Add support for GFM autolinks (#165, #169)

2026-02-04 13:54:44 +00:00 · 2017-11-17 21:28:27 +01:00
parent 9a30883e2a
commit 964538ec79
10 changed files with 325 additions and 82 deletions
--- a/src/Markdig.Tests/Specs/AutoLinks.md
+++ b/src/Markdig.Tests/Specs/AutoLinks.md
@@ -76,3 +76,67 @@ Check **http://www.a.com** or __http://www.b.com__
 .
 <p>Check <strong><a href="http://www.a.com">http://www.a.com</a></strong> or <strong><a href="http://www.b.com">http://www.b.com</a></strong></p>
 ````````````````````````````````
+
+### GFM Support
+
+Extract from [GFM Autolinks extensions specs](https://github.github.com/gfm/#autolinks-extension-)
+
+```````````````````````````````` example
+www.commonmark.org
+.
+<p><a href="http://www.commonmark.org">www.commonmark.org</a></p>
+````````````````````````````````
+
+```````````````````````````````` example
+Visit www.commonmark.org/help for more information.
+.
+<p>Visit <a href="http://www.commonmark.org/help">www.commonmark.org/help</a> for more information.</p>
+````````````````````````````````
+
+```````````````````````````````` example
+Visit www.commonmark.org.
+
+Visit www.commonmark.org/a.b.
+.
+<p>Visit <a href="http://www.commonmark.org">www.commonmark.org</a>.</p>
+<p>Visit <a href="http://www.commonmark.org/a.b">www.commonmark.org/a.b</a>.</p>
+````````````````````````````````
+
+
+```````````````````````````````` example
+www.google.com/search?q=Markup+(business)
+
+(www.google.com/search?q=Markup+(business))
+.
+<p><a href="http://www.google.com/search?q=Markup+(business)">www.google.com/search?q=Markup+(business)</a></p>
+<p>(<a href="http://www.google.com/search?q=Markup+(business)">www.google.com/search?q=Markup+(business)</a>)</p>
+````````````````````````````````
+
+
+```````````````````````````````` example
+www.google.com/search?q=commonmark&hl=en
+
+www.google.com/search?q=commonmark&hl;
+.
+<p><a href="http://www.google.com/search?q=commonmark&amp;hl=en">www.google.com/search?q=commonmark&amp;hl=en</a></p>
+<p><a href="http://www.google.com/search?q=commonmark">www.google.com/search?q=commonmark</a>&amp;hl;</p>
+````````````````````````````````
+
+
+```````````````````````````````` example
+www.commonmark.org/he<lp
+.
+<p><a href="http://www.commonmark.org/he">www.commonmark.org/he</a>&lt;lp</p>
+````````````````````````````````
+
+```````````````````````````````` example
+http://commonmark.org
+
+(Visit https://encrypted.google.com/search?q=Markup+(business))
+
+Anonymous FTP is available at ftp://foo.bar.baz.
+.
+<p><a href="http://commonmark.org">http://commonmark.org</a></p>
+<p>(Visit <a href="https://encrypted.google.com/search?q=Markup+(business)">https://encrypted.google.com/search?q=Markup+(business)</a>)</p>
+<p>Anonymous FTP is available at <a href="ftp://foo.bar.baz">ftp://foo.bar.baz</a>.</p>
+````````````````````````````````
--- a/src/Markdig.Tests/Specs/Specs.cs
+++ b/src/Markdig.Tests/Specs/Specs.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using NUnit.Framework;

 namespace Markdig.Tests
@@ -20874,6 +20874,157 @@ namespace Markdig.Tests
            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 7, "Extensions AutoLinks");
 			TestParser.TestSpec("Check **http://www.a.com** or __http://www.b.com__", "<p>Check <strong><a href=\"http://www.a.com\">http://www.a.com</a></strong> or <strong><a href=\"http://www.b.com\">http://www.b.com</a></strong></p>", "autolinks|advanced");
        }
+    }
+        // ### GFM Support
+        //
+        // Extract from [GFM Autolinks extensions specs](https://github.github.com/gfm/#autolinks-extension-)
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example008()
+        {
+            // Example 8
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     www.commonmark.org
+            //
+            // Should be rendered as:
+            //     <p><a href="http://www.commonmark.org">www.commonmark.org</a></p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 8, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("www.commonmark.org", "<p><a href=\"http://www.commonmark.org\">www.commonmark.org</a></p>", "autolinks|advanced");
+        }
+    }
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example009()
+        {
+            // Example 9
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     Visit www.commonmark.org/help for more information.
+            //
+            // Should be rendered as:
+            //     <p>Visit <a href="http://www.commonmark.org/help">www.commonmark.org/help</a> for more information.</p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 9, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("Visit www.commonmark.org/help for more information.", "<p>Visit <a href=\"http://www.commonmark.org/help\">www.commonmark.org/help</a> for more information.</p>", "autolinks|advanced");
+        }
+    }
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example010()
+        {
+            // Example 10
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     Visit www.commonmark.org.
+            //     
+            //     Visit www.commonmark.org/a.b.
+            //
+            // Should be rendered as:
+            //     <p>Visit <a href="http://www.commonmark.org">www.commonmark.org</a>.</p>
+            //     <p>Visit <a href="http://www.commonmark.org/a.b">www.commonmark.org/a.b</a>.</p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 10, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("Visit www.commonmark.org.\n\nVisit www.commonmark.org/a.b.", "<p>Visit <a href=\"http://www.commonmark.org\">www.commonmark.org</a>.</p>\n<p>Visit <a href=\"http://www.commonmark.org/a.b\">www.commonmark.org/a.b</a>.</p>", "autolinks|advanced");
+        }
+    }
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example011()
+        {
+            // Example 11
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     www.google.com/search?q=Markup+(business)
+            //     
+            //     (www.google.com/search?q=Markup+(business))
+            //
+            // Should be rendered as:
+            //     <p><a href="http://www.google.com/search?q=Markup+(business)">www.google.com/search?q=Markup+(business)</a></p>
+            //     <p>(<a href="http://www.google.com/search?q=Markup+(business)">www.google.com/search?q=Markup+(business)</a>)</p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 11, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("www.google.com/search?q=Markup+(business)\n\n(www.google.com/search?q=Markup+(business))", "<p><a href=\"http://www.google.com/search?q=Markup+(business)\">www.google.com/search?q=Markup+(business)</a></p>\n<p>(<a href=\"http://www.google.com/search?q=Markup+(business)\">www.google.com/search?q=Markup+(business)</a>)</p>", "autolinks|advanced");
+        }
+    }
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example012()
+        {
+            // Example 12
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     www.google.com/search?q=commonmark&hl=en
+            //     
+            //     www.google.com/search?q=commonmark&hl;
+            //
+            // Should be rendered as:
+            //     <p><a href="http://www.google.com/search?q=commonmark&amp;hl=en">www.google.com/search?q=commonmark&amp;hl=en</a></p>
+            //     <p><a href="http://www.google.com/search?q=commonmark">www.google.com/search?q=commonmark</a>&amp;hl;</p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 12, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("www.google.com/search?q=commonmark&hl=en\n\nwww.google.com/search?q=commonmark&hl;", "<p><a href=\"http://www.google.com/search?q=commonmark&amp;hl=en\">www.google.com/search?q=commonmark&amp;hl=en</a></p>\n<p><a href=\"http://www.google.com/search?q=commonmark\">www.google.com/search?q=commonmark</a>&amp;hl;</p>", "autolinks|advanced");
+        }
+    }
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example013()
+        {
+            // Example 13
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     www.commonmark.org/he<lp
+            //
+            // Should be rendered as:
+            //     <p><a href="http://www.commonmark.org/he">www.commonmark.org/he</a>&lt;lp</p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 13, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("www.commonmark.org/he<lp", "<p><a href=\"http://www.commonmark.org/he\">www.commonmark.org/he</a>&lt;lp</p>", "autolinks|advanced");
+        }
+    }
+    [TestFixture]
+    public partial class TestExtensionsAutoLinksGFMSupport
+    {
+        [Test]
+        public void Example014()
+        {
+            // Example 14
+            // Section: Extensions AutoLinks GFM Support
+            //
+            // The following CommonMark:
+            //     http://commonmark.org
+            //     
+            //     (Visit https://encrypted.google.com/search?q=Markup+(business))
+            //     
+            //     Anonymous FTP is available at ftp://foo.bar.baz.
+            //
+            // Should be rendered as:
+            //     <p><a href="http://commonmark.org">http://commonmark.org</a></p>
+            //     <p>(Visit <a href="https://encrypted.google.com/search?q=Markup+(business)">https://encrypted.google.com/search?q=Markup+(business)</a>)</p>
+            //     <p>Anonymous FTP is available at <a href="ftp://foo.bar.baz">ftp://foo.bar.baz</a>.</p>
+
+            Console.WriteLine("Example {0}" + Environment.NewLine + "Section: {0}" + Environment.NewLine, 14, "Extensions AutoLinks GFM Support");
+			TestParser.TestSpec("http://commonmark.org\n\n(Visit https://encrypted.google.com/search?q=Markup+(business))\n\nAnonymous FTP is available at ftp://foo.bar.baz.", "<p><a href=\"http://commonmark.org\">http://commonmark.org</a></p>\n<p>(Visit <a href=\"https://encrypted.google.com/search?q=Markup+(business)\">https://encrypted.google.com/search?q=Markup+(business)</a>)</p>\n<p>Anonymous FTP is available at <a href=\"ftp://foo.bar.baz\">ftp://foo.bar.baz</a>.</p>", "autolinks|advanced");
+        }
    }
        // ## Jira Links
        //
--- a/src/Markdig.Tests/TestLinkHelper.cs
+++ b/src/Markdig.Tests/TestLinkHelper.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.

@@ -39,7 +39,7 @@ namespace Markdig.Tests
        {
            var text = new StringSlice(uri);
            string link;
-            Assert.True(LinkHelper.TryParseUrl(ref text, out link));
+            Assert.True(LinkHelper.TryParseUrl(ref text, out link, true));
            Assert.AreEqual("http://google.com", link);
            Assert.AreEqual('.', text.CurrentChar);
        }
--- a/src/Markdig/Extensions/AutoLinks/AutoLinkParser.cs
+++ b/src/Markdig/Extensions/AutoLinks/AutoLinkParser.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.

@@ -30,11 +30,18 @@ namespace Markdig.Extensions.AutoLinks
            };
        }

+
+        private static bool IsValidPreviousCharacter(char c)
+        {
+            // All such recognized autolinks can only come at the beginning of a line, after whitespace, or any of the delimiting characters *, _, ~, and (.
+            return c.IsWhiteSpaceOrZero() || c == '*' || c == '_' || c == '~' || c == '(';
+        }
+
        public override bool Match(InlineProcessor processor, ref StringSlice slice)
        {
            // Previous char must be a whitespace or a punctuation
            var previousChar = slice.PeekCharExtra(-1);
-            if (!previousChar.IsAsciiPunctuation() && !previousChar.IsWhiteSpaceOrZero())
+            if (!IsValidPreviousCharacter(previousChar))
            {
                return false;
            }
@@ -72,7 +79,7 @@ namespace Markdig.Extensions.AutoLinks
                    break;

                case 'w':
-                    if (!slice.MatchLowercase("ww.", 1) || previousChar == '/') // We won't match http:/www. or /www.xxx
+                    if (!slice.MatchLowercase("ww.", 1)) // We won't match http:/www. or /www.xxx
                    {
                        return false;
                    }
@@ -81,7 +88,7 @@ namespace Markdig.Extensions.AutoLinks

            // Parse URL
            string link;
-            if (!LinkHelper.TryParseUrl(ref slice, out link))
+            if (!LinkHelper.TryParseUrl(ref slice, out link, true))
            {
                return false;
            }
--- a/src/Markdig/Helpers/HtmlHelper.cs
+++ b/src/Markdig/Helpers/HtmlHelper.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.

@@ -472,10 +472,10 @@ namespace Markdig.Helpers
                }
                else if (c == '&')
                {
-                    string namedEntity;
+                    int entityNameStart;
+                    int entityNameLength;
                    int numericEntity;
-                    var match = ScanEntity(text, searchPos, text.Length - searchPos, out namedEntity,
-                        out numericEntity);
+                    var match = ScanEntity(new StringSlice(text, searchPos, text.Length - 1), out numericEntity, out entityNameStart, out entityNameLength);
                    if (match == 0)
                    {
                        searchPos++;
@@ -484,9 +484,10 @@ namespace Markdig.Helpers
                    {
                        searchPos += match;

-                        if (namedEntity != null)
+                        if (entityNameLength > 0)
                        {
-                            var decoded = EntityHelper.DecodeEntity(namedEntity);
+                            var namedEntity = new StringSlice(text, entityNameStart, entityNameStart + entityNameLength - 1);
+                            var decoded = EntityHelper.DecodeEntity(namedEntity.ToString());
                            if (decoded != null)
                            {
                                sb.Append(text, lastPos, searchPos - match - lastPos);
@@ -533,7 +534,7 @@ namespace Markdig.Helpers
        /// Scans an entity.
        /// Returns number of chars matched.
        /// </summary>
-        public static int ScanEntity(string s, int pos, int length, out string namedEntity, out int numericEntity)
+        public static int ScanEntity<T>(T slice, out int numericEntity, out int namedEntityStart,  out int namedEntityLength) where T : ICharIterator
        {
            // Credits: code from CommonMark.NET
            // Copyright (c) 2014, Kārlis Gaņģis All rights reserved. 
@@ -545,29 +546,29 @@ namespace Markdig.Helpers
                  .? { return 0; }
                */

-            var lastPos = pos + length;
-
-            namedEntity = null;
            numericEntity = 0;
+            namedEntityStart = 0;
+            namedEntityLength = 0;

-            if (pos + 3 >= lastPos)
-                return 0;
-
-            if (s[pos] != '&')
-                return 0;
-
-            char c;
-            int i;
-            int counter = 0;
-            if (s[pos + 1] == '#')
+            if (slice.CurrentChar != '&' || slice.PeekChar(3) == '\0')
            {
-                c = s[pos + 2];
+                return 0;
+            }
+
+            var start = slice.Start;
+            char c = slice.NextChar();
+            int counter = 0;
+            
+            if (c == '#')
+            {
+                c = slice.PeekChar();
                if (c == 'x' || c == 'X')
                {
+                    c = slice.NextChar(); // skip #
                    // expect 1-8 hex digits starting from pos+3
-                    for (i = pos + 3; i < lastPos; i++)
+                    while (c != '\0')
                    {
-                        c = s[i];
+                        c = slice.NextChar();
                        if (c >= '0' && c <= '9')
                        {
                            if (++counter == 9) return 0;
@@ -588,7 +589,7 @@ namespace Markdig.Helpers
                        }

                        if (c == ';')
-                            return counter == 0 ? 0 : i - pos + 1;
+                            return counter == 0 ? 0 : slice.Start - start + 1;

                        return 0;
                    }
@@ -596,9 +597,10 @@ namespace Markdig.Helpers
                else
                {
                    // expect 1-8 digits starting from pos+2
-                    for (i = pos + 2; i < lastPos; i++)
+                    while (c != '\0')
                    {
-                        c = s[i];
+                        c = slice.NextChar();
+
                        if (c >= '0' && c <= '9')
                        {
                            if (++counter == 9) return 0;
@@ -607,7 +609,7 @@ namespace Markdig.Helpers
                        }

                        if (c == ';')
-                            return counter == 0 ? 0 : i - pos + 1;
+                            return counter == 0 ? 0 : slice.Start - start + 1;

                        return 0;
                    }
@@ -616,25 +618,26 @@ namespace Markdig.Helpers
            else
            {
                // expect a letter and 1-31 letters or digits
-                c = s[pos + 1];
                if (!((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')))
                    return 0;

-                for (i = pos + 2; i < lastPos; i++)
+                namedEntityStart = slice.Start;
+                namedEntityLength++;
+
+                while (c != '\0')
                {
-                    c = s[i];
+                    c = slice.NextChar();
                    if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z'))
                    {
                        if (++counter == 32)
                            return 0;
-
+                        namedEntityLength++;
                        continue;
                    }

                    if (c == ';')
                    {
-                        namedEntity = s.Substring(pos + 1, counter + 1);
-                        return counter == 0 ? 0 : i - pos + 1;
+                        return counter == 0 ? 0 : slice.Start - start + 1;
                    }

                    return 0;
--- a/src/Markdig/Helpers/ICharIterator.cs
+++ b/src/Markdig/Helpers/ICharIterator.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.

@@ -34,8 +34,9 @@ namespace Markdig.Helpers
        /// <summary>
        /// Peeks at the next character, without incrementing the <see cref="Start"/> position.
        /// </summary>
+        /// <param name="offset"></param>
        /// <returns>The next character. `\0` is end of the iteration.</returns>
-        char PeekChar();
+        char PeekChar(int offset = 1);

        /// <summary>
        /// Gets a value indicating whether this instance is empty.
--- a/src/Markdig/Helpers/LinkHelper.cs
+++ b/src/Markdig/Helpers/LinkHelper.cs
@@ -4,6 +4,7 @@
 using System;
 using System.Runtime.CompilerServices;
 using System.Text;
+using Markdig.Parsers.Inlines;
 using Markdig.Syntax;

 namespace Markdig.Helpers
@@ -513,7 +514,7 @@ namespace Markdig.Helpers
            return TryParseUrl(ref text, out link);
        }

-        public static bool TryParseUrl<T>(ref T text, out string link) where T : ICharIterator
+        public static bool TryParseUrl<T>(ref T text, out string link, bool isAutoLink = false) where T : ICharIterator
        {
            bool isValid = false;
            var buffer = StringBuilderCache.Local();
@@ -610,16 +611,30 @@ namespace Markdig.Helpers

                    hasEscape = false;

-                    if (IsEndOfUri(c))
+                    if (IsEndOfUri(c, isAutoLink))
                    {
                        isValid = true;
                        break;
                    }

-                    if (c == '.' && IsEndOfUri(text.PeekChar()))
+                    if (isAutoLink)
                    {
-                        isValid = true;
-                        break;
+                        if (c == '&')
+                        {
+                            int entityNameStart;
+                            int entityNameLength;
+                            int entityValue;
+                            if (HtmlHelper.ScanEntity(text, out entityValue, out entityNameStart, out entityNameLength) > 0)
+                            {
+                                isValid = true;
+                                break;
+                            }
+                        }
+                        if (IsTrailingUrlStopCharacter(c) && IsEndOfUri(text.PeekChar(), true))
+                        {
+                            isValid = true;
+                            break;
+                        }
                    }

                    buffer.Append(c);
@@ -638,9 +653,17 @@ namespace Markdig.Helpers
            return isValid;
        }

-        private static bool IsEndOfUri(char c)
+        [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
+        private static bool IsTrailingUrlStopCharacter(char c)
        {
-            return c == '\0' || c.IsSpaceOrTab() || c.IsControl(); // TODO: specs unclear. space is strict or relaxed? (includes tabs?)
+            // Trailing punctuation (specifically, ?, !, ., ,, :, *, _, and ~) will not be considered part of the autolink, though they may be included in the interior of the link:
+            return c == '?' || c == '!' || c == '.' || c == ',' || c == ':' || c == '*' || c == '*' || c == '_' || c == '~';
+        }
+
+        [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
+        private static bool IsEndOfUri(char c, bool isAutoLink)
+        {
+            return c == '\0' || c.IsSpaceOrTab() || c.IsControl() || (isAutoLink && c == '<'); // TODO: specs unclear. space is strict or relaxed? (includes tabs?)
        }

        public static bool TryParseLinkReferenceDefinition<T>(T text, out string label, out string url,
--- a/src/Markdig/Helpers/StringLineGroup.cs
+++ b/src/Markdig/Helpers/StringLineGroup.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.

@@ -197,14 +197,14 @@ namespace Markdig.Helpers
        /// <seealso cref="ICharIterator" />
        public struct Iterator : ICharIterator
        {
-            private readonly StringLineGroup lines;
-            private int offset;
+            private readonly StringLineGroup _lines;
+            private int _offset;

            public Iterator(StringLineGroup lines)
            {
-                this.lines = lines;
+                this._lines = lines;
                Start = -1;
-                offset = -1;
+                _offset = -1;
                SliceIndex = 0;
                CurrentChar = '\0';
                End = -2; 
@@ -228,45 +228,47 @@ namespace Markdig.Helpers
            public char NextChar()
            {
                Start++;
-                offset++;
+                _offset++;
                if (Start <= End)
                {
-                    var slice = (StringSlice)lines.Lines[SliceIndex];
-                    if (offset < slice.Length)
+                    var slice = (StringSlice)_lines.Lines[SliceIndex];
+                    if (_offset < slice.Length)
                    {
-                        CurrentChar = slice[slice.Start + offset];
+                        CurrentChar = slice[slice.Start + _offset];
                    }
                    else
                    {
                        CurrentChar = '\n';
                        SliceIndex++;
-                        offset = -1;
+                        _offset = -1;
                    }
                }
                else
                {
                    CurrentChar = '\0';
                    Start = End + 1;
-                    SliceIndex = lines.Count;
-                    offset--;
+                    SliceIndex = _lines.Count;
+                    _offset--;
                }
                return CurrentChar;
            }

-            public char PeekChar()
+            public char PeekChar(int offset = 1)
            {
-                if (Start + 1 > End)
+                if (offset < 0) throw new ArgumentOutOfRangeException("Negative offset are not supported for StringLineGroup", nameof(offset));
+
+                if (Start + offset > End)
                {
                    return '\0';
                }

-                var slice = (StringSlice)lines.Lines[SliceIndex];
-                if (offset + 1 >= slice.Length)
+                var slice = (StringSlice)_lines.Lines[SliceIndex];
+                if (_offset + offset >= slice.Length)
                {
                    return '\n';
                }

-                return slice[slice.Start + offset + 1];
+                return slice[slice.Start + _offset + offset];
            }

            public bool TrimStart()
--- a/src/Markdig/Helpers/StringSlice.cs
+++ b/src/Markdig/Helpers/StringSlice.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.

@@ -112,17 +112,6 @@ namespace Markdig.Helpers
            return index >= Start && index <= End ? Text[index] : (char) 0;
        }

-        /// <summary>
-        /// Peeks the character immediately after the current <see cref="Start"/> position
-        /// or returns `\0` if after the <see cref="End"/> position.
-        /// </summary>
-        /// <returns>The next character, returns `\0` if none.</returns>
-        [MethodImpl(MethodImplOptionPortable.AggressiveInlining)]
-        public char PeekChar()
-        {
-            return PeekChar(1);
-        }
-
        /// <summary>
        /// Peeks a character at the specified offset from the current beginning of the string, without taking into account <see cref="Start"/> and <see cref="End"/>
        /// </summary>
--- a/src/Markdig/Parsers/Inlines/HtmlEntityParser.cs
+++ b/src/Markdig/Parsers/Inlines/HtmlEntityParser.cs
@@ -1,6 +1,8 @@
 // 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.Text;
 using Markdig.Helpers;
 using Markdig.Syntax;
 using Markdig.Syntax.Inlines;
@@ -25,17 +27,18 @@ namespace Markdig.Parsers.Inlines
        public static bool TryParse(ref StringSlice slice, out string literal, out int match)
        {
            literal = null;
-            string entityName;
+            int entityNameStart;
+            int entityNameLength;
            int entityValue;
-            match = HtmlHelper.ScanEntity(slice.Text, slice.Start, slice.Length, out entityName, out entityValue);
+            match = HtmlHelper.ScanEntity(slice, out entityValue, out entityNameStart, out entityNameLength);
            if (match == 0)
            {
                return false;
            }

-            if (entityName != null)
+            if (entityNameLength > 0)
            {
-                literal = EntityHelper.DecodeEntity(entityName);
+                literal = EntityHelper.DecodeEntity(new StringSlice(slice.Text, entityNameStart, entityNameStart + entityNameLength - 1).ToString());
            }
            else if (entityValue >= 0)
            {