org.geotools.filter.function

Class StringTemplateFunction

Object

StringTemplateFunction

All Implemented Interfaces:

Expression, Function

public class StringTemplateFunction
extends Object
implements Function

StringTemplate function, applies a regular expression with capturing groups, and them uses the groups to build a new string based on the provided template.

This function expects four expressions in input, the first three of which are mandatory.

1. The string to be matched
2. A regular expression, possibly using capturing groups
3. A template using ${0} for the fully matched string, ${n} for the n-th matching group
4. An optional value returned if the regular expresion does not match the input string

Here are some examples using CQL as the expression language:

1. stringTemplate('2002-03-01T13:00:00Z', '\d{4}-\d{2}-\d{2}T(\d{2}):\d{2}:\d{2}', '${1}') will result in 13 (the only matching group returns the hour of the timestamp)
2. stringTemplate('abcd', '\d{4}-\d{2}-\d{2}T(\d{2}):\d{2}:\d{2}', '${1}') will return null (no match)
3. stringTemplate('abcd', '\d{4}-\d{2}-\d{2}T(\d{2}):\d{2}:\d{2}', '${1}', 'default') will return default (no match, but there is a default value

Field Summary

Fields

Modifier and Type	Field and Description
static FunctionName	NAME Make the instance of FunctionName available in a consistent spot.

Fields inherited from interface Expression

NIL

Constructor Summary

Constructors

Constructor and Description
StringTemplateFunction()
StringTemplateFunction(List<Expression> parameters, Literal fallback)

Method Summary

Modifier and Type	Method and Description
Object	accept(ExpressionVisitor visitor, Object extraData) Accepts a visitor.
Object	evaluate(Object object) Evaluates the given expression based on the content of the given object.
<T> T	evaluate(Object object, Class<T> context) Evaluates the given expressoin based on the content of the given object and the context type.
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() 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 class Object

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

Field Detail

NAME

public static final FunctionName NAME

Make the instance of FunctionName available in a consistent spot.

Constructor Detail

StringTemplateFunction

public StringTemplateFunction()

StringTemplateFunction

public StringTemplateFunction(List<Expression> parameters,
                              Literal fallback)

Method Detail

getName

public String getName()

Description copied from interface: Function

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.

Specified by:

getName in interface 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.

getParameters

public List<Expression> getParameters()

Description copied from interface: Function

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

Specified by:

getParameters in interface Function

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

evaluate

public Object evaluate(Object object)

Description copied from interface: Expression

Evaluates the given expression based on the content of the given object.

Specified by:

evaluate in interface Expression

evaluate

public <T> T evaluate(Object object,
                      Class<T> context)

Description copied from interface: Expression

Evaluates the given expressoin based on the content of the given object and the context type.

The context parameter is used to control the type of the result of the expression. A particular expression may not be able to evaluate to an instance of context. Therefore to be safe calling code should do a null check on the return value of this method, and call Expression.evaluate(Object) if neccessary. Example:

  Object input = ...;
  String result = expression.evaluate( input, String.class );
  if ( result == null ) {
     result = expression.evalute( input ).toString();
  }
  ...
 

Implementations that can not return a result as an instance of context should return null.

Specified by:

evaluate in interface Expression

Type Parameters:

T - The type of the returned object.

Parameters:

object - The object to evaluate the expression against.

context - The type of the resulting value of the expression.

Returns:

Evaluates the given expression based on the content of the given object an an instance of context.

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.