Package org.apache.commons.jelly.expression

Interface Expression

All Known Implementing Classes:
CompositeExpression, ConstantExpression, EscapingExpression, ExpressionSupport, JexlExpression, XPathExpression
public interface Expression

Expression represents an arbitrary expression using some pluggable expression language.

Version:
$Revision: 155420 $
Author:
James Strachan

  • Field Details

    • NULL

      static final Expression NULL
      Singleton instance that represents the expression that evaluates to null.

  • Method Details

    • getExpressionText

      String getExpressionText()
      Returns:
      the textual representation of this expression

    • evaluate

      Object evaluate(JellyContext context)
      Evaluates the expression with the given context and returns the result

    • evaluateAsString

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

    • evaluateAsBoolean

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

    • evaluateAsIterator

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

    • evaluateRecurse

      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.