org.opengis.filter.expression
Interface Function

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All Superinterfaces:

Expression

@XmlElement(value="Function")
public interface Function
extends Expression

Instances of this class represent a function call into some implementation-specific function.

Each execution environment should provide a list of supported functions (and the number of arguments they expect) as part of a FilterCapabilities data structure.

This is included for completeness with respect to the OGC Filter specification. However, no functions are required to be supported by that specification.

Since:

GeoAPI 2.0

Field Summary

Fields inherited from interface Expression

NIL

Method Summary

Literal	getFallbackValue() The value of the fallbackValue attribute is used as a default value, if the SE implementation does not support the function.
String	getName() Returns the name of the function to be called.
List<Expression>	getParameters() Returns the list subexpressions that will be evaluated to provide the parameters to the function.

Methods inherited from interface Expression

accept, evaluate, evaluate

Method Detail

getName

String getName()

Returns the name of the function to be called. For example, this might be "cos" or "atan2".

You can use this name to look up the number of required parameters in a FilterCapabilities data structure. For the specific meaning of the required parameters you will need to consult the documentation.

getParameters

List<Expression> getParameters()

Returns the list subexpressions that will be evaluated to provide the parameters to the function.

getFallbackValue

@XmlElement(value="fallbackValue")
Literal getFallbackValue()

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.

Returns:

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

Since:

GeoAPI 2.2