FunctionExpressionImpl (Geotools modules 27-SNAPSHOT API)

Object
- ExpressionAbstract
- - DefaultExpression
  - - FunctionExpressionImpl

All Implemented Interfaces:

FunctionExpression, Factory, Expression, Function

Direct Known Subclasses:

AndFunction, AreaFunction, ArrayFunction, AsMultiGeometryFunctionExpression, AtFunction, AttributeCountFunction, ClassifyFunction, Collection_AverageFunction, Collection_BoundsFunction, Collection_CountFunction, Collection_MaxFunction, Collection_MedianFunction, Collection_MinFunction, Collection_SumFunction, Collection_UniqueFunction, CollectionIdFunction, CollectionLinkFunction, DateDifferenceFunction, EnvFunction, FallbackFunction, FilterFunction_abs, FilterFunction_abs_2, FilterFunction_abs_3, FilterFunction_abs_4, FilterFunction_acos, FilterFunction_area, FilterFunction_asin, FilterFunction_atan, FilterFunction_atan2, FilterFunction_between, FilterFunction_boundary, FilterFunction_boundaryDimension, FilterFunction_buffer, FilterFunction_bufferWithSegments, FilterFunction_ceil, FilterFunction_centroid, FilterFunction_contains, FilterFunction_Convert, FilterFunction_convexHull, FilterFunction_cos, FilterFunction_crosses, FilterFunction_dateFormat, FilterFunction_dateParse, FilterFunction_difference, FilterFunction_dimension, FilterFunction_disjoint, FilterFunction_disjoint3D, FilterFunction_distance, FilterFunction_distance3D, FilterFunction_double2bool, FilterFunction_endAngle, FilterFunction_endPoint, FilterFunction_envelope, FilterFunction_equalsExact, FilterFunction_equalsExactTolerance, FilterFunction_equalTo, FilterFunction_exp, FilterFunction_exteriorRing, FilterFunction_floor, FilterFunction_geometryType, FilterFunction_geomFromWKT, FilterFunction_geomLength, FilterFunction_getGeometryN, FilterFunction_getX, FilterFunction_getY, FilterFunction_getZ, FilterFunction_greaterEqualThan, FilterFunction_greaterThan, FilterFunction_IEEEremainder, FilterFunction_if_then_else, FilterFunction_in10, FilterFunction_in2, FilterFunction_in3, FilterFunction_in4, FilterFunction_in5, FilterFunction_in6, FilterFunction_in7, FilterFunction_in8, FilterFunction_in9, FilterFunction_int2bbool, FilterFunction_int2ddouble, FilterFunction_interiorPoint, FilterFunction_interiorRingN, FilterFunction_intersection, FilterFunction_intersects, FilterFunction_intersects3D, FilterFunction_isClosed, FilterFunction_isCoverage, FilterFunction_isEmpty, FilterFunction_isLike, FilterFunction_isNull, FilterFunction_isometric, FilterFunction_isRing, FilterFunction_isSimple, FilterFunction_isValid, FilterFunction_isWithinDistance, FilterFunction_isWithinDistance3D, FilterFunction_lessEqualThan, FilterFunction_lessThan, FilterFunction_list, FilterFunction_listMultiply, FilterFunction_log, FilterFunction_max, FilterFunction_max_2, FilterFunction_max_3, FilterFunction_max_4, FilterFunction_min, FilterFunction_min_2, FilterFunction_min_3, FilterFunction_min_4, FilterFunction_minimumCircle, FilterFunction_minimumDiameter, FilterFunction_minimumRectangle, FilterFunction_not, FilterFunction_notEqualTo, FilterFunction_numberFormat, FilterFunction_numberFormat2, FilterFunction_numGeometries, FilterFunction_numInteriorRing, FilterFunction_numPoints, FilterFunction_octagonalEnvelope, FilterFunction_offset, FilterFunction_overlaps, FilterFunction_parseBoolean, FilterFunction_parseDouble, FilterFunction_parseInt, FilterFunction_parseLong, FilterFunction_pgNearest, FilterFunction_pointN, FilterFunction_pow, FilterFunction_property, FilterFunction_random, FilterFunction_relate, FilterFunction_relatePattern, FilterFunction_rint, FilterFunction_round, FilterFunction_round_2, FilterFunction_roundDouble, FilterFunction_sdonn, FilterFunction_setCRS, FilterFunction_sin, FilterFunction_sqrt, FilterFunction_startAngle, FilterFunction_startPoint, FilterFunction_strAbbreviate, FilterFunction_strCapitalize, FilterFunction_strConcat, FilterFunction_strDefaultIfBlank, FilterFunction_strEndsWith, FilterFunction_strEqualsIgnoreCase, FilterFunction_strIndexOf, FilterFunction_strLastIndexOf, FilterFunction_strLength, FilterFunction_strMatches, FilterFunction_strPosition, FilterFunction_strReplace, FilterFunction_strStartsWith, FilterFunction_strStripAccents, FilterFunction_strSubstring, FilterFunction_strSubstringStart, FilterFunction_strToLowerCase, FilterFunction_strToUpperCase, FilterFunction_strTrim, FilterFunction_strTrim2, FilterFunction_symDifference, FilterFunction_tan, FilterFunction_toDegrees, FilterFunction_toRadians, FilterFunction_touches, FilterFunction_toWKT, FilterFunction_union, FilterFunction_vertices, FilterFunction_within, GeometryFunction, GetFunction, HasFunction, IDFunction, IDFunctionExpression, InArrayFunction, InFunction, JsonPointerFunction, JsonSelectAllFunction, JsonSelectFunction, LapplyFunction, LengthFunction, ListSizeFunction, LitemFunction, LiterateFunction, MapBoxAnchorFunction, MapBoxLengthFunction, MapGetFunction, NestedCollectionLinkFunction, NowFunction, OrFunction, PaletteFunction, PiFunction, PropertyExistsFunction, RescaleToPixelsFunction, SizeFunction, ToRgb, URLEncodeFunction, ZoomLevelFunction
```
public abstract class FunctionExpressionImpl
extends DefaultExpression
implements FunctionExpression
```
Abstract class for a function expression implementation
By default this implementation returns the provided fallback value. To implement a function please override the evaluate(Object) method.

Author:

James Macgill, PSU

Field Summary

Fields
Modifier and Type	Field and Description
`protected Literal`	`fallback`
`protected FunctionName`	`functionName` FunctionName provided by subclass; or lazely created
`protected String`	`name` function name *
`protected List<Expression>`	`params` function params *

Fields inherited from interface Expression
NIL

Constructor Summary

Constructors
Modifier	Constructor and Description
`protected`	`FunctionExpressionImpl(FunctionName functionName)` Preferred constructor to ensure name and functionName match.
`protected`	`FunctionExpressionImpl(Name name)`
`protected`	`FunctionExpressionImpl(Name name, Literal fallback)` Creates a new instance of FunctionExpression
`protected`	`FunctionExpressionImpl(String name)`
`protected`	`FunctionExpressionImpl(String name, Literal fallback)` Creates a new instance of FunctionExpression

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`Object`	`accept(ExpressionVisitor visitor, Object extraData)` Accepts a visitor.
`boolean`	`equals(Object obj)`
`Object`	`evaluate(Object object)` Subclass should override, default implementation returns null.
`protected static FunctionName`	`functionName(String name, String ret, String... args)` Convenience method for creating a function name.
`protected Expression`	`getExpression(int index)` Utility method for subclasses to ask for an argument at a given index
`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.
`Map<RenderingHints.Key,?>`	`getImplementationHints()` Returns the implementation hints.
`String`	`getName()` Gets the name of this function.
`List<Expression>`	`getParameters()` Returns the function parameters.
`int`	`hashCode()`
`void`	`setFallbackValue(Literal fallback)` Fallback value to use in the event the function is unavailable in the requested environment.
`void`	`setParameters(List<Expression> params)` Sets the function parameters.
`String`	`toString()` Creates a String representation of this Function with the function name and the arguments.

Methods inherited from class DefaultExpression
isAttributeExpression, isExpression, isFunctionExpression, isGeometryExpression, isLiteralExpression, isMathExpression

Methods inherited from class ExpressionAbstract
evaluate

Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface Expression
evaluate

- Field Detail
  - name
```
protected String name
```
    function name *
  - params
```
protected List<Expression> params
```
    function params *
  - fallback
```
protected Literal fallback
```
  - functionName
```
protected FunctionName functionName
```
    FunctionName provided by subclass; or lazely created
- Constructor Detail
  - FunctionExpressionImpl
```
protected FunctionExpressionImpl(FunctionName functionName)
```
    Preferred constructor to ensure name and functionName match.
    Recommended use:
```
 import static org.geotools.filter.capability.FunctionNameImpl.*;
 public class AreaFunction extends FunctionExpressionImpl {

   public static FunctionName NAME = new FunctionNameImpl("Area",
        parameter("area",Double.class),
        parameter("geometry",Geometry.class));

 public AreaFunction() {
     super(NAME);
 }
 
```
    Parameters:
    
    functionName - FunctionName describing subclass
  - FunctionExpressionImpl
```
protected FunctionExpressionImpl(String name)
```
  - FunctionExpressionImpl
```
protected FunctionExpressionImpl(Name name)
```
  - FunctionExpressionImpl
```
protected FunctionExpressionImpl(String name,
                                 Literal fallback)
```
    Creates a new instance of FunctionExpression
  - FunctionExpressionImpl
```
protected FunctionExpressionImpl(Name name,
                                 Literal fallback)
```
    Creates a new instance of FunctionExpression
- Method Detail
  - 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.
  - 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.
  - setFallbackValue
```
public void setFallbackValue(Literal fallback)
```
    Description copied from interface: FunctionExpression
    
    Fallback value to use in the event the function is unavailable in the requested environment.
    The fallback value is not provided as one of the arguments, as it is an advanced option used in style layer descriptor documents to facilitate interoperability. It allows a user to specify an SQL function, and provide a value to use when the documented is used with a WFS that does not support the provided function.
    
    Specified by:
    
    setFallbackValue in interface FunctionExpression
  - getParameters
```
public List<Expression> getParameters()
```
    Returns the function parameters.
    
    Specified by:
    
    getParameters in interface Function
  - setParameters
```
public void setParameters(List<Expression> params)
```
    Sets the function parameters.
    
    Specified by:
    
    setParameters in interface FunctionExpression
  - 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
    
    See Also:
    
    Expression.accept(ExpressionVisitor, Object)
  - getImplementationHints
```
public Map<RenderingHints.Key,?> getImplementationHints()
```
    Returns the implementation hints. The default implementation returns an empty map.
    
    Specified by:
    
    getImplementationHints in interface Factory
    
    Returns:
    
    The map of hints, or an empty map if none.
  - functionName
```
protected static FunctionName functionName(String name,
                                           String ret,
                                           String... args)
```
    Convenience method for creating a function name.
    
    See Also:
    
    FunctionImpl.functionName(String, String, String...)
  - 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
  - getExpression
```
protected Expression getExpression(int index)
```
    Utility method for subclasses to ask for an argument at a given index
  - evaluate
```
public Object evaluate(Object object)
```
    Description copied from class: ExpressionAbstract
    
    Subclass should override, default implementation returns null.
    
    Specified by:
    
    evaluate in interface Expression
    
    Overrides:
    
    evaluate in class ExpressionAbstract
    
    Returns:
    
    default implementation returns null
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    
    equals in class Object

Class FunctionExpressionImpl

Field Summary

Fields inherited from interface Expression

Constructor Summary

Method Summary

Methods inherited from class DefaultExpression

Methods inherited from class ExpressionAbstract

Methods inherited from class Object

Methods inherited from interface Expression

Field Detail

name

params

fallback

functionName

Constructor Detail

FunctionExpressionImpl

FunctionExpressionImpl

FunctionExpressionImpl

FunctionExpressionImpl

FunctionExpressionImpl

Method Detail

getName

getFunctionName

getFallbackValue

setFallbackValue

getParameters

setParameters

accept

getImplementationHints

functionName

toString

getExpression

evaluate

hashCode

equals