| /* |
| * Copyright (c) 2001, 2003, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| package com.sun.corba.se.impl.orbutil ; |
| |
| import java.util.EmptyStackException ; |
| |
| // We implement a Stack here instead of using java.util.Stack because |
| // java.util.Stack is thread-safe, negatively impacting performance. |
| // We use an ArrayList instead since it is not thread-safe. |
| // RequestInfoStack is used quite frequently. |
| public class StackImpl { |
| // The stack for RequestInfo objects. |
| private Object[] data = new Object[3] ; |
| private int top = -1 ; |
| |
| // Tests if this stack is empty. |
| public final boolean empty() { |
| return top == -1; |
| } |
| |
| // Looks at the object at the top of this stack without removing it |
| // from the stack. |
| public final Object peek() { |
| if (empty()) |
| throw new EmptyStackException(); |
| |
| return data[ top ]; |
| } |
| |
| // Removes the object at the top of this stack and returns that |
| // object as the value of this function. |
| public final Object pop() { |
| Object obj = peek() ; |
| data[top] = null ; |
| top-- ; |
| return obj; |
| } |
| |
| private void ensure() |
| { |
| if (top == (data.length-1)) { |
| int newSize = 2*data.length ; |
| Object[] newData = new Object[ newSize ] ; |
| System.arraycopy( data, 0, newData, 0, data.length ) ; |
| data = newData ; |
| } |
| } |
| |
| // Pushes an item onto the top of the stack |
| public final Object push( Object item ) { |
| ensure() ; |
| top++ ; |
| data[top] = item; |
| return item; |
| } |
| } |