net.christopherschultz.evaluator
Class ConstantExpression

java.lang.Object
  net.christopherschultz.evaluator.Expression
      net.christopherschultz.evaluator.ConstantExpression

Direct Known Subclasses:

IdentifierExpression

public class ConstantExpression
extends Expression

An Expression which represents a fixed value (a constant).

Version:

$Revision: 1.2 $ $Date: 2008-06-20 22:58:48 $

Author:

Chris Schultz

Constructor Summary

ConstantExpression(Object value)
Creates a new ConstantExpression with the given value.

Method Summary

void	acceptVisitor(ExpressionVisitor visitor) Accepts an ExpressionVisitor.
boolean	equals(Object o) Returns true if the specified object is equal to this one.
Object	evaluate(EvaluationContext ec) Evaluates this Expression by returning its constant value.
List	getSubExpressions() Returns a list containing a single element: this ConstantExpression.
Object	getValue() Gets the value of this constant Expression.
int	hashCode() Returns the hash code for this ConstantExpression.
String	toString() Returns a String representation of this Expression.

Methods inherited from class net.christopherschultz.evaluator.Expression

getParent, setParent

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstantExpression

public ConstantExpression(Object value)

Creates a new ConstantExpression with the given value.

Parameters:

value - The value of the new ConstantExpressions.

Throws:

IllegalArgumentException - If the value is null.

Method Detail

evaluate

public Object evaluate(EvaluationContext ec)
                throws EvaluationException

Evaluates this Expression by returning its constant value.

Specified by:

evaluate in class Expression

Parameters:

ec - The EvaluationContext in which this expression should be evaluated.

Returns:

The value of this constant Expression.

Throws:

EvaluationException - If there is an error evaluating this Expression.

getSubExpressions

public List getSubExpressions()

Returns a list containing a single element: this ConstantExpression.

Specified by:

getSubExpressions in class Expression

Returns:

An immutable list containing this ConstantExpression.

getValue

public Object getValue()

Gets the value of this constant Expression.

Returns:

The value of this constant Expression.

hashCode

public int hashCode()

Returns the hash code for this ConstantExpression. The hash code of the ConstantExpression is equal to the hash code of the value of this ConstantExpression.

Overrides:

hashCode in class Object

Returns:

The hash code for this ConstantExpression.

toString

public String toString()

Returns a String representation of this Expression.

Overrides:

toString in class Object

Returns:

A String representation of this Expression.

equals

public boolean equals(Object o)

Returns true if the specified object is equal to this one.

Overrides:

equals in class Object

Parameters:

o - The object to test for equality.

Returns:

true if the specified object is equal to this one, false otherwise.

acceptVisitor

public void acceptVisitor(ExpressionVisitor visitor)

Description copied from class: Expression

Accepts an ExpressionVisitor.

Specified by:

acceptVisitor in class Expression