astempty.java

java属性邦定的（JSR-295）的一个实现

/*
 * Copyright (C) 2007 Sun Microsystems, Inc. All rights reserved. Use is
 * subject to license terms.
 *
 *//* Generated By:JJTree: Do not edit this line. AstEmpty.java */

package org.jdesktop.el.impl.parser;

import java.util.Collection;
import java.util.Map;
import org.jdesktop.el.ELContext;

import org.jdesktop.el.ELException;

import org.jdesktop.el.impl.lang.EvaluationContext;

/**
 * @author Jacob Hookom [[e-mail]]
 * @version $Change: 181177 $$DateTime: 2001/06/26 08:45:09 $$Author: kchung $
 */
public final class AstEmpty extends SimpleNode {
    public AstEmpty(int id) {
        super(id);
    }

    public Class getType(EvaluationContext ctx)
            throws ELException {
        return Boolean.class;
    }

    public Object getValue(EvaluationContext ctx)
            throws ELException {
        Object obj = this.children[0].getValue(ctx);
        if (obj == ELContext.UNRESOLVABLE_RESULT) {
            return ELContext.UNRESOLVABLE_RESULT;
        } else if (obj == null) {
            return Boolean.TRUE;
        } else if (obj instanceof String) {
            return Boolean.valueOf(((String) obj).length() == 0);
        } else if (obj instanceof Object[]) {
            return Boolean.valueOf(((Object[]) obj).length == 0);
        } else if (obj instanceof Collection) {
            return Boolean.valueOf(((Collection) obj).isEmpty());
        } else if (obj instanceof Map) {
            return Boolean.valueOf(((Map) obj).isEmpty());
        }
        return Boolean.FALSE;
    }
}