org.geotools.filter

Class FunctionImpl

Object

ExpressionAbstract

FunctionImpl

All Implemented Interfaces:

Expression, Function

Direct Known Subclasses:

AbstractHSLFunction, BoundedByFunction, Collection_NearestFunction, ConcatenateFunction, ConstrastFunction, CSSFunction, DefaultIfNullFunction, ExponentialFunction, FontAlternativesFunction, FootprintsTransformation, GrayscaleFunction, HSLFunction, InternalVolatileFunction, MapBoxFontBaseNameFunction, MapBoxFontStyleFunction, MapBoxFontWeightFunction, MBExpression, MixFunction, ShadeFunction, SpinFunction, StringInFunction, StringTransformFunction, TintFunction

public class FunctionImpl
extends ExpressionAbstract
implements Function

Default implementation of a Function; you may extend this class to implement specific functionality.

Author:

Cory Horner, Refractions Research

Field Summary

Fields

Modifier and Type	Field and Description
protected FunctionName	functionName FunctionName description for FilterCapabilities, may be provided by subclass in constructor, or will be lazily created based on name and number of arguments.

Fields inherited from interface Expression

NIL

Constructor Summary

Constructors

Constructor and Description
FunctionImpl()

Method Summary

Modifier and Type	Method and Description
Object	accept(ExpressionVisitor visitor, Object extraData) Accepts a visitor.
protected LinkedHashMap<String,Object>	dispatchArguments(Object obj) Gathers up and groups the parameters to the function based on the declared parameters.
boolean	equals(Object obj)
Object	evaluate(Object object) Default implementation simply returns the fallbackValue.
protected static FunctionName	functionName(String name, String ret, String... args) Convenience method for creating a function name from a set of strings describing the return and argument parameters of the function.
Literal	getFallbackValue() The value of the fallbackValue attribute is used as a default value, if the SE implementation does not support the function.
FunctionName	getFunctionName() Access to the FunctionName description as used in a FilterCapabilities document.
String	getName() Gets the name of this function.
List<Expression>	getParameters() Returns the function parameters.
protected Object	getParameterValue(Object object, int argumentIndex) Evaluates a specific argument against the context, checking for required values and proper conversion.
protected Object	getParameterValue(Object object, int argumentIndex, Object defaultValue) Evaluates a specific argument against the context, checking for required values and proper conversion.
int	hashCode()
void	setFallbackValue(Literal fallbackValue)
void	setName(String name) Sets the name of the function.
void	setParameters(List<Expression> params) Sets the function parameters.
String	toString() Creates a String representation of this Function with the function name and the arguments.

Methods inherited from class ExpressionAbstract

evaluate

Methods inherited from class Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface Expression

evaluate

Field Detail

functionName

protected FunctionName functionName

FunctionName description for FilterCapabilities, may be provided by subclass in constructor, or will be lazily created based on name and number of arguments.

Constructor Detail

FunctionImpl

public FunctionImpl()

Method Detail

getName

public String getName()

Gets the name of this function.

Specified by:

getName in interface Function

Returns:

the name of the function.

getFunctionName

public FunctionName getFunctionName()

Description copied from interface: Function

Access to the FunctionName description as used in a FilterCapabilities document.

Specified by:

getFunctionName in interface Function

Returns:

FunctionName description, if available.

setName

public void setName(String name)

Sets the name of the function.

getParameters

public List<Expression> getParameters()

Returns the function parameters.

Specified by:

getParameters in interface Function

evaluate

public Object evaluate(Object object)

Default implementation simply returns the fallbackValue.

Please override this method to produce a value based on the provided arguments.

Specified by:

evaluate in interface Expression

Overrides:

evaluate in class ExpressionAbstract

Parameters:

object - Object being evaluated; often a Feature

Returns:

value for the provided object

setParameters

public void setParameters(List<Expression> params)

Sets the function parameters.

setFallbackValue

public void setFallbackValue(Literal fallbackValue)

getFallbackValue

public Literal getFallbackValue()

Description copied from interface: Function

The value of the fallbackValue attribute is used as a default value, if the SE implementation does not support the function. If the implementation supports the function, then the result value is determined by executing the function.

Specified by:

getFallbackValue in interface Function

Returns:

Optional literal to use if an implementation for this function is not available.

accept

public Object accept(ExpressionVisitor visitor,
                     Object extraData)

Description copied from interface: Expression

Accepts a visitor. Subclasses must implement with a method whose content is the following:

return visitor.visit(this, extraData);

Specified by:

accept in interface Expression

toString

public String toString()

Creates a String representation of this Function with the function name and the arguments. The String created should be good for most subclasses

Overrides:

toString in class Object

getParameterValue

protected Object getParameterValue(Object object,
                                   int argumentIndex)

Evaluates a specific argument against the context, checking for required values and proper conversion.

getParameterValue

protected Object getParameterValue(Object object,
                                   int argumentIndex,
                                   Object defaultValue)

Evaluates a specific argument against the context, checking for required values and proper conversion. This version accepts a default value

dispatchArguments

protected LinkedHashMap<String,Object> dispatchArguments(Object obj)

Gathers up and groups the parameters to the function based on the declared parameters.

This method calls #validateArguments() which enforces java style argument conventions for multi valued parameters. Basically enforcing that only the last argument in a function can be variable.

functionName

protected static FunctionName functionName(String name,
                                           String ret,
                                           String... args)

Convenience method for creating a function name from a set of strings describing the return and argument parameters of the function.

The value of ret and each value of args is a string of the following structure:

  name[:type[:min,max]]
 

Where:

• name is the name of the parameter
• type is type (class name) of the parameter
• min is the minimum number of occurrences
• max is the maximum number of occurrences

Examples:

• foo
• foo:String
• foo:java.lang.Integer
• foo:Polygon:1,1
• foo:Polygon:1,
• foo:Polygon:,

The type parameter may be specified relative to the following well known packages:

• java.lang
• org.locationtech.jts.geom

Otherwise it must be specified as a full qualified class name.

Parameters:

name - The name of the function

ret - The parameter specification of the return of the function

args - The argument specifications of the function arguments

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object