDE and Expression.NIL where you can.

Parameters:

filter - the filter to be tested.

Returns:

true if all sub filters are supported, false otherwise.

See Also:

IsFullySupportedFilterVisitor

fullySupports

public boolean fullySupports(Expression expression)

Determines if the expression and all its sub expressions is supported.

The Expression visitor used for this work can handle null, even so care should be taken to useExpression.NIL where you can.

Parameters:

expression - the expression to be tested.

Returns:

true if all sub filters are supported, false otherwise.

See Also:

IsFullySupportedFilterVisitor

toOperationName

public String toOperationName(Filter filter)

Quickly look at the filter and determine the OperationName we need to check for in the FilterCapabilities data structure.

Returns:

Operation name

toOperationName

public String toOperationName(Class filterType)

Figure out the OperationName for the provided filterType.

The returned name can be used to check the FilterCapabilities to see if it type is supported in this execution context.

This approach is not applicable for Functions.

Parameters:

filterType - Filter type

Returns:

Operation name for the provided FilterType

addAll

public void addAll(Capabilities copy)

addAll

public void addAll(FilterCapabilities copy)