org.apache.commons.jelly.expression
Interface Expression

All Known Implementing Classes:
ExpressionSupport

public interface Expression

Expression represents an arbitrary expression using some pluggable expression language.

Version:
$Revision: 155420 $
Author:
James Strachan

Method Summary
 java.lang.Object evaluate(JellyContext context)
          Evaluates the expression with the given context and returns the result
 boolean evaluateAsBoolean(JellyContext context)
          Evaluates the expression with the given context coercing the result to be a boolean.
 java.util.Iterator evaluateAsIterator(JellyContext context)
          Evaluates the expression with the given context coercing the result to be an Iterator.
 java.lang.String evaluateAsString(JellyContext context)
          Evaluates the expression with the given context coercing the result to be a String.
 java.lang.Object evaluateRecurse(JellyContext context)
          This method evaluates the expression until a value (a non-Expression) object is returned.
 java.lang.String getExpressionText()
           
 

Method Detail

getExpressionText

public java.lang.String getExpressionText()
Returns:
the textual representation of this expression

evaluate

public java.lang.Object evaluate(JellyContext context)
Evaluates the expression with the given context and returns the result


evaluateAsString

public java.lang.String evaluateAsString(JellyContext context)
Evaluates the expression with the given context coercing the result to be a String.


evaluateAsBoolean

public boolean evaluateAsBoolean(JellyContext context)
Evaluates the expression with the given context coercing the result to be a boolean.


evaluateAsIterator

public java.util.Iterator evaluateAsIterator(JellyContext context)
Evaluates the expression with the given context coercing the result to be an Iterator.


evaluateRecurse

public java.lang.Object evaluateRecurse(JellyContext context)
This method evaluates the expression until a value (a non-Expression) object is returned. If the expression returns another expression, then the nested expression is evaluated.

Sometimes when Jelly is used inside Maven the value of an expression can actually be another expression. For example if a properties file is read, the values of variables can actually be expressions themselves.

e.g. ${foo.bar} can lookup "foo.bar" in a Maven context which could actually be another expression.

So using this method, nested expressions can be evaluated to the actual underlying value object.



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