Package 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 Details

    • 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 Details

    • FunctionImpl

      public FunctionImpl()

  • Method Details

    • 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