Class VocabFunction
- Object
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- VocabFunction
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- All Implemented Interfaces:
Expression
,Function
public class VocabFunction extends Object implements Function
Vocabulary translation; using an external lookup table.This is similar to a Recode function from the Symbology Enoding 1.1 specifcation with the difference that the lookup table is named by a URI. This URI can be handled internally as an optimization; or it can be resolved to an external URL which is dragged down (as a property file) and cached.
This function expects:
- Expression: often a property name expression
- Literal: URI defining the lookup table to use
- Author:
- Jody Garnett (GeoServer)
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Field Summary
Fields Modifier and Type Field Description static FunctionName
NAME
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Fields inherited from interface Expression
NIL
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Constructor Summary
Constructors Constructor Description VocabFunction()
VocabFunction(List<Expression> parameters, Literal fallback)
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method 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.static Properties
lookup(String urn)
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Field Detail
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NAME
public static final FunctionName NAME
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Constructor Detail
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VocabFunction
public VocabFunction()
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VocabFunction
public VocabFunction(List<Expression> parameters, Literal fallback)
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Method Detail
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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.
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getFunctionName
public FunctionName getFunctionName()
Description copied from interface:Function
Access to the FunctionName description as used in a FilterCapabilities document.- Specified by:
getFunctionName
in interfaceFunction
- Returns:
- FunctionName description, if available.
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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 interfaceFunction
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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 interfaceExpression
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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 interfaceExpression
- Returns:
- computed value
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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 ofcontext
. Therefore to be safe calling code should do a null check on the return value of this method, and callExpression.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 returnnull
.- Specified by:
evaluate
in interfaceExpression
- 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
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lookup
public static Properties lookup(String urn)
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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 interfaceFunction
- Returns:
- Optional literal to use if an implementation for this function is not available.
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