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}