Package org.apache.sis.filter

Class LeafExpression.Literal<R,V>

java.lang.Object

org.apache.sis.internal.filter.Node

org.apache.sis.filter.LeafExpression<R,V>

org.apache.sis.filter.LeafExpression.Literal<R,V>

Type Parameters:

R - the type of resources used as inputs.

V - the type of value computed by the expression.

All Implemented Interfaces:

Serializable, Function<R,V>, Expression<R,V>, FeatureExpression<R,V>, Literal<R,V>

Direct Known Subclasses:

LeafExpression.Transformed

Enclosing class:

LeafExpression<R,V>

static class LeafExpression.Literal<R,V>
extends LeafExpression<R,V>
implements Literal<R,V>

A constant, literal value that can be used in expressions. The apply(Object) method ignores the argument and always returns getValue().

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.sis.filter.LeafExpression

LeafExpression.Literal<R,V>, LeafExpression.Transformed<R,V>

Field Summary

Fields

Modifier and Type	Field	Description
private static final long	serialVersionUID	For cross-version compatibility.
private static final WeakValueHashMap<Class<?>,DefaultAttributeType<?>>	TYPES	A cache of DefaultAttributeType instances for literal classes.
protected final V	value	The constant value to be returned by getValue().

Constructor Summary

Constructors

Constructor	Description
Literal(V value)	Creates a new literal holding the given constant value.

Method Summary

Modifier and Type	Method	Description
V	apply(Object ignored)	Expression evaluation, which just returns the constant value.
PropertyTypeBuilder	expectedType(DefaultFeatureType ignored, FeatureTypeBuilder addTo)	Provides the type of values returned by apply(Object) wrapped in an DefaultAttributeType named "Literal".
protected Collection<?>	getChildren()	For Node.toString(), Node.hashCode() and Node.equals(Object) implementations.
V	getValue()	Returns the constant value held by this object.
Class<?>	getValueClass()	Returns the type of values computed by this expression.
private static <R> DefaultAttributeType<R>	newType(Class<R> standardType)	Invoked when a new attribute type need to be created for the given standard type.
<N> Expression<R,N>	toValueType(Class<N> target)	Returns an expression that provides values as instances of the specified class.

Methods inherited from class org.apache.sis.filter.LeafExpression

getParameters

Methods inherited from class org.apache.sis.internal.filter.Node

createName, createType, equals, getGeometryLibrary, hashCode, symbol, toGeometryWrapper, toString, unwrap, warning

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.util.function.Function

andThen, compose

Methods inherited from interface org.apache.sis.internal.geoapi.filter.Literal

getFunctionName, getParameters

Field Details

serialVersionUID

private static final long serialVersionUID

For cross-version compatibility.

See Also:

• Constant Field Values

value

protected final V value

The constant value to be returned by getValue().

TYPES

private static final WeakValueHashMap<Class<?>,DefaultAttributeType<?>> TYPES

A cache of DefaultAttributeType instances for literal classes. Used for avoiding to create duplicated instances when the literal is a common type like String or Integer.

Constructor Details

Literal

Literal(V value)

Creates a new literal holding the given constant value.

Method Details

getChildren

protected Collection<?> getChildren()

For Node.toString(), Node.hashCode() and Node.equals(Object) implementations.

Specified by:

getChildren in class Node

Returns:

the children of this node, or an empty collection if none.

getValue

public V getValue()

Returns the constant value held by this object.

Specified by:

getValue in interface Literal<R,V>

getValueClass

public Class<?> getValueClass()

Returns the type of values computed by this expression.

Specified by:

getValueClass in interface FeatureExpression<R,V>

Returns:

the type of values computed by this expression.

apply

public V apply(Object ignored)

Expression evaluation, which just returns the constant value.

Specified by:

apply in interface Expression<R,V>

Specified by:

apply in interface Function<R,V>

Parameters:

ignored - the object to be evaluated by the expression. Can be null if this expression allows null values.

Returns:

value computed by the expression.

toValueType

public <N> Expression<R,N> toValueType(Class<N> target)

Returns an expression that provides values as instances of the specified class.

Specified by:

toValueType in interface Expression<R,V>

Type Parameters:

N - compile-time value of type.

Parameters:

target - desired type of expression results.

Returns:

expression doing the same operation this this expression but with results of the specified type.

Throws:

ClassCastException - if values cannot be provided as instances of the specified class.

expectedType

public PropertyTypeBuilder expectedType(DefaultFeatureType ignored,
 FeatureTypeBuilder addTo)

Provides the type of values returned by apply(Object) wrapped in an DefaultAttributeType named "Literal".

Specified by:

expectedType in interface FeatureExpression<R,V>

Parameters:

addTo - where to add the type of properties evaluated by the given expression.

ignored - the type of features to be evaluated by the given expression.

Returns:

builder of the added property.

newType

private static <R> DefaultAttributeType<R> newType(Class<R> standardType)

Invoked when a new attribute type need to be created for the given standard type. The given standard type should be a GeoAPI interface, not the implementation class.