Implementing Simultaneous Bold and Italic in MarkdownTextBlock

Microsoft.Toolkit.Uwp.SampleApp/SamplePages/MarkdownTextBlock/InitialContent.md

@@ -1,7 +1,5 @@
 This control was originally written by [Quinn Damerell](https://github.com/QuinnDamerell) and [Paul Bartrum](https://github.com/paulbartrum) for [Baconit](https://github.com/QuinnDamerell/Baconit), a popular open source reddit UWP. The control *almost* supports the full markdown syntax, with a focus on super-efficient parsing and rendering. The control is efficient enough to be used in virtualizing lists.
 
- 
-
 *Note:* For a full list of markdown syntax, see the [official syntax guide](http://daringfireball.net/projects/markdown/syntax).
 
  
@@ -10,6 +8,19 @@
 
  
 
+# COMMENTS
+
+Comments can be added in Markdown, and they won't be rendered to the screen.
+
+To create a comment, enclose in XML style comment tags:
+
+><\!-- Comments are now Implemented -->
+
+There is a Comment below this line.
+<!-- Comments are now Implemented -->
+
+&nbsp;
+
 # PARAGRAPHS
 
 Paragraphs are delimited by a blank line.  Simply starting text on a new line won't create a new paragraph; It will remain on the same line in the final, rendered version as the previous line.  You need an extra, blank line to start a new paragraph.  This is especially important when dealing with quotes and, to a lesser degree, lists.
@@ -49,6 +60,18 @@ is displayed as:
 
 >This sentence includes **bold text**.
 
+### Bold & Italics
+
+Text can be displayed in a bold font by surrounding a word or words with either triple asterisks (\*) or triple underscores (\_).
+
+For example: 
+
+>This sentence includes \*\*\*bold & italic text\*\*\*.
+
+is displayed as:
+
+>This sentence includes ***bold & italic text***.
+
 ### Strikethrough
 
 Text can be displayed in a strikethrough font by surrounding a word or words with double tildes (~~).  For example:

Microsoft.Toolkit.Uwp.UI.Controls/MarkdownTextBlock/Display/XamlRenderer.cs

@@ -757,7 +757,10 @@ private void RenderInlineChildren(InlineCollection inlineCollection, IList<Markd
         {
             foreach (MarkdownInline element in inlineElements)
             {
-                RenderInline(inlineCollection, element, parent, context);
+                if (element.Type != MarkdownInlineType.Comment)
+                {
+                    RenderInline(inlineCollection, element, parent, context);
+                }
             }
         }
 

Microsoft.Toolkit.Uwp.UI.Controls/MarkdownTextBlock/Helpers/Common.cs

@@ -20,6 +20,11 @@ internal class Common
     {
         internal enum InlineParseMethod
         {
+            /// <summary>
+            /// A Comment text
+            /// </summary>
+            Comment,
+
             /// <summary>
             /// A bold element
             /// </summary>
@@ -35,6 +40,11 @@ internal enum InlineParseMethod
             /// </summary>
             Italic,
 
+            /// <summary>
+            /// An bold and italic block
+            /// </summary>
+            BoldItalic,
+
             /// <summary>
             /// A link block
             /// </summary>
@@ -106,10 +116,12 @@ internal class InlineTripCharHelper
 
         static Common()
         {
+            BoldItalicTextInline.AddTripChars(_triggerList);
             BoldTextInline.AddTripChars(_triggerList);
             ItalicTextInline.AddTripChars(_triggerList);
             MarkdownLinkInline.AddTripChars(_triggerList);
             HyperlinkInline.AddTripChars(_triggerList);
+            CommentInline.AddTripChars(_triggerList);
             StrikethroughTextInline.AddTripChars(_triggerList);
             SuperscriptTextInline.AddTripChars(_triggerList);
             CodeInline.AddTripChars(_triggerList);
@@ -219,6 +231,12 @@ private static InlineParseResult FindNextInlineElement(string markdown, int star
                         InlineParseResult parseResult = null;
                         switch (currentTripChar.Method)
                         {
+                            case InlineParseMethod.BoldItalic:
+                                parseResult = BoldItalicTextInline.Parse(markdown, pos, end);
+                                break;
+                            case InlineParseMethod.Comment:
+                                parseResult = CommentInline.Parse(markdown, pos, end);
+                                break;
                             case InlineParseMethod.Bold:
                                 parseResult = BoldTextInline.Parse(markdown, pos, end);
                                 break;

Microsoft.Toolkit.Uwp.UI.Controls/MarkdownTextBlock/Parse/Inlines/BoldItalicTextInline.cs

@@ -0,0 +1,126 @@
+// ******************************************************************
+// Copyright (c) Microsoft. All rights reserved.
+// This code is licensed under the MIT License (MIT).
+// THE CODE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
+// THE CODE OR THE USE OR OTHER DEALINGS IN THE CODE.
+// ******************************************************************
+
+using System.Collections.Generic;
+using Microsoft.Toolkit.Uwp.UI.Controls.Markdown.Helpers;
+
+namespace Microsoft.Toolkit.Uwp.UI.Controls.Markdown.Parse
+{
+    /// <summary>
+    /// Represents a span containing bold italic text.
+    /// </summary>
+    internal class BoldItalicTextInline : MarkdownInline, IInlineContainer
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="BoldItalicTextInline"/> class.
+        /// </summary>
+        public BoldItalicTextInline()
+            : base(MarkdownInlineType.Bold)
+        {
+        }
+
+        /// <summary>
+        /// Gets or sets the contents of the inline.
+        /// </summary>
+        public IList<MarkdownInline> Inlines { get; set; }
+
+        /// <summary>
+        /// Returns the chars that if found means we might have a match.
+        /// </summary>
+        internal static void AddTripChars(List<Common.InlineTripCharHelper> tripCharHelpers)
+        {
+            tripCharHelpers.Add(new Common.InlineTripCharHelper() { FirstChar = '*', Method = Common.InlineParseMethod.BoldItalic });
+            tripCharHelpers.Add(new Common.InlineTripCharHelper() { FirstChar = '_', Method = Common.InlineParseMethod.BoldItalic });
+        }
+
+        /// <summary>
+        /// Attempts to parse a bold text span.
+        /// </summary>
+        /// <param name="markdown"> The markdown text. </param>
+        /// <param name="start"> The location to start parsing. </param>
+        /// <param name="maxEnd"> The location to stop parsing. </param>
+        /// <returns> A parsed bold text span, or <c>null</c> if this is not a bold text span. </returns>
+        internal static Common.InlineParseResult Parse(string markdown, int start, int maxEnd)
+        {
+            if (start >= maxEnd - 1)
+            {
+                return null;
+            }
+
+            if (markdown == null || markdown.Length < 6)
+            {
+                return null;
+            }
+
+            // Check the start sequence.
+            string startSequence = markdown.Substring(start, 3);
+            if (startSequence != "***" && startSequence != "___")
+            {
+                return null;
+            }
+
+            // Find the end of the span.  The end sequence (either '***' or '___') must be the same
+            // as the start sequence.
+            var innerStart = start + 3;
+            int innerEnd = Common.IndexOf(markdown, startSequence, innerStart, maxEnd);
+            if (innerEnd == -1)
+            {
+                return null;
+            }
+
+            // The span must contain at least one character.
+            if (innerStart == innerEnd)
+            {
+                return null;
+            }
+
+            // The first character inside the span must NOT be a space.
+            if (Common.IsWhiteSpace(markdown[innerStart]))
+            {
+                return null;
+            }
+
+            // The last character inside the span must NOT be a space.
+            if (Common.IsWhiteSpace(markdown[innerEnd - 1]))
+            {
+                return null;
+            }
+
+            // We found something!
+            var bold = new BoldTextInline
+            {
+                Inlines = new List<MarkdownInline>
+                {
+                    new ItalicTextInline
+                    {
+                        Inlines = Common.ParseInlineChildren(markdown, innerStart, innerEnd)
+                    }
+                }
+            };
+            return new Common.InlineParseResult(bold, start, innerEnd + 3);
+        }
+
+        /// <summary>
+        /// Converts the object into it's textual representation.
+        /// </summary>
+        /// <returns> The textual representation of this object. </returns>
+        public override string ToString()
+        {
+            if (Inlines == null)
+            {
+                return base.ToString();
+            }
+
+            return "***" + string.Join(string.Empty, Inlines) + "***";
+        }
+    }
+}

Microsoft.Toolkit.Uwp.UI.Controls/MarkdownTextBlock/Parse/Inlines/CommentInline.cs

@@ -0,0 +1,93 @@
+// ******************************************************************
+// Copyright (c) Microsoft. All rights reserved.
+// This code is licensed under the MIT License (MIT).
+// THE CODE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH
+// THE CODE OR THE USE OR OTHER DEALINGS IN THE CODE.
+// ******************************************************************
+
+using System.Collections.Generic;
+using Microsoft.Toolkit.Uwp.UI.Controls.Markdown.Helpers;
+
+namespace Microsoft.Toolkit.Uwp.UI.Controls.Markdown.Parse
+{
+    /// <summary>
+    /// Represents a span that contains comment.
+    /// </summary>
+    internal class CommentInline : MarkdownInline, IInlineContainer
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CommentInline"/> class.
+        /// </summary>
+        public CommentInline()
+            : base(MarkdownInlineType.Comment)
+        {
+        }
+
+        /// <summary>
+        /// Gets or sets the contents of the inline.
+        /// </summary>
+        public IList<MarkdownInline> Inlines { get; set; }
+
+        /// <summary>
+        /// Returns the chars that if found means we might have a match.
+        /// </summary>
+        internal static void AddTripChars(List<Common.InlineTripCharHelper> tripCharHelpers)
+        {
+            tripCharHelpers.Add(new Common.InlineTripCharHelper() { FirstChar = '<', Method = Common.InlineParseMethod.Comment });
+        }
+
+        /// <summary>
+        /// Attempts to parse a comment span.
+        /// </summary>
+        /// <param name="markdown"> The markdown text. </param>
+        /// <param name="start"> The location to start parsing. </param>
+        /// <param name="maxEnd"> The location to stop parsing. </param>
+        /// <returns> A parsed bold text span, or <c>null</c> if this is not a bold text span. </returns>
+        internal static Common.InlineParseResult Parse(string markdown, int start, int maxEnd)
+        {
+            if (start >= maxEnd - 1)
+            {
+                return null;
+            }
+
+            // Check the start sequence.
+            string startSequence = markdown.Substring(start, 4);
+            if (startSequence != "<!--")
+            {
+                return null;
+            }
+
+            // Find the end of the span.  The end sequence ('-->')
+            var innerStart = start + 4;
+            int innerEnd = Common.IndexOf(markdown, "-->", innerStart, maxEnd);
+            if (innerEnd == -1)
+            {
+                return null;
+            }
+
+            // We found something!
+            var result = new CommentInline();
+            result.Inlines = Common.ParseInlineChildren(string.Empty, 0, 0);
+            return new Common.InlineParseResult(result, start, innerEnd + 3);
+        }
+
+        /// <summary>
+        /// Converts the object into it's textual representation.
+        /// </summary>
+        /// <returns> The textual representation of this object. </returns>
+        public override string ToString()
+        {
+            if (Inlines == null)
+            {
+                return base.ToString();
+            }
+
+            return "<!--" + string.Join(string.Empty, Inlines) + "-->";
+        }
+    }
+}

Microsoft.Toolkit.Uwp.UI.Controls/MarkdownTextBlock/Parse/MarkdownInline.cs

@@ -14,6 +14,11 @@ namespace Microsoft.Toolkit.Uwp.UI.Controls.Markdown.Parse
 {
     internal enum MarkdownInlineType
     {
+        /// <summary>
+        /// A comment
+        /// </summary>
+        Comment,
+
         /// <summary>
         /// A text run
         /// </summary>