    001/*
    002 * Licensed to the Apache Software Foundation (ASF) under one
    003 * or more contributor license agreements.  See the NOTICE file
    004 * distributed with this work for additional information
    005 * regarding copyright ownership.  The ASF licenses this file
    006 * to you under the Apache License, Version 2.0 (the
    007 * "License"); you may not use this file except in compliance
    008 * with the License.  You may obtain a copy of the License at
    009 *
    010 *   https://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing,
    013 * software distributed under the License is distributed on an
    014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    015 * KIND, either express or implied.  See the License for the
    016 * specific language governing permissions and limitations
    017 * under the License.
    018 */
    019package org.apache.bcel.util;
    020
    021import java.util.Stack;
    022
    023import org.apache.bcel.classfile.JavaClass;
    024
    025/**
    026 * Utility class implementing a (typesafe) stack of JavaClass objects.
    027 *
    028 * @see Stack
    029 */
    030public class ClassStack {
    031
    032    private final Stack<JavaClass> stack = new Stack<>();
    033
    034    /**
    035     * Constructs a new ClassStack.
    036     */
    037    public ClassStack() {
    038    }
    039
    040    /**
    041     * Checks if the stack is empty.
    042     *
    043     * @return true if the stack is empty.
    044     */
    045    public boolean empty() {
    046        return stack.empty();
    047    }
    048
    049    /**
    050     * Pops a JavaClass from the stack.
    051     *
    052     * @return the JavaClass from the top of the stack.
    053     */
    054    public JavaClass pop() {
    055        return stack.pop();
    056    }
    057
    058    /**
    059     * Pushes a JavaClass onto the stack.
    060     *
    061     * @param clazz the JavaClass to push.
    062     */
    063    public void push(final JavaClass clazz) {
    064        stack.push(clazz);
    065    }
    066
    067    /**
    068     * Gets the top JavaClass from the stack without removing it.
    069     *
    070     * @return the JavaClass at the top of the stack.
    071     */
    072    public JavaClass top() {
    073        return stack.peek();
    074    }
    075}