source/modules/juce_core/streams/juce_SubregionStream.cpp

   1 /*
   2   ==============================================================================
   3
   4    This file is part of the JUCE library.
   5    Copyright (c) 2022 - Raw Material Software Limited
   6
   7    JUCE is an open source library subject to commercial or open-source
   8    licensing.
   9
  10    The code included in this file is provided under the terms of the ISC license
  11    http://www.isc.org/downloads/software-support-policy/isc-license. Permission
  12    To use, copy, modify, and/or distribute this software for any purpose with or
  13    without fee is hereby granted provided that the above copyright notice and
  14    this permission notice appear in all copies.
  15
  16    JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
  17    EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
  18    DISCLAIMED.
  19
  20   ==============================================================================
  21 */
  22
  23 namespace juce
  24 {
  25
  26 SubregionStream::SubregionStream (InputStream* sourceStream,
  27                                   int64 start, int64 length,
  28                                   bool deleteSourceWhenDestroyed)
  29   : source (sourceStream, deleteSourceWhenDestroyed),
  30     startPositionInSourceStream (start),
  31     lengthOfSourceStream (length)
  32 {
  33     SubregionStream::setPosition (0);
  34 }
  35
  36 SubregionStream::~SubregionStream()
  37 {
  38 }
  39
  40 int64 SubregionStream::getTotalLength()
  41 {
  42     auto srcLen = source->getTotalLength() - startPositionInSourceStream;
  43
  44     return lengthOfSourceStream >= 0 ? jmin (lengthOfSourceStream, srcLen)
  45                                      : srcLen;
  46 }
  47
  48 int64 SubregionStream::getPosition()
  49 {
  50     return source->getPosition() - startPositionInSourceStream;
  51 }
  52
  53 bool SubregionStream::setPosition (int64 newPosition)
  54 {
  55     return source->setPosition (jmax ((int64) 0, newPosition + startPositionInSourceStream));
  56 }
  57
  58 int SubregionStream::read (void* destBuffer, int maxBytesToRead)
  59 {
  60     jassert (destBuffer != nullptr && maxBytesToRead >= 0);
  61
  62     if (lengthOfSourceStream < 0)
  63         return source->read (destBuffer, maxBytesToRead);
  64
  65     maxBytesToRead = (int) jmin ((int64) maxBytesToRead, lengthOfSourceStream - getPosition());
  66
  67     if (maxBytesToRead <= 0)
  68         return 0;
  69
  70     return source->read (destBuffer, maxBytesToRead);
  71 }
  72
  73 bool SubregionStream::isExhausted()
  74 {
  75     if (lengthOfSourceStream >= 0 && getPosition() >= lengthOfSourceStream)
  76         return true;
  77
  78     return source->isExhausted();
  79 }
  80
  81
  82 //==============================================================================
  83 //==============================================================================
  84 #if JUCE_UNIT_TESTS
  85
  86 struct SubregionInputStreamTests   : public UnitTest
  87 {
  88     SubregionInputStreamTests()
  89         : UnitTest ("SubregionInputStream", UnitTestCategories::streams)
  90     {}
  91
  92     void runTest() override
  93     {
  94         const MemoryBlock data ("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz", 52);
  95         MemoryInputStream mi (data, true);
  96
  97         const int offset = getRandom().nextInt ((int) data.getSize());
  98         const size_t subregionSize = data.getSize() - (size_t) offset;
  99
 100         SubregionStream stream (&mi, offset, (int) subregionSize, false);
 101
 102         beginTest ("Read");
 103
 104         expectEquals (stream.getPosition(), (int64) 0);
 105         expectEquals (stream.getTotalLength(), (int64) subregionSize);
 106         expectEquals (stream.getNumBytesRemaining(), stream.getTotalLength());
 107         expect (! stream.isExhausted());
 108
 109         size_t numBytesRead = 0;
 110         MemoryBlock readBuffer (subregionSize);
 111
 112         while (numBytesRead < subregionSize)
 113         {
 114             numBytesRead += (size_t) stream.read (&readBuffer[numBytesRead], 3);
 115
 116             expectEquals (stream.getPosition(), (int64) numBytesRead);
 117             expectEquals (stream.getNumBytesRemaining(), (int64) (subregionSize - numBytesRead));
 118             expect (stream.isExhausted() == (numBytesRead == subregionSize));
 119         }
 120
 121         expectEquals (stream.getPosition(), (int64) subregionSize);
 122         expectEquals (stream.getNumBytesRemaining(), (int64) 0);
 123         expect (stream.isExhausted());
 124
 125         const MemoryBlock memoryBlockToCheck (data.begin() + (size_t) offset, data.getSize() - (size_t) offset);
 126         expect (readBuffer == memoryBlockToCheck);
 127
 128         beginTest ("Skip");
 129
 130         stream.setPosition (0);
 131         expectEquals (stream.getPosition(), (int64) 0);
 132         expectEquals (stream.getTotalLength(), (int64) subregionSize);
 133         expectEquals (stream.getNumBytesRemaining(), stream.getTotalLength());
 134         expect (! stream.isExhausted());
 135
 136         numBytesRead = 0;
 137         const int64 numBytesToSkip = 5;
 138
 139         while (numBytesRead < subregionSize)
 140         {
 141             stream.skipNextBytes (numBytesToSkip);
 142             numBytesRead += numBytesToSkip;
 143             numBytesRead = std::min (numBytesRead, subregionSize);
 144
 145             expectEquals (stream.getPosition(), (int64) numBytesRead);
 146             expectEquals (stream.getNumBytesRemaining(), (int64) (subregionSize - numBytesRead));
 147             expect (stream.isExhausted() == (numBytesRead == subregionSize));
 148         }
 149
 150         expectEquals (stream.getPosition(), (int64) subregionSize);
 151         expectEquals (stream.getNumBytesRemaining(), (int64) 0);
 152         expect (stream.isExhausted());
 153     }
 154 };
 155
 156 static SubregionInputStreamTests subregionInputStreamTests;
 157
 158 #endif
 159
 160 } // namespace juce