org.apache.commons.jexl
Interface Expression

All Known Implementing Classes:

ExpressionImpl

public interface Expression

Represents a single JEXL expression. This simple interface provides access to the underlying expression through getExpression(), and it provides hooks to add a pre- and post- expression resolver.

An expression is different than a script - it is simply a reference of an expression.

Since:

1.0

Version:

$Id: Expression.java 397092 2006-04-26 05:11:28Z dion $

Author:

Geir Magnusson Jr.

Method Summary

void	addPostResolver(JexlExprResolver resolver) Allows addition of a resolver to allow custom interdiction of expression evaluation.
void	addPreResolver(JexlExprResolver resolver) Allows addition of a resolver to allow custom interdiction of expression evaluation.
java.lang.Object	evaluate(JexlContext context) Evaluates the expression with the variables contained in the supplied JexlContext.
java.lang.String	getExpression() Returns the JEXL expression this Expression was created with.

Method Detail

evaluate

java.lang.Object evaluate(JexlContext context)
                          throws java.lang.Exception

Evaluates the expression with the variables contained in the supplied JexlContext.

Parameters:

context - A JexlContext containing variables.

Returns:

The result of this evaluation

Throws:

java.lang.Exception - on any error

getExpression

java.lang.String getExpression()

Returns the JEXL expression this Expression was created with.

Returns:

The JEXL expression to be evaluated

addPreResolver

void addPreResolver(JexlExprResolver resolver)

Allows addition of a resolver to allow custom interdiction of expression evaluation.

Parameters:

resolver - resolver to be called before Jexl expression evaluated

addPostResolver

void addPostResolver(JexlExprResolver resolver)

Allows addition of a resolver to allow custom interdiction of expression evaluation.

Parameters:

resolver - resolver to be called if Jexl expression evaluated to null.