xoofx · xoofx · Mar 9, 2021 · Mar 8, 2021
diff --git a/src/Markdig/Helpers/CharNormalizer.cs b/src/Markdig/Helpers/CharNormalizer.cs
@@ -1,7 +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.
 
+#nullable enable
+
 using System.Collections.Generic;
 
 namespace Markdig.Helpers
@@ -18,9 +20,9 @@ public static class CharNormalizer
         /// </summary>
         /// <param name="c">The input char.</param>
         /// <returns>The simple ASCII string or null if the char itself cannot be simplified</returns>
-        public static string ConvertToAscii(char c)
+        public static string? ConvertToAscii(char c)
         {
-            return CodeToAscii.TryGetValue(c, out string str) ? str : null;
+            return CodeToAscii.TryGetValue(c, out string? str) ? str : null;
         }
 
         static CharNormalizer()

diff --git a/src/Markdig/Helpers/HtmlHelper.cs b/src/Markdig/Helpers/HtmlHelper.cs
@@ -2,6 +2,8 @@
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
 
+#nullable enable
+
 using System;
 using System.Text;
 
@@ -30,7 +32,8 @@ static HtmlHelper()
                 }
             }
         }
-        public static string EscapeUrlCharacter(char c)
+
+        public static string? EscapeUrlCharacter(char c)
         {
             return c < 128 ? EscapeUrlsForAscii[c] : null;
         }
@@ -431,7 +434,7 @@ private static bool TryParseHtmlTagProcessingInstruction(ref StringSlice text, S
         /// <param name="text">The string data that will be changed by unescaping any punctuation or symbol characters.</param>
         /// <param name="removeBackSlash">if set to <c>true</c> [remove back slash].</param>
         /// <returns></returns>
-        public static string Unescape(string text, bool removeBackSlash = true)
+        public static string Unescape(string? text, bool removeBackSlash = true)
         {
             // Credits: code from CommonMark.NET
             // Copyright (c) 2014, Kārlis Gaņģis All rights reserved. 
@@ -446,9 +449,9 @@ public static string Unescape(string text, bool removeBackSlash = true)
             int lastPos = 0;
             char c;
             char[] search = removeBackSlash ? SearchBackAndAmp : SearchAmp;
-            StringBuilder sb = null;
+            StringBuilder? sb = null;
 
-            while ((searchPos = text.IndexOfAny(search, searchPos)) != -1)
+            while ((searchPos = text!.IndexOfAny(search, searchPos)) != -1)
             {
                 sb ??= StringBuilderCache.Local();
                 c = text[searchPos];

diff --git a/src/Markdig/Helpers/LinkHelper.cs b/src/Markdig/Helpers/LinkHelper.cs
@@ -2,7 +2,9 @@
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
 
-using System;
+#nullable enable
+
+using System.Diagnostics.CodeAnalysis;
 using System.Runtime.CompilerServices;
 using System.Text;
 using Markdig.Syntax;
@@ -14,7 +16,7 @@ namespace Markdig.Helpers
     /// </summary>
     public static class LinkHelper
     {
-        public static bool TryParseAutolink(StringSlice text, out string link, out bool isEmail)
+        public static bool TryParseAutolink(StringSlice text, [NotNullWhen(true)] out string? link, out bool isEmail)
         {
             return TryParseAutolink(ref text, out link, out isEmail);
         }
@@ -118,7 +120,7 @@ private static bool IsReservedPunctuation(char c)
             return c == '_' || c == '-' || c == '.';
         }
 
-        public static bool TryParseAutolink(ref StringSlice text, out string link, out bool isEmail)
+        public static bool TryParseAutolink(ref StringSlice text, [NotNullWhen(true)] out string? link, out bool isEmail)
         {
             link = null;
             isEmail = false;
@@ -322,22 +324,22 @@ public static bool TryParseAutolink(ref StringSlice text, out string link, out b
             return false;
         }
 
-        public static bool TryParseInlineLink(StringSlice text, out string link, out string title)
+        public static bool TryParseInlineLink(StringSlice text, out string? link, out string? title)
         {
             return TryParseInlineLink(ref text, out link, out title, out _, out _);
         }
 
-        public static bool TryParseInlineLink(StringSlice text, out string link, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan)
+        public static bool TryParseInlineLink(StringSlice text, out string? link, out string? title, out SourceSpan linkSpan, out SourceSpan titleSpan)
         {
             return TryParseInlineLink(ref text, out link, out title, out linkSpan, out titleSpan);
         }
 
-        public static bool TryParseInlineLink(ref StringSlice text, out string link, out string title)
+        public static bool TryParseInlineLink(ref StringSlice text, out string? link, out string? title)
         {
             return TryParseInlineLink(ref text, out link, out title, out SourceSpan linkSpan, out SourceSpan titleSpan);
         }
 
-        public static bool TryParseInlineLink(ref StringSlice text, out string link, out string title, out SourceSpan linkSpan, out SourceSpan titleSpan)
+        public static bool TryParseInlineLink(ref StringSlice text, out string? link, out string? title, out SourceSpan linkSpan, out SourceSpan titleSpan)
         {
             // 1. An inline link consists of a link text followed immediately by a left parenthesis (, 
             // 2. optional whitespace,  TODO: specs: is it whitespace or multiple whitespaces?
@@ -417,9 +419,9 @@ public static bool TryParseInlineLink(ref StringSlice text, out string link, out
 
         public static bool TryParseInlineLinkTrivia(
             ref StringSlice text,
-            out string link,
+            out string? link,
             out SourceSpan unescapedLink,
-            out string title,
+            out string? title,
             out SourceSpan unescapedTitle,
             out char titleEnclosingCharacter,
             out SourceSpan linkSpan,
@@ -521,12 +523,12 @@ public static bool TryParseInlineLinkTrivia(
             return isValid;
         }
 
-        public static bool TryParseTitle<T>(T text, out string title) where T : ICharIterator
+        public static bool TryParseTitle<T>(T text, out string? title) where T : ICharIterator
         {
             return TryParseTitle(ref text, out title, out _);
         }
 
-        public static bool TryParseTitle<T>(ref T text, out string title, out char enclosingCharacter) where T : ICharIterator
+        public static bool TryParseTitle<T>(ref T text, out string? title, out char enclosingCharacter) where T : ICharIterator
         {
             bool isValid = false;
             var buffer = StringBuilderCache.Local();
@@ -620,7 +622,7 @@ public static bool TryParseTitle<T>(ref T text, out string title, out char enclo
             return isValid;
         }
 
-        public static bool TryParseTitleTrivia<T>(ref T text, out string title, out char enclosingCharacter) where T : ICharIterator
+        public static bool TryParseTitleTrivia<T>(ref T text, out string? title, out char enclosingCharacter) where T : ICharIterator
         {
             bool isValid = false;
             var buffer = StringBuilderCache.Local();
@@ -714,12 +716,12 @@ public static bool TryParseTitleTrivia<T>(ref T text, out string title, out char
             return isValid;
         }
 
-        public static bool TryParseUrl<T>(T text, out string link) where T : ICharIterator
+        public static bool TryParseUrl<T>(T text, out string? link) where T : ICharIterator
         {
             return TryParseUrl(ref text, out link, out _);
         }
 
-        public static bool TryParseUrl<T>(ref T text, out string link, out bool hasPointyBrackets, bool isAutoLink = false) where T : ICharIterator
+        public static bool TryParseUrl<T>(ref T text, out string? link, out bool hasPointyBrackets, bool isAutoLink = false) where T : ICharIterator
         {
             bool isValid = false;
             hasPointyBrackets = false;
@@ -859,7 +861,7 @@ public static bool TryParseUrl<T>(ref T text, out string link, out bool hasPoint
             return isValid;
         }
 
-        public static bool TryParseUrlTrivia<T>(ref T text, out string link, out bool hasPointyBrackets, bool isAutoLink = false) where T : ICharIterator
+        public static bool TryParseUrlTrivia<T>(ref T text, out string? link, out bool hasPointyBrackets, bool isAutoLink = false) where T : ICharIterator
         {
             bool isValid = false;
             hasPointyBrackets = false;
@@ -1069,7 +1071,7 @@ public static bool IsValidDomain(string link, int prefixLength)
                 segmentCount - lastUnderscoreSegment >= 2; // No underscores are present in the last two segments of the domain
         }
 
-        public static bool TryParseLinkReferenceDefinition<T>(ref T text, out string label, out string url, out string title, out SourceSpan labelSpan, out SourceSpan urlSpan, out SourceSpan titleSpan) where T : ICharIterator
+        public static bool TryParseLinkReferenceDefinition<T>(ref T text, out string? label, out string? url, out string? title, out SourceSpan labelSpan, out SourceSpan urlSpan, out SourceSpan titleSpan) where T : ICharIterator
         {
             url = null;
             title = null;
@@ -1158,14 +1160,14 @@ public static bool TryParseLinkReferenceDefinition<T>(ref T text, out string lab
         public static bool TryParseLinkReferenceDefinitionTrivia<T>(
             ref T text,
             out SourceSpan triviaBeforeLabel,
-            out string label,
+            out string? label,
             out SourceSpan labelWithTrivia,
             out SourceSpan triviaBeforeUrl, // can contain newline
-            out string url,
+            out string? url,
             out SourceSpan unescapedUrl,
             out bool urlHasPointyBrackets,
             out SourceSpan triviaBeforeTitle, // can contain newline
-            out string title, // can contain non-consecutive newlines
+            out string? title, // can contain non-consecutive newlines
             out SourceSpan unescapedTitle,
             out char titleEnclosingCharacter,
             out NewLine newLine,
@@ -1303,32 +1305,32 @@ public static bool TryParseLinkReferenceDefinitionTrivia<T>(
             return true;
         }
 
-        public static bool TryParseLabel<T>(T lines, out string label) where T : ICharIterator
+        public static bool TryParseLabel<T>(T lines, out string? label) where T : ICharIterator
         {
             return TryParseLabel(ref lines, false, out label, out SourceSpan labelSpan);
         }
 
-        public static bool TryParseLabel<T>(T lines, out string label, out SourceSpan labelSpan) where T : ICharIterator
+        public static bool TryParseLabel<T>(T lines, out string? label, out SourceSpan labelSpan) where T : ICharIterator
         {
             return TryParseLabel(ref lines, false, out label, out labelSpan);
         }
 
-        public static bool TryParseLabel<T>(ref T lines, out string label) where T : ICharIterator
+        public static bool TryParseLabel<T>(ref T lines, out string? label) where T : ICharIterator
         {
             return TryParseLabel(ref lines, false, out label, out SourceSpan labelSpan);
         }
 
-        public static bool TryParseLabel<T>(ref T lines, out string label, out SourceSpan labelSpan) where T : ICharIterator
+        public static bool TryParseLabel<T>(ref T lines, out string? label, out SourceSpan labelSpan) where T : ICharIterator
         {
             return TryParseLabel(ref lines, false, out label, out labelSpan);
         }
 
-        public static bool TryParseLabelTrivia<T>(ref T lines, out string label, out SourceSpan labelSpan) where T : ICharIterator
+        public static bool TryParseLabelTrivia<T>(ref T lines, out string? label, out SourceSpan labelSpan) where T : ICharIterator
         {
             return TryParseLabelTrivia(ref lines, false, out label, out labelSpan);
         }
 
-        public static bool TryParseLabel<T>(ref T lines, bool allowEmpty, out string label, out SourceSpan labelSpan) where T : ICharIterator
+        public static bool TryParseLabel<T>(ref T lines, bool allowEmpty, out string? label, out SourceSpan labelSpan) where T : ICharIterator
         {
             label = null;
             char c = lines.CurrentChar;
@@ -1443,7 +1445,7 @@ public static bool TryParseLabel<T>(ref T lines, bool allowEmpty, out string lab
             return isValid;
         }
 
-        public static bool TryParseLabelTrivia<T>(ref T lines, bool allowEmpty, out string label, out SourceSpan labelSpan) where T : ICharIterator
+        public static bool TryParseLabelTrivia<T>(ref T lines, bool allowEmpty, out string? label, out SourceSpan labelSpan) where T : ICharIterator
         {
             label = null;
             char c = lines.CurrentChar;

diff --git a/src/Markdig/Helpers/StringLineGroup.cs b/src/Markdig/Helpers/StringLineGroup.cs
@@ -2,6 +2,8 @@
 // This file is licensed under the BSD-Clause 2 license. 
 // See the license.txt file in the project root for more information.
 
+#nullable enable
+
 using System;
 using System.Collections;
 using System.Collections.Generic;
@@ -30,6 +32,7 @@ public StringLineGroup(int capacity)
             Lines = _pool.Rent(capacity);
             Count = 0;
         }
+
         internal StringLineGroup(int capacity, bool willRelease)
         {
             if (capacity <= 0) ThrowHelper.ArgumentOutOfRangeException(nameof(capacity));
@@ -116,7 +119,7 @@ public readonly override string ToString()
         /// </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 readonly StringSlice ToSlice(List<LineOffset> lineOffsets = null)
+        public readonly StringSlice ToSlice(List<LineOffset>? lineOffsets = null)
         {
             // Optimization case for a single line.
             if (Count == 1)
@@ -201,7 +204,7 @@ internal void Release()
         {
             Array.Clear(Lines, 0, Count);
             _pool.Return(Lines);
-            Lines = null;
+            Lines = null!;
             Count = -1;
         }
 

diff --git a/src/Markdig/Helpers/ThrowHelper.cs b/src/Markdig/Helpers/ThrowHelper.cs
@@ -15,24 +15,52 @@ namespace Markdig.Helpers
     [ExcludeFromCodeCoverage]
     internal static class ThrowHelper
     {
+        [DoesNotReturn]
         public static void ArgumentNullException(string paramName) => throw new ArgumentNullException(paramName);
+
+        [DoesNotReturn]
         public static void ArgumentNullException_item() => throw new ArgumentNullException("item");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_text() => throw new ArgumentNullException("text");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_label() => throw new ArgumentNullException("label");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_key() => throw new ArgumentNullException("key");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_name() => throw new ArgumentNullException("name");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_markdown() => throw new ArgumentNullException("markdown");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_writer() => throw new ArgumentNullException("writer");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_leafBlock() => throw new ArgumentNullException("leafBlock");
+
+        [DoesNotReturn]
         public static void ArgumentNullException_markdownObject() => throw new ArgumentNullException("markdownObject");
 
+        [DoesNotReturn]
         public static void ArgumentException(string message) => throw new ArgumentException(message);
+
+        [DoesNotReturn]
         public static void ArgumentException(string message, string paramName) => throw new ArgumentException(message, paramName);
 
+        [DoesNotReturn]
         public static void ArgumentOutOfRangeException(string paramName) => throw new ArgumentOutOfRangeException(paramName);
+
+        [DoesNotReturn]
         public static void ArgumentOutOfRangeException(string message, string paramName) => throw new ArgumentOutOfRangeException(message, paramName);
+
+        [DoesNotReturn]
         public static void ArgumentOutOfRangeException_index() => throw new ArgumentOutOfRangeException("index");
 
+        [DoesNotReturn]
         public static void InvalidOperationException(string message) => throw new InvalidOperationException(message);
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
@@ -57,21 +85,25 @@ public static void CheckDepthLimit(int depth, bool useLargeLimit = false)
             static void DepthLimitExceeded() => throw new ArgumentException("Markdown elements in the input are too deeply nested - depth limit exceeded. Input is most likely not sensible or is a very large table.");
         }
 
+        [DoesNotReturn]
         public static void ThrowArgumentNullException(ExceptionArgument argument)
         {
             throw new ArgumentNullException(argument.ToString());
         }
 
+        [DoesNotReturn]
         public static void ThrowArgumentException(ExceptionArgument argument, ExceptionReason reason)
         {
             throw new ArgumentException(argument.ToString(), GetExceptionReason(reason));
         }
 
+        [DoesNotReturn]
         public static void ThrowArgumentOutOfRangeException(ExceptionArgument argument, ExceptionReason reason)
         {
             throw new ArgumentOutOfRangeException(argument.ToString(), GetExceptionReason(reason));
         }
 
+        [DoesNotReturn]
         public static void ThrowIndexOutOfRangeException()
         {
             throw new IndexOutOfRangeException();