org.geotools.filter.expression
Class ConstantExpression

java.lang.Object
  org.geotools.filter.expression.ConstantExpression

All Implemented Interfaces:

java.lang.Cloneable, org.opengis.filter.expression.Expression, Expression, ExpressionType, org.opengis.filter.expression.Literal, LiteralExpression

public class ConstantExpression

extends java.lang.Object

implements LiteralExpression, java.lang.Cloneable

The Expression class is not immutable!

However we do have a need for immutable literal expressions when defining our API for SLD, and any other standards based on Expression.

Author:

Jody Garnett, Refractions Research

Field Summary

static ConstantExpression	BLACK
static ConstantExpression	NULL
static ConstantExpression	ONE
static ConstantExpression	TWO
static ConstantExpression	UNNAMED
static ConstantExpression	ZERO

Fields inherited from interface org.geotools.filter.expression.ExpressionType

ATTRIBUTE, ATTRIBUTE_DOUBLE, ATTRIBUTE_GEOMETRY, ATTRIBUTE_INTEGER, ATTRIBUTE_STRING, ATTRIBUTE_UNDECLARED, FUNCTION, LITERAL_DOUBLE, LITERAL_GEOMETRY, LITERAL_INTEGER, LITERAL_STRING, MATH_ADD, MATH_DIVIDE, MATH_MULTIPLY, MATH_SUBTRACT

Method Summary

java.lang.Object	accept(org.opengis.filter.expression.ExpressionVisitor visitor, java.lang.Object extraData)
void	accept(FilterVisitor visitor) Used by FilterVisitors to perform some action on this filter instance.
protected java.lang.Object	clone()
static ConstantExpression	color(java.awt.Color color) Encode provided color as a String
static ConstantExpression	constant(double number)
static ConstantExpression	constant(int number)
static ConstantExpression	constant(java.lang.Object value)
boolean	equals(java.lang.Object obj)
java.lang.Object	evaluate(Feature feature) Evaluates the expression against an instance of Feature.
java.lang.Object	evaluate(java.lang.Object object)
java.lang.Object	getLiteral() Retrieves the literal of this expression.
short	getType() Returns the literal type.
java.lang.Object	getValue()
java.lang.Object	getValue(Feature feature) Gets the value of this literal.
int	hashCode()
void	setLiteral(java.lang.Object literal) Sets the literal.
void	setValue(java.lang.Object constant)
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

NULL

public static final ConstantExpression NULL

BLACK

public static final ConstantExpression BLACK

ZERO

public static final ConstantExpression ZERO

ONE

public static final ConstantExpression ONE

TWO

public static final ConstantExpression TWO

UNNAMED

public static final ConstantExpression UNNAMED

Method Detail

setLiteral

public final void setLiteral(java.lang.Object literal)
                      throws IllegalFilterException

Deprecated. use setValue(Object)

Description copied from interface: LiteralExpression

Sets the literal.

Specified by:

setLiteral in interface LiteralExpression

Parameters:

literal - The literal to store inside this expression.

Throws:

IllegalFilterException - This literal type is not in scope.

getValue

public final java.lang.Object getValue(Feature feature)

Deprecated. use evaluate(Feature)

Description copied from interface: LiteralExpression

Gets the value of this literal.

Specified by:

getValue in interface LiteralExpression

Parameters:

feature - Required by the interface but not used.

Returns:

the literal held by this expression. Ignores the passed in feature.

evaluate

public java.lang.Object evaluate(Feature feature)

Description copied from interface: Expression

Evaluates the expression against an instance of Feature.

Specified by:

evaluate in interface Expression

Parameters:

feature - The feature being evaluated.

Returns:

The result.

evaluate

public java.lang.Object evaluate(java.lang.Object object)

Specified by:

evaluate in interface org.opengis.filter.expression.Expression

getValue

public java.lang.Object getValue()

Specified by:

getValue in interface org.opengis.filter.expression.Literal

setValue

public void setValue(java.lang.Object constant)

Specified by:

setValue in interface org.opengis.filter.expression.Literal

getType

public short getType()

Description copied from interface: LiteralExpression

Returns the literal type.

Specified by:

getType in interface LiteralExpression

Returns:

the short representation of the literal expression type.

getLiteral

public final java.lang.Object getLiteral()

Deprecated. use getValue()

Description copied from interface: LiteralExpression

Retrieves the literal of this expression.

Specified by:

getLiteral in interface LiteralExpression

Returns:

the literal held by this expression.

accept

public void accept(FilterVisitor visitor)

Deprecated. use accept(ExpressionVisitor, Object).

Description copied from interface: Expression

Used by FilterVisitors to perform some action on this filter instance. Typicaly used by Filter decoders, but may also be used by any thing which needs infomration from filter structure. Implementations should always call: visitor.visit(this); It is importatant that this is not left to a parent class unless the parents API is identical.

Specified by:

accept in interface Expression

Parameters:

visitor - The visitor which requires access to this filter, the method must call visitor.visit(this);

accept

public java.lang.Object accept(org.opengis.filter.expression.ExpressionVisitor visitor,
                               java.lang.Object extraData)

Specified by:

accept in interface org.opengis.filter.expression.Expression

clone

protected java.lang.Object clone()
                          throws java.lang.CloneNotSupportedException

Throws:

java.lang.CloneNotSupportedException

equals

public boolean equals(java.lang.Object obj)

hashCode

public int hashCode()

toString

public java.lang.String toString()

color

public static ConstantExpression color(java.awt.Color color)

Encode provided color as a String

constant

public static ConstantExpression constant(double number)

constant

public static ConstantExpression constant(int number)

constant

public static ConstantExpression constant(java.lang.Object value)