zkoss/zk

/* XelNode.java

    Purpose:
        
    Description:
        
    History:
        Sat Sep 17 15:47:54     2005, Created by tomyeh

Copyright (C) 2004 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.web.servlet.dsp.impl;

import java.io.IOException;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.zkoss.xel.Expression;
import org.zkoss.xel.XelException;

/**
 * Represents an expression.
 *
 * @author tomyeh
 * @since 3.0.0
 */
class XelNode extends Node {
    private static final Logger log = LoggerFactory.getLogger(XelNode.class);
    private final Expression _expr;

    XelNode(String expr, ParseContext ctx) throws XelException {
        _expr = ctx.getExpressionFactory().parseExpression(ctx, expr, String.class);
    }

    //-- super --//
    void interpret(InterpretContext ic) throws IOException {
        try {
            final String result = (String) _expr.evaluate(ic.xelc);
            if (result != null)
                ic.dc.getOut().write(result);
        } catch (XelException ex) {
            log.error("", ex); //Web server might 'eat'
            throw ex;
        }
    }

    void addChild(Node node) {
        throw new IllegalStateException("No child allowed");
    }

    public String toString() {
        return "EL[" + _expr + ']';
    }
}