Bump to 0.18.0

10% time and 50% memory improvement

.github/FUNDING.yml

@@ -0,0 +1,12 @@
+# These are supported funding model platforms
+
+github: [xoofx]
+patreon: # Replace with a single Patreon username
+open_collective: # Replace with a single Open Collective username
+ko_fi: # Replace with a single Ko-fi username
+tidelift: # Replace with a single Tidelift platform-name/package-name e.g., npm/babel
+community_bridge: # Replace with a single Community Bridge project-name e.g., cloud-foundry
+liberapay: # Replace with a single Liberapay username
+issuehunt: # Replace with a single IssueHunt username
+otechie: # Replace with a single Otechie username
+custom: # Replace with up to 4 custom sponsorship URLs e.g., ['link1', 'link2']

.gitignore

@@ -7,6 +7,7 @@
 *.userosscache
 *.sln.docstates
 *.nuget.props
+*.nuget.targets
 
 # User-specific files (MonoDevelop/Xamarin Studio)
 *.userprefs

appveyor.yml

@@ -1,11 +1,15 @@
 version: 10.0.{build}
-image: Visual Studio 2017
+image: Visual Studio 2019
 configuration: Release
-
+environment:
+  COVERALLS_REPO_TOKEN:
+    secure: /SEtLgIE6ZrJaWBC1xFZIeESiwfwiXEk9N4pSJ53rFhqBZC2sXJg7ZxZ1DBhnZGu
 install:
 - ps: >-
     cd src
 
+    dotnet tool install -g coveralls.net --version 1.0.0
+
     nuget restore Markdig.sln
 
     $env:MARKDIG_BUILD_NUMBER = ([int]$env:APPVEYOR_BUILD_NUMBER).ToString("000")
@@ -31,22 +35,35 @@ build:
   project: src/Markdig.sln
   verbosity: minimal
 
-after_build:
-- cmd: >-
-    dotnet run --project SpecFileGen/SpecFileGen.csproj -c Release
+after_build: >
+  dotnet SpecFileGen/bin/Release/netcoreapp2.2/SpecFileGen.dll
 
-    dotnet test -v n Markdig.Tests
+test_script:
+- cmd: >-
+    dotnet test Markdig.Tests -c Release --no-build
+
+    dotnet test Markdig.Tests -c Debug
+
+    dotnet test Markdig.Tests -c Release -f netcoreapp2.1 /p:CollectCoverage=true /p:Include=\"[Markdig]*\" /p:CoverletOutputFormat=opencover /p:CoverletOutput=../../coverage.xml
+
+after_test:
+- ps: >-
+    if($env:APPVEYOR_REPO_BRANCH -eq "master") {
+      cd ..
+      if (Test-Path "./coverage.xml") {
+        csmacnz.Coveralls --opencover -i "./coverage.xml" --repoToken $env:COVERALLS_REPO_TOKEN --basePath "$env:APPVEYOR_BUILD_FOLDER" --useRelativePath --commitId $env:APPVEYOR_REPO_COMMIT --commitBranch $env:APPVEYOR_REPO_BRANCH --commitAuthor $env:APPVEYOR_REPO_COMMIT_AUTHOR --commitEmail $env:APPVEYOR_REPO_COMMIT_AUTHOR_EMAIL --commitMessage $env:APPVEYOR_REPO_COMMIT_MESSAGE --jobId $env:APPVEYOR_BUILD_NUMBER --serviceName appveyor
+      }
+      cd src
+    }
 
 before_package:
 - cmd: >-
     msbuild /t:pack /p:VersionSuffix="%MARKDIG_VERSION_SUFFIX%" /p:Configuration=Release Markdig/Markdig.csproj
 
-    msbuild /t:Clean Markdig/Markdig.csproj
-
-    msbuild /t:pack /p:VersionSuffix="%MARKDIG_VERSION_SUFFIX%" /p:Configuration=Release;SignAssembly=true Markdig/Markdig.csproj
+    msbuild /t:pack /p:VersionSuffix="%MARKDIG_VERSION_SUFFIX%" /p:Configuration=Release Markdig.Signed/Markdig.Signed.csproj
 
 artifacts:
-- path: src\Markdig\Bin\Release\*.nupkg
+- path: src\**\*.nupkg
   name: Markdig Nugets
 
 deploy:

changelog.md

@@ -1,5 +1,16 @@
 # Changelog
 
+## 0.18.0 (24 Oct 2019)
+- Ignore backslashes in GFM AutoLinks ([(PR #357)](https://github.com/lunet-io/markdig/pull/357))
+- Fix SmartyPants quote matching ([(PR #360)](https://github.com/lunet-io/markdig/pull/360))
+- Fix generic attributes with values of length 1 ([(PR #361)](https://github.com/lunet-io/markdig/pull/361))
+- Fix link text balanced bracket matching ([(PR #375)](https://github.com/lunet-io/markdig/pull/375))
+- Improve overall performance and substantially reduce allocations ([(PR #377)](https://github.com/lunet-io/markdig/pull/377))
+
+## 0.17.1 (04 July 2019)
+- Fix regression when escaping HTML characters ([(PR #340)](https://github.com/lunet-io/markdig/pull/340))
+- Update Emoji Dictionary ([(PR #346)](https://github.com/lunet-io/markdig/pull/346))
+
 ## 0.17.0 (10 May 2019)
 - Update to latest CommonMark specs 0.29 ([(PR #327)](https://github.com/lunet-io/markdig/pull/327))
 - Add `AutoLinkOptions` with `OpenInNewWindow`, `UseHttpsForWWWLinks` ([(PR #327)](https://github.com/lunet-io/markdig/pull/327))

readme.md

@@ -1,4 +1,4 @@
-# Markdig [![Build status](https://ci.appveyor.com/api/projects/status/hk391x8jcskxt1u8?svg=true)](https://ci.appveyor.com/project/xoofx/markdig) [![NuGet](https://img.shields.io/nuget/v/Markdig.svg)](https://www.nuget.org/packages/Markdig/) [![Donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_SM.gif)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FRGHXBTP442JL)
+# Markdig [![Build status](https://ci.appveyor.com/api/projects/status/hk391x8jcskxt1u8?svg=true)](https://ci.appveyor.com/project/xoofx/markdig) [![Coverage Status](https://coveralls.io/repos/github/lunet-io/markdig/badge.svg?branch=master)](https://coveralls.io/github/lunet-io/markdig?branch=master) [![NuGet](https://img.shields.io/nuget/v/Markdig.svg)](https://www.nuget.org/packages/Markdig/) [![Donate](https://www.paypalobjects.com/en_US/i/btn/btn_donate_SM.gif)](https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=FRGHXBTP442JL)
 
 <img align="right" width="160px" height="160px" src="img/markdig.png">
 

src/Markdig.Benchmarks/Markdig.Benchmarks.csproj

@@ -1,43 +1,12 @@
-<?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="14.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
-  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
+<Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
-    <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>
-    <ProjectGuid>{6A19F040-BC7C-4283-873A-177B5324F1ED}</ProjectGuid>
+    <TargetFrameworks>net471</TargetFrameworks>
     <OutputType>Exe</OutputType>
-    <AppDesignerFolder>Properties</AppDesignerFolder>
-    <RootNamespace>Markdig.Benchmarks</RootNamespace>
-    <AssemblyName>Markdig.Benchmarks</AssemblyName>
-    <TargetFrameworkVersion>v4.6</TargetFrameworkVersion>
-    <FileAlignment>512</FileAlignment>
-    <AutoGenerateBindingRedirects>true</AutoGenerateBindingRedirects>
-    <TargetFrameworkProfile />
-    <CopyNuGetImplementations>true</CopyNuGetImplementations>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
-    <PlatformTarget>x86</PlatformTarget>
-    <DebugSymbols>true</DebugSymbols>
-    <DebugType>full</DebugType>
-    <Optimize>false</Optimize>
-    <OutputPath>bin\Debug\</OutputPath>
-    <DefineConstants>DEBUG;TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <Prefer32Bit>true</Prefer32Bit>
-  </PropertyGroup>
-  <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|AnyCPU' ">
-    <PlatformTarget>x86</PlatformTarget>
-    <DebugType>pdbonly</DebugType>
-    <Optimize>true</Optimize>
-    <OutputPath>bin\Release\</OutputPath>
-    <DefineConstants>TRACE</DefineConstants>
-    <ErrorReport>prompt</ErrorReport>
-    <WarningLevel>4</WarningLevel>
-    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <Prefer32Bit>true</Prefer32Bit>
   </PropertyGroup>
+  <ItemGroup>
+    <None Remove="spec.md" />
+  </ItemGroup>
   <ItemGroup>
     <Reference Include="CommonMarkNew, Version=0.1.0.0, Culture=neutral, PublicKeyToken=001ef8810438905d, processorArchitecture=MSIL">
       <HintPath>lib\CommonMarkNew.dll</HintPath>
@@ -45,31 +14,12 @@
       <Aliases>newcmark</Aliases>
       <Private>True</Private>
     </Reference>
-    <Reference Include="Microsoft.Build" />
-    <Reference Include="Microsoft.Build.Framework" />
-    <Reference Include="Microsoft.Build.Utilities.v4.0" />
     <Reference Include="MoonShine">
       <HintPath>lib\MoonShine.dll</HintPath>
     </Reference>
     <Reference Include="MarkdownDeep">
       <HintPath>lib\MarkdownDeep.dll</HintPath>
     </Reference>
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="System.Management" />
-    <Reference Include="System.Xml.Linq" />
-    <Reference Include="System.Data.DataSetExtensions" />
-    <Reference Include="Microsoft.CSharp" />
-    <Reference Include="System.Data" />
-    <Reference Include="System.Net.Http" />
-    <Reference Include="System.Xml" />
-  </ItemGroup>
-  <ItemGroup>
-    <Compile Include="CommonMarkLib.cs" />
-    <Compile Include="Program.cs" />
-    <Compile Include="Properties\AssemblyInfo.cs" />
-    <Compile Include="TestMatchPerf.cs" />
-    <Compile Include="TestStringPerf.cs" />
   </ItemGroup>
   <ItemGroup>
     <Content Include="cmark.dll">
@@ -83,21 +33,16 @@
     <Content Include="spec.md">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </Content>
-    <None Include="app.config" />
-    <None Include="project.json" />
   </ItemGroup>
   <ItemGroup>
-    <Reference Include="Markdig">
-      <SpecificVersion>False</SpecificVersion>
-      <HintPath>..\Markdig\Bin\$(Configuration)\net40\Markdig.dll</HintPath>
-    </Reference>
+    <PackageReference Include="BenchmarkDotNet" Version="0.10.6" />
+    <PackageReference Include="BenchmarkDotNet.Diagnostics.Windows" Version="0.10.6" />
+    <PackageReference Include="CommonMark.NET" Version="0.15.1" />
+    <PackageReference Include="MarkdownSharp" Version="1.13.0.0" />
+    <PackageReference Include="Microsoft.Diagnostics.Runtime" Version="0.8.31-beta" />
+    <PackageReference Include="Microsoft.Diagnostics.Tracing.TraceEvent" Version="1.0.41.0" />
   </ItemGroup>
-  <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
-  <!-- To modify your build process, add your task inside one of the targets below and uncomment it. 
-       Other similar extension points exist, see Microsoft.Common.targets.
-  <Target Name="BeforeBuild">
-  </Target>
-  <Target Name="AfterBuild">
-  </Target>
-  -->
-</Project>
+  <ItemGroup>
+    <ProjectReference Include="..\Markdig\Markdig.csproj" />
+  </ItemGroup>
+</Project>

src/Markdig.Benchmarks/Properties/AssemblyInfo.cs

@@ -1,36 +0,0 @@
-using System.Reflection;
-using System.Runtime.CompilerServices;
-using System.Runtime.InteropServices;
-
-// General Information about an assembly is controlled through the following 
-// set of attributes. Change these attribute values to modify the information
-// associated with an assembly.
-[assembly: AssemblyTitle("Testamina.Markdig.Benchmarks")]
-[assembly: AssemblyDescription("")]
-[assembly: AssemblyConfiguration("")]
-[assembly: AssemblyCompany("")]
-[assembly: AssemblyProduct("Testamina.Markdig.Benchmarks")]
-[assembly: AssemblyCopyright("Copyright ©  2016")]
-[assembly: AssemblyTrademark("")]
-[assembly: AssemblyCulture("")]
-
-// Setting ComVisible to false makes the types in this assembly not visible 
-// to COM components.  If you need to access a type in this assembly from 
-// COM, set the ComVisible attribute to true on that type.
-[assembly: ComVisible(false)]
-
-// The following GUID is for the ID of the typelib if this project is exposed to COM
-[assembly: Guid("6a19f040-bc7c-4283-873a-177b5324f1ed")]
-
-// Version information for an assembly consists of the following four values:
-//
-//      Major Version
-//      Minor Version 
-//      Build Number
-//      Revision
-//
-// You can specify all the values or you can default the Build and Revision Numbers 
-// by using the '*' as shown below:
-// [assembly: AssemblyVersion("1.0.*")]
-[assembly: AssemblyVersion("1.0.0.0")]
-[assembly: AssemblyFileVersion("1.0.0.0")]

src/Markdig.Benchmarks/Properties/launchSettings.json

@@ -1,8 +0,0 @@
-{
-  "profiles": {
-    "CLASSIC": {
-      "executablePath": "Testamina.Markdig.Benchmarks.dll",
-      "workingDirectory": "..\\..\\artifacts\\bin\\Testamina.Markdig.Benchmarks\\Debug\\net45"
-    }
-  }
-}

src/Markdig.Benchmarks/app.config

@@ -1,3 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<configuration>
-<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6"/></startup></configuration>

src/Markdig.Benchmarks/project.json

@@ -1,29 +0,0 @@
-{
-  "runtimes": {
-    "win-x86": {},
-    "win-x64": {}
-  },
-  "frameworks": {
-    "net46": {
-      "compilationOptions": {
-        "define": [
-          "CLASSIC"
-        ]
-      },
-      "frameworkAssemblies": {
-        "Microsoft.Build": "4.0.0.0",
-        "Microsoft.Build.Framework": "4.0.0.0",
-        "Microsoft.Build.Utilities.v4.0": "4.0.0.0",
-        "System.Management": "4.0.0.0"
-      }
-    }
-  },
-  "dependencies": {
-    "BenchmarkDotNet": "0.10.6",
-    "BenchmarkDotNet.Diagnostics.Windows": "0.10.6",
-    "CommonMark.NET": "0.15.1",
-    "MarkdownSharp": "1.13.0.0",
-    "Microsoft.Diagnostics.Runtime": "0.8.31-beta",
-    "Microsoft.Diagnostics.Tracing.TraceEvent": "1.0.41.0"
-  }
-}

src/Markdig.Signed/Markdig.Signed.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <PackageId>Markdig.Signed</PackageId>
+    <AssemblyOriginatorKeyFile>key.snk</AssemblyOriginatorKeyFile>
+    <SignAssembly>true</SignAssembly>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="..\Markdig\**\*.cs" Exclude="..\Markdig\obj\**;..\Markdig\bin\**">
+      <Link>%(RecursiveDir)%(Filename)%(Extension)</Link>
+    </Compile>
+  </ItemGroup>
+  <Import Project="..\Markdig\Markdig.targets" />
+</Project>

src/Markdig.Tests/Markdig.Tests.csproj

@@ -6,8 +6,12 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="coverlet.msbuild" Version="2.6.2">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.0.1" />
-    <PackageReference Include="NUnit" Version="3.11.0" />
+    <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="NUnit3TestAdapter" Version="3.13.0" />
   </ItemGroup>
 

src/Markdig.Tests/MiscTests.cs

@@ -1,5 +1,6 @@
 using System;
 using System.IO;
+using System.Linq;
 using System.Text.RegularExpressions;
 using Markdig.Extensions.AutoLinks;
 using NUnit.Framework;
@@ -8,6 +9,63 @@ namespace Markdig.Tests
 {
     public class MiscTests
     {
+        [TestCase("link [foo [bar]]")] // https://spec.commonmark.org/0.29/#example-508
+        [TestCase("link [foo][bar]")]
+        [TestCase("link [][foo][bar][]")]
+        [TestCase("link [][foo][bar][[]]")]
+        [TestCase("link [foo] [bar]")]
+        [TestCase("link [[foo] [] [bar] [[abc]def]]")]
+        [TestCase("[]")]
+        [TestCase("[ ]")]
+        [TestCase("[bar][]")]
+        [TestCase("[bar][ foo]")]
+        [TestCase("[bar][foo ][]")]
+        [TestCase("[bar][fo[ ]o ][][]")]
+        [TestCase("[a]b[c[d[e]f]g]h")]
+        [TestCase("a[b[c[d]e]f[g]h]i foo [j]k[l[m]n]o")]
+        [TestCase("a[b[c[d]e]f[g]h]i[] [][foo][bar][] foo [j]k[l[m]n]o")]
+        [TestCase("a[b[c[d]e]f[g]h]i foo [j]k[l[m]n]o[][]")]
+        public void LinkTextMayContainBalancedBrackets(string linkText)
+        {
+            string markdown = $"[{linkText}](/uri)";
+            string expected = $@"<p><a href=""/uri"">{linkText}</a></p>";
+
+            TestParser.TestSpec(markdown, expected);
+
+            // Make the link text unbalanced
+            foreach (var bracketIndex in linkText
+                .Select((c, i) => new Tuple<char, int>(c, i))
+                .Where(t => t.Item1 == '[' || t.Item1 == ']')
+                .Select(t => t.Item2))
+            {
+                string brokenLinkText = linkText.Remove(bracketIndex, 1);
+
+                markdown = $"[{brokenLinkText}](/uri)";
+                expected = $@"<p><a href=""/uri"">{brokenLinkText}</a></p>";
+
+                string actual = Markdown.ToHtml(markdown);
+                Assert.AreNotEqual(expected, actual);
+            }
+        }
+
+        [Test]
+        public void IsIssue356Corrected()
+        {
+            string input = @"https://foo.bar/path/\#m4mv5W0GYKZpGvfA.97";
+            string expected = @"<p><a href=""https://foo.bar/path/%5C#m4mv5W0GYKZpGvfA.97"">https://foo.bar/path/\#m4mv5W0GYKZpGvfA.97</a></p>";
+
+            TestParser.TestSpec($"<{input}>", expected);
+            TestParser.TestSpec(input, expected, "autolinks|advanced");
+        }
+
+        [Test]
+        public void TestAltTextIsCorrectlyEscaped()
+        {
+            TestParser.TestSpec(
+                @"![This is image alt text with quotation ' and double quotation ""hello"" world](girl.png)",
+                @"<p><img src=""girl.png"" alt=""This is image alt text with quotation ' and double quotation &quot;hello&quot; world"" /></p>");
+        }
+
         [Test]
         public void TestChangelogPRLinksMatchDescription()
         {

src/Markdig.Tests/Specs/GenericAttributesSpecs.generated.cs

@@ -1,4 +1,4 @@
-// Generated: 2019-04-05 16:06:14
+// Generated: 2019-08-01 13:57:17
 
 // --------------------------------
 //        Generic Attributes
@@ -79,5 +79,28 @@ namespace Markdig.Tests.Specs.GenericAttributes
             Console.WriteLine("Example 2\nSection Extensions / Generic Attributes\n");
             TestParser.TestSpec("{#fenced-id .fenced-class}\n~~~\nThis is a fenced with attached attributes\n~~~ ", "<pre><code id=\"fenced-id\" class=\"fenced-class\">This is a fenced with attached attributes\n</code></pre>", "attributes|advanced");
         }
+
+        // Attribute values can be one character long
+        [Test]
+        public void ExtensionsGenericAttributes_Example003()
+        {
+            // Example 3
+            // Section: Extensions / Generic Attributes
+            //
+            // The following Markdown:
+            //     [Foo](url){data-x=1}
+            //     
+            //     [Foo](url){data-x='1'}
+            //     
+            //     [Foo](url){data-x=11}
+            //
+            // Should be rendered as:
+            //     <p><a href="url" data-x="1">Foo</a></p>
+            //     <p><a href="url" data-x="1">Foo</a></p>
+            //     <p><a href="url" data-x="11">Foo</a></p>
+
+            Console.WriteLine("Example 3\nSection Extensions / Generic Attributes\n");
+            TestParser.TestSpec("[Foo](url){data-x=1}\n\n[Foo](url){data-x='1'}\n\n[Foo](url){data-x=11}", "<p><a href=\"url\" data-x=\"1\">Foo</a></p>\n<p><a href=\"url\" data-x=\"1\">Foo</a></p>\n<p><a href=\"url\" data-x=\"11\">Foo</a></p>", "attributes|advanced");
+        }
     }
 }

src/Markdig.Tests/Specs/GenericAttributesSpecs.md

@@ -47,3 +47,17 @@ This is a fenced with attached attributes
 <pre><code id="fenced-id" class="fenced-class">This is a fenced with attached attributes
 </code></pre>
 ````````````````````````````````
+
+Attribute values can be one character long
+
+```````````````````````````````` example
+[Foo](url){data-x=1}
+
+[Foo](url){data-x='1'}
+
+[Foo](url){data-x=11}
+.
+<p><a href="url" data-x="1">Foo</a></p>
+<p><a href="url" data-x="1">Foo</a></p>
+<p><a href="url" data-x="11">Foo</a></p>
+````````````````````````````````

src/Markdig.Tests/Specs/SmartyPantsSpecs.generated.cs

@@ -1,4 +1,4 @@
-// Generated: 2019-04-05 16:06:14
+// Generated: 2019-08-01 12:33:23
 
 // --------------------------------
 //           Smarty Pants
@@ -140,13 +140,13 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Section: Extensions / SmartyPants Quotes
             //
             // The following Markdown:
-            //     This is a 'text <<with' a another text>>
+            //     This is 'a "text 'with" a another text'
             //
             // Should be rendered as:
-            //     <p>This is a &lsquo;text &lt;&lt;with&rsquo; a another text&gt;&gt;</p>
+            //     <p>This is &lsquo;a &ldquo;text 'with&rdquo; a another text&rsquo;</p>
 
             Console.WriteLine("Example 8\nSection Extensions / SmartyPants Quotes\n");
-            TestParser.TestSpec("This is a 'text <<with' a another text>>", "<p>This is a &lsquo;text &lt;&lt;with&rsquo; a another text&gt;&gt;</p>", "pipetables+smartypants|advanced+smartypants");
+            TestParser.TestSpec("This is 'a \"text 'with\" a another text'", "<p>This is &lsquo;a &ldquo;text 'with&rdquo; a another text&rsquo;</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         [Test]
@@ -156,20 +156,36 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Section: Extensions / SmartyPants Quotes
             //
             // The following Markdown:
+            //     This is a 'text <<with' a another text>>
+            //
+            // Should be rendered as:
+            //     <p>This is a &lsquo;text &lt;&lt;with&rsquo; a another text&gt;&gt;</p>
+
+            Console.WriteLine("Example 9\nSection Extensions / SmartyPants Quotes\n");
+            TestParser.TestSpec("This is a 'text <<with' a another text>>", "<p>This is a &lsquo;text &lt;&lt;with&rsquo; a another text&gt;&gt;</p>", "pipetables+smartypants|advanced+smartypants");
+        }
+
+        [Test]
+        public void ExtensionsSmartyPantsQuotes_Example010()
+        {
+            // Example 10
+            // Section: Extensions / SmartyPants Quotes
+            //
+            // The following Markdown:
             //     This is a <<text 'with>> a another text'
             //
             // Should be rendered as:
             //     <p>This is a &laquo;text 'with&raquo; a another text'</p>
 
-            Console.WriteLine("Example 9\nSection Extensions / SmartyPants Quotes\n");
+            Console.WriteLine("Example 10\nSection Extensions / SmartyPants Quotes\n");
             TestParser.TestSpec("This is a <<text 'with>> a another text'", "<p>This is a &laquo;text 'with&raquo; a another text'</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         // Quotes requires to have the same rules than emphasis `_` regarding left/right frankling rules:
         [Test]
-        public void ExtensionsSmartyPantsQuotes_Example010()
+        public void ExtensionsSmartyPantsQuotes_Example011()
         {
-            // Example 10
+            // Example 11
             // Section: Extensions / SmartyPants Quotes
             //
             // The following Markdown:
@@ -178,24 +194,8 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Should be rendered as:
             //     <p>It's not quotes'</p>
 
-            Console.WriteLine("Example 10\nSection Extensions / SmartyPants Quotes\n");
-            TestParser.TestSpec("It's not quotes'", "<p>It's not quotes'</p>", "pipetables+smartypants|advanced+smartypants");
-        }
-
-        [Test]
-        public void ExtensionsSmartyPantsQuotes_Example011()
-        {
-            // Example 11
-            // Section: Extensions / SmartyPants Quotes
-            //
-            // The following Markdown:
-            //     They are ' not matching quotes '
-            //
-            // Should be rendered as:
-            //     <p>They are ' not matching quotes '</p>
-
             Console.WriteLine("Example 11\nSection Extensions / SmartyPants Quotes\n");
-            TestParser.TestSpec("They are ' not matching quotes '", "<p>They are ' not matching quotes '</p>", "pipetables+smartypants|advanced+smartypants");
+            TestParser.TestSpec("It's not quotes'", "<p>It's not quotes'</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         [Test]
@@ -205,20 +205,36 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Section: Extensions / SmartyPants Quotes
             //
             // The following Markdown:
+            //     They are ' not matching quotes '
+            //
+            // Should be rendered as:
+            //     <p>They are ' not matching quotes '</p>
+
+            Console.WriteLine("Example 12\nSection Extensions / SmartyPants Quotes\n");
+            TestParser.TestSpec("They are ' not matching quotes '", "<p>They are ' not matching quotes '</p>", "pipetables+smartypants|advanced+smartypants");
+        }
+
+        [Test]
+        public void ExtensionsSmartyPantsQuotes_Example013()
+        {
+            // Example 13
+            // Section: Extensions / SmartyPants Quotes
+            //
+            // The following Markdown:
             //     They are' not matching 'quotes
             //
             // Should be rendered as:
             //     <p>They are' not matching 'quotes</p>
 
-            Console.WriteLine("Example 12\nSection Extensions / SmartyPants Quotes\n");
+            Console.WriteLine("Example 13\nSection Extensions / SmartyPants Quotes\n");
             TestParser.TestSpec("They are' not matching 'quotes", "<p>They are' not matching 'quotes</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         // An emphasis starting inside left/right quotes will span over the right quote:
         [Test]
-        public void ExtensionsSmartyPantsQuotes_Example013()
+        public void ExtensionsSmartyPantsQuotes_Example014()
         {
-            // Example 13
+            // Example 14
             // Section: Extensions / SmartyPants Quotes
             //
             // The following Markdown:
@@ -227,9 +243,26 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Should be rendered as:
             //     <p>This is &ldquo;a <em>text&rdquo; with an emphasis</em></p>
 
-            Console.WriteLine("Example 13\nSection Extensions / SmartyPants Quotes\n");
+            Console.WriteLine("Example 14\nSection Extensions / SmartyPants Quotes\n");
             TestParser.TestSpec("This is \"a *text\" with an emphasis*", "<p>This is &ldquo;a <em>text&rdquo; with an emphasis</em></p>", "pipetables+smartypants|advanced+smartypants");
         }
+
+        // Multiple sets of quotes can be used
+        [Test]
+        public void ExtensionsSmartyPantsQuotes_Example015()
+        {
+            // Example 15
+            // Section: Extensions / SmartyPants Quotes
+            //
+            // The following Markdown:
+            //     "aaa" "bbb" "ccc" "ddd"
+            //
+            // Should be rendered as:
+            //     <p>&ldquo;aaa&rdquo; &ldquo;bbb&rdquo; &ldquo;ccc&rdquo; &ldquo;ddd&rdquo;</p>
+
+            Console.WriteLine("Example 15\nSection Extensions / SmartyPants Quotes\n");
+            TestParser.TestSpec("\"aaa\" \"bbb\" \"ccc\" \"ddd\"", "<p>&ldquo;aaa&rdquo; &ldquo;bbb&rdquo; &ldquo;ccc&rdquo; &ldquo;ddd&rdquo;</p>", "pipetables+smartypants|advanced+smartypants");
+        }
     }
 
     [TestFixture]
@@ -237,9 +270,9 @@ namespace Markdig.Tests.Specs.SmartyPants
     {
         // ## SmartyPants Separators
         [Test]
-        public void ExtensionsSmartyPantsSeparators_Example014()
+        public void ExtensionsSmartyPantsSeparators_Example016()
         {
-            // Example 14
+            // Example 16
             // Section: Extensions / SmartyPants Separators
             //
             // The following Markdown:
@@ -248,14 +281,14 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Should be rendered as:
             //     <p>This is a &ndash; text</p>
 
-            Console.WriteLine("Example 14\nSection Extensions / SmartyPants Separators\n");
+            Console.WriteLine("Example 16\nSection Extensions / SmartyPants Separators\n");
             TestParser.TestSpec("This is a -- text", "<p>This is a &ndash; text</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         [Test]
-        public void ExtensionsSmartyPantsSeparators_Example015()
+        public void ExtensionsSmartyPantsSeparators_Example017()
         {
-            // Example 15
+            // Example 17
             // Section: Extensions / SmartyPants Separators
             //
             // The following Markdown:
@@ -264,14 +297,14 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Should be rendered as:
             //     <p>This is a &mdash; text</p>
 
-            Console.WriteLine("Example 15\nSection Extensions / SmartyPants Separators\n");
+            Console.WriteLine("Example 17\nSection Extensions / SmartyPants Separators\n");
             TestParser.TestSpec("This is a --- text", "<p>This is a &mdash; text</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         [Test]
-        public void ExtensionsSmartyPantsSeparators_Example016()
+        public void ExtensionsSmartyPantsSeparators_Example018()
         {
-            // Example 16
+            // Example 18
             // Section: Extensions / SmartyPants Separators
             //
             // The following Markdown:
@@ -280,15 +313,15 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Should be rendered as:
             //     <p>This is a en ellipsis&hellip;</p>
 
-            Console.WriteLine("Example 16\nSection Extensions / SmartyPants Separators\n");
+            Console.WriteLine("Example 18\nSection Extensions / SmartyPants Separators\n");
             TestParser.TestSpec("This is a en ellipsis...", "<p>This is a en ellipsis&hellip;</p>", "pipetables+smartypants|advanced+smartypants");
         }
 
         // Check that a smartypants are not breaking pipetable parsing:
         [Test]
-        public void ExtensionsSmartyPantsSeparators_Example017()
+        public void ExtensionsSmartyPantsSeparators_Example019()
         {
-            // Example 17
+            // Example 19
             // Section: Extensions / SmartyPants Separators
             //
             // The following Markdown:
@@ -312,15 +345,15 @@ namespace Markdig.Tests.Specs.SmartyPants
             //     </tbody>
             //     </table>
 
-            Console.WriteLine("Example 17\nSection Extensions / SmartyPants Separators\n");
+            Console.WriteLine("Example 19\nSection Extensions / SmartyPants Separators\n");
             TestParser.TestSpec("a  | b\n-- | --\n0  | 1", "<table>\n<thead>\n<tr>\n<th>a</th>\n<th>b</th>\n</tr>\n</thead>\n<tbody>\n<tr>\n<td>0</td>\n<td>1</td>\n</tr>\n</tbody>\n</table>", "pipetables+smartypants|advanced+smartypants");
         }
 
         // Check quotes and dash:
         [Test]
-        public void ExtensionsSmartyPantsSeparators_Example018()
+        public void ExtensionsSmartyPantsSeparators_Example020()
         {
-            // Example 18
+            // Example 20
             // Section: Extensions / SmartyPants Separators
             //
             // The following Markdown:
@@ -329,7 +362,7 @@ namespace Markdig.Tests.Specs.SmartyPants
             // Should be rendered as:
             //     <p>A &ldquo;quote&rdquo; with a &mdash;</p>
 
-            Console.WriteLine("Example 18\nSection Extensions / SmartyPants Separators\n");
+            Console.WriteLine("Example 20\nSection Extensions / SmartyPants Separators\n");
             TestParser.TestSpec("A \"quote\" with a ---", "<p>A &ldquo;quote&rdquo; with a &mdash;</p>", "pipetables+smartypants|advanced+smartypants");
         }
     }

src/Markdig.Tests/Specs/SmartyPantsSpecs.md

@@ -52,6 +52,12 @@ This is a "text 'with" a another text'
 <p>This is a &ldquo;text 'with&rdquo; a another text'</p>
 ````````````````````````````````
 
+```````````````````````````````` example
+This is 'a "text 'with" a another text'
+.
+<p>This is &lsquo;a &ldquo;text 'with&rdquo; a another text&rsquo;</p>
+````````````````````````````````
+
 ```````````````````````````````` example
 This is a 'text <<with' a another text>>
 .
@@ -91,6 +97,14 @@ This is "a *text" with an emphasis*
 <p>This is &ldquo;a <em>text&rdquo; with an emphasis</em></p>
 ````````````````````````````````
 
+Multiple sets of quotes can be used
+
+```````````````````````````````` example
+"aaa" "bbb" "ccc" "ddd"
+.
+<p>&ldquo;aaa&rdquo; &ldquo;bbb&rdquo; &ldquo;ccc&rdquo; &ldquo;ddd&rdquo;</p>
+````````````````````````````````
+
 ## SmartyPants Separators
 
 ```````````````````````````````` example

src/Markdig.Tests/TestParser.cs

@@ -33,9 +33,9 @@ namespace Markdig.Tests
 
                 // If file creation times aren't preserved by git, add some leeway
                 // If specs have come from git, assume that they were regenerated since CI would fail otherwise
-                testTime = testTime.AddSeconds(2);
+                testTime = testTime.AddMinutes(3);
 
-                // This might not catch a changed spec every time, but should most of the time. Otherwise CI will catch it
+                // This might not catch a changed spec every time, but should at least sometimes. Otherwise CI will catch it
 
                 // This could also trigger, if a user has modified the spec file but reverted the change - can't think of a good workaround
                 Assert.Less(specTime, testTime,

src/Markdig.Tests/TestStringSliceList.cs

@@ -1,4 +1,4 @@
-using NUnit.Framework;
+using NUnit.Framework;
 using System.Collections.Generic;
 using System.Text;
 using Markdig.Helpers;
@@ -81,8 +81,18 @@ namespace Markdig.Tests
         public void TestSkipWhitespaces()
         {
             var text = new StringLineGroup("             ABC").ToCharIterator();
-            Assert.True(text.TrimStart());
+            Assert.False(text.TrimStart());
             Assert.AreEqual('A', text.CurrentChar);
+
+            text = new StringLineGroup("        ").ToCharIterator();
+            Assert.True(text.TrimStart());
+            Assert.AreEqual('\0', text.CurrentChar);
+
+            var slice = new StringSlice("             ABC");
+            Assert.False(slice.TrimStart());
+
+            slice = new StringSlice("        ");
+            Assert.True(slice.TrimStart());
         }
 
         [Test]

src/Markdig/Extensions/AutoIdentifiers/AutoIdentifierExtension.cs

@@ -22,6 +22,7 @@ namespace Markdig.Extensions.AutoIdentifiers
     {
         private const string AutoIdentifierKey = "AutoIdentifier";
         private readonly AutoIdentifierOptions options;
+        private readonly StripRendererCache rendererCache = new StripRendererCache();
 
         /// <summary>
         /// Initializes a new instance of the <see cref="AutoIdentifierExtension"/> class.
@@ -159,17 +160,11 @@ namespace Markdig.Extensions.AutoIdentifiers
             }
 
             // Use internally a HtmlRenderer to strip links from a heading
-            var headingWriter = new StringWriter();
-            var stripRenderer = new HtmlRenderer(headingWriter)
-            {
-                // Set to false both to avoid having any HTML tags in the output
-                EnableHtmlForInline = false,
-                EnableHtmlEscape = false
-            };
+            var stripRenderer = rendererCache.Get();
 
             stripRenderer.Render(headingBlock.Inline);
-            var headingText = headingWriter.ToString();
-            headingWriter.GetStringBuilder().Length = 0;
+            var headingText = stripRenderer.Writer.ToString();
+            rendererCache.Release(stripRenderer);
 
             // Urilize the link
             headingText = (options & AutoIdentifierOptions.GitHub) != 0
@@ -195,5 +190,25 @@ namespace Markdig.Extensions.AutoIdentifiers
 
             attributes.Id = headingId;
         }
+
+        private sealed class StripRendererCache : ObjectCache<HtmlRenderer>
+        {
+            protected override HtmlRenderer NewInstance()
+            {
+                var headingWriter = new StringWriter();
+                var stripRenderer = new HtmlRenderer(headingWriter)
+                {
+                    // Set to false both to avoid having any HTML tags in the output
+                    EnableHtmlForInline = false,
+                    EnableHtmlEscape = false
+                };
+                return stripRenderer;
+            }
+
+            protected override void Reset(HtmlRenderer instance)
+            {
+                instance.Reset();
+            }
+        }
     }
 }

src/Markdig/Extensions/AutoLinks/AutoLinkParser.cs

@@ -14,7 +14,7 @@ namespace Markdig.Extensions.AutoLinks
     /// <summary>
     /// The inline parser used to for autolinks.
     /// </summary>
-    /// <seealso cref="Markdig.Parsers.InlineParser" />
+    /// <seealso cref="InlineParser" />
     public class AutoLinkParser : InlineParser
     {
         /// <summary>
@@ -30,10 +30,14 @@ namespace Markdig.Extensions.AutoLinks
                 'f', // for ftp://
                 'm', // for mailto:
                 'w', // for www.
-            };
-        }
-
-        public readonly AutoLinkOptions Options;
+            };
+
+            _listOfCharCache = new ListOfCharCache();
+        }
+
+        public readonly AutoLinkOptions Options;
+
+        private readonly ListOfCharCache _listOfCharCache;
 
         public override bool Match(InlineProcessor processor, ref StringSlice slice)
         {
@@ -44,159 +48,162 @@ namespace Markdig.Extensions.AutoLinks
                 return false;
             }
 
-            List<char> pendingEmphasis;
-            // Check that an autolink is possible in the current context
-            if (!IsAutoLinkValidInCurrentContext(processor, out pendingEmphasis))
-            {
-                return false;
-            }
-
-            var startPosition = slice.Start;
-            int domainOffset = 0;
-
-            var c = slice.CurrentChar;
-            // Precheck URL
-            switch (c)
-            {
-                case 'h':
-                    if (slice.MatchLowercase("ttp://", 1))
-                    {
-                        domainOffset = 7; // http://
-                    }
-                    else if (slice.MatchLowercase("ttps://", 1))
-                    {
-                        domainOffset = 8; // https://
-                    }
-                    else return false;
-                    break;
-                case 'f':
-                    if (!slice.MatchLowercase("tp://", 1))
-                    {
-                        return false;
-                    }
-                    domainOffset = 6; // ftp://
-                    break;
-                case 'm':
-                    if (!slice.MatchLowercase("ailto:", 1))
-                    {
-                        return false;
-                    }
-                    break;
-
-                case 'w':
-                    if (!slice.MatchLowercase("ww.", 1)) // We won't match http:/www. or /www.xxx
-                    {
-                        return false;
-                    }
-                    domainOffset = 4; // www.
-                    break;
-            }
-
-            // Parse URL
-            string link;
-            if (!LinkHelper.TryParseUrl(ref slice, out link, true))
-            {
-                return false;
-            }
-
-
-            // If we have any pending emphasis, remove any pending emphasis characters from the end of the link
-            if (pendingEmphasis != null)
-            {
-                for (int i = link.Length - 1; i >= 0; i--)
-                {
-                    if (pendingEmphasis.Contains(link[i]))
-                    {
-                        slice.Start--;
-                    }
-                    else
-                    {
-                        if (i < link.Length - 1)
-                        {
-                            link = link.Substring(0, i + 1);
-                        }
-                        break;
-                    }
-                }
-            }
-
-            // Post-check URL
-            switch (c)
-            {
-                case 'h':
-                    if (string.Equals(link, "http://", StringComparison.OrdinalIgnoreCase) ||
-                        string.Equals(link, "https://", StringComparison.OrdinalIgnoreCase))
-                    {
-                        return false;
-                    }
-                    break;
-                case 'f':
-                    if (string.Equals(link, "ftp://", StringComparison.OrdinalIgnoreCase))
-                    {
-                        return false;
-                    }
-                    break;
-                case 'm':
-                    int atIndex = link.IndexOf('@');
-                    if (atIndex == -1 ||
-                        atIndex == 7) // mailto:@ - no email part
-                    {
-                        return false;
-                    }
-                    domainOffset = atIndex + 1;
-                    break;
-            }
-
-            if (!LinkHelper.IsValidDomain(link, domainOffset))
+            List<char> pendingEmphasis = _listOfCharCache.Get();
+            try
             {
-                return false;
+                // Check that an autolink is possible in the current context
+                if (!IsAutoLinkValidInCurrentContext(processor, pendingEmphasis))
+                {
+                    return false;
+                }
+
+                var startPosition = slice.Start;
+                int domainOffset = 0;
+
+                var c = slice.CurrentChar;
+                // Precheck URL
+                switch (c)
+                {
+                    case 'h':
+                        if (slice.MatchLowercase("ttp://", 1))
+                        {
+                            domainOffset = 7; // http://
+                        }
+                        else if (slice.MatchLowercase("ttps://", 1))
+                        {
+                            domainOffset = 8; // https://
+                        }
+                        else return false;
+                        break;
+                    case 'f':
+                        if (!slice.MatchLowercase("tp://", 1))
+                        {
+                            return false;
+                        }
+                        domainOffset = 6; // ftp://
+                        break;
+                    case 'm':
+                        if (!slice.MatchLowercase("ailto:", 1))
+                        {
+                            return false;
+                        }
+                        break;
+
+                    case 'w':
+                        if (!slice.MatchLowercase("ww.", 1)) // We won't match http:/www. or /www.xxx
+                        {
+                            return false;
+                        }
+                        domainOffset = 4; // www.
+                        break;
+                }
+
+                // Parse URL
+                if (!LinkHelper.TryParseUrl(ref slice, out string link, true))
+                {
+                    return false;
+                }
+
+
+                // If we have any pending emphasis, remove any pending emphasis characters from the end of the link
+                if (pendingEmphasis.Count > 0)
+                {
+                    for (int i = link.Length - 1; i >= 0; i--)
+                    {
+                        if (pendingEmphasis.Contains(link[i]))
+                        {
+                            slice.Start--;
+                        }
+                        else
+                        {
+                            if (i < link.Length - 1)
+                            {
+                                link = link.Substring(0, i + 1);
+                            }
+                            break;
+                        }
+                    }
+                }
+
+                // Post-check URL
+                switch (c)
+                {
+                    case 'h':
+                        if (string.Equals(link, "http://", StringComparison.OrdinalIgnoreCase) ||
+                            string.Equals(link, "https://", StringComparison.OrdinalIgnoreCase))
+                        {
+                            return false;
+                        }
+                        break;
+                    case 'f':
+                        if (string.Equals(link, "ftp://", StringComparison.OrdinalIgnoreCase))
+                        {
+                            return false;
+                        }
+                        break;
+                    case 'm':
+                        int atIndex = link.IndexOf('@');
+                        if (atIndex == -1 ||
+                            atIndex == 7) // mailto:@ - no email part
+                        {
+                            return false;
+                        }
+                        domainOffset = atIndex + 1;
+                        break;
+                }
+
+                if (!LinkHelper.IsValidDomain(link, domainOffset))
+                {
+                    return false;
+                }
+
+                var inline = new LinkInline()
+                {
+                    Span =
+                    {
+                        Start = processor.GetSourcePosition(startPosition, out int line, out int column),
+                    },
+                    Line = line,
+                    Column = column,
+                    Url = c == 'w' ? ((Options.UseHttpsForWWWLinks ? "https://" : "http://") + link) : link,
+                    IsClosed = true,
+                    IsAutoLink = true,
+                };
+
+                var skipFromBeginning = c == 'm' ? 7 : 0; // For mailto: skip "mailto:" for content
+
+                inline.Span.End = inline.Span.Start + link.Length - 1;
+                inline.UrlSpan = inline.Span;
+                inline.AppendChild(new LiteralInline()
+                {
+                    Span = inline.Span,
+                    Line = line,
+                    Column = column,
+                    Content = new StringSlice(slice.Text, startPosition + skipFromBeginning, startPosition + link.Length - 1),
+                    IsClosed = true
+                });
+                processor.Inline = inline;
+
+                if (Options.OpenInNewWindow)
+                {
+                    inline.GetAttributes().AddPropertyIfNotExist("target", "blank");
+                }
+
+                return true;
             }
-
-            var inline = new LinkInline()
-            {
-                Span =
-                {
-                    Start = processor.GetSourcePosition(startPosition, out int line, out int column),
-                },
-                Line = line,
-                Column = column,
-                Url = c == 'w' ? ((Options.UseHttpsForWWWLinks ? "https://" : "http://") + link) : link,
-                IsClosed = true,
-                IsAutoLink = true,
-            };
-
-            var skipFromBeginning = c == 'm' ? 7 : 0; // For mailto: skip "mailto:" for content
-
-            inline.Span.End = inline.Span.Start + link.Length - 1;
-            inline.UrlSpan = inline.Span;
-            inline.AppendChild(new LiteralInline()
-            {
-                Span = inline.Span,
-                Line = line,
-                Column = column,
-                Content = new StringSlice(slice.Text, startPosition + skipFromBeginning, startPosition + link.Length - 1),
-                IsClosed = true
-            });
-            processor.Inline = inline;
-
-            if (Options.OpenInNewWindow)
+            finally
             {
-                inline.GetAttributes().AddPropertyIfNotExist("target", "blank");
+                _listOfCharCache.Release(pendingEmphasis);
             }
-
-            return true;
         }
 
-        private bool IsAutoLinkValidInCurrentContext(InlineProcessor processor, out List<char> pendingEmphasis)
+        private bool IsAutoLinkValidInCurrentContext(InlineProcessor processor, List<char> pendingEmphasis)
         {
-            pendingEmphasis = null;
-
             // Case where there is a pending HtmlInline <a>
             var currentInline = processor.Inline;
             while (currentInline != null)
             {
-                var htmlInline = currentInline as HtmlInline;
-                if (htmlInline != null)
+                if (currentInline is HtmlInline htmlInline)
                 {
                     // If we have a </a> we don't expect nested <a>
                     if (htmlInline.Tag.StartsWith("</a", StringComparison.OrdinalIgnoreCase))
@@ -211,7 +218,7 @@ namespace Markdig.Extensions.AutoLinks
                     }
                 }
 
-                // Check previous sibling and parents in the tree 
+                // Check previous sibling and parents in the tree
                 currentInline = currentInline.PreviousSibling ?? currentInline.Parent;
             }
 
@@ -221,8 +228,7 @@ namespace Markdig.Extensions.AutoLinks
             int countBrackets = 0;
             while (currentInline != null)
             {
-                var linkDelimiterInline = currentInline as LinkDelimiterInline;
-                if (linkDelimiterInline != null && linkDelimiterInline.IsActive)
+                if (currentInline is LinkDelimiterInline linkDelimiterInline && linkDelimiterInline.IsActive)
                 {
                     if (linkDelimiterInline.Type == DelimiterType.Open)
                     {
@@ -236,14 +242,8 @@ namespace Markdig.Extensions.AutoLinks
                 else
                 {
                     // Record all pending characters for emphasis
-                    var emphasisDelimiter = currentInline as EmphasisDelimiterInline;
-                    if (emphasisDelimiter != null)
+                    if (currentInline is EmphasisDelimiterInline emphasisDelimiter)
                     {
-                        if (pendingEmphasis == null)
-                        {
-                            // Not optimized for GC, but we don't expect this case much
-                            pendingEmphasis = new List<char>();
-                        }
                         if (!pendingEmphasis.Contains(emphasisDelimiter.DelimiterChar))
                         {
                             pendingEmphasis.Add(emphasisDelimiter.DelimiterChar);
@@ -254,6 +254,14 @@ namespace Markdig.Extensions.AutoLinks
             }
 
             return countBrackets <= 0;
+        }
+
+        private sealed class ListOfCharCache : DefaultObjectCache<List<char>>
+        {
+            protected override void Reset(List<char> instance)
+            {
+                instance.Clear();
+            }
         }
     }
 }

src/Markdig/Extensions/Emoji/EmojiParser.cs

@@ -3,7 +3,7 @@
 // See the license.txt file in the project root for more information.
 
 using System;
-using System.Collections.Generic;
+using System.Collections.Generic;
 using Markdig.Helpers;
 using Markdig.Parsers;
 
@@ -47,9 +47,9 @@ namespace Markdig.Extensions.Emoji
         public override bool Match(InlineProcessor processor, ref StringSlice slice)
         {
             // Previous char must be a space
-            if (!slice.PeekCharExtra(-1).IsWhiteSpaceOrZero())
-            {
-                return false;
+            if (!slice.PeekCharExtra(-1).IsWhiteSpaceOrZero())
+            {
+                return false;
             }
 
             // Try to match an emoji
@@ -75,8 +75,8 @@ namespace Markdig.Extensions.Emoji
             slice.Start += match.Key.Length;
 
             return true;
-        }
-
+        }
+
         #region Emojis and Smileys
         static EmojiParser()
         {
@@ -961,6 +961,733 @@ namespace Markdig.Extensions.Emoji
                 { ":custom_arrow_left_strong:", "⇐"},
                 { ":custom_arrow_right_strong:", "⇒"},
                 { ":custom_arrow_left_right_strong:", "⇔"},
+                {":rofl:","🤣"},
+                {":slightly_smiling_face:","🙂"},
+                {":upside_down_face:","🙃"},
+                {":star_struck:","🤩"},
+                {":zany_face:","🤪"},
+                {":money_mouth_face:","🤑"},
+                {":hugs:","🤗"},
+                {":hand_over_mouth:","🤭"},
+                {":shushing_face:","🤫"},
+                {":thinking:","🤔"},
+                {":zipper_mouth_face:","🤐"},
+                {":raised_eyebrow:","🤨"},
+                {":roll_eyes:","🙄"},
+                {":lying_face:","🤥"},
+                {":drooling_face:","🤤"},
+                {":face_with_thermometer:","🤒"},
+                {":face_with_head_bandage:","🤕"},
+                {":nauseated_face:","🤢"},
+                {":vomiting_face:","🤮"},
+                {":sneezing_face:","🤧"},
+                {":exploding_head:","🤯"},
+                {":cowboy_hat_face:","🤠"},
+                {":nerd_face:","🤓"},
+                {":monocle_face:","🧐"},
+                {":slightly_frowning_face:","🙁"},
+                {":frowning_face:","☹️"},
+                {":cursing_face:","🤬"},
+                {":skull_and_crossbones:","☠️"},
+                {":clown_face:","🤡"},
+                {":robot:","🤖"},
+                {":heavy_heart_exclamation:","❣️"},
+                {":orange_heart:","🧡"},
+                {":black_heart:","🖤"},
+                {":hole:","🕳️"},
+                {":eye_speech_bubble:","👁️‍🗨️"},
+                {":left_speech_bubble:","🗨️"},
+                {":right_anger_bubble:","🗯️"},
+                {":raised_back_of_hand:","🤚"},
+                {":raised_hand_with_fingers_splayed:","🖐️"},
+                {":vulcan_salute:","🖖"},
+                {":crossed_fingers:","🤞"},
+                {":love_you_gesture:","🤟"},
+                {":metal:","🤘"},
+                {":call_me_hand:","🤙"},
+                {":middle_finger:","🖕"},
+                {":fist_raised:","✊"},
+                {":fist_oncoming:","👊"},
+                {":fist_left:","🤛"},
+                {":fist_right:","🤜"},
+                {":palms_up_together:","🤲"},
+                {":handshake:","🤝"},
+                {":writing_hand:","✍️"},
+                {":selfie:","🤳"},
+                {":brain:","🧠"},
+                {":eye:","👁️"},
+                {":child:","🧒"},
+                {":adult:","🧑"},
+                {":blond_haired_person:","👱"},
+                {":bearded_person:","🧔"},
+                {":blond_haired_man:","👱‍♂️"},
+                {":blond_haired_woman:","👱‍♀️"},
+                {":older_adult:","🧓"},
+                {":frowning_person:","🙍"},
+                {":frowning_man:","🙍‍♂️"},
+                {":frowning_woman:","🙍‍♀️"},
+                {":pouting_face:","🙎"},
+                {":pouting_man:","🙎‍♂️"},
+                {":pouting_woman:","🙎‍♀️"},
+                {":no_good_man:","🙅‍♂️"},
+                {":no_good_woman:","🙅‍♀️"},
+                {":ok_person:","🙆"},
+                {":ok_man:","🙆‍♂️"},
+                {":tipping_hand_person:","💁"},
+                {":tipping_hand_man:","💁‍♂️"},
+                {":tipping_hand_woman:","💁‍♀️"},
+                {":raising_hand_man:","🙋‍♂️"},
+                {":raising_hand_woman:","🙋‍♀️"},
+                {":bowing_man:","🙇‍♂️"},
+                {":bowing_woman:","🙇‍♀️"},
+                {":facepalm:","🤦"},
+                {":man_facepalming:","🤦‍♂️"},
+                {":woman_facepalming:","🤦‍♀️"},
+                {":shrug:","🤷"},
+                {":man_shrugging:","🤷‍♂️"},
+                {":woman_shrugging:","🤷‍♀️"},
+                {":man_health_worker:","👨‍⚕️"},
+                {":woman_health_worker:","👩‍⚕️"},
+                {":man_student:","👨‍🎓"},
+                {":woman_student:","👩‍🎓"},
+                {":man_teacher:","👨‍🏫"},
+                {":woman_teacher:","👩‍🏫"},
+                {":man_judge:","👨‍⚖️"},
+                {":woman_judge:","👩‍⚖️"},
+                {":man_farmer:","👨‍🌾"},
+                {":woman_farmer:","👩‍🌾"},
+                {":man_cook:","👨‍🍳"},
+                {":woman_cook:","👩‍🍳"},
+                {":man_mechanic:","👨‍🔧"},
+                {":woman_mechanic:","👩‍🔧"},
+                {":man_factory_worker:","👨‍🏭"},
+                {":woman_factory_worker:","👩‍🏭"},
+                {":man_office_worker:","👨‍💼"},
+                {":woman_office_worker:","👩‍💼"},
+                {":man_scientist:","👨‍🔬"},
+                {":woman_scientist:","👩‍🔬"},
+                {":man_technologist:","👨‍💻"},
+                {":woman_technologist:","👩‍💻"},
+                {":man_singer:","👨‍🎤"},
+                {":woman_singer:","👩‍🎤"},
+                {":man_artist:","👨‍🎨"},
+                {":woman_artist:","👩‍🎨"},
+                {":man_pilot:","👨‍✈️"},
+                {":woman_pilot:","👩‍✈️"},
+                {":man_astronaut:","👨‍🚀"},
+                {":woman_astronaut:","👩‍🚀"},
+                {":man_firefighter:","👨‍🚒"},
+                {":woman_firefighter:","👩‍🚒"},
+                {":police_officer:","👮"},
+                {":policeman:","👮‍♂️"},
+                {":policewoman:","👮‍♀️"},
+                {":detective:","🕵️"},
+                {":male_detective:","🕵️‍♂️"},
+                {":female_detective:","🕵️‍♀️"},
+                {":guard:","💂"},
+                {":guardswoman:","💂‍♀️"},
+                {":construction_worker_man:","👷‍♂️"},
+                {":construction_worker_woman:","👷‍♀️"},
+                {":prince:","🤴"},
+                {":person_with_turban:","👳"},
+                {":woman_with_turban:","👳‍♀️"},
+                {":woman_with_headscarf:","🧕"},
+                {":man_in_tuxedo:","🤵"},
+                {":pregnant_woman:","🤰"},
+                {":breast_feeding:","🤱"},
+                {":mrs_claus:","🤶"},
+                {":mage:","🧙"},
+                {":mage_man:","🧙‍♂️"},
+                {":mage_woman:","🧙‍♀️"},
+                {":fairy:","🧚"},
+                {":fairy_man:","🧚‍♂️"},
+                {":fairy_woman:","🧚‍♀️"},
+                {":vampire:","🧛"},
+                {":vampire_man:","🧛‍♂️"},
+                {":vampire_woman:","🧛‍♀️"},
+                {":merperson:","🧜"},
+                {":merman:","🧜‍♂️"},
+                {":mermaid:","🧜‍♀️"},
+                {":elf:","🧝"},
+                {":elf_man:","🧝‍♂️"},
+                {":elf_woman:","🧝‍♀️"},
+                {":genie:","🧞"},
+                {":genie_man:","🧞‍♂️"},
+                {":genie_woman:","🧞‍♀️"},
+                {":zombie:","🧟"},
+                {":zombie_man:","🧟‍♂️"},
+                {":zombie_woman:","🧟‍♀️"},
+                {":massage_man:","💆‍♂️"},
+                {":massage_woman:","💆‍♀️"},
+                {":haircut_man:","💇‍♂️"},
+                {":haircut_woman:","💇‍♀️"},
+                {":walking_man:","🚶‍♂️"},
+                {":walking_woman:","🚶‍♀️"},
+                {":running_man:","🏃‍♂️"},
+                {":running_woman:","🏃‍♀️"},
+                {":woman_dancing:","💃"},
+                {":man_dancing:","🕺"},
+                {":business_suit_levitating:","🕴️"},
+                {":dancing_men:","👯‍♂️"},
+                {":dancing_women:","👯‍♀️"},
+                {":sauna_person:","🧖"},
+                {":sauna_man:","🧖‍♂️"},
+                {":sauna_woman:","🧖‍♀️"},
+                {":climbing:","🧗"},
+                {":climbing_man:","🧗‍♂️"},
+                {":climbing_woman:","🧗‍♀️"},
+                {":person_fencing:","🤺"},
+                {":skier:","⛷️"},
+                {":golfing:","🏌️"},
+                {":golfing_man:","🏌️‍♂️"},
+                {":golfing_woman:","🏌️‍♀️"},
+                {":surfing_man:","🏄‍♂️"},
+                {":surfing_woman:","🏄‍♀️"},
+                {":rowing_man:","🚣‍♂️"},
+                {":rowing_woman:","🚣‍♀️"},
+                {":swimming_man:","🏊‍♂️"},
+                {":swimming_woman:","🏊‍♀️"},
+                {":bouncing_ball_person:","⛹️"},
+                {":bouncing_ball_man:","⛹️‍♂️"},
+                {":bouncing_ball_woman:","⛹️‍♀️"},
+                {":weight_lifting:","🏋️"},
+                {":weight_lifting_man:","🏋️‍♂️"},
+                {":weight_lifting_woman:","🏋️‍♀️"},
+                {":biking_man:","🚴‍♂️"},
+                {":biking_woman:","🚴‍♀️"},
+                {":mountain_biking_man:","🚵‍♂️"},
+                {":mountain_biking_woman:","🚵‍♀️"},
+                {":cartwheeling:","🤸"},
+                {":man_cartwheeling:","🤸‍♂️"},
+                {":woman_cartwheeling:","🤸‍♀️"},
+                {":wrestling:","🤼"},
+                {":men_wrestling:","🤼‍♂️"},
+                {":women_wrestling:","🤼‍♀️"},
+                {":water_polo:","🤽"},
+                {":man_playing_water_polo:","🤽‍♂️"},
+                {":woman_playing_water_polo:","🤽‍♀️"},
+                {":handball_person:","🤾"},
+                {":man_playing_handball:","🤾‍♂️"},
+                {":woman_playing_handball:","🤾‍♀️"},
+                {":juggling_person:","🤹"},
+                {":man_juggling:","🤹‍♂️"},
+                {":woman_juggling:","🤹‍♀️"},
+                {":lotus_position:","🧘"},
+                {":lotus_position_man:","🧘‍♂️"},
+                {":lotus_position_woman:","🧘‍♀️"},
+                {":sleeping_bed:","🛌"},
+                {":people_holding_hands:","🧑‍🤝‍🧑"},
+                {":couplekiss_man_woman:","👩‍❤️‍💋‍👨"},
+                {":couplekiss_man_man:","👨‍❤️‍💋‍👨"},
+                {":couplekiss_woman_woman:","👩‍❤️‍💋‍👩"},
+                {":couple_with_heart_woman_man:","👩‍❤️‍👨"},
+                {":couple_with_heart_man_man:","👨‍❤️‍👨"},
+                {":couple_with_heart_woman_woman:","👩‍❤️‍👩"},
+                {":family_man_woman_boy:","👨‍👩‍👦"},
+                {":family_man_woman_girl:","👨‍👩‍👧"},
+                {":family_man_woman_girl_boy:","👨‍👩‍👧‍👦"},
+                {":family_man_woman_boy_boy:","👨‍👩‍👦‍👦"},
+                {":family_man_woman_girl_girl:","👨‍👩‍👧‍👧"},
+                {":family_man_man_boy:","👨‍👨‍👦"},
+                {":family_man_man_girl:","👨‍👨‍👧"},
+                {":family_man_man_girl_boy:","👨‍👨‍👧‍👦"},
+                {":family_man_man_boy_boy:","👨‍👨‍👦‍👦"},
+                {":family_man_man_girl_girl:","👨‍👨‍👧‍👧"},
+                {":family_woman_woman_boy:","👩‍👩‍👦"},
+                {":family_woman_woman_girl:","👩‍👩‍👧"},
+                {":family_woman_woman_girl_boy:","👩‍👩‍👧‍👦"},
+                {":family_woman_woman_boy_boy:","👩‍👩‍👦‍👦"},
+                {":family_woman_woman_girl_girl:","👩‍👩‍👧‍👧"},
+                {":family_man_boy:","👨‍👦"},
+                {":family_man_boy_boy:","👨‍👦‍👦"},
+                {":family_man_girl:","👨‍👧"},
+                {":family_man_girl_boy:","👨‍👧‍👦"},
+                {":family_man_girl_girl:","👨‍👧‍👧"},
+                {":family_woman_boy:","👩‍👦"},
+                {":family_woman_boy_boy:","👩‍👦‍👦"},
+                {":family_woman_girl:","👩‍👧"},
+                {":family_woman_girl_boy:","👩‍👧‍👦"},
+                {":family_woman_girl_girl:","👩‍👧‍👧"},
+                {":speaking_head:","🗣️"},
+                {":gorilla:","🦍"},
+                {":fox_face:","🦊"},
+                {":lion:","🦁"},
+                {":unicorn:","🦄"},
+                {":zebra:","🦓"},
+                {":deer:","🦌"},
+                {":giraffe:","🦒"},
+                {":rhinoceros:","🦏"},
+                {":chipmunk:","🐿️"},
+                {":hedgehog:","🦔"},
+                {":bat:","🦇"},
+                {":turkey:","🦃"},
+                {":dove:","🕊️"},
+                {":eagle:","🦅"},
+                {":duck:","🦆"},
+                {":owl:","🦉"},
+                {":lizard:","🦎"},
+                {":sauropod:","🦕"},
+                {":t-rex:","🦖"},
+                {":shark:","🦈"},
+                {":butterfly:","🦋"},
+                {":cricket:","🦗"},
+                {":spider:","🕷️"},
+                {":spider_web:","🕸️"},
+                {":scorpion:","🦂"},
+                {":rosette:","🏵️"},
+                {":wilted_flower:","🥀"},
+                {":shamrock:","☘️"},
+                {":kiwi_fruit:","🥝"},
+                {":coconut:","🥥"},
+                {":avocado:","🥑"},
+                {":potato:","🥔"},
+                {":carrot:","🥕"},
+                {":hot_pepper:","🌶️"},
+                {":cucumber:","🥒"},
+                {":broccoli:","🥦"},
+                {":peanuts:","🥜"},
+                {":croissant:","🥐"},
+                {":baguette_bread:","🥖"},
+                {":pretzel:","🥨"},
+                {":pancakes:","🥞"},
+                {":cheese:","🧀"},
+                {":cut_of_meat:","🥩"},
+                {":bacon:","🥓"},
+                {":hotdog:","🌭"},
+                {":sandwich:","🥪"},
+                {":taco:","🌮"},
+                {":burrito:","🌯"},
+                {":stuffed_flatbread:","🥙"},
+                {":fried_egg:","🍳"},
+                {":shallow_pan_of_food:","🥘"},
+                {":bowl_with_spoon:","🥣"},
+                {":green_salad:","🥗"},
+                {":popcorn:","🍿"},
+                {":canned_food:","🥫"},
+                {":dumpling:","🥟"},
+                {":fortune_cookie:","🥠"},
+                {":takeout_box:","🥡"},
+                {":crab:","🦀"},
+                {":shrimp:","🦐"},
+                {":squid:","🦑"},
+                {":pie:","🥧"},
+                {":milk_glass:","🥛"},
+                {":champagne:","🍾"},
+                {":clinking_glasses:","🥂"},
+                {":tumbler_glass:","🥃"},
+                {":cup_with_straw:","🥤"},
+                {":chopsticks:","🥢"},
+                {":plate_with_cutlery:","🍽️"},
+                {":spoon:","🥄"},
+                {":amphora:","🏺"},
+                {":world_map:","🗺️"},
+                {":mountain_snow:","🏔️"},
+                {":mountain:","⛰️"},
+                {":camping:","🏕️"},
+                {":beach_umbrella:","🏖️"},
+                {":desert:","🏜️"},
+                {":desert_island:","🏝️"},
+                {":national_park:","🏞️"},
+                {":stadium:","🏟️"},
+                {":classical_building:","🏛️"},
+                {":building_construction:","🏗️"},
+                {":houses:","🏘️"},
+                {":derelict_house:","🏚️"},
+                {":mosque:","🕌"},
+                {":synagogue:","🕍"},
+                {":shinto_shrine:","⛩️"},
+                {":kaaba:","🕋"},
+                {":cityscape:","🏙️"},
+                {":racing_car:","🏎️"},
+                {":motorcycle:","🏍️"},
+                {":motor_scooter:","🛵"},
+                {":kick_scooter:","🛴"},
+                {":motorway:","🛣️"},
+                {":railway_track:","🛤️"},
+                {":oil_drum:","🛢️"},
+                {":stop_sign:","🛑"},
+                {":canoe:","🛶"},
+                {":passenger_ship:","🛳️"},
+                {":ferry:","⛴️"},
+                {":motor_boat:","🛥️"},
+                {":small_airplane:","🛩️"},
+                {":flight_departure:","🛫"},
+                {":flight_arrival:","🛬"},
+                {":artificial_satellite:","🛰️"},
+                {":flying_saucer:","🛸"},
+                {":bellhop_bell:","🛎️"},
+                {":stopwatch:","⏱️"},
+                {":timer_clock:","⏲️"},
+                {":mantelpiece_clock:","🕰️"},
+                {":thermometer:","🌡️"},
+                {":cloud_with_lightning_and_rain:","⛈️"},
+                {":sun_behind_small_cloud:","🌤️"},
+                {":sun_behind_large_cloud:","🌥️"},
+                {":sun_behind_rain_cloud:","🌦️"},
+                {":cloud_with_rain:","🌧️"},
+                {":cloud_with_snow:","🌨️"},
+                {":cloud_with_lightning:","🌩️"},
+                {":tornado:","🌪️"},
+                {":fog:","🌫️"},
+                {":wind_face:","🌬️"},
+                {":open_umbrella:","☂️"},
+                {":parasol_on_ground:","⛱️"},
+                {":snowman_with_snow:","☃️"},
+                {":comet:","☄️"},
+                {":reminder_ribbon:","🎗️"},
+                {":tickets:","🎟️"},
+                {":medal_military:","🎖️"},
+                {":medal_sports:","🏅"},
+                {":1st_place_medal:","🥇"},
+                {":2nd_place_medal:","🥈"},
+                {":3rd_place_medal:","🥉"},
+                {":volleyball:","🏐"},
+                {":cricket_game:","🏏"},
+                {":field_hockey:","🏑"},
+                {":ice_hockey:","🏒"},
+                {":ping_pong:","🏓"},
+                {":badminton:","🏸"},
+                {":boxing_glove:","🥊"},
+                {":martial_arts_uniform:","🥋"},
+                {":goal_net:","🥅"},
+                {":ice_skate:","⛸️"},
+                {":sled:","🛷"},
+                {":curling_stone:","🥌"},
+                {":joystick:","🕹️"},
+                {":chess_pawn:","♟️"},
+                {":framed_picture:","🖼️"},
+                {":dark_sunglasses:","🕶️"},
+                {":scarf:","🧣"},
+                {":gloves:","🧤"},
+                {":coat:","🧥"},
+                {":socks:","🧦"},
+                {":shopping:","🛍️"},
+                {":billed_cap:","🧢"},
+                {":rescue_worker_helmet:","⛑️"},
+                {":prayer_beads:","📿"},
+                {":studio_microphone:","🎙️"},
+                {":level_slider:","🎚️"},
+                {":control_knobs:","🎛️"},
+                {":drum:","🥁"},
+                {":desktop_computer:","🖥️"},
+                {":printer:","🖨️"},
+                {":keyboard:","⌨️"},
+                {":computer_mouse:","🖱️"},
+                {":trackball:","🖲️"},
+                {":film_strip:","🎞️"},
+                {":film_projector:","📽️"},
+                {":camera_flash:","📸"},
+                {":candle:","🕯️"},
+                {":newspaper_roll:","🗞️"},
+                {":label:","🏷️"},
+                {":ballot_box:","🗳️"},
+                {":fountain_pen:","🖋️"},
+                {":pen:","🖊️"},
+                {":paintbrush:","🖌️"},
+                {":crayon:","🖍️"},
+                {":card_index_dividers:","🗂️"},
+                {":spiral_notepad:","🗒️"},
+                {":spiral_calendar:","🗓️"},
+                {":paperclips:","🖇️"},
+                {":card_file_box:","🗃️"},
+                {":file_cabinet:","🗄️"},
+                {":wastebasket:","🗑️"},
+                {":old_key:","🗝️"},
+                {":pick:","⛏️"},
+                {":hammer_and_pick:","⚒️"},
+                {":hammer_and_wrench:","🛠️"},
+                {":dagger:","🗡️"},
+                {":crossed_swords:","⚔️"},
+                {":bow_and_arrow:","🏹"},
+                {":shield:","🛡️"},
+                {":gear:","⚙️"},
+                {":clamp:","🗜️"},
+                {":balance_scale:","⚖️"},
+                {":chains:","⛓️"},
+                {":alembic:","⚗️"},
+                {":bed:","🛏️"},
+                {":couch_and_lamp:","🛋️"},
+                {":shopping_cart:","🛒"},
+                {":coffin:","⚰️"},
+                {":funeral_urn:","⚱️"},
+                {":radioactive:","☢️"},
+                {":biohazard:","☣️"},
+                {":place_of_worship:","🛐"},
+                {":atom_symbol:","⚛️"},
+                {":om:","🕉️"},
+                {":star_of_david:","✡️"},
+                {":wheel_of_dharma:","☸️"},
+                {":yin_yang:","☯️"},
+                {":latin_cross:","✝️"},
+                {":orthodox_cross:","☦️"},
+                {":star_and_crescent:","☪️"},
+                {":peace_symbol:","☮️"},
+                {":menorah:","🕎"},
+                {":next_track_button:","⏭️"},
+                {":play_or_pause_button:","⏯️"},
+                {":previous_track_button:","⏮️"},
+                {":pause_button:","⏸️"},
+                {":stop_button:","⏹️"},
+                {":record_button:","⏺️"},
+                {":eject_button:","⏏️"},
+                {":female_sign:","♀️"},
+                {":male_sign:","♂️"},
+                {":medical_symbol:","⚕️"},
+                {":infinity:","♾️"},
+                {":fleur_de_lis:","⚜️"},
+                {":asterisk:","*️⃣"},
+                {":black_flag:","🏴"},
+                {":white_flag:","🏳️"},
+                {":rainbow_flag:","🏳️‍🌈"},
+                {":pirate_flag:","🏴‍☠️"},
+                {":ascension_island:","🇦🇨"},
+                {":andorra:","🇦🇩"},
+                {":united_arab_emirates:","🇦🇪"},
+                {":afghanistan:","🇦🇫"},
+                {":antigua_barbuda:","🇦🇬"},
+                {":anguilla:","🇦🇮"},
+                {":albania:","🇦🇱"},
+                {":armenia:","🇦🇲"},
+                {":angola:","🇦🇴"},
+                {":antarctica:","🇦🇶"},
+                {":argentina:","🇦🇷"},
+                {":american_samoa:","🇦🇸"},
+                {":austria:","🇦🇹"},
+                {":australia:","🇦🇺"},
+                {":aruba:","🇦🇼"},
+                {":aland_islands:","🇦🇽"},
+                {":azerbaijan:","🇦🇿"},
+                {":bosnia_herzegovina:","🇧🇦"},
+                {":barbados:","🇧🇧"},
+                {":bangladesh:","🇧🇩"},
+                {":belgium:","🇧🇪"},
+                {":burkina_faso:","🇧🇫"},
+                {":bulgaria:","🇧🇬"},
+                {":bahrain:","🇧🇭"},
+                {":burundi:","🇧🇮"},
+                {":benin:","🇧🇯"},
+                {":st_barthelemy:","🇧🇱"},
+                {":bermuda:","🇧🇲"},
+                {":brunei:","🇧🇳"},
+                {":bolivia:","🇧🇴"},
+                {":caribbean_netherlands:","🇧🇶"},
+                {":brazil:","🇧🇷"},
+                {":bahamas:","🇧🇸"},
+                {":bhutan:","🇧🇹"},
+                {":bouvet_island:","🇧🇻"},
+                {":botswana:","🇧🇼"},
+                {":belarus:","🇧🇾"},
+                {":belize:","🇧🇿"},
+                {":canada:","🇨🇦"},
+                {":cocos_islands:","🇨🇨"},
+                {":congo_kinshasa:","🇨🇩"},
+                {":central_african_republic:","🇨🇫"},
+                {":congo_brazzaville:","🇨🇬"},
+                {":switzerland:","🇨🇭"},
+                {":cote_divoire:","🇨🇮"},
+                {":cook_islands:","🇨🇰"},
+                {":chile:","🇨🇱"},
+                {":cameroon:","🇨🇲"},
+                {":colombia:","🇨🇴"},
+                {":clipperton_island:","🇨🇵"},
+                {":costa_rica:","🇨🇷"},
+                {":cuba:","🇨🇺"},
+                {":cape_verde:","🇨🇻"},
+                {":curacao:","🇨🇼"},
+                {":christmas_island:","🇨🇽"},
+                {":cyprus:","🇨🇾"},
+                {":czech_republic:","🇨🇿"},
+                {":diego_garcia:","🇩🇬"},
+                {":djibouti:","🇩🇯"},
+                {":denmark:","🇩🇰"},
+                {":dominica:","🇩🇲"},
+                {":dominican_republic:","🇩🇴"},
+                {":algeria:","🇩🇿"},
+                {":ceuta_melilla:","🇪🇦"},
+                {":ecuador:","🇪🇨"},
+                {":estonia:","🇪🇪"},
+                {":egypt:","🇪🇬"},
+                {":western_sahara:","🇪🇭"},
+                {":eritrea:","🇪🇷"},
+                {":ethiopia:","🇪🇹"},
+                {":eu:","🇪🇺"},
+                {":finland:","🇫🇮"},
+                {":fiji:","🇫🇯"},
+                {":falkland_islands:","🇫🇰"},
+                {":micronesia:","🇫🇲"},
+                {":faroe_islands:","🇫🇴"},
+                {":gabon:","🇬🇦"},
+                {":grenada:","🇬🇩"},
+                {":georgia:","🇬🇪"},
+                {":french_guiana:","🇬🇫"},
+                {":guernsey:","🇬🇬"},
+                {":ghana:","🇬🇭"},
+                {":gibraltar:","🇬🇮"},
+                {":greenland:","🇬🇱"},
+                {":gambia:","🇬🇲"},
+                {":guinea:","🇬🇳"},
+                {":guadeloupe:","🇬🇵"},
+                {":equatorial_guinea:","🇬🇶"},
+                {":greece:","🇬🇷"},
+                {":south_georgia_south_sandwich_islands:","🇬🇸"},
+                {":guatemala:","🇬🇹"},
+                {":guam:","🇬🇺"},
+                {":guinea_bissau:","🇬🇼"},
+                {":guyana:","🇬🇾"},
+                {":hong_kong:","🇭🇰"},
+                {":heard_mcdonald_islands:","🇭🇲"},
+                {":honduras:","🇭🇳"},
+                {":croatia:","🇭🇷"},
+                {":haiti:","🇭🇹"},
+                {":hungary:","🇭🇺"},
+                {":canary_islands:","🇮🇨"},
+                {":indonesia:","🇮🇩"},
+                {":ireland:","🇮🇪"},
+                {":israel:","🇮🇱"},
+                {":isle_of_man:","🇮🇲"},
+                {":india:","🇮🇳"},
+                {":british_indian_ocean_territory:","🇮🇴"},
+                {":iraq:","🇮🇶"},
+                {":iran:","🇮🇷"},
+                {":iceland:","🇮🇸"},
+                {":jersey:","🇯🇪"},
+                {":jamaica:","🇯🇲"},
+                {":jordan:","🇯🇴"},
+                {":kenya:","🇰🇪"},
+                {":kyrgyzstan:","🇰🇬"},
+                {":cambodia:","🇰🇭"},
+                {":kiribati:","🇰🇮"},
+                {":comoros:","🇰🇲"},
+                {":st_kitts_nevis:","🇰🇳"},
+                {":north_korea:","🇰🇵"},
+                {":kuwait:","🇰🇼"},
+                {":cayman_islands:","🇰🇾"},
+                {":kazakhstan:","🇰🇿"},
+                {":laos:","🇱🇦"},
+                {":lebanon:","🇱🇧"},
+                {":st_lucia:","🇱🇨"},
+                {":liechtenstein:","🇱🇮"},
+                {":sri_lanka:","🇱🇰"},
+                {":liberia:","🇱🇷"},
+                {":lesotho:","🇱🇸"},
+                {":lithuania:","🇱🇹"},
+                {":luxembourg:","🇱🇺"},
+                {":latvia:","🇱🇻"},
+                {":libya:","🇱🇾"},
+                {":morocco:","🇲🇦"},
+                {":monaco:","🇲🇨"},
+                {":moldova:","🇲🇩"},
+                {":montenegro:","🇲🇪"},
+                {":st_martin:","🇲🇫"},
+                {":madagascar:","🇲🇬"},
+                {":marshall_islands:","🇲🇭"},
+                {":macedonia:","🇲🇰"},
+                {":mali:","🇲🇱"},
+                {":myanmar:","🇲🇲"},
+                {":mongolia:","🇲🇳"},
+                {":macau:","🇲🇴"},
+                {":northern_mariana_islands:","🇲🇵"},
+                {":martinique:","🇲🇶"},
+                {":mauritania:","🇲🇷"},
+                {":montserrat:","🇲🇸"},
+                {":malta:","🇲🇹"},
+                {":mauritius:","🇲🇺"},
+                {":maldives:","🇲🇻"},
+                {":malawi:","🇲🇼"},
+                {":mexico:","🇲🇽"},
+                {":malaysia:","🇲🇾"},
+                {":mozambique:","🇲🇿"},
+                {":namibia:","🇳🇦"},
+                {":new_caledonia:","🇳🇨"},
+                {":niger:","🇳🇪"},
+                {":norfolk_island:","🇳🇫"},
+                {":nigeria:","🇳🇬"},
+                {":nicaragua:","🇳🇮"},
+                {":netherlands:","🇳🇱"},
+                {":norway:","🇳🇴"},
+                {":nepal:","🇳🇵"},
+                {":nauru:","🇳🇷"},
+                {":niue:","🇳🇺"},
+                {":new_zealand:","🇳🇿"},
+                {":oman:","🇴🇲"},
+                {":panama:","🇵🇦"},
+                {":peru:","🇵🇪"},
+                {":french_polynesia:","🇵🇫"},
+                {":papua_new_guinea:","🇵🇬"},
+                {":philippines:","🇵🇭"},
+                {":pakistan:","🇵🇰"},
+                {":poland:","🇵🇱"},
+                {":st_pierre_miquelon:","🇵🇲"},
+                {":pitcairn_islands:","🇵🇳"},
+                {":puerto_rico:","🇵🇷"},
+                {":palestinian_territories:","🇵🇸"},
+                {":portugal:","🇵🇹"},
+                {":palau:","🇵🇼"},
+                {":paraguay:","🇵🇾"},
+                {":qatar:","🇶🇦"},
+                {":reunion:","🇷🇪"},
+                {":romania:","🇷🇴"},
+                {":serbia:","🇷🇸"},
+                {":rwanda:","🇷🇼"},
+                {":saudi_arabia:","🇸🇦"},
+                {":solomon_islands:","🇸🇧"},
+                {":seychelles:","🇸🇨"},
+                {":sudan:","🇸🇩"},
+                {":sweden:","🇸🇪"},
+                {":singapore:","🇸🇬"},
+                {":st_helena:","🇸🇭"},
+                {":slovenia:","🇸🇮"},
+                {":svalbard_jan_mayen:","🇸🇯"},
+                {":slovakia:","🇸🇰"},
+                {":sierra_leone:","🇸🇱"},
+                {":san_marino:","🇸🇲"},
+                {":senegal:","🇸🇳"},
+                {":somalia:","🇸🇴"},
+                {":suriname:","🇸🇷"},
+                {":south_sudan:","🇸🇸"},
+                {":sao_tome_principe:","🇸🇹"},
+                {":el_salvador:","🇸🇻"},
+                {":sint_maarten:","🇸🇽"},
+                {":syria:","🇸🇾"},
+                {":swaziland:","🇸🇿"},
+                {":tristan_da_cunha:","🇹🇦"},
+                {":turks_caicos_islands:","🇹🇨"},
+                {":chad:","🇹🇩"},
+                {":french_southern_territories:","🇹🇫"},
+                {":togo:","🇹🇬"},
+                {":thailand:","🇹🇭"},
+                {":tajikistan:","🇹🇯"},
+                {":tokelau:","🇹🇰"},
+                {":timor_leste:","🇹🇱"},
+                {":turkmenistan:","🇹🇲"},
+                {":tunisia:","🇹🇳"},
+                {":tonga:","🇹🇴"},
+                {":tr:","🇹🇷"},
+                {":trinidad_tobago:","🇹🇹"},
+                {":tuvalu:","🇹🇻"},
+                {":taiwan:","🇹🇼"},
+                {":tanzania:","🇹🇿"},
+                {":ukraine:","🇺🇦"},
+                {":uganda:","🇺🇬"},
+                {":us_outlying_islands:","🇺🇲"},
+                {":united_nations:","🇺🇳"},
+                {":uruguay:","🇺🇾"},
+                {":uzbekistan:","🇺🇿"},
+                {":vatican_city:","🇻🇦"},
+                {":st_vincent_grenadines:","🇻🇨"},
+                {":venezuela:","🇻🇪"},
+                {":british_virgin_islands:","🇻🇬"},
+                {":us_virgin_islands:","🇻🇮"},
+                {":vietnam:","🇻🇳"},
+                {":vanuatu:","🇻🇺"},
+                {":wallis_futuna:","🇼🇫"},
+                {":samoa:","🇼🇸"},
+                {":kosovo:","🇽🇰"},
+                {":yemen:","🇾🇪"},
+                {":mayotte:","🇾🇹"},
+                {":south_africa:","🇿🇦"},
+                {":zambia:","🇿🇲"},
+                {":zimbabwe:","🇿🇼"}
             };
 
             SmileyToEmojiDefault = new Dictionary<string, string>()
@@ -1039,31 +1766,31 @@ namespace Markdig.Extensions.Emoji
                 {"<=", ":custom_arrow_left_strong:" },
                 {"=>", ":custom_arrow_right_strong:" },
                 {"<=>", ":custom_arrow_left_right_strong:" },
-            };
-
-            // Build Emoji and Smiley CompactPrefixTree
-            EmojiPrefixTreeDefault = new CompactPrefixTree<string>(EmojiToUnicodeDefault);
-
-            int jointCount = EmojiToUnicodeDefault.Count + SmileyToEmojiDefault.Count;
-            // Count * 2 seems to be a good fit for the data set
-            EmojiSmileyPrefixTreeDefault = new CompactPrefixTree<string>(jointCount, jointCount * 2, jointCount * 2);
-
-            // This is not the best data set for the prefix tree as it will have to check the first character linearly
-            // A work-around would require a bunch of substrings / removing the leading ':' from emojis, neither one is pretty
-            // This way we sacrifice a few microseconds for not introducing breaking changes, emojis aren't all that common anyhow
-
+            };
+
+            // Build Emoji and Smiley CompactPrefixTree
+            EmojiPrefixTreeDefault = new CompactPrefixTree<string>(EmojiToUnicodeDefault);
+
+            int jointCount = EmojiToUnicodeDefault.Count + SmileyToEmojiDefault.Count;
+            // Count * 2 seems to be a good fit for the data set
+            EmojiSmileyPrefixTreeDefault = new CompactPrefixTree<string>(jointCount, jointCount * 2, jointCount * 2);
+
+            // This is not the best data set for the prefix tree as it will have to check the first character linearly
+            // A work-around would require a bunch of substrings / removing the leading ':' from emojis, neither one is pretty
+            // This way we sacrifice a few microseconds for not introducing breaking changes, emojis aren't all that common anyhow
+
             var firstChars = new HashSet<char> { ':' };
-            foreach (var emoji in EmojiToUnicodeDefault)
+            foreach (var emoji in EmojiToUnicodeDefault)
                 EmojiSmileyPrefixTreeDefault.Add(emoji);
-            foreach (var smiley in SmileyToEmojiDefault)
-            {
-                if (!EmojiToUnicodeDefault.TryGetValue(smiley.Value, out string unicode))
-                    throw new ArgumentException("Invalid smiley target: {0} is not present in the emoji dictionary", smiley.Value);
-
-                firstChars.Add(smiley.Key[0]);
-
-                if (!EmojiSmileyPrefixTreeDefault.TryAdd(smiley.Key, unicode))
-                    throw new ArgumentException("Smiley {0} is already present in the Emoji dictionary", smiley.Key);
+            foreach (var smiley in SmileyToEmojiDefault)
+            {
+                if (!EmojiToUnicodeDefault.TryGetValue(smiley.Value, out string unicode))
+                    throw new ArgumentException("Invalid smiley target: {0} is not present in the emoji dictionary", smiley.Value);
+
+                firstChars.Add(smiley.Key[0]);
+
+                if (!EmojiSmileyPrefixTreeDefault.TryAdd(smiley.Key, unicode))
+                    throw new ArgumentException("Smiley {0} is already present in the Emoji dictionary", smiley.Key);
             }
 
             EmojiOpeningCharactersDefault = new[] { ':' };

src/Markdig/Extensions/GenericAttributes/GenericAttributesExtension.cs

@@ -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.
 
@@ -16,7 +16,7 @@ namespace Markdig.Extensions.GenericAttributes
     /// Extension that allows to attach HTML attributes to the previous <see cref="Inline"/> or current <see cref="Block"/>.
     /// This extension should be enabled last after enabling other extensions.
     /// </summary>
-    /// <seealso cref="Markdig.IMarkdownExtension" />
+    /// <seealso cref="IMarkdownExtension" />
     public class GenericAttributesExtension : IMarkdownExtension
     {
         public void Setup(MarkdownPipelineBuilder pipeline)
@@ -29,8 +29,7 @@ namespace Markdig.Extensions.GenericAttributes
             // Plug into all IAttributesParseable
             foreach (var parser in pipeline.BlockParsers)
             {
-                var attributesParseable = parser as IAttributesParseable;
-                if (attributesParseable != null)
+                if (parser is IAttributesParseable attributesParseable)
                 {
                     attributesParseable.TryParseAttributes = TryProcessAttributesForHeading;
                 }
@@ -53,8 +52,7 @@ namespace Markdig.Extensions.GenericAttributes
                     var copy = line;
                     copy.Start = indexOfAttributes;
                     var startOfAttributes = copy.Start;
-                    HtmlAttributes attributes;
-                    if (GenericAttributesParser.TryParse(ref copy, out attributes))
+                    if (GenericAttributesParser.TryParse(ref copy, out HtmlAttributes attributes))
                     {
                         var htmlAttributes = block.GetAttributes();
                         attributes.CopyTo(htmlAttributes);

src/Markdig/Extensions/GenericAttributes/GenericAttributesParser.cs

@@ -14,7 +14,7 @@ namespace Markdig.Extensions.GenericAttributes
     /// <summary>
     /// An inline parser used to parse a HTML attributes that can be attached to the previous <see cref="Inline"/> or current <see cref="Block"/>.
     /// </summary>
-    /// <seealso cref="Markdig.Parsers.InlineParser" />
+    /// <seealso cref="InlineParser" />
     public class GenericAttributesParser : InlineParser
     {
         /// <summary>
@@ -27,9 +27,8 @@ namespace Markdig.Extensions.GenericAttributes
 
         public override bool Match(InlineProcessor processor, ref StringSlice slice)
         {
-            HtmlAttributes attributes;
             var startPosition = slice.Start;
-            if (TryParse(ref slice, out attributes))
+            if (TryParse(ref slice, out HtmlAttributes attributes))
             {
                 var inline = processor.Inline;
 
@@ -50,8 +49,10 @@ namespace Markdig.Extensions.GenericAttributes
 
                 // If the current block is a Paragraph, but only the HtmlAttributes is used,
                 // Try to attach the attributes to the following block
-                var paragraph = objectToAttach as ParagraphBlock;
-                if (paragraph != null && paragraph.Inline.FirstChild == null && processor.Inline == null && slice.IsEmptyOrWhitespace())
+                if (objectToAttach is ParagraphBlock paragraph &&
+                    paragraph.Inline.FirstChild == null &&
+                    processor.Inline == null &&
+                    slice.IsEmptyOrWhitespace())
                 {
                     var parent = paragraph.Parent;
                     var indexOfParagraph = parent.IndexOf(paragraph);
@@ -67,9 +68,7 @@ namespace Markdig.Extensions.GenericAttributes
                 attributes.CopyTo(currentHtmlAttributes, true, false);
 
                 // Update the position of the attributes
-                int line;
-                int column;
-                currentHtmlAttributes.Span.Start = processor.GetSourcePosition(startPosition, out line, out column);
+                currentHtmlAttributes.Span.Start = processor.GetSourcePosition(startPosition, out int line, out int column);
                 currentHtmlAttributes.Line = line;
                 currentHtmlAttributes.Column = column;
                 currentHtmlAttributes.Span.End = currentHtmlAttributes.Span.Start + slice.Start - startPosition - 1;
@@ -223,6 +222,7 @@ namespace Markdig.Extensions.GenericAttributes
                     {
                         // Parse until we match a space or a special html character
                         startValue = line.Start;
+                        bool valid = false;
                         while (true)
                         {
                             if (c == '\0')
@@ -234,9 +234,10 @@ namespace Markdig.Extensions.GenericAttributes
                                 break;
                             }
                             c = line.NextChar();
+                            valid = true;
                         }
                         endValue = line.Start - 1;
-                        if (endValue == startValue)
+                        if (!valid)
                         {
                             break;
                         }

src/Markdig/Extensions/SmartyPants/HtmlSmartyPantRenderer.cs

@@ -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.
 using System;
@@ -10,7 +10,7 @@ namespace Markdig.Extensions.SmartyPants
     /// <summary>
     /// A HTML renderer for a <see cref="SmartyPant"/>.
     /// </summary>
-    /// <seealso cref="Markdig.Renderers.Html.HtmlObjectRenderer{SmartyPant}" />
+    /// <seealso cref="HtmlObjectRenderer{SmartyPant}" />
     public class HtmlSmartyPantRenderer : HtmlObjectRenderer<SmartyPant>
     {
         private static readonly SmartyPantOptions DefaultOptions = new SmartyPantOptions();
@@ -21,17 +21,15 @@ namespace Markdig.Extensions.SmartyPants
         /// Initializes a new instance of the <see cref="HtmlSmartyPantRenderer"/> class.
         /// </summary>
         /// <param name="options">The options.</param>
-        /// <exception cref="System.ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException"></exception>
         public HtmlSmartyPantRenderer(SmartyPantOptions options)
         {
-            if (options == null) throw new ArgumentNullException(nameof(options));
-            this.options = options;
+            this.options = options ?? throw new ArgumentNullException(nameof(options));
         }
 
         protected override void Write(HtmlRenderer renderer, SmartyPant obj)
         {
-            string text;
-            if (!options.Mapping.TryGetValue(obj.Type, out text))
+            if (!options.Mapping.TryGetValue(obj.Type, out string text))
             {
                 DefaultOptions.Mapping.TryGetValue(obj.Type, out text);
             }

src/Markdig/Extensions/SmartyPants/SmartyPant.cs

@@ -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.
 using System.Diagnostics;
@@ -45,5 +45,15 @@ namespace Markdig.Extensions.SmartyPants
             }
             return OpeningCharacter != 0 ? OpeningCharacter.ToString() : string.Empty;
         }
+
+        public LiteralInline AsLiteralInline()
+        {
+            return new LiteralInline(ToString())
+            {
+                Span = Span,
+                Line = Line,
+                Column = Column,
+            };
+        }
     }
 }

src/Markdig/Extensions/SmartyPants/SmartyPantsExtension.cs

@@ -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.
 
@@ -37,8 +37,7 @@ namespace Markdig.Extensions.SmartyPants
 
         public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
         {
-            var htmlRenderer = renderer as HtmlRenderer;
-            if (htmlRenderer != null)
+            if (renderer is HtmlRenderer htmlRenderer)
             {
                 if (!htmlRenderer.ObjectRenderers.Contains<HtmlSmartyPantRenderer>())
                 {

src/Markdig/Extensions/SmartyPants/SmartyPantsInlineParser.cs

@@ -49,7 +49,7 @@ namespace Markdig.Extensions.SmartyPants
             {
                 case '\'':
                     type = SmartyPantType.Quote; // We will resolve them at the end of parsing all inlines
-                    if (slice.PeekChar(1) == '\'')
+                    if (slice.PeekChar() == '\'')
                     {
                         slice.NextChar();
                         type = SmartyPantType.DoubleQuote; // We will resolve them at the end of parsing all inlines
@@ -95,9 +95,7 @@ namespace Markdig.Extensions.SmartyPants
             // Skip char
             c = slice.NextChar();
 
-            bool canOpen;
-            bool canClose;
-            CharHelper.CheckOpenCloseDelimiter(pc, c, false, out canOpen, out canClose);
+            CharHelper.CheckOpenCloseDelimiter(pc, c, false, out bool canOpen, out bool canClose);
 
             bool postProcess = false;
 
@@ -156,11 +154,9 @@ namespace Markdig.Extensions.SmartyPants
             }
 
             // Create the SmartyPant inline
-            int line;
-            int column;
             var pant = new SmartyPant()
             {
-                Span = {Start = processor.GetSourcePosition(startingPosition, out line, out column)},
+                Span = { Start = processor.GetSourcePosition(startingPosition, out int line, out int column) },
                 Line = line,
                 Column = column,
                 OpeningCharacter = openingChar,
@@ -195,96 +191,90 @@ namespace Markdig.Extensions.SmartyPants
             return quotePants;
         }
 
+        private readonly struct Opener
+        {
+            public readonly int Type;
+            public readonly int Index;
+
+            public Opener(int type, int index)
+            {
+                Type = type;
+                Index = index;
+            }
+        }
+
         private void BlockOnProcessInlinesEnd(InlineProcessor processor, Inline inline)
         {
             processor.Block.ProcessInlinesEnd -= BlockOnProcessInlinesEnd;
 
             var pants = (ListSmartyPants) processor.ParserStates[Index];
 
-            // We only change quote into left or right quotes if we find proper balancing
-            var previousIndices = new int[3] {-1, -1, -1};
+            Stack<Opener> openers = new Stack<Opener>(4);
 
             for (int i = 0; i < pants.Count; i++)
             {
                 var quote = pants[i];
+                var quoteType = quote.Type;
 
-                int currentTypeIndex = -1;
-                SmartyPantType expectedLeftQuote = 0;
-                SmartyPantType expectedRightQuote = 0;
+                int type;
+                bool isLeft;
 
-                if (quote.Type == SmartyPantType.LeftQuote || quote.Type == SmartyPantType.RightQuote)
+                if (quoteType == SmartyPantType.LeftQuote || quoteType == SmartyPantType.RightQuote)
                 {
-                    currentTypeIndex = 0;
-                    expectedLeftQuote = SmartyPantType.LeftQuote;
-                    expectedRightQuote = SmartyPantType.RightQuote;
+                    type = 0;
+                    isLeft = quoteType == SmartyPantType.LeftQuote;
                 }
-                else if (quote.Type == SmartyPantType.LeftDoubleQuote || quote.Type == SmartyPantType.RightDoubleQuote)
+                else if (quoteType == SmartyPantType.LeftDoubleQuote || quoteType == SmartyPantType.RightDoubleQuote)
                 {
-                    currentTypeIndex = 1;
-                    expectedLeftQuote = SmartyPantType.LeftDoubleQuote;
-                    expectedRightQuote = SmartyPantType.RightDoubleQuote;
+                    type = 1;
+                    isLeft = quoteType == SmartyPantType.LeftDoubleQuote;
                 }
-                else if (quote.Type == SmartyPantType.LeftAngleQuote || quote.Type == SmartyPantType.RightAngleQuote)
+                else if (quoteType == SmartyPantType.LeftAngleQuote || quoteType == SmartyPantType.RightAngleQuote)
                 {
-                    currentTypeIndex = 2;
-                    expectedLeftQuote = SmartyPantType.LeftAngleQuote;
-                    expectedRightQuote = SmartyPantType.RightAngleQuote;
-                }
-
-                if (currentTypeIndex < 0)
-                {
-                    continue;
-                }
-
-                int previousIndex = previousIndices[currentTypeIndex];
-                var previousQuote = previousIndex >= 0 ? pants[previousIndex] : null;
-                if (previousQuote == null)
-                {
-                    if (quote.Type == expectedLeftQuote)
-                    {
-                        previousIndices[currentTypeIndex] = i;
-                    }
+                    type = 2;
+                    isLeft = quoteType == SmartyPantType.LeftAngleQuote;
                 }
                 else
                 {
-                    if (quote.Type == expectedRightQuote)
-                    {
-                        // Replace all intermediate unmatched left or right SmartyPants to their literal equivalent
-                        pants.RemoveAt(i);
-                        i--;
-                        for (int j = i; j > previousIndex; j--)
-                        {
-                            var toReplace = pants[j];
-                            pants.RemoveAt(j);
-                            toReplace.ReplaceBy(new LiteralInline(toReplace.ToString())
-                            {
-                                Span = toReplace.Span,
-                                Line = toReplace.Line,
-                                Column = toReplace.Column,
-                            });
-                            i--;
-                        }
+                    quote.ReplaceBy(quote.AsLiteralInline());
+                    continue;
+                }
 
-                        // If we matched, we remove left/right quotes from the list
-                        pants.RemoveAt(previousIndex);
-                        previousIndices[currentTypeIndex] = -1;
-                    }
-                    else
+                if (isLeft)
+                {
+                    openers.Push(new Opener(type, i));
+                }
+                else
+                {
+                    bool found = false;
+
+                    while (openers.Count > 0)
                     {
-                        previousIndices[currentTypeIndex] = i;
+                        Opener opener = openers.Pop();
+                        var previousQuote = pants[opener.Index];
+
+                        if (opener.Type == type)
+                        {
+                            found = true;
+                            break;
+                        }
+                        else
+                        {
+                            previousQuote.ReplaceBy(previousQuote.AsLiteralInline());
+                        }
+                    }
+
+                    if (!found)
+                    {
+                        quote.ReplaceBy(quote.AsLiteralInline());
                     }
                 }
             }
 
-            // If we have any quotes lefts, replace them by there literal equivalent
-            foreach (var quote in pants)
+            foreach (var opener in openers)
             {
-                quote.ReplaceBy(new LiteralInline(quote.ToString())
-                {
-                    Span = quote.Span,
-                    Line = quote.Line,
-                    Column = quote.Column,
-                });
+                var quote = pants[opener.Index];
+                quote.ReplaceBy(quote.AsLiteralInline());
             }
 
             pants.Clear();
@@ -294,8 +284,7 @@ namespace Markdig.Extensions.SmartyPants
             bool isFinalProcessing)
         {
             // Don't try to process anything if there are no dash
-            var quotePants = state.ParserStates[Index] as ListSmartyPants;
-            if (quotePants == null || !quotePants.HasDash)
+            if (!(state.ParserStates[Index] is ListSmartyPants quotePants) || !quotePants.HasDash)
             {
                 return true;
             }
@@ -309,10 +298,8 @@ namespace Markdig.Extensions.SmartyPants
                 {
                     var next = child.NextSibling;
 
-                    if (child is LiteralInline)
+                    if (child is LiteralInline literal)
                     {
-                        var literal = (LiteralInline) child;
-
                         var startIndex = 0;
 
                         var indexOfDash = literal.Content.IndexOf("--", startIndex);
@@ -372,7 +359,7 @@ namespace Markdig.Extensions.SmartyPants
         }
 
 
-        private class ListSmartyPants : List<SmartyPant>
+        private sealed class ListSmartyPants : List<SmartyPant>
         {
             public bool HasDash { get; set; }
         }

src/Markdig/Extensions/Tables/GridTableParser.cs

@@ -1,4 +1,4 @@
-
+
 // 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.
@@ -138,7 +138,7 @@ namespace Markdig.Extensions.Tables
         private static void SetRowSpanState(List<GridTableState.ColumnSlice> columns, StringSlice line, out bool isHeaderRow, out bool hasRowSpan)
         {
             var lineStart = line.Start;
-            isHeaderRow = line.PeekChar(1) == '=' || line.PeekChar(2) == '=';
+            isHeaderRow = line.PeekChar() == '=' || line.PeekChar(2) == '=';
             hasRowSpan = false;
             foreach (var columnSlice in columns)
             {

src/Markdig/Extensions/Tables/GridTableState.cs

@@ -10,7 +10,7 @@ namespace Markdig.Extensions.Tables
     /// <summary>
     /// Internal state used by the <see cref="GridTableParser"/>
     /// </summary>
-    internal class GridTableState
+    internal sealed class GridTableState
     {
         public int Start { get; set; }
 

src/Markdig/Helpers/CharHelper.cs

@@ -36,7 +36,8 @@ using System;
 using System.Globalization;
 using System.Collections.Generic;
 using System.Runtime.CompilerServices;
-
+using System.Diagnostics;
+
 namespace Markdig.Helpers
 {
     /// <summary>
@@ -130,9 +131,9 @@ namespace Markdig.Helpers
             int result = 0;
             for (int i = 0; i < text.Length; i++)
             {
-                var character = Char.ToUpperInvariant(text[i]);
+                var character = char.ToUpperInvariant(text[i]);
                 var candidate = romanMap[character];
-                if (i + 1 < text.Length && candidate < romanMap[Char.ToUpperInvariant(text[i + 1])])
+                if (i + 1 < text.Length && candidate < romanMap[char.ToUpperInvariant(text[i + 1])])
                 {
                     result -= candidate;
                 }
@@ -147,7 +148,9 @@ namespace Markdig.Helpers
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public static int AddTab(int column)
         {
-            return ((column + TabSize) / TabSize) * TabSize;
+            // return ((column + TabSize) / TabSize) * TabSize;
+            Debug.Assert(TabSize == 4, "Change the AddTab implementation if TabSize is no longer a power of 2");
+            return TabSize + (column & ~(TabSize - 1));
         }
 
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
@@ -180,7 +183,7 @@ namespace Markdig.Helpers
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public static bool IsControl(this char c)
         {
-            return c < ' ' || Char.IsControl(c);
+            return c < ' ' || char.IsControl(c);
         }
 
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
@@ -193,7 +196,7 @@ namespace Markdig.Helpers
         //[MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public static bool IsWhiteSpaceOrZero(this char c)
         {
-            return IsWhitespace(c) || IsZero(c);
+            return IsZero(c) || IsWhitespace(c);
         }
 
         // Note that we are not considering the character & as a punctuation in HTML
@@ -294,14 +297,14 @@ namespace Markdig.Helpers
 
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public static bool IsAlphaUpper(this char c)
-        {
-            return c >= 'A' && c <= 'Z';
+        {
+            return (uint)(c - 'A') <= ('Z' - 'A');
         }
 
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public static bool IsAlpha(this char c)
         {
-            return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z');
+            return ((uint)(c - 'a') <= ('z' - 'a')) || ((uint)(c - 'A') <= ('Z' - 'A'));
         }
 
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
@@ -313,7 +316,7 @@ namespace Markdig.Helpers
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public static bool IsDigit(this char c)
         {
-            return c >= '0' && c <= '9';
+            return (uint)(c - '0') <= ('9' - '0');
         }
 
         public static bool IsAsciiPunctuation(this char c)

src/Markdig/Helpers/CharacterMap.cs

@@ -118,20 +118,11 @@ namespace Markdig.Helpers
         public int IndexOfOpeningCharacter(string text, int start, int end)
         {
             var maxChar = isOpeningCharacter.Length;
-#if SUPPORT_UNSAFE
+
             unsafe
-#endif
             {
-#if SUPPORT_FIXED_STRING
-            fixed (char* pText = text)
-#else
-                var pText = text;
-#endif
-#if SUPPORT_UNSAFE
+                fixed (char* pText = text)
                 fixed (bool* openingChars = isOpeningCharacter)
-#else
-                var openingChars = isOpeningCharacter;
-#endif
                 {
                     if (nonAsciiMap == null)
                     {

src/Markdig/Helpers/CompactPrefixTree.cs

@@ -25,7 +25,7 @@ namespace Markdig.Helpers
     /// <para>Something between a Trie and a full Radix tree, but stored linearly in memory</para>
     /// </summary>
     /// <typeparam name="TValue">The value associated with the key</typeparam>
-    internal class CompactPrefixTree<TValue>
+    internal sealed class CompactPrefixTree<TValue>
 //#if !LEGACY
 //        : IReadOnlyDictionary<string, TValue>, IReadOnlyList<KeyValuePair<string, TValue>>
 //#endif

src/Markdig/Helpers/CustomArrayPool.cs

@@ -0,0 +1,86 @@
+using System.Threading;
+
+namespace Markdig.Helpers
+{
+    internal sealed class CustomArrayPool<T>
+    {
+        private sealed class Bucket
+        {
+            private readonly T[][] _buffers;
+
+            private int _index;
+            private int _lock;
+
+            public Bucket(int numberOfBuffers)
+            {
+                _buffers = new T[numberOfBuffers][];
+            }
+
+            public T[] Rent()
+            {
+                T[][] buffers = _buffers;
+                T[] buffer = null;
+                if (Interlocked.CompareExchange(ref _lock, 1, 0) == 0)
+                {
+                    int index = _index;
+                    if ((uint)index < (uint)buffers.Length)
+                    {
+                        buffer = buffers[index];
+                        buffers[index] = null;
+                        _index = index + 1;
+                    }
+                    Interlocked.Decrement(ref _lock);
+                }
+                return buffer;
+            }
+
+            public void Return(T[] array)
+            {
+                var buffers = _buffers;
+                if (Interlocked.CompareExchange(ref _lock, 1, 0) == 0)
+                {
+                    int index = _index - 1;
+                    if ((uint)index < (uint)buffers.Length)
+                    {
+                        buffers[index] = array;
+                        _index = index;
+                    }
+                    Interlocked.Decrement(ref _lock);
+                }
+            }
+        }
+
+        private readonly Bucket _bucket4, _bucket8, _bucket16, _bucket32;
+
+        public CustomArrayPool(int size4, int size8, int size16, int size32)
+        {
+            _bucket4 = new Bucket(size4);
+            _bucket8 = new Bucket(size8);
+            _bucket16 = new Bucket(size16);
+            _bucket32 = new Bucket(size32);
+        }
+
+        private Bucket SelectBucket(int length)
+        {
+            switch (length)
+            {
+                case 4: return _bucket4;
+                case 8: return _bucket8;
+                case 16: return _bucket16;
+                case 32: return _bucket32;
+
+                default: return null;
+            }
+        }
+
+        public T[] Rent(int length)
+        {
+            return SelectBucket(length)?.Rent() ?? new T[length];
+        }
+
+        public void Return(T[] array)
+        {
+            SelectBucket(array.Length)?.Return(array);
+        }
+    }
+}

src/Markdig/Helpers/HtmlHelper.cs

@@ -373,7 +373,7 @@ namespace Markdig.Helpers
             }
             builder.Append('-');
             builder.Append('-');
-            if (text.PeekChar(1) == '>')
+            if (text.PeekChar() == '>')
             {
                 return false;
             }

src/Markdig/Helpers/LinkHelper.cs

@@ -597,20 +597,23 @@ namespace Markdig.Helpers
                         }
                     }
 
-                    if (hasEscape && !c.IsAsciiPunctuation())
+                    if (!isAutoLink)
                     {
-                        buffer.Append('\\');
-                    }
+                        if (hasEscape && !c.IsAsciiPunctuation())
+                        {
+                            buffer.Append('\\');
+                        }
 
-                    // If we have an escape
-                    if (c == '\\')
-                    {
-                        hasEscape = true;
-                        c = text.NextChar();
-                        continue;
-                    }
+                        // If we have an escape
+                        if (c == '\\')
+                        {
+                            hasEscape = true;
+                            c = text.NextChar();
+                            continue;
+                        }
 
-                    hasEscape = false;
+                        hasEscape = false;
+                    }
 
                     if (IsEndOfUri(c, isAutoLink))
                     {
@@ -622,10 +625,7 @@ namespace Markdig.Helpers
                     {
                         if (c == '&')
                         {
-                            int entityNameStart;
-                            int entityNameLength;
-                            int entityValue;
-                            if (HtmlHelper.ScanEntity(text, out entityValue, out entityNameStart, out entityNameLength) > 0)
+                            if (HtmlHelper.ScanEntity(text, out _, out _, out _) > 0)
                             {
                                 isValid = true;
                                 break;

src/Markdig/Helpers/StringBuilderExtensions.cs

@@ -6,7 +6,7 @@ using System.Text;
 namespace Markdig.Helpers
 {
     /// <summary>
-    /// Extensions for StringBuilder with <see cref="StringSlice"/>
+    /// Extensions for StringBuilder
     /// </summary>
     public static class StringBuilderExtensions
     {
@@ -19,5 +19,12 @@ namespace Markdig.Helpers
         {
             return builder.Append(slice.Text, slice.Start, slice.Length);
         }
+
+        internal static string GetStringAndReset(this StringBuilder builder)
+        {
+            string text = builder.ToString();
+            builder.Length = 0;
+            return text;
+        }
     }
 }

src/Markdig/Helpers/StringLine.cs

@@ -77,7 +77,7 @@ namespace Markdig.Helpers
             return line.Slice;
         }
 
-        public override string ToString()
+        public readonly override string ToString()
         {
             return Slice.ToString();
         }

src/Markdig/Helpers/StringLineGroup.cs

@@ -5,26 +5,28 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
-using System.Diagnostics;
 using System.Runtime.CompilerServices;
-using Markdig.Extensions.Tables;
 
 namespace Markdig.Helpers
 {
     /// <summary>
     /// A group of <see cref="StringLine"/>.
     /// </summary>
-    /// <seealso cref="System.Collections.IEnumerable" />
+    /// <seealso cref="IEnumerable" />
     public struct StringLineGroup : IEnumerable
     {
+        // Feel free to change these numbers if you see a positive change
+        private static readonly CustomArrayPool<StringLine> _pool
+            = new CustomArrayPool<StringLine>(512, 386, 128, 64);
+
         /// <summary>
         /// Initializes a new instance of the <see cref="StringLineGroup"/> class.
         /// </summary>
         /// <param name="capacity"></param>
-        public StringLineGroup(int capacity)
+        public StringLineGroup(int capacity, bool willRelease = false)
         {
             if (capacity <= 0) throw new ArgumentOutOfRangeException(nameof(capacity));
-            Lines = new StringLine[capacity];
+            Lines = _pool.Rent(willRelease ? Math.Max(8, capacity) : capacity);
             Count = 0;
         }
 
@@ -100,7 +102,7 @@ namespace Markdig.Helpers
             Lines[Count++] = new StringLine(ref slice);
         }
 
-        public override string ToString()
+        public readonly override string ToString()
         {
             return ToSlice().ToString();
         }
@@ -110,7 +112,7 @@ namespace Markdig.Helpers
         /// </summary>
         /// <param name="lineOffsets">The position of the `\n` line offsets from the beginning of the returned slice.</param>
         /// <returns>A single slice concatenating the lines of this instance</returns>
-        public StringSlice ToSlice(List<LineOffset> lineOffsets = null)
+        public readonly StringSlice ToSlice(List<LineOffset> lineOffsets = null)
         {
             // Optimization case when no lines
             if (Count == 0)
@@ -128,6 +130,11 @@ namespace Markdig.Helpers
                 return Lines[0];
             }
 
+            if (lineOffsets != null && lineOffsets.Capacity < lineOffsets.Count + Count)
+            {
+                lineOffsets.Capacity = Math.Max(lineOffsets.Count + Count, lineOffsets.Capacity * 2);
+            }
+
             // Else use a builder
             var builder = StringBuilderCache.Local();
             int previousStartOfLine = 0;
@@ -151,16 +158,14 @@ namespace Markdig.Helpers
             {
                 lineOffsets.Add(new LineOffset(Lines[Count - 1].Position, Lines[Count - 1].Column, Lines[Count - 1].Slice.Start - Lines[Count - 1].Position, previousStartOfLine, builder.Length));
             }
-            var str = builder.ToString();
-            builder.Length = 0;
-            return new StringSlice(str);
+            return new StringSlice(builder.GetStringAndReset());
         }
 
         /// <summary>
         /// Converts this instance into a <see cref="ICharIterator"/>.
         /// </summary>
         /// <returns></returns>
-        public Iterator ToCharIterator()
+        public readonly Iterator ToCharIterator()
         {
             return new Iterator(this);
         }
@@ -183,14 +188,24 @@ namespace Markdig.Helpers
 
         private void IncreaseCapacity()
         {
-            var newItems = new StringLine[Lines.Length * 2];
+            var newItems = _pool.Rent(Lines.Length * 2);
             if (Count > 0)
             {
                 Array.Copy(Lines, 0, newItems, 0, Count);
+                Array.Clear(Lines, 0, Count);
             }
+            _pool.Return(Lines);
             Lines = newItems;
         }
 
+        internal void Release()
+        {
+            Array.Clear(Lines, 0, Count);
+            _pool.Return(Lines);
+            Lines = null;
+            Count = -1;
+        }
+
         /// <summary>
         /// The iterator used to iterate other the lines.
         /// </summary>
@@ -207,7 +222,7 @@ namespace Markdig.Helpers
                 _offset = -1;
                 SliceIndex = 0;
                 CurrentChar = '\0';
-                End = -2; 
+                End = -2;
                 for (int i = 0; i < lines.Count; i++)
                 {
                     End += lines.Lines[i].Slice.Length + 1; // Add chars
@@ -221,7 +236,7 @@ namespace Markdig.Helpers
 
             public int End { get; private set; }
 
-            public bool IsEmpty => Start > End;
+            public readonly bool IsEmpty => Start > End;
 
             public int SliceIndex { get; private set; }
 
@@ -277,7 +292,7 @@ namespace Markdig.Helpers
                 return CurrentChar;
             }
 
-            public char PeekChar(int offset = 1)
+            public readonly char PeekChar(int offset = 1)
             {
                 if (offset < 0) throw new ArgumentOutOfRangeException("Negative offset are not supported for StringLineGroup", nameof(offset));
 
@@ -298,17 +313,15 @@ namespace Markdig.Helpers
             public bool TrimStart()
             {
                 var c = CurrentChar;
-                bool hasSpaces = false;
                 while (c.IsWhitespace())
                 {
-                    hasSpaces = true;
                     c = NextChar();
                 }
-                return hasSpaces;
+                return IsEmpty;
             }
         }
 
-        public struct LineOffset
+        public readonly struct LineOffset
         {
             public LineOffset(int linePosition, int column, int offset, int start, int end)
             {

src/Markdig/Helpers/StringSlice.cs

@@ -38,8 +38,7 @@ namespace Markdig.Helpers
         /// <exception cref="System.ArgumentNullException"></exception>
         public StringSlice(string text, int start, int end)
         {
-            if (text == null) throw new ArgumentNullException(nameof(text));
-            Text = text;
+            Text = text ?? throw new ArgumentNullException(nameof(text));
             Start = start;
             End = end;
         }
@@ -62,24 +61,40 @@ namespace Markdig.Helpers
         /// <summary>
         /// Gets the length.
         /// </summary>
-        public int Length => End - Start + 1;
+        public readonly int Length => End - Start + 1;
 
         /// <summary>
         /// Gets the current character.
         /// </summary>
-        public char CurrentChar => Start <= End ? this[Start] : '\0';
+        public readonly char CurrentChar
+        {
+            get
+            {
+                int start = Start;
+                return start <= End ? Text[start] : '\0';
+            }
+        }
 
         /// <summary>
         /// Gets a value indicating whether this instance is empty.
         /// </summary>
-        public bool IsEmpty => Start > End;
+        public readonly bool IsEmpty
+        {
+            [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
+            get => Start > End;
+        }
 
         /// <summary>
         /// Gets the <see cref="System.Char"/> at the specified index.
         /// </summary>
         /// <param name="index">The index.</param>
         /// <returns>A character in the slice at the specified index (not from <see cref="Start"/> but from the begining of the slice)</returns>
-        public char this[int index] => Text[index];
+        public readonly char this[int index]
+        {
+            [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
+            get => Text[index];
+        }
+
 
         /// <summary>
         /// Goes to the next character, incrementing the <see cref="Start" /> position.
@@ -90,13 +105,27 @@ namespace Markdig.Helpers
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
         public char NextChar()
         {
-            Start++;
-            if (Start > End)
+            int start = Start;
+            if (start >= End)
             {
                 Start = End + 1;
                 return '\0';
             }
-            return Text[Start];
+            start++;
+            Start = start;
+            return Text[start];
+        }
+
+        /// <summary>
+        /// Peeks a character at the offset of 1 from the current <see cref="Start"/> position
+        /// inside the range <see cref="Start"/> and <see cref="End"/>, returns `\0` if outside this range.
+        /// </summary>
+        /// <returns>The character at offset, returns `\0` if none.</returns>
+        [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
+        public readonly char PeekChar()
+        {
+            int index = Start + 1;
+            return index <= End ? Text[index] : '\0';
         }
 
         /// <summary>
@@ -106,10 +135,10 @@ namespace Markdig.Helpers
         /// <param name="offset">The offset.</param>
         /// <returns>The character at offset, returns `\0` if none.</returns>
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
-        public char PeekChar(int offset = 1)
+        public readonly char PeekChar(int offset)
         {
             var index = Start + offset;
-            return index >= Start && index <= End ? Text[index] : (char) 0;
+            return index >= Start && index <= End ? Text[index] : '\0';
         }
 
         /// <summary>
@@ -117,9 +146,10 @@ namespace Markdig.Helpers
         /// </summary>
         /// <returns>The character at offset, returns `\0` if none.</returns>
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
-        public char PeekCharAbsolute(int index)
+        public readonly char PeekCharAbsolute(int index)
         {
-            return index >= 0 && index < Text.Length ? Text[index] : (char)0;
+            string text = Text;
+            return (uint)index < (uint)text.Length ? text[index] : '\0';
         }
 
         /// <summary>
@@ -129,10 +159,11 @@ namespace Markdig.Helpers
         /// <param name="offset">The offset.</param>
         /// <returns>The character at offset, returns `\0` if none.</returns>
         [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
-        public char PeekCharExtra(int offset)
+        public readonly char PeekCharExtra(int offset)
         {
             var index = Start + offset;
-            return index >= 0 && index < Text.Length ? Text[index] : (char)0;
+            var text = Text;
+            return (uint)index < (uint)text.Length ? text[index] : '\0';
         }
 
         /// <summary>
@@ -141,7 +172,7 @@ namespace Markdig.Helpers
         /// <param name="text">The text.</param>
         /// <param name="offset">The offset.</param>
         /// <returns><c>true</c> if the text matches; <c>false</c> otherwise</returns>
-        public bool Match(string text, int offset = 0)
+        public readonly bool Match(string text, int offset = 0)
         {
             return Match(text, End, offset);
         }
@@ -153,19 +184,22 @@ namespace Markdig.Helpers
         /// <param name="end">The end.</param>
         /// <param name="offset">The offset.</param>
         /// <returns><c>true</c> if the text matches; <c>false</c> otherwise</returns>
-        public bool Match(string text, int end, int offset)
+        public readonly bool Match(string text, int end, int offset)
         {
             var index = Start + offset;
-            int i = 0;
-            for (; index <= end && i < text.Length; i++, index++)
+
+            if (end - index + 1 < text.Length)
+                return false;
+
+            string sliceText = Text;
+            for (int i = 0; i < text.Length; i++, index++)
             {
-                if (text[i] != Text[index])
+                if (text[i] != sliceText[index])
                 {
                     return false;
                 }
             }
-
-            return i == text.Length;
+            return true;
         }
 
         /// <summary>
@@ -196,7 +230,7 @@ namespace Markdig.Helpers
         /// <param name="text">The text.</param>
         /// <param name="offset">The offset.</param>
         /// <returns><c>true</c> if the text matches; <c>false</c> otherwise</returns>
-        public bool MatchLowercase(string text, int offset = 0)
+        public readonly bool MatchLowercase(string text, int offset = 0)
         {
             return MatchLowercase(text, End, offset);
         }
@@ -208,19 +242,22 @@ namespace Markdig.Helpers
         /// <param name="end">The end.</param>
         /// <param name="offset">The offset.</param>
         /// <returns><c>true</c> if the text matches; <c>false</c> otherwise</returns>
-        public bool MatchLowercase(string text, int end, int offset)
+        public readonly bool MatchLowercase(string text, int end, int offset)
         {
             var index = Start + offset;
-            int i = 0;
-            for (; index <= end && i < text.Length; i++, index++)
+
+            if (end - index + 1 < text.Length)
+                return false;
+
+            string sliceText = Text;
+            for (int i = 0; i < text.Length; i++, index++)
             {
-                if (text[i] != char.ToLowerInvariant(Text[index]))
+                if (text[i] != char.ToLowerInvariant(sliceText[index]))
                 {
                     return false;
                 }
             }
-
-            return i == text.Length;
+            return true;
         }
 
         /// <summary>
@@ -230,46 +267,41 @@ namespace Markdig.Helpers
         /// <param name="offset">The offset.</param>
         /// <param name="ignoreCase">true if ignore case</param>
         /// <returns><c>true</c> if the text was found; <c>false</c> otherwise</returns>
-        public int IndexOf(string text, int offset = 0, bool ignoreCase = false)
+        public readonly int IndexOf(string text, int offset = 0, bool ignoreCase = false)
         {
-            var end = End - text.Length + 1;
-            if (ignoreCase)
-            {
-                for (int i = Start + offset; i <= end; i++)
-                {
-                    if (MatchLowercase(text, End, i - Start))
-                    {
-                        return i; ;
-                    }
-                }
-            }
-            else
-            {
-                for (int i = Start + offset; i <= end; i++)
-                {
-                    if (Match(text, End, i - Start))
-                    {
-                        return i; ;
-                    }
-                }
-            }
-            return -1;
+            offset += Start;
+            int length = End - offset + 1;
+
+            if (length <= 0)
+                return -1;
+
+#if NETCORE
+            var span = Text.AsSpan(offset, length);
+            int index = ignoreCase ? span.IndexOf(text, StringComparison.OrdinalIgnoreCase) : span.IndexOf(text);
+            return index == -1 ? index : index + offset;
+#else
+            return Text.IndexOf(text, offset, length, ignoreCase ? StringComparison.OrdinalIgnoreCase : StringComparison.Ordinal);
+#endif
         }
 
         /// <summary>
         /// Searches for the specified character within this slice.
         /// </summary>
         /// <returns>A value >= 0 if the character was found, otherwise &lt; 0</returns>
-        public int IndexOf(char c)
+        public readonly int IndexOf(char c)
         {
-            for (int i = Start; i <= End; i++)
-            {
-                if (Text[i] == c)
-                {
-                    return i;
-                }
-            }
-            return -1;
+            int start = Start;
+            int length = End - start + 1;
+
+            if (length <= 0)
+                return -1;
+
+#if NETCORE
+            int index = Text.AsSpan(start, length).IndexOf(c);
+            return index == -1 ? index : index + start;
+#else
+            return Text.IndexOf(c, start, length);
+#endif
         }
 
         /// <summary>
@@ -281,7 +313,6 @@ namespace Markdig.Helpers
         public bool TrimStart()
         {
             // Strip leading spaces
-            var start = Start;
             for (; Start <= End; Start++)
             {
                 if (!Text[Start].IsWhitespace())
@@ -289,7 +320,7 @@ namespace Markdig.Helpers
                     break;
                 }
             }
-            return start != Start;
+            return IsEmpty;
         }
 
         /// <summary>
@@ -336,31 +367,29 @@ namespace Markdig.Helpers
         }
 
         /// <summary>
-        /// Returns a <see cref="System.String" /> that represents this instance.
+        /// Returns a <see cref="string" /> that represents this instance.
         /// </summary>
         /// <returns>
-        /// A <see cref="System.String" /> that represents this instance.
+        /// A <see cref="string" /> that represents this instance.
         /// </returns>
-        public override string ToString()
+        public readonly override string ToString()
         {
-            if (Text != null && Start <= End)
-            {
-                var length = Length;
-                if (Start == 0 && Text.Length == length)
-                {
-                    return Text;
-                }
+            string text = Text;
+            int start = Start;
+            int length = End - start + 1;
 
-                return Text.Substring(Start, length);
+            if (text is null || length <= 0)
+            {
+                return string.Empty;
             }
-            return string.Empty;
+            return text.Substring(start, length);
         }
 
         /// <summary>
         /// Determines whether this slice is empty or made only of whitespaces.
         /// </summary>
         /// <returns><c>true</c> if this slice is empty or made only of whitespaces; <c>false</c> otherwise</returns>
-        public bool IsEmptyOrWhitespace()
+        public readonly bool IsEmptyOrWhitespace()
         {
             for (int i = Start; i <= End; i++)
             {

src/Markdig/Markdig.csproj

@@ -1,84 +1,6 @@
 <Project Sdk="Microsoft.NET.Sdk">
-
   <PropertyGroup>
-    <Description>A fast, powerful, CommonMark compliant, extensible Markdown processor for .NET with 20+ builtin extensions (pipetables, footnotes, definition lists... etc.)</Description>
-    <Copyright>Alexandre Mutel</Copyright>
-    <AssemblyTitle>Markdig</AssemblyTitle>
-    <NeutralLanguage>en-US</NeutralLanguage>
-    <VersionPrefix>0.17.0</VersionPrefix>
-    <Authors>Alexandre Mutel</Authors>
-    <TargetFrameworks>net35;net40;netstandard2.0;uap10.0;netcoreapp2.1</TargetFrameworks>
-    <AssemblyName>Markdig</AssemblyName>
     <PackageId>Markdig</PackageId>
-    <PackageId Condition="'$(SignAssembly)' == 'true'">Markdig.Signed</PackageId>
-    <PackageTags>Markdown CommonMark md html md2html</PackageTags>
-    <PackageReleaseNotes>https://github.com/lunet-io/markdig/blob/master/changelog.md</PackageReleaseNotes>
-    <PackageLicenseExpression>BSD-2-Clause</PackageLicenseExpression>
-    <PackageIconUrl>https://raw.githubusercontent.com/lunet-io/markdig/master/img/markdig.png</PackageIconUrl>
-    <PackageProjectUrl>https://github.com/lunet-io/markdig</PackageProjectUrl>
-    <NetStandardImplicitPackageVersion Condition=" '$(TargetFramework)' == 'netstandard1.1' ">1.6.0</NetStandardImplicitPackageVersion>
-    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
-    <LangVersion>7.3</LangVersion>
   </PropertyGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net35' ">
-    <Reference Include="mscorlib" />
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'net40' ">
-    <Reference Include="mscorlib" />
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-    <Reference Include="Microsoft.CSharp" />
-  </ItemGroup>
-
-  <ItemGroup Condition=" '$(TargetFramework)' == 'portable40-net40+sl5+win8+wp8+wpa81' ">
-    <Reference Include="mscorlib" />
-    <Reference Include="System" />
-    <Reference Include="System.Core" />
-  </ItemGroup>
-
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'net35' ">
-    <DefineConstants>$(DefineConstants);SUPPORT_FIXED_STRING;SUPPORT_UNSAFE</DefineConstants>
-  </PropertyGroup>
-
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'net40' ">
-    <DefineConstants>$(DefineConstants);SUPPORT_FIXED_STRING;SUPPORT_UNSAFE</DefineConstants>
-  </PropertyGroup>
-
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netstandard2.0' ">
-    <DefineConstants>$(DefineConstants);SUPPORT_FIXED_STRING;SUPPORT_UNSAFE</DefineConstants>
-  </PropertyGroup>
- 
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
-    <DefineConstants>$(DefineConstants);SUPPORT_FIXED_STRING;SUPPORT_UNSAFE;NETCORE</DefineConstants>
-  </PropertyGroup>
-
-  <PropertyGroup Condition=" '$(TargetFramework)' == 'uap10.0' ">
-    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
-    <TargetPlatformVersion Condition="'$(TargetPlatformVersion)' == ''">10.0.17763.0</TargetPlatformVersion>
-    <TargetPlatformMinVersion Condition="'$(TargetPlatformMinVersion)' == ''">10.0.10240.0</TargetPlatformMinVersion>
-    <DefineConstants>$(DefineConstants);NETSTANDARD_11;SUPPORT_UNSAFE</DefineConstants>
-  </PropertyGroup>
-
-  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
-    <NoWarn>$(NoWarn);CS1591</NoWarn>
-    <GenerateDocumentationFile>true</GenerateDocumentationFile>
-  </PropertyGroup>
-
-  <PropertyGroup Condition=" '$(SignAssembly)' == 'true' ">
-    <AssemblyOriginatorKeyFile>key.snk</AssemblyOriginatorKeyFile>
-    <PublicSign Condition=" '$(OS)' != 'Windows_NT' ">true</PublicSign>
-  </PropertyGroup>
-
-  <!-- Special packages and imports for UWP support -->
-  <ItemGroup>
-    <PackageReference Include="MSBuild.Sdk.Extras" Version="1.0.9" PrivateAssets="all" />
-  </ItemGroup>
-  <ItemGroup Condition=" '$(TargetFramework)' == 'uap10.0' ">
-    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform " Version="5.2.2" />
-  </ItemGroup>
-  <Import Project="$(MSBuildSDKExtrasTargets)" Condition="Exists('$(MSBuildSDKExtrasTargets)')" />
+  <Import Project="Markdig.targets" />
 </Project>

src/Markdig/Markdig.targets

@@ -0,0 +1,43 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup>
+    <Description>A fast, powerful, CommonMark compliant, extensible Markdown processor for .NET with 20+ builtin extensions (pipetables, footnotes, definition lists... etc.)</Description>
+    <Copyright>Alexandre Mutel</Copyright>
+    <NeutralLanguage>en-US</NeutralLanguage>
+    <VersionPrefix>0.18.0</VersionPrefix>
+    <Authors>Alexandre Mutel</Authors>
+    <TargetFrameworks>net35;net40;netstandard2.0;uap10.0;netcoreapp2.1</TargetFrameworks>
+    <PackageTags>Markdown CommonMark md html md2html</PackageTags>
+    <PackageReleaseNotes>https://github.com/lunet-io/markdig/blob/master/changelog.md</PackageReleaseNotes>
+    <PackageLicenseExpression>BSD-2-Clause</PackageLicenseExpression>
+    <PackageIconUrl>https://raw.githubusercontent.com/lunet-io/markdig/master/img/markdig.png</PackageIconUrl>
+    <PackageProjectUrl>https://github.com/lunet-io/markdig</PackageProjectUrl>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
+    <LangVersion>8.0</LangVersion>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'netcoreapp2.1' ">
+    <DefineConstants>$(DefineConstants);NETCORE</DefineConstants>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(TargetFramework)' == 'uap10.0' ">
+    <TargetPlatformIdentifier>UAP</TargetPlatformIdentifier>
+    <TargetPlatformVersion Condition="'$(TargetPlatformVersion)' == ''">10.0.17763.0</TargetPlatformVersion>
+    <TargetPlatformMinVersion Condition="'$(TargetPlatformMinVersion)' == ''">10.0.10240.0</TargetPlatformMinVersion>
+    <DefineConstants>$(DefineConstants);UAP</DefineConstants>
+  </PropertyGroup>
+
+  <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
+    <NoWarn>$(NoWarn);CS1591</NoWarn>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+  </PropertyGroup>
+
+  <!-- Special packages and imports for UWP support -->
+  <ItemGroup>
+    <PackageReference Include="MSBuild.Sdk.Extras" Version="1.0.9" PrivateAssets="all" />
+  </ItemGroup>
+  <ItemGroup Condition=" '$(TargetFramework)' == 'uap10.0' ">
+    <PackageReference Include="Microsoft.NETCore.UniversalWindowsPlatform " Version="5.2.2" />
+  </ItemGroup>
+  <Import Project="$(MSBuildSDKExtrasTargets)" Condition="Exists('$(MSBuildSDKExtrasTargets)')" />
+</Project>

src/Markdig/Markdown.cs

@@ -17,7 +17,7 @@ namespace Markdig
     /// </summary>
     public static partial class Markdown
     {
-#if NETSTANDARD_11
+#if UAP
         public static readonly string Version = typeof(Markdown).GetTypeInfo().Assembly.GetCustomAttribute<AssemblyFileVersionAttribute>().Version;
 #else
         public static readonly string Version = ((AssemblyFileVersionAttribute) typeof(Markdown).Assembly.GetCustomAttributes(typeof(AssemblyFileVersionAttribute), false)[0]).Version;
@@ -73,9 +73,18 @@ namespace Markdig
         public static string ToHtml(string markdown, MarkdownPipeline pipeline = null)
         {
             if (markdown == null) throw new ArgumentNullException(nameof(markdown));
-            var writer = new StringWriter();
-            ToHtml(markdown, writer, pipeline);
-            return writer.ToString();
+            pipeline = pipeline ?? new MarkdownPipelineBuilder().Build();
+            pipeline = CheckForSelfPipeline(pipeline, markdown);
+
+            var renderer = pipeline.GetCacheableHtmlRenderer();
+
+            var document = Parse(markdown, pipeline);
+            renderer.Render(document);
+            renderer.Writer.Flush();
+
+            string html = renderer.Writer.ToString();
+            pipeline.ReleaseCacheableHtmlRenderer(renderer);
+            return html;
         }
 
         /// <summary>
@@ -184,7 +193,8 @@ namespace Markdig
             var renderer = new HtmlRenderer(writer)
             {
                 EnableHtmlForBlock = false,
-                EnableHtmlForInline = false
+                EnableHtmlForInline = false,
+                EnableHtmlEscape = false,
             };
             pipeline.Setup(renderer);
 

src/Markdig/MarkdownPipeline.cs

@@ -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.
 using System;
@@ -63,5 +63,42 @@ namespace Markdig
                 extension.Setup(this, renderer);
             }
         }
+
+
+        private HtmlRendererCache _rendererCache = null;
+
+        internal HtmlRenderer GetCacheableHtmlRenderer()
+        {
+            if (_rendererCache is null)
+            {
+                _rendererCache = new HtmlRendererCache
+                {
+                    OnNewInstanceCreated = Setup
+                };
+            }
+            return _rendererCache.Get();
+        }
+        internal void ReleaseCacheableHtmlRenderer(HtmlRenderer renderer)
+        {
+            _rendererCache.Release(renderer);
+        }
+
+        private sealed class HtmlRendererCache : ObjectCache<HtmlRenderer>
+        {
+            public Action<HtmlRenderer> OnNewInstanceCreated;
+
+            protected override HtmlRenderer NewInstance()
+            {
+                var writer = new StringWriter();
+                var renderer = new HtmlRenderer(writer);
+                OnNewInstanceCreated(renderer);
+                return renderer;
+            }
+
+            protected override void Reset(HtmlRenderer instance)
+            {
+                instance.Reset();
+            }
+        }
     }
 }

src/Markdig/Parsers/BlockProcessor.cs

@@ -500,6 +500,11 @@ namespace Markdig.Parsers
                 if (!block.Parser.Close(this, block))
                 {
                     block.Parent?.Remove(block);
+
+                    if (block is LeafBlock leaf)
+                    {
+                        leaf.Lines.Release();
+                    }
                 }
                 else
                 {
@@ -873,7 +878,7 @@ namespace Markdig.Parsers
             NewBlocks.Clear();
         }
 
-        private class BlockParserStateCache : ObjectCache<BlockProcessor>
+        private sealed class BlockParserStateCache : ObjectCache<BlockProcessor>
         {
             private readonly BlockProcessor root;
 

src/Markdig/Parsers/FencedBlockParserBase.cs

@@ -124,7 +124,9 @@ namespace Markdig.Parsers
             }
             else
             {
-                infoString = line.ToString().Trim();
+                var lineCopy = line;
+                lineCopy.Trim();
+                infoString = lineCopy.ToString();
             }
 
             fenced.Info = HtmlHelper.Unescape(infoString);

src/Markdig/Parsers/HtmlBlockParser.cs

@@ -100,7 +100,7 @@ namespace Markdig.Parsers
             if (c == '!')
             {
                 c = line.NextChar();
-                if (c == '-' && line.PeekChar(1) == '-')
+                if (c == '-' && line.PeekChar() == '-')
                 {
                     return CreateHtmlBlock(state, HtmlBlockType.Comment, startColumn, startPosition); // group 2
                 }
@@ -140,7 +140,7 @@ namespace Markdig.Parsers
             }
 
             if (
-                !(c == '>' || (!hasLeadingClose && c == '/' && line.PeekChar(1) == '>') || c.IsWhitespace() ||
+                !(c == '>' || (!hasLeadingClose && c == '/' && line.PeekChar() == '>') || c.IsWhitespace() ||
                   c == '\0'))
             {
                 return BlockState.None;

src/Markdig/Parsers/InlineProcessor.cs

@@ -192,7 +192,7 @@ namespace Markdig.Parsers
             previousLineIndexForSliceOffset = 0;
             lineOffsets.Clear();
             var text = leafBlock.Lines.ToSlice(lineOffsets);
-            leafBlock.Lines = new StringLineGroup();
+            leafBlock.Lines.Release();
 
             int previousStart = -1;
 

src/Markdig/Parsers/Inlines/LinkInlineParser.cs

@@ -28,9 +28,7 @@ namespace Markdig.Parsers.Inlines
 
             var c = slice.CurrentChar;
 
-            int line;
-            int column;
-            var startPosition = processor.GetSourcePosition(slice.Start, out line, out column);
+            var startPosition = processor.GetSourcePosition(slice.Start, out int line, out int column);
 
             bool isImage = false;
             if (c == '!')
@@ -49,11 +47,9 @@ namespace Markdig.Parsers.Inlines
                     // If this is not an image, we may have a reference link shortcut
                     // so we try to resolve it here
                     var saved = slice;
-                    string label;
 
-                    SourceSpan labelSpan;
                     // If the label is followed by either a ( or a [, this is not a shortcut
-                    if (LinkHelper.TryParseLabel(ref slice, out label, out labelSpan))
+                    if (LinkHelper.TryParseLabel(ref slice, out string label, out SourceSpan labelSpan))
                     {
                         if (!processor.Document.ContainsLinkReferenceDefinition(label))
                         {
@@ -97,230 +93,208 @@ namespace Markdig.Parsers.Inlines
 
         private bool ProcessLinkReference(InlineProcessor state, string label, bool isShortcut, SourceSpan labelSpan, LinkDelimiterInline parent, int endPosition)
         {
-            bool isValidLink = false;
-            LinkReferenceDefinition linkRef;
-            if (state.Document.TryGetLinkReferenceDefinition(label, out linkRef))
+            if (!state.Document.TryGetLinkReferenceDefinition(label, out LinkReferenceDefinition linkRef))
             {
-                Inline link = null;
-                // Try to use a callback directly defined on the LinkReferenceDefinition
-                if (linkRef.CreateLinkInline != null)
-                {
-                    link = linkRef.CreateLinkInline(state, linkRef, parent.FirstChild);
-                }
+                return false;
+            }
 
-                // Create a default link if the callback was not found
-                if (link == null)
+            Inline link = null;
+            // Try to use a callback directly defined on the LinkReferenceDefinition
+            if (linkRef.CreateLinkInline != null)
+            {
+                link = linkRef.CreateLinkInline(state, linkRef, parent.FirstChild);
+            }
+
+            // Create a default link if the callback was not found
+            if (link == null)
+            {
+                // Inline Link
+                link = new LinkInline()
                 {
-                    // Inline Link
-                    link = new LinkInline()
+                    Url = HtmlHelper.Unescape(linkRef.Url),
+                    Title = HtmlHelper.Unescape(linkRef.Title),
+                    Label = label,
+                    LabelSpan = labelSpan,
+                    UrlSpan = linkRef.UrlSpan,
+                    IsImage = parent.IsImage,
+                    IsShortcut = isShortcut,
+                    Reference = linkRef,
+                    Span = new SourceSpan(parent.Span.Start, endPosition),
+                    Line = parent.Line,
+                    Column = parent.Column,
+                };
+            }
+
+            if (link is ContainerInline containerLink)
+            {
+                var child = parent.FirstChild;
+                if (child == null)
+                {
+                    child = new LiteralInline()
                     {
-                        Url = HtmlHelper.Unescape(linkRef.Url),
-                        Title = HtmlHelper.Unescape(linkRef.Title),
-                        Label = label,
-                        LabelSpan = labelSpan,
-                        UrlSpan = linkRef.UrlSpan,
-                        IsImage = parent.IsImage,
-                        IsShortcut = isShortcut,
-                        Reference = linkRef,
-                        Span = new SourceSpan(parent.Span.Start, endPosition),
+                        Content = StringSlice.Empty,
+                        IsClosed = true,
+                        // Not exact but we leave it like this
+                        Span = parent.Span,
                         Line = parent.Line,
                         Column = parent.Column,
                     };
+                    containerLink.AppendChild(child);
                 }
-
-                var containerLink = link as ContainerInline;
-                if (containerLink != null)
+                else
                 {
-                    var child = parent.FirstChild;
-                    if (child == null)
+                    // Insert all child into the link
+                    while (child != null)
                     {
-                        child = new LiteralInline()
-                        {
-                            Content = StringSlice.Empty,
-                            IsClosed = true,
-                            // Not exact but we leave it like this
-                            Span = parent.Span,
-                            Line = parent.Line,
-                            Column = parent.Column,
-                        };
+                        var next = child.NextSibling;
+                        child.Remove();
                         containerLink.AppendChild(child);
-                    }
-                    else
-                    {
-                        // Insert all child into the link
-                        while (child != null)
-                        {
-                            var next = child.NextSibling;
-                            child.Remove();
-                            containerLink.AppendChild(child);
-                            child = next;
-                        }
+                        child = next;
                     }
                 }
-
-                link.IsClosed = true;
-
-                // Process emphasis delimiters
-                state.PostProcessInlines(0, link, null, false);
-
-                state.Inline = link;
-                isValidLink = true;
             }
-            //else
-            //{
-            //    // Else output a literal, leave it opened as we may have literals after
-            //    // that could be append to this one
-            //    var literal = new LiteralInline()
-            //    {
-            //        ContentBuilder = processor.StringBuilders.Get().Append('[').Append(label).Append(']')
-            //    };
-            //    processor.Inline = literal;
-            //}
-            return isValidLink;
+
+            link.IsClosed = true;
+
+            // Process emphasis delimiters
+            state.PostProcessInlines(0, link, null, false);
+
+            state.Inline = link;
+
+            return true;
         }
 
         private bool TryProcessLinkOrImage(InlineProcessor inlineState, ref StringSlice text)
         {
-            LinkDelimiterInline openParent = null;
-            foreach (var parent in inlineState.Inline.FindParentOfType<LinkDelimiterInline>())
+            LinkDelimiterInline openParent = inlineState.Inline.FirstParentOfType<LinkDelimiterInline>();
+
+            if (openParent is null)
             {
-                openParent = parent;
-                break;
-            }
-
-            if (openParent != null)
-            {
-                // If we do find one, but it’s not active,
-                // we remove the inactive delimiter from the stack,
-                // and return a literal text node ].
-                if (!openParent.IsActive)
-                {
-                    inlineState.Inline = new LiteralInline()
-                    {
-                        Content = new StringSlice("["),
-                        Span = openParent.Span,
-                        Line = openParent.Line,
-                        Column = openParent.Column,
-                    };
-                    openParent.ReplaceBy(inlineState.Inline);
-                    return false;
-                }
-
-                // If we find one and it’s active,
-                // then we parse ahead to see if we have
-                // an inline link/image, reference link/image,
-                // compact reference link/image,
-                // or shortcut reference link/image
-                var parentDelimiter = openParent.Parent;
-                var savedText = text;
-                switch (text.CurrentChar)
-                {
-                    case '(':
-                        string url;
-                        string title;
-                        SourceSpan linkSpan;
-                        SourceSpan titleSpan;
-                        if (LinkHelper.TryParseInlineLink(ref text, out url, out title, out linkSpan, out titleSpan))
-                        {
-                            // Inline Link
-                            var link = new LinkInline()
-                            {
-                                Url = HtmlHelper.Unescape(url),
-                                Title = HtmlHelper.Unescape(title),
-                                IsImage = openParent.IsImage,
-                                LabelSpan = openParent.LabelSpan,
-                                UrlSpan = inlineState.GetSourcePositionFromLocalSpan(linkSpan),
-                                TitleSpan = inlineState.GetSourcePositionFromLocalSpan(titleSpan),
-                                Span = new SourceSpan(openParent.Span.Start, inlineState.GetSourcePosition(text.Start -1)),
-                                Line = openParent.Line,
-                                Column = openParent.Column,
-                            };
-
-                            openParent.ReplaceBy(link);
-                            // Notifies processor as we are creating an inline locally
-                            inlineState.Inline = link;
-
-                            // Process emphasis delimiters
-                            inlineState.PostProcessInlines(0, link, null, false);
-
-                            // If we have a link (and not an image),
-                            // we also set all [ delimiters before the opening delimiter to inactive.
-                            // (This will prevent us from getting links within links.)
-                            if (!openParent.IsImage)
-                            {
-                                MarkParentAsInactive(parentDelimiter);
-                            }
-
-                            link.IsClosed = true;
-
-                            return true;
-                        }
-
-                        text = savedText;
-                        goto default;
-                    default:
-                        var labelSpan = SourceSpan.Empty;
-                        string label = null;
-                        bool isLabelSpanLocal = true;
-
-                        bool isShortcut = false;
-                        // Handle Collapsed links
-                        if (text.CurrentChar == '[')
-                        {
-                            if (text.PeekChar(1) == ']')
-                            {
-                                label = openParent.Label;
-                                labelSpan = openParent.LabelSpan;
-                                isLabelSpanLocal = false;
-                                text.NextChar(); // Skip [
-                                text.NextChar(); // Skip ]
-                            }
-                        }
-                        else
-                        {
-                            label = openParent.Label;
-                            isShortcut = true;
-                        }
-
-                        if (label != null || LinkHelper.TryParseLabel(ref text, true, out label, out labelSpan))
-                        {
-                            if (isLabelSpanLocal)
-                            {
-                                labelSpan = inlineState.GetSourcePositionFromLocalSpan(labelSpan);
-                            }
-
-                            if (ProcessLinkReference(inlineState, label, isShortcut, labelSpan, openParent, inlineState.GetSourcePosition(text.Start - 1)))
-                            {
-                                // Remove the open parent
-                                openParent.Remove();
-                                if (!openParent.IsImage)
-                                {
-                                    MarkParentAsInactive(parentDelimiter);
-                                }
-                            }
-                            else
-                            {
-                                return false;
-                            }
-                            return true;
-                        }
-                        break;
-                }
-
-                // We have a nested [ ]
-                // firstParent.Remove();
-                // The opening [ will be transformed to a literal followed by all the children of the [
-
-                var literal = new LiteralInline()
-                {
-                    Span = openParent.Span,
-                    Content = new StringSlice(openParent.IsImage ? "![" : "[")
-                };
-
-                inlineState.Inline = openParent.ReplaceBy(literal);
                 return false;
             }
 
+            // If we do find one, but it’s not active,
+            // we remove the inactive delimiter from the stack,
+            // and return a literal text node ].
+            if (!openParent.IsActive)
+            {
+                inlineState.Inline = new LiteralInline()
+                {
+                    Content = new StringSlice("["),
+                    Span = openParent.Span,
+                    Line = openParent.Line,
+                    Column = openParent.Column,
+                };
+                openParent.ReplaceBy(inlineState.Inline);
+                return false;
+            }
+
+            // If we find one and it’s active,
+            // then we parse ahead to see if we have
+            // an inline link/image, reference link/image,
+            // compact reference link/image,
+            // or shortcut reference link/image
+            var parentDelimiter = openParent.Parent;
+            var savedText = text;
+
+            if (text.CurrentChar == '(')
+            {
+                if (LinkHelper.TryParseInlineLink(ref text, out string url, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan))
+                {
+                    // Inline Link
+                    var link = new LinkInline()
+                    {
+                        Url = HtmlHelper.Unescape(url),
+                        Title = HtmlHelper.Unescape(title),
+                        IsImage = openParent.IsImage,
+                        LabelSpan = openParent.LabelSpan,
+                        UrlSpan = inlineState.GetSourcePositionFromLocalSpan(linkSpan),
+                        TitleSpan = inlineState.GetSourcePositionFromLocalSpan(titleSpan),
+                        Span = new SourceSpan(openParent.Span.Start, inlineState.GetSourcePosition(text.Start - 1)),
+                        Line = openParent.Line,
+                        Column = openParent.Column,
+                    };
+
+                    openParent.ReplaceBy(link);
+                    // Notifies processor as we are creating an inline locally
+                    inlineState.Inline = link;
+
+                    // Process emphasis delimiters
+                    inlineState.PostProcessInlines(0, link, null, false);
+
+                    // If we have a link (and not an image),
+                    // we also set all [ delimiters before the opening delimiter to inactive.
+                    // (This will prevent us from getting links within links.)
+                    if (!openParent.IsImage)
+                    {
+                        MarkParentAsInactive(parentDelimiter);
+                    }
+
+                    link.IsClosed = true;
+
+                    return true;
+                }
+
+                text = savedText;
+            }
+
+            var labelSpan = SourceSpan.Empty;
+            string label = null;
+            bool isLabelSpanLocal = true;
+
+            bool isShortcut = false;
+            // Handle Collapsed links
+            if (text.CurrentChar == '[')
+            {
+                if (text.PeekChar() == ']')
+                {
+                    label = openParent.Label;
+                    labelSpan = openParent.LabelSpan;
+                    isLabelSpanLocal = false;
+                    text.NextChar(); // Skip [
+                    text.NextChar(); // Skip ]
+                }
+            }
+            else
+            {
+                label = openParent.Label;
+                isShortcut = true;
+            }
+
+            if (label != null || LinkHelper.TryParseLabel(ref text, true, out label, out labelSpan))
+            {
+                if (isLabelSpanLocal)
+                {
+                    labelSpan = inlineState.GetSourcePositionFromLocalSpan(labelSpan);
+                }
+
+                if (ProcessLinkReference(inlineState, label, isShortcut, labelSpan, openParent, inlineState.GetSourcePosition(text.Start - 1)))
+                {
+                    // Remove the open parent
+                    openParent.Remove();
+                    if (!openParent.IsImage)
+                    {
+                        MarkParentAsInactive(parentDelimiter);
+                    }
+                    return true;
+                }
+                else if (text.CurrentChar != ']' && text.CurrentChar != '[')
+                {
+                    return false;
+                }
+            }
+
+            // We have a nested [ ]
+            // firstParent.Remove();
+            // The opening [ will be transformed to a literal followed by all the children of the [
+
+            var literal = new LiteralInline()
+            {
+                Span = openParent.Span,
+                Content = new StringSlice(openParent.IsImage ? "![" : "[")
+            };
+
+            inlineState.Inline = openParent.ReplaceBy(literal);
             return false;
         }
 

src/Markdig/Parsers/MarkdownParser.cs

@@ -28,6 +28,8 @@ namespace Markdig.Parsers
         private readonly ProcessDocumentDelegate documentProcessed;
         private readonly bool preciseSourceLocation;
 
+        private readonly int roughLineCountEstimate;
+
         private LineReader lineReader;
 
         /// <summary>
@@ -42,6 +44,8 @@ namespace Markdig.Parsers
         {
             if (text == null) throw new ArgumentNullException(nameof(text));
             if (pipeline == null) throw new ArgumentNullException(nameof(pipeline));
+
+            roughLineCountEstimate = text.Length / 40;
             text = FixupZero(text);
             lineReader = new LineReader(text);
             preciseSourceLocation = pipeline.PreciseSourceLocation;
@@ -82,13 +86,16 @@ namespace Markdig.Parsers
         }
 
         /// <summary>
-        /// Parses the current <see cref="Reader"/> into a Markdown <see cref="MarkdownDocument"/>.
+        /// Parses the current <see cref="lineReader"/> into a Markdown <see cref="MarkdownDocument"/>.
         /// </summary>
         /// <returns>A document instance</returns>
         private MarkdownDocument Parse()
         {
             if (preciseSourceLocation)
-                document.LineStartIndexes = new List<int>();
+            {
+                // Save some List resizing allocations
+                document.LineStartIndexes = new List<int>(Math.Min(512, roughLineCountEstimate));
+            }
 
             ProcessBlocks();
             ProcessInlines();
@@ -127,7 +134,7 @@ namespace Markdig.Parsers
             return text.Replace('\0', CharHelper.ZeroSafeChar);
         }
 
-        private class ContainerItemCache : DefaultObjectCache<ContainerItem>
+        private sealed class ContainerItemCache : DefaultObjectCache<ContainerItem>
         {
             protected override void Reset(ContainerItem instance)
             {

src/Markdig/Renderers/Html/Inlines/HtmlEntityInlineRenderer.cs

@@ -13,7 +13,7 @@ namespace Markdig.Renderers.Html.Inlines
     {
         protected override void Write(HtmlRenderer renderer, HtmlEntityInline obj)
         {
-            if (renderer.EnableHtmlForInline)
+            if (renderer.EnableHtmlEscape)
             {
                 renderer.WriteEscape(obj.Transcoded);
             }

src/Markdig/Renderers/Html/Inlines/LiteralInlineRenderer.cs

@@ -13,13 +13,13 @@ namespace Markdig.Renderers.Html.Inlines
     {
         protected override void Write(HtmlRenderer renderer, LiteralInline obj)
         {
-            if (renderer.EnableHtmlForInline)
+            if (renderer.EnableHtmlEscape)
             {
-                renderer.WriteEscape(obj.Content);
+                renderer.WriteEscape(ref obj.Content);
             }
             else
             {
-                renderer.Write(obj.Content);
+                renderer.Write(ref obj.Content);
             }
         }
     }

src/Markdig/Renderers/TextRendererBase.cs

@@ -70,7 +70,9 @@ namespace Markdig.Renderers
     public abstract class TextRendererBase<T> : TextRendererBase where T : TextRendererBase<T>
     {
         private bool previousWasLine;
+#if !NETCORE
         private char[] buffer;
+#endif
         private readonly List<string> indents;
 
         /// <summary>
@@ -79,12 +81,29 @@ namespace Markdig.Renderers
         /// <param name="writer">The writer.</param>
         protected TextRendererBase(TextWriter writer) : base(writer)
         {
+#if !NETCORE
             buffer = new char[1024];
+#endif
             // We assume that we are starting as if we had previously a newline
             previousWasLine = true;
             indents = new List<string>();
         }
 
+        internal void Reset()
+        {
+            if (Writer is StringWriter stringWriter)
+            {
+                stringWriter.GetStringBuilder().Length = 0;
+            }
+            else
+            {
+                throw new InvalidOperationException("Cannot reset this TextWriter instance");
+            }
+
+            previousWasLine = true;
+            indents.Clear();
+        }
+
         /// <summary>
         /// Ensures a newline.
         /// </summary>
@@ -193,6 +212,10 @@ namespace Markdig.Renderers
 
             WriteIndent();
             previousWasLine = false;
+
+#if NETCORE
+            Writer.Write(content.AsSpan(offset, length));
+#else
             if (offset == 0 && content.Length == length)
             {
                 Writer.Write(content);
@@ -210,6 +233,7 @@ namespace Markdig.Renderers
                     Writer.Write(buffer, 0, length);
                 }
             }
+#endif
             return (T) this;
         }
 

src/Markdig/Syntax/ContainerBlock.cs

@@ -189,12 +189,17 @@ namespace Markdig.Syntax
         {
             get
             {
-                if (index < 0 || index >= Count) throw new ArgumentOutOfRangeException(nameof(index));
-                return children[index];
+                var array = children;
+                if ((uint)index >= (uint)array.Length || index >= Count)
+                {
+                    ThrowHelper.ThrowIndexOutOfRangeException();
+                    return null;
+                }
+                return array[index];
             }
             set
             {
-                if (index < 0 || index >= Count) throw new ArgumentOutOfRangeException(nameof(index));
+                if ((uint)index >= (uint)Count) ThrowHelper.ThrowIndexOutOfRangeException();
                 children[index] = value;
             }
         }

src/Markdig/Syntax/Inlines/Inline.cs

@@ -215,15 +215,28 @@ namespace Markdig.Syntax.Inlines
             var inline = this;
             while (inline != null)
             {
-                var delimiter = inline as T;
-                if (delimiter != null)
+                if (inline is T inlineOfT)
                 {
-                    yield return delimiter;
+                    yield return inlineOfT;
                 }
                 inline = inline.Parent;
             }
         }
 
+        internal T FirstParentOfType<T>() where T : Inline
+        {
+            var inline = this;
+            while (inline != null)
+            {
+                if (inline is T inlineOfT)
+                {
+                    return inlineOfT;
+                }
+                inline = inline.Parent;
+            }
+            return null;
+        }
+
         public Inline FindBestParent()
         {
             var current = this;

src/Markdig/Syntax/LeafBlock.cs

@@ -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.
 using System.Diagnostics;
@@ -51,7 +51,7 @@ namespace Markdig.Syntax
         {
             if (Lines.Lines == null)
             {
-                Lines = new StringLineGroup(4);
+                Lines = new StringLineGroup(4, ProcessInlines);
             }
 
             var stringLine = new StringLine(ref slice, line, column, sourceLinePosition);
@@ -64,12 +64,9 @@ namespace Markdig.Syntax
             {
                 // We need to expand tabs to spaces
                 var builder = StringBuilderCache.Local();
-                for (int i = column; i < CharHelper.AddTab(column); i++)
-                {
-                    builder.Append(' ');
-                }
+                builder.Append(' ', CharHelper.AddTab(column) - column);
                 builder.Append(slice.Text, slice.Start + 1, slice.Length - 1);
-                stringLine.Slice = new StringSlice(builder.ToString());
+                stringLine.Slice = new StringSlice(builder.GetStringAndReset());
                 Lines.Add(ref stringLine);
             }
         }

src/SpecFileGen/Program.cs

@@ -103,12 +103,12 @@ namespace SpecFileGen
                     continue;
                 }
 
-                string source = ParseSpecification(spec, File.ReadAllText(spec.Path));
+                string source = ParseSpecification(spec, File.ReadAllText(spec.Path)).Replace("\r\n", "\n", StringComparison.Ordinal);
                 totalTests += spec.TestCount;
 
                 if (File.Exists(spec.OutputPath))  // If the source hasn't changed, don't bump the generated tag
                 {
-                    string previousSource = File.ReadAllText(spec.OutputPath);
+                    string previousSource = File.ReadAllText(spec.OutputPath).Replace("\r\n", "\n", StringComparison.Ordinal);
                     int start = previousSource.IndexOf('\n', StringComparison.Ordinal) + 1;
                     int previousLength = previousSource.Length - start;
                     if (start != 0 && previousLength == source.Length)

src/markdig.sln

@@ -13,12 +13,14 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Build", "Build", "{061866E2
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Markdig", "Markdig\Markdig.csproj", "{8A58A7E2-627C-4F41-933F-5AC92ADFAB48}"
 EndProject
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Markdig.Signed", "Markdig.Signed\Markdig.Signed.csproj", "{C37C7B94-1219-4ED9-ABAC-C0B4B8FE8750}"
+EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Markdig.Tests", "Markdig.Tests\Markdig.Tests.csproj", "{A0C5CB5F-5568-40AB-B945-D6D2664D51B0}"
 	ProjectSection(ProjectDependencies) = postProject
 		{8A58A7E2-627C-4F41-933F-5AC92ADFAB48} = {8A58A7E2-627C-4F41-933F-5AC92ADFAB48}
 	EndProjectSection
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Markdig.Benchmarks", "Markdig.Benchmarks\Markdig.Benchmarks.csproj", "{6A19F040-BC7C-4283-873A-177B5324F1ED}"
+Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "Markdig.Benchmarks", "Markdig.Benchmarks\Markdig.Benchmarks.csproj", "{6A19F040-BC7C-4283-873A-177B5324F1ED}"
 	ProjectSection(ProjectDependencies) = postProject
 		{8A58A7E2-627C-4F41-933F-5AC92ADFAB48} = {8A58A7E2-627C-4F41-933F-5AC92ADFAB48}
 	EndProjectSection
@@ -41,6 +43,10 @@ Global
 		{8A58A7E2-627C-4F41-933F-5AC92ADFAB48}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{8A58A7E2-627C-4F41-933F-5AC92ADFAB48}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{8A58A7E2-627C-4F41-933F-5AC92ADFAB48}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C37C7B94-1219-4ED9-ABAC-C0B4B8FE8750}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C37C7B94-1219-4ED9-ABAC-C0B4B8FE8750}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C37C7B94-1219-4ED9-ABAC-C0B4B8FE8750}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C37C7B94-1219-4ED9-ABAC-C0B4B8FE8750}.Release|Any CPU.Build.0 = Release|Any CPU
 		{A0C5CB5F-5568-40AB-B945-D6D2664D51B0}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{A0C5CB5F-5568-40AB-B945-D6D2664D51B0}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{A0C5CB5F-5568-40AB-B945-D6D2664D51B0}.Release|Any CPU.ActiveCfg = Release|Any CPU