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comparison src/com/tmate/hgkit/fs/DataAccess.java @ 10:382cfe9463db

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Dirstate parsing. DataAccess refactored to allow reuse and control over constants
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Sat, 25 Dec 2010 21:50:12 +0100
parents
children 9429c7bd1920
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9:d6d2a630f4a6 10:382cfe9463db
1 /*
2 * Copyright (c) 2010 Artem Tikhomirov
3 */
4 package com.tmate.hgkit.fs;
5
6 import java.io.IOException;
7
8 /**
9 * relevant parts of DataInput, non-stream nature (seek operation), explicit check for end of data.
10 * convenient skip (+/- bytes)
11 * Primary goal - effective file read, so that clients don't need to care whether to call few
12 * distinct getInt() or readBytes(totalForFewInts) and parse themselves instead in an attempt to optimize.
13 */
14 public class DataAccess {
15 public boolean isEmpty() {
16 return true;
17 }
18 // absolute positioning
19 public void seek(long offset) throws IOException {
20 throw new UnsupportedOperationException();
21 }
22 // relative positioning
23 public void skip(int bytes) throws IOException {
24 throw new UnsupportedOperationException();
25 }
26 // shall be called once this object no longer needed
27 public void done() {
28 // no-op in this empty implementation
29 }
30 public int readInt() throws IOException {
31 byte[] b = new byte[4];
32 readBytes(b, 0, 4);
33 return b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
34 }
35 public long readLong() throws IOException {
36 byte[] b = new byte[8];
37 readBytes(b, 0, 8);
38 int i1 = b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
39 int i2 = b[4] << 24 | (b[5] & 0xFF) << 16 | (b[6] & 0xFF) << 8 | (b[7] & 0xFF);
40 return ((long) i1) << 32 | ((long) i2 & 0xFFFFFFFF);
41 }
42 public void readBytes(byte[] buf, int offset, int length) throws IOException {
43 throw new UnsupportedOperationException();
44 }
45 public byte readByte() throws IOException {
46 throw new UnsupportedOperationException();
47 }
48 }