org.geotools.filter
Class LiteralExpressionImpl

java.lang.Object
  org.geotools.filter.expression.ExpressionAbstract
      org.geotools.filter.DefaultExpression
          org.geotools.filter.LiteralExpressionImpl

All Implemented Interfaces:

org.opengis.filter.expression.Expression, Expression, ExpressionType, org.opengis.filter.expression.Literal, LiteralExpression

Direct Known Subclasses:

BBoxExpressionImpl

public class LiteralExpressionImpl

extends DefaultExpression

implements LiteralExpression

Defines an expression that holds a literal for return.

Version:

$Id: LiteralExpressionImpl.java 18021 2006-02-14 20:36:18Z jdeolive $

Author:

Rob Hranac, Vision for New York

Field Summary

Fields inherited from class org.geotools.filter.DefaultExpression

expressionType, permissiveConstruction

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

Constructor Summary

protected	LiteralExpressionImpl() Constructor with literal.
protected	LiteralExpressionImpl(double value) Constructor with literal.
protected	LiteralExpressionImpl(int value) Constructor with literal.
protected	LiteralExpressionImpl(java.lang.Object literal) Constructor with literal.
protected	LiteralExpressionImpl(java.lang.String value) Constructor with literal.

Method Summary

java.lang.Object	accept(org.opengis.filter.expression.ExpressionVisitor visitor, java.lang.Object extraData) Used by FilterVisitors to perform some action on this filter instance.
boolean	equals(java.lang.Object obj) Compares this filter to the specified object.
java.lang.Object	evaluate(Feature feature) Gets the value of this literal.
java.lang.Object	getLiteral() Deprecated. use getValue().
short	getType() Returns the literal type.
java.lang.Object	getValue() Retrieves the literal of this expression.
int	hashCode() Override of hashCode method.
void	setLiteral(java.lang.Object literal) Deprecated. use setValue(Object).
void	setValue(java.lang.Object literal) Sets the literal.
java.lang.String	toString() Return this filter as a string.

Methods inherited from class org.geotools.filter.DefaultExpression

accept, evaluate, getValue, isAttributeExpression, isExpression, isGeometryExpression, isLiteralExpression, isMathExpression, isMathExpression

Methods inherited from class org.geotools.filter.expression.ExpressionAbstract

eval

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.geotools.filter.expression.LiteralExpression

getValue

Methods inherited from interface org.geotools.filter.expression.Expression

accept

Methods inherited from interface org.opengis.filter.expression.Expression

evaluate

Constructor Detail

LiteralExpressionImpl

protected LiteralExpressionImpl()

Constructor with literal.

LiteralExpressionImpl

protected LiteralExpressionImpl(java.lang.Object literal)
                         throws IllegalFilterException

Constructor with literal.

Parameters:

literal - The literal to store inside this expression.

Throws:

IllegalFilterException - This literal type is not in scope.

LiteralExpressionImpl

protected LiteralExpressionImpl(int value)

Constructor with literal. This alternative constructor is a convinience one for integers an Integer object will be constructed, and no IllegalFilterException can ever be thrown.

Parameters:

value - The integer to store inside this expression.

LiteralExpressionImpl

protected LiteralExpressionImpl(double value)

Constructor with literal. This alternative constructor is a convinience one for doubles an Double object will be constructed, and no IllegalFilterException can ever be thrown.

Parameters:

value - The double to store inside this expression.

LiteralExpressionImpl

protected LiteralExpressionImpl(java.lang.String value)

Constructor with literal. This alternative constructor is a convinience one for doubles an Double object will be constructed, and no IllegalFilterException can ever be thrown.

Parameters:

value - The double to store inside this expression.

Method Detail

getType

public short getType()

Returns the literal type.

Specified by:

getType in interface LiteralExpression

Overrides:

getType in class DefaultExpression

Returns:

the short representation of the expression type.

setLiteral

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

Deprecated. use setValue(Object).

This method calls setValue(Object).

Specified by:

setLiteral in interface LiteralExpression

Parameters:

literal - The literal to store inside this expression.

Throws:

IllegalFilterException - This literal type is not in scope.

getLiteral

public final java.lang.Object getLiteral()

Deprecated. use getValue().

This method calls getValue().

Specified by:

getLiteral in interface LiteralExpression

Returns:

the literal held by this expression.

getValue

public java.lang.Object getValue()

Retrieves the literal of this expression.

Specified by:

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

Returns:

the literal held by this expression.

setValue

public final void setValue(java.lang.Object literal)

Sets the literal.

Specified by:

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

Parameters:

literal - The literal to store inside this expression.

Throws:

IllegalFilterException - This literal type is not in scope.

evaluate

public java.lang.Object evaluate(Feature feature)
                          throws java.lang.IllegalArgumentException

Gets the value of this literal.

Specified by:

evaluate in interface Expression

Overrides:

evaluate in class DefaultExpression

Parameters:

feature - Required by the interface but not used.

Returns:

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

Throws:

java.lang.IllegalArgumentException - Feature does not match declared schema.

toString

public java.lang.String toString()

Return this filter as a string.

Returns:

String representation of this geometry filter.

equals

public boolean equals(java.lang.Object obj)

Compares this filter to the specified object. Returns true if the passed in object is the same as this expression. Checks to make sure the expression types are the same as well as the literals.

Parameters:

obj - - the object to compare this ExpressionLiteral against.

Returns:

true if specified object is equal to this expression; false otherwise.

Task:

REVISIT: missmatched types now considered not equal. This may be a problem when comparing Doubles and Integers

hashCode

public int hashCode()

Override of hashCode method.

Returns:

the hash code for this literal expression

accept

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

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 org.opengis.filter.expression.Expression

Overrides:

accept in class ExpressionAbstract

Parameters:

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