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annotate hg4j/src/main/java/org/tmatesoft/hg/internal/DataAccess.java @ 213:6ec4af642ba8 gradle

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Project uses Gradle for build - actual changes
author Alexander Kitaev <kitaev@gmail.com>
date Tue, 10 May 2011 10:52:53 +0200
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6ec4af642ba8 Project uses Gradle for build - actual changes
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1 /*
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2 * Copyright (c) 2010-2011 TMate Software Ltd
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3 *
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4 * This program is free software; you can redistribute it and/or modify
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5 * it under the terms of the GNU General Public License as published by
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6 * the Free Software Foundation; version 2 of the License.
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7 *
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8 * This program is distributed in the hope that it will be useful,
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9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
6ec4af642ba8 Project uses Gradle for build - actual changes
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11 * GNU General Public License for more details.
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12 *
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13 * For information on how to redistribute this software under
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14 * the terms of a license other than GNU General Public License
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15 * contact TMate Software at support@hg4j.com
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16 */
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17 package org.tmatesoft.hg.internal;
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18
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19 import java.io.IOException;
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20 import java.nio.ByteBuffer;
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21
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22 /**
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23 * relevant parts of DataInput, non-stream nature (seek operation), explicit check for end of data.
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24 * convenient skip (+/- bytes)
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25 * Primary goal - effective file read, so that clients don't need to care whether to call few
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26 * distinct getInt() or readBytes(totalForFewInts) and parse themselves instead in an attempt to optimize.
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27 *
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28 * @author Artem Tikhomirov
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29 * @author TMate Software Ltd.
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30 */
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31 public class DataAccess {
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32 public boolean isEmpty() {
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33 return true;
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34 }
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35 public int length() {
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36 return 0;
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37 }
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38 /**
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39 * get this instance into initial state
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40 * @throws IOException
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41 * @return <code>this</code> for convenience
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42 */
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43 public DataAccess reset() throws IOException {
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44 // nop, empty instance is always in the initial state
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45 return this;
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46 }
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47 // absolute positioning
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48 public void seek(int offset) throws IOException {
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49 throw new UnsupportedOperationException();
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50 }
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51 // relative positioning
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52 public void skip(int bytes) throws IOException {
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53 throw new UnsupportedOperationException();
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54 }
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55 // shall be called once this object no longer needed
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56 public void done() {
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57 // no-op in this empty implementation
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58 }
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59 public int readInt() throws IOException {
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60 byte[] b = new byte[4];
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61 readBytes(b, 0, 4);
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62 return b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
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63 }
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64 public long readLong() throws IOException {
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65 byte[] b = new byte[8];
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66 readBytes(b, 0, 8);
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67 int i1 = b[0] << 24 | (b[1] & 0xFF) << 16 | (b[2] & 0xFF) << 8 | (b[3] & 0xFF);
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68 int i2 = b[4] << 24 | (b[5] & 0xFF) << 16 | (b[6] & 0xFF) << 8 | (b[7] & 0xFF);
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69 return ((long) i1) << 32 | ((long) i2 & 0xFFFFFFFFl);
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70 }
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71 public void readBytes(byte[] buf, int offset, int length) throws IOException {
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72 throw new UnsupportedOperationException();
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73 }
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74 // reads bytes into ByteBuffer, up to its limit or total data length, whichever smaller
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75 // FIXME perhaps, in DataAccess paradigm (when we read known number of bytes, we shall pass specific byte count to read)
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76 public void readBytes(ByteBuffer buf) throws IOException {
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77 // int toRead = Math.min(buf.remaining(), (int) length());
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78 // if (buf.hasArray()) {
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79 // readBytes(buf.array(), buf.arrayOffset(), toRead);
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80 // } else {
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81 // byte[] bb = new byte[toRead];
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82 // readBytes(bb, 0, bb.length);
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83 // buf.put(bb);
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84 // }
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85 // FIXME optimize to read as much as possible at once
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86 while (!isEmpty() && buf.hasRemaining()) {
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87 buf.put(readByte());
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88 }
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89 }
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90 public byte readByte() throws IOException {
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91 throw new UnsupportedOperationException();
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92 }
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93
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94 // XXX decide whether may or may not change position in the DataAccess
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95 // FIXME exception handling is not right, just for the sake of quick test
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96 public byte[] byteArray() throws IOException {
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97 reset();
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98 byte[] rv = new byte[length()];
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99 readBytes(rv, 0, rv.length);
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100 return rv;
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101 }
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102 }