TokenBuffer.java revision 608:7e06bf1dcb09 
1/*
2 * Copyright (c) 1999, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25/*
26 * COMPONENT_NAME: idl.parser
27 *
28 * ORIGINS: 27
29 *
30 * Licensed Materials - Property of IBM
31 * 5639-D57 (C) COPYRIGHT International Business Machines Corp. 1997, 1999
32 * RMI-IIOP v1.0
33 *
34 */
35
36package com.sun.tools.corba.se.idl;
37
38// NOTES:
39
40class TokenBuffer
41{
42  private final int DEFAULT_SIZE = 10;
43
44  private int   _size      = 0;
45  private Token _buffer [] = null;
46  private int   _currPos   = -1;
47
48  TokenBuffer ()
49  {
50    _size    = DEFAULT_SIZE;
51    _buffer  = new Token [_size];
52    _currPos = -1;
53  } // ctor
54
55  TokenBuffer (int size) throws Exception
56  {
57    _size    = size;   // _size == 0 is legal, but useless and problematic
58    _buffer  = new Token [_size];
59    _currPos = -1;
60  } // ctor
61
62  /** Inserts a token at the head of the buffer. */
63  void insert (Token token)
64  {
65    // _size == 0 ==> ArithmeticException: divide by zero
66    _currPos = ++_currPos % _size;
67    _buffer [_currPos] = token;
68  }
69
70  /** Returns the token residing "i" elements from the head of the buffer. */
71  Token lookBack (int i)
72  {
73    // Beware: i > _size ==> idx < 0 ==> ArrayOutOfBoundsException
74    return _buffer [(_currPos - i) >= 0 ? _currPos - i : _currPos - i + _size];
75  }
76
77  /** Return the token most recently inserted into the buffer (i.e., the head of the buffer.) */
78  Token current ()
79  {
80    // Beware: _buffer empty || _size == 0 ==> ArrayOutOfBoundsException
81    return _buffer [_currPos];
82  }
83}   // class TokenBuffer
84
85
86/*==================================================================================
87  DATE<AUTHOR>   ACTION
88  ----------------------------------------------------------------------------------
89  11aug1997<daz> Initial version completed.  Buffer used to maintain history of
90                 comments extracted from source file during parse.
91  ==================================================================================*/
92