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Optimize LineReader.ReadLine #393

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Jan 31, 2020
Merged

Optimize LineReader.ReadLine #393

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62 changes: 31 additions & 31 deletions src/Markdig.Tests/TestLineReader.cs
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
// Copyright (c) Alexandre Mutel. All rights reserved.
// Copyright (c) Alexandre Mutel. All rights reserved.
// This file is licensed under the BSD-Clause 2 license.
// See the license.txt file in the project root for more information.

Expand All @@ -18,90 +18,90 @@ public class TestLineReader
public void TestEmpty()
{
var lineReader = new LineReader("");
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestLinesOnlyLf()
{
var lineReader = new LineReader("\n\n\n");
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.AreEqual(1, lineReader.SourcePosition);
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.AreEqual(2, lineReader.SourcePosition);
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestLinesOnlyCr()
{
var lineReader = new LineReader("\r\r\r");
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.AreEqual(1, lineReader.SourcePosition);
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.AreEqual(2, lineReader.SourcePosition);
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestLinesOnlyCrLf()
{
var lineReader = new LineReader("\r\n\r\n\r\n");
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.AreEqual(2, lineReader.SourcePosition);
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.AreEqual(4, lineReader.SourcePosition);
Assert.AreEqual(string.Empty, lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual(string.Empty, lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestNoEndOfLine()
{
var lineReader = new LineReader("123");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestLf()
{
var lineReader = new LineReader("123\n");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.AreEqual(4, lineReader.SourcePosition);
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestLf2()
{
// When limited == true, we limit the internal buffer exactly after the first new line char '\n'
var lineReader = new LineReader("123\n456");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.AreEqual(4, lineReader.SourcePosition);
Assert.AreEqual("456", lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual("456", lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestCr()
{
var lineReader = new LineReader("123\r");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.AreEqual(4, lineReader.SourcePosition);
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestCr2()
{
var lineReader = new LineReader("123\r456");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.AreEqual(4, lineReader.SourcePosition);
Assert.AreEqual("456", lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual("456", lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
Expand All @@ -110,19 +110,19 @@ public void TestCrLf()
// When limited == true, we limit the internal buffer exactly after the first new line char '\r'
// and we check that we don't get a new line for `\n`
var lineReader = new LineReader("123\r\n");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.AreEqual(5, lineReader.SourcePosition);
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine().Text);
}

[Test]
public void TestCrLf2()
{
var lineReader = new LineReader("123\r\n456");
Assert.AreEqual("123", lineReader.ReadLine()?.ToString());
Assert.AreEqual("123", lineReader.ReadLine().ToString());
Assert.AreEqual(5, lineReader.SourcePosition);
Assert.AreEqual("456", lineReader.ReadLine()?.ToString());
Assert.Null(lineReader.ReadLine()?.ToString());
Assert.AreEqual("456", lineReader.ReadLine().ToString());
Assert.Null(lineReader.ReadLine().Text);
}
}
}
49 changes: 21 additions & 28 deletions src/Markdig/Helpers/LineReader.cs
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Original file line number Diff line number Diff line change
@@ -1,10 +1,9 @@
// Copyright (c) Alexandre Mutel. All rights reserved.
// Copyright (c) Alexandre Mutel. All rights reserved.
// This file is licensed under the BSD-Clause 2 license.
// See the license.txt file in the project root for more information.

using System;
using System.IO;
using System.Text;

namespace Markdig.Helpers
{
Expand All @@ -13,17 +12,16 @@ namespace Markdig.Helpers
/// </summary>
public struct LineReader
{
private readonly string text;
private readonly string _text;

/// <summary>
/// Initializes a new instance of the <see cref="LineReader"/> class.
/// </summary>
/// <exception cref="System.ArgumentNullException"></exception>
/// <exception cref="System.ArgumentOutOfRangeException">bufferSize cannot be &lt;= 0</exception>
/// <exception cref="ArgumentNullException"></exception>
/// <exception cref="ArgumentOutOfRangeException">bufferSize cannot be &lt;= 0</exception>
public LineReader(string text)
{
if (text == null) throw new ArgumentNullException(nameof(text));
this.text = text;
_text = text ?? throw new ArgumentNullException(nameof(text));
SourcePosition = 0;
}

Expand All @@ -36,36 +34,31 @@ public LineReader(string text)
/// Reads a new line from the underlying <see cref="TextReader"/> and update the <see cref="SourcePosition"/> for the next line.
/// </summary>
/// <returns>A new line or null if the end of <see cref="TextReader"/> has been reached</returns>
public StringSlice? ReadLine()
public StringSlice ReadLine()
{
if (SourcePosition >= text.Length)
{
return null;
}
string text = _text;
int sourcePosition = SourcePosition;

var startPosition = SourcePosition;
var position = SourcePosition;
var slice = new StringSlice(text, startPosition, startPosition);
for (;position < text.Length; position++)
for (int i = sourcePosition; i < text.Length; i++)
{
var c = text[position];
char c = text[i];
if (c == '\r' || c == '\n')
{
slice.End = position - 1;
if (c == '\r' && position + 1 < text.Length && text[position + 1] == '\n')
{
position++;
}
position++;
SourcePosition = position;
var slice = new StringSlice(text, sourcePosition, i - 1);

if (c == '\r' && (uint)(i + 1) < (uint)text.Length && text[i + 1] == '\n')
i++;

SourcePosition = i + 1;
return slice;
}
}

slice.End = position - 1;
SourcePosition = position;
if (sourcePosition >= text.Length)
return default;

return slice;
SourcePosition = int.MaxValue;
return new StringSlice(text, sourcePosition, text.Length - 1);
}
}
}
}
4 changes: 2 additions & 2 deletions src/Markdig/Parsers/MarkdownParser.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -116,11 +116,11 @@ private void ProcessBlocks()
var lineText = lineReader.ReadLine();

// If this is the end of file and the last line is empty
if (lineText == null)
if (lineText.Text is null)
{
break;
}
blockProcessor.ProcessLine(lineText.Value);
blockProcessor.ProcessLine(lineText);
}
blockProcessor.CloseAll(true);
}
Expand Down