/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.alibaba.citrus.generictype;
import java.lang.reflect.WildcardType;
/**
* 和{@link WildcardType}对应，代表一个通配符类型变量的信息。
*
* @author Michael Zhou
*/
public interface WildcardTypeInfo extends BoundedTypeInfo {
/**
* 判断wildcard是否为“unknown wildcard”。
* <p>
* Wildcard有两种：
* </p>
* <ol>
* <li>一种是“unknown wildcard”的，例如：<code>Collection<?></code>
* ，意思为：Collection of Unknown。换言之，“<code>?</code>”可以匹配任意类型。</li>
* <li>另一种是“bounded wildcard”，例如：
* <code>Collection<? extends Number></code>。</li>
* </ol>
* <p/>
* 对于unknown wildcard，尽管JDK提供的API，仍然返回其upper bound为<code>Object</code>
* ，然而其事实上的upper bound取决于对应的<code>TypeVariable</code>的upper bound。
*/
boolean isUnknown();
}