Package org.geotools.appschema.filter.expression

Class ToLineStringFunction

  • All Implemented Interfaces:
    Expression, Function
    public class ToLineStringFunction
extends Object
implements Function
    This function converts double values to 1D LineString geometry object. This is needed when the data store doesn't have geometry type columns (or they want to use custom CRS). If custom SRS name is used, a 1D CRS will be created. This function expects:
    1. Expression: SRS name (could be custom SRS name)
    2. Expression: name of column pointing to first double value
    3. Expression: name of column pointing to second double value
    Author:
    Rini Angreani (CSIRO Earth Science and Resource Engineering)

    • Method Summary

      All 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.

      • Methods inherited from class Object

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

    • Constructor Detail

      • ToLineStringFunction

        public ToLineStringFunction()

      • ToLineStringFunction

        public ToLineStringFunction​(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

      • 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

      • 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
        Returns:
        computed value

      • 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.