Random improvements

src/Markdig.Tests/Markdig.Tests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-  	<TargetFrameworks>net451;netcoreapp2.1</TargetFrameworks>
+  	<TargetFrameworks>netcoreapp2.1;netcoreapp3.1</TargetFrameworks>
     <OutputType>Library</OutputType>
     <IsPackable>false</IsPackable>
   </PropertyGroup>

src/Markdig.Tests/TestDescendantsOrder.cs

@@ -1,9 +1,9 @@
 using NUnit.Framework;
 using Markdig.Syntax;
 using Markdig.Syntax.Inlines;
+using System;
 using System.Linq;
 using System.Collections.Generic;
-using Markdig.Helpers;
 
 namespace Markdig.Tests
 {
@@ -33,9 +33,9 @@ public void TestSchemas()
 
                 foreach (LiteralInline literalInline in syntaxTree.Descendants<LiteralInline>())
                 {
-                    Assert.AreSame(ArrayHelper<ListBlock>.Empty, literalInline.Descendants<ListBlock>());
-                    Assert.AreSame(ArrayHelper<ParagraphBlock>.Empty, literalInline.Descendants<ParagraphBlock>());
-                    Assert.AreSame(ArrayHelper<ContainerInline>.Empty, literalInline.Descendants<ContainerInline>());
+                    Assert.AreSame(Array.Empty<ListBlock>(), literalInline.Descendants<ListBlock>());
+                    Assert.AreSame(Array.Empty<ParagraphBlock>(), literalInline.Descendants<ParagraphBlock>());
+                    Assert.AreSame(Array.Empty<ContainerInline>(), literalInline.Descendants<ContainerInline>());
                 }
 
                 foreach (ContainerInline containerInline in syntaxTree.Descendants<ContainerInline>())
@@ -50,13 +50,13 @@ public void TestSchemas()
 
                     if (containerInline.FirstChild is null)
                     {
-                        Assert.AreSame(ArrayHelper<LiteralInline>.Empty, containerInline.Descendants<LiteralInline>());
-                        Assert.AreSame(ArrayHelper<LiteralInline>.Empty, containerInline.FindDescendants<LiteralInline>());
-                        Assert.AreSame(ArrayHelper<LiteralInline>.Empty, (containerInline as MarkdownObject).Descendants<LiteralInline>());
+                        Assert.AreSame(Array.Empty<LiteralInline>(), containerInline.Descendants<LiteralInline>());
+                        Assert.AreSame(Array.Empty<LiteralInline>(), containerInline.FindDescendants<LiteralInline>());
+                        Assert.AreSame(Array.Empty<LiteralInline>(), (containerInline as MarkdownObject).Descendants<LiteralInline>());
                     }
 
-                    Assert.AreSame(ArrayHelper<ListBlock>.Empty, containerInline.Descendants<ListBlock>());
-                    Assert.AreSame(ArrayHelper<ParagraphBlock>.Empty, containerInline.Descendants<ParagraphBlock>());
+                    Assert.AreSame(Array.Empty<ListBlock>(), containerInline.Descendants<ListBlock>());
+                    Assert.AreSame(Array.Empty<ParagraphBlock>(), containerInline.Descendants<ParagraphBlock>());
                 }
 
                 foreach (ParagraphBlock paragraphBlock in syntaxTree.Descendants<ParagraphBlock>())
@@ -65,7 +65,7 @@ public void TestSchemas()
                         (paragraphBlock as MarkdownObject).Descendants<LiteralInline>(),
                         paragraphBlock.Descendants<LiteralInline>());
 
-                    Assert.AreSame(ArrayHelper<ParagraphBlock>.Empty, paragraphBlock.Descendants<ParagraphBlock>());
+                    Assert.AreSame(Array.Empty<ParagraphBlock>(), paragraphBlock.Descendants<ParagraphBlock>());
                 }
 
                 foreach (ContainerBlock containerBlock in syntaxTree.Descendants<ContainerBlock>())
@@ -80,9 +80,9 @@ public void TestSchemas()
 
                     if (containerBlock.Count == 0)
                     {
-                        Assert.AreSame(ArrayHelper<LiteralInline>.Empty, containerBlock.Descendants<LiteralInline>());
-                        Assert.AreSame(ArrayHelper<LiteralInline>.Empty, (containerBlock as Block).Descendants<LiteralInline>());
-                        Assert.AreSame(ArrayHelper<LiteralInline>.Empty, (containerBlock as MarkdownObject).Descendants<LiteralInline>());
+                        Assert.AreSame(Array.Empty<LiteralInline>(), containerBlock.Descendants<LiteralInline>());
+                        Assert.AreSame(Array.Empty<LiteralInline>(), (containerBlock as Block).Descendants<LiteralInline>());
+                        Assert.AreSame(Array.Empty<LiteralInline>(), (containerBlock as MarkdownObject).Descendants<LiteralInline>());
                     }
                 }
             }

src/Markdig/Extensions/Abbreviations/AbbreviationHelper.cs

@@ -1,8 +1,9 @@
-// Copyright (c) Alexandre Mutel. All rights reserved.
+// Copyright (c) Alexandre Mutel. All rights reserved.
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
 using System;
 using System.Collections.Generic;
+using Markdig.Helpers;
 using Markdig.Syntax;
 
 namespace Markdig.Extensions.Abbreviations
@@ -21,9 +22,9 @@ public static bool HasAbbreviations(this MarkdownDocument document)
 
         public static void AddAbbreviation(this MarkdownDocument document, string label, Abbreviation abbr)
         {
-            if (document == null) throw new ArgumentNullException(nameof(document));
-            if (label == null) throw new ArgumentNullException(nameof(label));
-            if (abbr == null) throw new ArgumentNullException(nameof(abbr));
+            if (document == null) ThrowHelper.ArgumentNullException(nameof(document));
+            if (label == null) ThrowHelper.ArgumentNullException_label();
+            if (abbr == null) ThrowHelper.ArgumentNullException(nameof(abbr));
 
             var map = document.GetAbbreviations();
             if (map == null)

src/Markdig/Extensions/Abbreviations/AbbreviationParser.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Alexandre Mutel. All rights reserved.
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
+using System;
 using System.Collections.Generic;
 using Markdig.Helpers;
 using Markdig.Parsers;
@@ -115,7 +116,7 @@ private void DocumentOnProcessInlinesBegin(InlineProcessor inlineProcessor, Inli
 
                 ValidAbbreviationStart:;
 
-                    if (prefixTree.TryMatchLongest(text, i, content.End - i + 1, out KeyValuePair<string, Abbreviation> abbreviationMatch))
+                    if (prefixTree.TryMatchLongest(text.AsSpan(i, content.End - i + 1), out KeyValuePair<string, Abbreviation> abbreviationMatch))
                     {
                         var match = abbreviationMatch.Key;
                         if (!IsValidAbbreviationEnding(match, content, i))

src/Markdig/Extensions/Emoji/EmojiMapping.cs

@@ -1747,10 +1747,10 @@ public EmojiMapping(bool enableSmileys = true)
         public EmojiMapping(IDictionary<string, string> shortcodeToUnicode, IDictionary<string, string> smileyToShortcode)
         {
             if (shortcodeToUnicode == null)
-                throw new ArgumentNullException(nameof(shortcodeToUnicode));
+                ThrowHelper.ArgumentNullException(nameof(shortcodeToUnicode));
 
             if (smileyToShortcode == null)
-                throw new ArgumentNullException(nameof(smileyToShortcode));
+                ThrowHelper.ArgumentNullException(nameof(smileyToShortcode));
 
             // Build emojis and smileys CompactPrefixTree
 
@@ -1768,7 +1768,7 @@ public EmojiMapping(IDictionary<string, string> shortcodeToUnicode, IDictionary<
             foreach (var shortcode in shortcodeToUnicode)
             {
                 if (string.IsNullOrEmpty(shortcode.Key) || string.IsNullOrEmpty(shortcode.Value))
-                    throw new ArgumentException("The dictionaries cannot contain null or empty keys/values", nameof(shortcodeToUnicode));
+                    ThrowHelper.ArgumentException("The dictionaries cannot contain null or empty keys/values", nameof(shortcodeToUnicode));
 
                 firstChars.Add(shortcode.Key[0]);
                 PrefixTree.Add(shortcode);
@@ -1777,15 +1777,15 @@ public EmojiMapping(IDictionary<string, string> shortcodeToUnicode, IDictionary<
             foreach (var smiley in smileyToShortcode)
             {
                 if (string.IsNullOrEmpty(smiley.Key) || string.IsNullOrEmpty(smiley.Value))
-                    throw new ArgumentException("The dictionaries cannot contain null or empty keys/values", nameof(smileyToShortcode));
+                    ThrowHelper.ArgumentException("The dictionaries cannot contain null or empty keys/values", nameof(smileyToShortcode));
 
                 if (!shortcodeToUnicode.TryGetValue(smiley.Value, out string unicode))
-                    throw new ArgumentException(string.Format("Invalid smiley target: {0} is not present in the emoji shortcodes dictionary", smiley.Value));
+                    ThrowHelper.ArgumentException(string.Format("Invalid smiley target: {0} is not present in the emoji shortcodes dictionary", smiley.Value));
 
                 firstChars.Add(smiley.Key[0]);
 
                 if (!PrefixTree.TryAdd(smiley.Key, unicode))
-                    throw new ArgumentException(string.Format("Smiley {0} is already present in the emoji mapping", smiley.Key));
+                    ThrowHelper.ArgumentException(string.Format("Smiley {0} is already present in the emoji mapping", smiley.Key));
             }
 
             OpeningCharacters = new List<char>(firstChars).ToArray();

src/Markdig/Extensions/Emoji/EmojiParser.cs

@@ -2,6 +2,7 @@
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
 
+using System;
 using System.Collections.Generic;
 using Markdig.Helpers;
 using Markdig.Parsers;
@@ -34,7 +35,7 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
             }
 
             // Try to match an emoji shortcode or smiley
-            if (!_emojiMapping.PrefixTree.TryMatchLongest(slice.Text, slice.Start, slice.Length, out KeyValuePair<string, string> match))
+            if (!_emojiMapping.PrefixTree.TryMatchLongest(slice.Text.AsSpan(slice.Start, slice.Length), out KeyValuePair<string, string> match))
             {
                 return false;
             }

src/Markdig/Extensions/ListExtras/ListExtraItemParser.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.
 
@@ -45,24 +45,24 @@ public override bool TryParse(BlockProcessor state, char pendingBulletType, out
             if ((isRomanLow || isRomanUp) && (pendingBulletType == '\0' || pendingBulletType == 'i' || pendingBulletType == 'I'))
             {
                 int startChar = state.Start;
-                int endChar = 0;
                 // With a roman, we can have multiple characters
                 // Note that we don't validate roman numbers
-                while (isRomanLow ? CharHelper.IsRomanLetterLowerPartial(c) : CharHelper.IsRomanLetterUpperPartial(c))
+                do
                 {
-                    endChar = state.Start;
                     c = state.NextChar();
                 }
+                while (isRomanLow ? CharHelper.IsRomanLetterLowerPartial(c) : CharHelper.IsRomanLetterUpperPartial(c));
 
-                result.OrderedStart = CharHelper.RomanToArabic(state.Line.Text.Substring(startChar, endChar - startChar + 1)).ToString();
+                int orderValue = CharHelper.RomanToArabic(state.Line.Text.AsSpan(startChar, state.Start - startChar));
+                result.OrderedStart = CharHelper.SmallNumberToString(orderValue);
                 result.BulletType = isRomanLow ? 'i' : 'I';
                 result.DefaultOrderedStart = isRomanLow ? "i" : "I";
             }
             else
             {
                 // otherwise we expect a regular alpha lettered list with a single character.
                 var isUpper = c.IsAlphaUpper();
-                result.OrderedStart = (Char.ToUpperInvariant(c) - 64).ToString();
+                result.OrderedStart = CharHelper.SmallNumberToString((c | 0x20) - 'a' + 1);
                 result.BulletType = isUpper ? 'A' : 'a';
                 result.DefaultOrderedStart = isUpper ? "A" : "a";
                 state.NextChar();

src/Markdig/Extensions/MediaLinks/HostProviderBuilder.cs

@@ -2,6 +2,7 @@
 // This file is licensed under the BSD-Clause 2 license.
 // See the license.txt file in the project root for more information.
 
+using Markdig.Helpers;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -40,9 +41,10 @@ public bool TryHandle(Uri mediaUri, bool isSchemaRelative, out string iframeUrl)
         public static IHostProvider Create(string hostPrefix, Func<Uri, string> handler, bool allowFullScreen = true, string iframeClass = null)
         {
             if (string.IsNullOrEmpty(hostPrefix))
-                throw new ArgumentException("hostPrefix is null or empty.", nameof(hostPrefix));
+                ThrowHelper.ArgumentException("hostPrefix is null or empty.", nameof(hostPrefix));
             if (handler == null)
-                throw new ArgumentNullException(nameof(handler));
+                ThrowHelper.ArgumentNullException(nameof(handler));
+
             return new DelegateProvider { HostPrefix = hostPrefix, Delegate = handler, AllowFullScreen = allowFullScreen, Class = iframeClass };
         }
 

src/Markdig/Extensions/SelfPipeline/SelfPipelineExtension.cs

@@ -1,8 +1,9 @@
-// Copyright (c) Alexandre Mutel. All rights reserved.
+// Copyright (c) Alexandre Mutel. All rights reserved.
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
 
 using System;
+using Markdig.Helpers;
 using Markdig.Renderers;
 
 namespace Markdig.Extensions.SelfPipeline
@@ -29,7 +30,7 @@ public SelfPipelineExtension(string tag = null, string defaultExtensions = null)
             tag = string.IsNullOrEmpty(tag) ? DefaultTag : tag;
             if (tag.IndexOfAny(new []{'<', '>'}) >= 0)
             {
-                throw new ArgumentException("Tag cannot contain `<`  or `>` characters", nameof(tag));
+                ThrowHelper.ArgumentException("Tag cannot contain `<`  or `>` characters", nameof(tag));
             }
 
             if (defaultExtensions != null)
@@ -57,7 +58,7 @@ public void Setup(MarkdownPipelineBuilder pipeline)
             // Make sure that this pipeline has only one extension (itself)
             if (pipeline.Extensions.Count > 1)
             {
-                throw new InvalidOperationException(
+                ThrowHelper.InvalidOperationException(
                     "The SelfPipeline extension cannot be configured with other extensions");
             }
         }
@@ -74,7 +75,7 @@ public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
         /// <exception cref="System.ArgumentNullException"></exception>
         public MarkdownPipeline CreatePipelineFromInput(string inputText)
         {
-            if (inputText == null) throw new ArgumentNullException(nameof(inputText));
+            if (inputText == null) ThrowHelper.ArgumentNullException(nameof(inputText));
 
             var builder = new MarkdownPipelineBuilder();
             string defaultConfig = DefaultExtensions;

src/Markdig/Extensions/Tables/PipeTableParser.cs

@@ -30,8 +30,7 @@ public class PipeTableParser : InlineParser, IPostInlineProcessor
         /// <param name="options">The options.</param>
         public PipeTableParser(LineBreakInlineParser lineBreakParser, PipeTableOptions options = null)
         {
-            if (lineBreakParser == null) throw new ArgumentNullException(nameof(lineBreakParser));
-            this.lineBreakParser = lineBreakParser;
+            this.lineBreakParser = lineBreakParser ?? throw new ArgumentNullException(nameof(lineBreakParser));
             OpeningCharacters = new[] { '|', '\n' };
             Options = options ?? new PipeTableOptions();
         }