org.apache.jasper.runtime
Class ExpressionEvaluatorImpl

java.lang.Object
  extended by javax.servlet.jsp.el.ExpressionEvaluator
      extended by org.apache.jasper.runtime.ExpressionEvaluatorImpl

public class ExpressionEvaluatorImpl
extends ExpressionEvaluator

This is the implementation of ExpreesioEvaluator using implementation of JSP2.1.

Version:
$Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: tcfujii $
Author:
Kin-man Chung

Constructor Summary
ExpressionEvaluatorImpl(PageContext pageContext)
          Constructor
 
Method Summary
 Object evaluate(String expression, Class expectedType, VariableResolver vResolver, FunctionMapper fMapper)
          Evaluates an expression.
 Expression parseExpression(String expression, Class expectedType, FunctionMapper fMapper)
          Prepare an expression for later evaluation.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ExpressionEvaluatorImpl

public ExpressionEvaluatorImpl(PageContext pageContext)
Constructor

Method Detail

parseExpression

public Expression parseExpression(String expression,
                                  Class expectedType,
                                  FunctionMapper fMapper)
                           throws ELException
Description copied from class: ExpressionEvaluator
Prepare an expression for later evaluation. This method should perform syntactic validation of the expression; if in doing so it detects errors, it should raise an ELParseException.

Specified by:
parseExpression in class ExpressionEvaluator
Parameters:
expression - The expression to be evaluated.
expectedType - The expected type of the result of the evaluation
fMapper - A FunctionMapper to resolve functions found in the expression. It can be null, in which case no functions are supported for this invocation. The ExpressionEvaluator must not hold on to the FunctionMapper reference after returning from parseExpression(). The Expression object returned must invoke the same functions regardless of whether the mappings in the provided FunctionMapper instance change between calling ExpressionEvaluator.parseExpression() and Expression.evaluate().
Returns:
The Expression object encapsulating the arguments.
Throws:
ELException - Thrown if parsing errors were found.

evaluate

public Object evaluate(String expression,
                       Class expectedType,
                       VariableResolver vResolver,
                       FunctionMapper fMapper)
                throws ELException
Description copied from class: ExpressionEvaluator
Evaluates an expression. This method may perform some syntactic validation and, if so, it should raise an ELParseException error if it encounters syntactic errors. EL evaluation errors should cause an ELException to be raised.

Specified by:
evaluate in class ExpressionEvaluator
Parameters:
expression - The expression to be evaluated.
expectedType - The expected type of the result of the evaluation
vResolver - A VariableResolver instance that can be used at runtime to resolve the name of implicit objects into Objects.
fMapper - A FunctionMapper to resolve functions found in the expression. It can be null, in which case no functions are supported for this invocation.
Returns:
The result of the expression evaluation.
Throws:
ELException - Thrown if the expression evaluation failed.


Copyright © 2007 Mort Bay Consulting. All Rights Reserved.