osu/osu.Game/IO/LineBufferedReader.cs

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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
namespace osu.Game.IO
{
/// <summary>
/// A <see cref="StreamReader"/>-like decorator (with more limited API) for <see cref="Stream"/>s
/// that allows lines to be peeked without consuming.
/// </summary>
public class LineBufferedReader : IDisposable
{
private readonly StreamReader streamReader;
private readonly Queue<string> lineBuffer;
public LineBufferedReader(Stream stream, bool leaveOpen = false)
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{
streamReader = new StreamReader(stream, Encoding.UTF8, true, 1024, leaveOpen);
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lineBuffer = new Queue<string>();
}
/// <summary>
/// Reads the next line from the stream without consuming it.
/// Subsequent calls to <see cref="PeekLine"/> without a <see cref="ReadLine"/> will return the same string.
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/// </summary>
public string PeekLine()
{
if (lineBuffer.Count > 0)
return lineBuffer.Peek();
var line = streamReader.ReadLine();
if (line != null)
lineBuffer.Enqueue(line);
return line;
}
/// <summary>
/// Reads the next line from the stream and consumes it.
/// If a line was peeked, that same line will then be consumed and returned.
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/// </summary>
public string ReadLine() => lineBuffer.Count > 0 ? lineBuffer.Dequeue() : streamReader.ReadLine();
/// <summary>
/// Reads the stream to its end and returns the text read.
/// This includes any peeked but unconsumed lines.
/// </summary>
public string ReadToEnd()
{
var remainingText = streamReader.ReadToEnd();
if (lineBuffer.Count == 0)
return remainingText;
var builder = new StringBuilder();
// this might not be completely correct due to varying platform line endings
while (lineBuffer.Count > 0)
builder.AppendLine(lineBuffer.Dequeue());
builder.Append(remainingText);
return builder.ToString();
}
public void Dispose()
{
streamReader?.Dispose();
}
}
}