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喻斌
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resolved #74 
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‎src/CatLib.Core.Tests/CatLib.Core.Tests.csproj‎

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<Compile Include="Support\Storage\MemoryStorageTests.cs" />
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<Compile Include="Support\Stream\CombineStreamTests.cs" />
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<Compile Include="Support\Stream\PipelineStreamTests.cs" />
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<Compile Include="Support\Stream\SegmentStreamTests.cs" />
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<Compile Include="Support\Stream\StorageStreamTests.cs" />
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<Compile Include="Support\Template\ManagerTests.cs" />
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<Compile Include="Support\Template\SingleManagerTests.cs" />

‎src/CatLib.Core.Tests/Support/Stream/SegmentStreamTests.cs‎

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/*
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* This file is part of the CatLib package.
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*
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* (c) Yu Bin <[email protected]>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*
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* Document: http://catlib.io/
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*/
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using System;
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using System.IO;
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using Microsoft.VisualStudio.TestTools.UnitTesting;
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namespace CatLib.Core.Tests.Support.Stream
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{
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[TestClass]
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public class SegmentStreamTests
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{
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[TestMethod]
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public void TestRead()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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Assert.AreEqual("hello world", segmentStream.ToText());
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}
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[TestMethod]
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public void TestReadMiddle()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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baseStream.Seek(14, SeekOrigin.Begin);
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var segmentStream = new SegmentStream(baseStream, 10);
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Assert.AreEqual("my name is", segmentStream.ToText());
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}
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[TestMethod]
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public void TestReadEnd()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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baseStream.Seek(14, SeekOrigin.Begin);
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var segmentStream = new SegmentStream(baseStream);
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Assert.AreEqual("my name is miaomiao", segmentStream.ToText());
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}
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[TestMethod]
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public void TestSeekEnd()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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segmentStream.Seek(-5, SeekOrigin.End);
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Assert.AreEqual("world", segmentStream.ToText());
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}
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[TestMethod]
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public void TestSeekCurrent()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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baseStream.Seek(2, SeekOrigin.Begin);
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var segmentStream = new SegmentStream(baseStream, 9);
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segmentStream.Seek(4, SeekOrigin.Current);
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Assert.AreEqual("world", segmentStream.ToText());
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}
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[TestMethod]
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public void TestSeekBegin()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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segmentStream.ToText(null, false);
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segmentStream.Seek(0, SeekOrigin.Begin);
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Assert.AreEqual("hello world", segmentStream.ToText());
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}
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[TestMethod]
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public void TestGetLength()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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Assert.AreEqual(11, segmentStream.Length);
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}
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[TestMethod]
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public void TestGetPosition()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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baseStream.Seek(2, SeekOrigin.Begin);
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var segmentStream = new SegmentStream(baseStream, 9) {Position = 4};
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Assert.AreEqual(4, segmentStream.Position);
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}
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[TestMethod]
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public void TestReadBuffer()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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var buffer = new byte[255];
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Assert.AreEqual(11, segmentStream.Read(buffer, 0, 255));
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Assert.AreEqual("hello world", CatLib.Util.Encoding.GetString(buffer, 0, 11));
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}
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[TestMethod]
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public void TestReadBufferEnd()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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var buffer = new byte[255];
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Assert.AreEqual(11, segmentStream.Read(buffer, 0, 255));
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Assert.AreEqual("hello world", CatLib.Util.Encoding.GetString(buffer, 0, 11));
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Assert.AreEqual(0, segmentStream.Read(buffer, 0, 255));
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}
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[TestMethod]
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public void TestReadBufferMin()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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var buffer = new byte[5];
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Assert.AreEqual(5, segmentStream.Read(buffer, 0, 5));
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Assert.AreEqual("hello", CatLib.Util.Encoding.GetString(buffer, 0, 5));
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}
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[TestMethod]
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[ExpectedException(typeof(NotSupportedException))]
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public void TestSetLength()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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segmentStream.SetLength(100);
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}
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[TestMethod]
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[ExpectedException(typeof(NotSupportedException))]
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public void TestWrite()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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var buffer = CatLib.Util.Encoding.GetBytes("hello world");
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segmentStream.Write(buffer, 0, buffer.Length);
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}
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[TestMethod]
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[ExpectedException(typeof(ArgumentOutOfRangeException))]
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public void TestNotSupportSeekOrigin()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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segmentStream.Seek(0, (SeekOrigin) 100);
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}
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[TestMethod]
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public void TestSeekEndToRead()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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segmentStream.Seek(100, SeekOrigin.End);
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Assert.AreEqual(string.Empty, segmentStream.ToText());
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}
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[TestMethod]
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public void TestSeekSmallThenStart()
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{
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var baseStream = "hello world , my name is miaomiao".ToStream();
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var segmentStream = new SegmentStream(baseStream, 11);
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segmentStream.Seek(-100, SeekOrigin.Begin);
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Assert.AreEqual("hello world", segmentStream.ToText());
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}
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private class CanNotSeekStream : WrapperStream
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{
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public override bool CanSeek => false;
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}
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[TestMethod]
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[ExpectedException(typeof(InvalidOperationException))]
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public void TestGivenCanNotSeek()
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{
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var segmentStream = new SegmentStream(new CanNotSeekStream());
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}
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}
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}

‎src/CatLib.Core/Support/Stream/SegmentStream.cs‎

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/*
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* This file is part of the CatLib package.
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*
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* (c) Yu Bin <[email protected]>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*
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* Document: http://catlib.io/
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*/
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using System;
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using System.IO;
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namespace CatLib
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{
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/// <summary>
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/// 分片流可以用于包装指定分片的流。
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/// 使指定分片的流访问起来就像传统流那样从开头到结尾。
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/// </summary>
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public class SegmentStream : WrapperStream
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{
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/// <summary>
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/// 基础流的初始的位置
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/// </summary>
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private readonly long initialPosition;
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/// <summary>
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/// 分片的大小
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/// </summary>
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private readonly long partSize;
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/// <summary>
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/// 构造一个分片流
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/// </summary>
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/// <param name="stream">基础流</param>
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/// <param name="partSize">分片大小</param>
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public SegmentStream(Stream stream, long partSize = 0)
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: base(stream)
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{
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if (!stream.CanSeek)
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{
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throw new InvalidOperationException($"Base stream of {nameof(SegmentStream)} must be seekable");
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}
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initialPosition = stream.Position;
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var remainingSize = stream.Length - stream.Position;
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if (partSize == 0 || remainingSize < partSize)
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{
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this.partSize = remainingSize;
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}
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else
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{
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this.partSize = partSize;
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}
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}
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/// <summary>
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/// 剩余长度
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/// </summary>
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private long RemainingSize => partSize - Position;
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/// <summary>
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/// 流的长度
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/// </summary>
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public override long Length
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{
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get
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{
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var length = base.Length - initialPosition;
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if (length > partSize)
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{
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length = partSize;
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}
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return length;
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}
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}
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/// <summary>
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/// 当前流的位置
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/// </summary>
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public override long Position
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{
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get => base.Position - initialPosition;
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set => base.Position = value;
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}
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/// <summary>
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/// 设定流的位置
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/// </summary>
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/// <param name="offset">偏移量</param>
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/// <param name="origin">偏移方向</param>
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/// <returns>流的位置</returns>
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public override long Seek(long offset, SeekOrigin origin)
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{
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long position;
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switch (origin)
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{
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case SeekOrigin.Begin:
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position = initialPosition + offset;
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break;
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case SeekOrigin.Current:
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position = base.Position + offset;
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break;
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case SeekOrigin.End:
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position = base.Position + partSize + offset;
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break;
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default:
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throw new ArgumentOutOfRangeException(nameof(origin), origin, null);
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}
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if (position < initialPosition)
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{
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position = initialPosition;
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}
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else if (position > initialPosition + partSize)
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{
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position = initialPosition + partSize;
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}
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base.Seek(position, SeekOrigin.Begin);
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return Position;
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}
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/// <summary>
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/// 读取流的数据到指定缓冲区
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/// </summary>
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/// <param name="buffer">指定缓冲区</param>
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/// <param name="offset">缓冲区偏移量</param>
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/// <param name="count">希望读取的长度</param>
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/// <returns>实际读取的长度</returns>
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public override int Read(byte[] buffer, int offset, int count)
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{
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var bytesToRead = count < RemainingSize ? count : (int)RemainingSize;
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return bytesToRead < 0 ? 0 : base.Read(buffer, offset, bytesToRead);
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}
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/// <summary>
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/// 设定流的长度
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/// </summary>
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/// <param name="value"></param>
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public override void SetLength(long value)
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{
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throw new NotSupportedException();
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}
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/// <summary>
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/// 将指定缓冲区的数据写入流中
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/// </summary>
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/// <param name="buffer">指定缓冲区</param>
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/// <param name="offset">缓冲区偏移量</param>
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/// <param name="count">写入数据的长度</param>
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public override void Write(byte[] buffer, int offset, int count)
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{
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throw new NotSupportedException();
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}
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}
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}

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