PageRenderTime 73ms CodeModel.GetById 40ms app.highlight 10ms RepoModel.GetById 21ms app.codeStats 0ms

/jEdit/tags/jedit-4-0-pre3/gnu/regexp/CharIndexedInputStream.java

#
Java | 131 lines | 87 code | 18 blank | 26 comment | 32 complexity | 3f8476adc37a8bdbf2999fc0114fee3b MD5 | raw file
  1/*
  2 *  gnu/regexp/CharIndexedReader.java
  3 *  Copyright (C) 1998-2001 Wes Biggs
  4 *
  5 *  This library is free software; you can redistribute it and/or modify
  6 *  it under the terms of the GNU Lesser General Public License as published
  7 *  by the Free Software Foundation; either version 2.1 of the License, or
  8 *  (at your option) any later version.
  9 *
 10 *  This library is distributed in the hope that it will be useful,
 11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 *  GNU Lesser General Public License for more details.
 14 *
 15 *  You should have received a copy of the GNU Lesser General Public License
 16 *  along with this program; if not, write to the Free Software
 17 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 18 */
 19
 20package gnu.regexp;
 21import java.io.InputStream;
 22import java.io.BufferedInputStream;
 23import java.io.IOException;
 24
 25// TODO: move(x) shouldn't rely on calling next() x times
 26
 27class CharIndexedInputStream implements CharIndexed {
 28    private static final int BUFFER_INCREMENT = 1024;
 29    private static final int UNKNOWN = Integer.MAX_VALUE; // value for end
 30    
 31    private BufferedInputStream br;
 32
 33    // so that we don't try to reset() right away
 34    private int index = -1;
 35
 36    private int bufsize = BUFFER_INCREMENT;
 37
 38    private int end = UNKNOWN;
 39
 40    private char cached = OUT_OF_BOUNDS;
 41
 42    // Big enough for a \r\n pair
 43    // lookBehind[0] = most recent
 44    // lookBehind[1] = second most recent
 45    private char[] lookBehind = new char[] { OUT_OF_BOUNDS, OUT_OF_BOUNDS }; 
 46    
 47    CharIndexedInputStream(InputStream str, int index) {
 48	if (str instanceof BufferedInputStream) br = (BufferedInputStream) str;
 49	else br = new BufferedInputStream(str,BUFFER_INCREMENT);
 50	next();
 51	if (index > 0) move(index);
 52    }
 53    
 54    private boolean next() {
 55	if (end == 1) return false;
 56	end--; // closer to end
 57
 58	try {
 59	    if (index != -1) {
 60		br.reset();
 61	    }
 62	    int i = br.read();
 63	    br.mark(bufsize);
 64	    if (i == -1) {
 65		end = 1;
 66		cached = OUT_OF_BOUNDS;
 67		return false;
 68	    }
 69	    cached = (char) i;
 70	    index = 1;
 71	} catch (IOException e) { 
 72	    e.printStackTrace();
 73	    cached = OUT_OF_BOUNDS;
 74	    return false; 
 75	}
 76	return true;
 77    }
 78    
 79    public char charAt(int index) {
 80	if (index == 0) {
 81	    return cached;
 82	} else if (index >= end) {
 83	    return OUT_OF_BOUNDS;
 84	} else if (index == -1) {
 85	    return lookBehind[0];
 86	} else if (index == -2) {
 87	    return lookBehind[1];
 88	} else if (index < -2) {
 89	    return OUT_OF_BOUNDS;
 90	} else if (index >= bufsize) {
 91	    // Allocate more space in the buffer.
 92	    try {
 93		while (bufsize <= index) bufsize += BUFFER_INCREMENT;
 94		br.reset();
 95		br.mark(bufsize);
 96		br.skip(index-1);
 97	    } catch (IOException e) { }
 98	} else if (this.index != index) {
 99	    try {
100		br.reset();
101		br.skip(index-1);
102	    } catch (IOException e) { }
103	}
104	char ch = OUT_OF_BOUNDS;
105	
106	try {
107	    int i = br.read();
108	    this.index = index+1; // this.index is index of next pos relative to charAt(0)
109	    if (i == -1) {
110		// set flag that next should fail next time?
111		end = index;
112		return ch;
113	    }
114	    ch = (char) i;
115	} catch (IOException ie) { }
116	
117	return ch;
118    }
119    
120    public boolean move(int index) {
121	// move read position [index] clicks from 'charAt(0)'
122	boolean retval = true;
123	while (retval && (index-- > 0)) retval = next();
124	return retval;
125    }
126    
127    public boolean isValid() {
128	return (cached != OUT_OF_BOUNDS);
129    }
130}
131