Make sure that an emphasis is not added twice (issue #4)

src/Markdig.Tests/TestPlayParser.cs

@@ -27,34 +27,47 @@ Later in a text we are using HTML and it becomes an abbr tag HTML
             Console.WriteLine(result);
         }
 
-// Test for emoji and smileys
-//        var text = @" This is a test with a :) and a :angry: smiley";
+        [Test]
+        public void TestSamePipelineAllExtensions()
+        {
+            var pipeline = new MarkdownPipeline().UseAllExtensions();
+
+            // Reuse the same pipeline 
+            var result1 = Markdown.ToHtml("This is a \"\"citation\"\"", pipeline);
+            var result2 = Markdown.ToHtml("This is a \"\"citation\"\"", pipeline);
+
+            Assert.AreEqual("<p>This is a <cite>citation</cite></p>", result1.Trim());
+            Assert.AreEqual(result1, result2);
+        }
+
+        // Test for emoji and smileys
+        //        var text = @" This is a test with a :) and a :angry: smiley";
 
 
-// Test for definition lists:
-//
-//        var text = @"
-//Term 1
-//:   This is a definition item
-//    With a paragraph
-//    > This is a block quote
+        // Test for definition lists:
+        //
+        //        var text = @"
+        //Term 1
+        //:   This is a definition item
+        //    With a paragraph
+        //    > This is a block quote
 
-//    - This is a list
-//    - item2
+        //    - This is a list
+        //    - item2
 
-//    ```java
-//    Test
+        //    ```java
+        //    Test
 
 
-//    ```
+        //    ```
 
-//    And a lazy line
-//:   This ia another definition item
+        //    And a lazy line
+        //:   This ia another definition item
 
-//Term2
-//Term3 *with some inline*
-//:   This is another definition for term2
-//";
+        //Term2
+        //Term3 *with some inline*
+        //:   This is another definition for term2
+        //";
 
 
         // Test for grid table

src/Markdig/Extensions/Cites/CiteExtension.cs

@@ -18,15 +18,8 @@ namespace Markdig.Extensions.Cites
         public void Setup(MarkdownPipeline pipeline)
         {
             var parser = pipeline.InlineParsers.FindExact<EmphasisInlineParser>();
-            if (parser != null)
+            if (parser != null && !parser.HasEmphasisChar('"'))
             {
-                foreach (var emphasis in parser.EmphasisDescriptors)
-                {
-                    if (emphasis.Character == '"')
-                    {
-                        return;
-                    }
-                }
                 parser.EmphasisDescriptors.Add(new EmphasisDescriptor('"', 2, 2, false));
             }
 
@@ -37,6 +30,7 @@ namespace Markdig.Extensions.Cites
                 var emphasisRenderer = htmlRenderer.ObjectRenderers.FindExact<EmphasisInlineRenderer>();
                 if (emphasisRenderer != null)
                 {
+                    // TODO: Use an ordered list instead as we don't know if this specific GetTag has been already added
                     var previousTag = emphasisRenderer.GetTag;
                     emphasisRenderer.GetTag = inline => GetTag(inline) ?? previousTag(inline);
                 }

src/Markdig/Extensions/CustomContainers/CustomContainerExtension.cs

@@ -23,7 +23,7 @@ namespace Markdig.Extensions.CustomContainers
 
             // Plug the inline parser for CustomContainerInline
             var inlineParser = pipeline.InlineParsers.Find<EmphasisInlineParser>();
-            if (inlineParser != null)
+            if (inlineParser != null && !inlineParser.HasEmphasisChar(':'))
             {
                 inlineParser.EmphasisDescriptors.Add(new EmphasisDescriptor(':', 2, 2, true));
                 var previousCreateEmphasisInline = inlineParser.CreateEmphasisInline;

src/Markdig/MarkdownPipeline.cs

@@ -13,6 +13,7 @@ namespace Markdig
     /// <summary>
     /// This class allows to modify the pipeline to parse and render a Markdown document.
     /// </summary>
+    /// <remarks>NOTE: A pipeline is not thread-safe.</remarks>
     public class MarkdownPipeline
     {
         /// <summary>
@@ -95,6 +96,11 @@ namespace Markdig
         /// <exception cref="System.InvalidOperationException">An extension cannot be null</exception>
         public void Initialize()
         {
+            // TODO: Review the whole initialization process for extensions
+            // - It does not prevent a user to modify the pipeline after it has been used
+            // - a pipeline is not thread safe.
+            // We should find a proper way to make the pipeline safely modifiable/freezable (PipelineBuilder -> Pipeline)
+
             // Allow extensions to modify existing BlockParsers, InlineParsers and Renderer
             foreach (var extension in Extensions)
             {

src/Markdig/Parsers/Inlines/EmphasisInlineParser.cs

@@ -41,6 +41,23 @@ namespace Markdig.Parsers.Inlines
         /// </summary>
         public List<EmphasisDescriptor> EmphasisDescriptors { get; }
 
+        /// <summary>
+        /// Determines whether this parser is using the specified character as an emphasis delimiter.
+        /// </summary>
+        /// <param name="c">The character to look for.</param>
+        /// <returns><c>true</c> if this parser is using the specified character as an emphasis delimiter; otherwise <c>false</c></returns>
+        public bool HasEmphasisChar(char c)
+        {
+            foreach (var emphasis in EmphasisDescriptors)
+            {
+                if (emphasis.Character == c)
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
+
         /// <summary>
         /// Gets or sets the create emphasis inline delegate (allowing to create a different emphasis inline class)
         /// </summary>