/interpreter/tags/at2-build060407/src/edu/vub/util/regexp/CharIndexed.java
Java | 96 lines | 9 code | 7 blank | 80 comment | 0 complexity | 1c3f9b4ae17a36950780dd2863fe242a MD5 | raw file
1/* gnu/regexp/CharIndexed.java 2 Copyright (C) 1998-2001, 2004, 2006 Free Software Foundation, Inc. 3 4This file is part of GNU Classpath. 5 6GNU Classpath is free software; you can redistribute it and/or modify 7it under the terms of the GNU General Public License as published by 8the Free Software Foundation; either version 2, or (at your option) 9any later version. 10 11GNU Classpath is distributed in the hope that it will be useful, but 12WITHOUT ANY WARRANTY; without even the implied warranty of 13MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14General Public License for more details. 15 16You should have received a copy of the GNU General Public License 17along with GNU Classpath; see the file COPYING. If not, write to the 18Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 1902110-1301 USA. 20 21Linking this library statically or dynamically with other modules is 22making a combined work based on this library. Thus, the terms and 23conditions of the GNU General Public License cover the whole 24combination. 25 26As a special exception, the copyright holders of this library give you 27permission to link this library with independent modules to produce an 28executable, regardless of the license terms of these independent 29modules, and to copy and distribute the resulting executable under 30terms of your choice, provided that you also meet, for each linked 31independent module, the terms and conditions of the license of that 32module. An independent module is a module which is not derived from 33or based on this library. If you modify this library, you may extend 34this exception to your version of the library, but you are not 35obligated to do so. If you do not wish to do so, delete this 36exception statement from your version. */ 37 38package edu.vub.util.regexp; 39 40/** 41 * Defines the interface used internally so that different types of source 42 * text can be accessed in the same way. Built-in concrete classes provide 43 * support for String, StringBuffer, InputStream and char[] types. 44 * A class that is CharIndexed supports the notion of a cursor within a 45 * block of text. The cursor must be able to be advanced via the move() 46 * method. The charAt() method returns the character at the cursor position 47 * plus a given offset. 48 * 49 * @author <A HREF="mailto:wes@cacas.org">Wes Biggs</A> 50 */ 51public interface CharIndexed { 52 /** 53 * Defines a constant (0xFFFF was somewhat arbitrarily chosen) 54 * that can be returned by the charAt() function indicating that 55 * the specified index is out of range. 56 */ 57 char OUT_OF_BOUNDS = '\uFFFF'; 58 59 /** 60 * Returns the character at the given offset past the current cursor 61 * position in the input. The index of the current position is zero. 62 * It is possible for this method to be called with a negative index. 63 * This happens when using the '^' operator in multiline matching mode 64 * or the '\b' or '\<' word boundary operators. In any case, the lower 65 * bound is currently fixed at -2 (for '^' with a two-character newline). 66 * 67 * @param index the offset position in the character field to examine 68 * @return the character at the specified index, or the OUT_OF_BOUNDS 69 * character defined by this interface. 70 */ 71 char charAt(int index); 72 73 /** 74 * Shifts the input buffer by a given number of positions. Returns 75 * true if the new cursor position is valid. 76 */ 77 boolean move(int index); 78 79 /** 80 * Returns true if the most recent move() operation placed the cursor 81 * position at a valid position in the input. 82 */ 83 boolean isValid(); 84 85 /** 86 * Returns another CharIndexed containing length characters to the left 87 * of the given index. The given length is an expected maximum and 88 * the returned CharIndexed may not necessarily contain so many characters. 89 */ 90 CharIndexed lookBehind(int index, int length); 91 92 /** 93 * Returns the effective length of this CharIndexed 94 */ 95 int length(); 96}