public class RecodeFunction extends Object implements Function
The Recode function provides a lookup table facility (think HashTable) where both keys and
values can be any Expression. The first parameter to the function specifies the source of
the value to lookup, e.g. the name of a feature property as a Literal. The remaining
parameters define the lookup table as key:value pairs. Thus there should be an odd number of
parameters in total: the lookup value parameter plus the set of key value pairs.
Where the lookup involves String values, comparisons are done case-insensitively.
If the lookup value does not match any of the keys defined this function returns null.
| Modifier and Type | Field and Description |
|---|---|
static FunctionName |
NAME
Make the instance of FunctionName available in a consistent spot.
|
NIL| Constructor and Description |
|---|
RecodeFunction() |
RecodeFunction(List<Expression> parameters,
Literal fallback) |
| 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.
|
String |
toString()
Creates a String representation of this Function with the function name and the arguments.
|
public static final FunctionName NAME
public RecodeFunction()
public RecodeFunction(List<Expression> parameters, Literal fallback)
public String getName()
Functioncos" 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.
public FunctionName getFunctionName()
FunctiongetFunctionName in interface Functionpublic List<Expression> getParameters()
FunctiongetParameters in interface Functionpublic Object accept(ExpressionVisitor visitor, Object extraData)
Expressionreturn visitor.visit(this, extraData);
accept in interface Expressionpublic Object evaluate(Object object)
Expressionevaluate in interface Expressionpublic <T> T evaluate(Object object, Class<T> context)
ExpressionThe 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.
evaluate in interface ExpressionT - The type of the returned object.object - The object to evaluate the expression against.context - The type of the resulting value of the expression.context.public Literal getFallbackValue()
FunctiongetFallbackValue in interface FunctionCopyright © 1996–2018 Geotools. All rights reserved.