Add methods for iterating over a Block/Inline

src/Textamina.Markdig/Syntax/MarkdownObjectExtensions.cs

@@ -0,0 +1,110 @@
+// 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.Collections.Generic;
+using Textamina.Markdig.Syntax.Inlines;
+
+namespace Textamina.Markdig.Syntax
+{
+    /// <summary>
+    /// Extensions for visiting <see cref="Block"/> or <see cref="Inline"/>
+    /// </summary>
+    public static class MarkdownObjectExtensions
+    {
+        /// <summary>
+        /// Iterates over the descendant elements for the specified markdown element, including <see cref="Block"/> and <see cref="Inline"/>.
+        /// </summary>
+        /// <param name="markdownObject">The markdown object.</param>
+        /// <returns>An iteration over the descendant elements</returns>
+        public static IEnumerable<MarkdownObject> Descendants(this MarkdownObject markdownObject)
+        {
+            var block = markdownObject as ContainerBlock;
+            if (block != null)
+            {
+                foreach (var subBlock in block)
+                {
+                    yield return subBlock;
+
+                    foreach (var sub in subBlock.Descendants())
+                    {
+                        yield return sub;
+                    }
+                }
+            }
+            else
+            {
+                var inline = markdownObject as ContainerInline;
+                if (inline != null)
+                {
+                    var child = inline.FirstChild;
+                    while (child != null)
+                    {
+                        var next = child.NextSibling;
+                        yield return child;
+
+                        foreach (var sub in child.Descendants())
+                        {
+                            yield return sub;
+                        }
+
+                        child = next;
+                    }
+                }
+            }
+        }
+
+        /// <summary>
+        /// Iterates over the descendant elements for the specified markdown element and filters by the type {T}, including <see cref="Block" /> and <see cref="Inline" />.
+        /// </summary>
+        /// <typeparam name="T">Type to use for filtering the descendants</typeparam>
+        /// <param name="markdownObject">The markdown object.</param>
+        /// <returns>
+        /// An iteration over the descendant elements
+        /// </returns>
+        public static IEnumerable<T> Descendants<T>(this MarkdownObject markdownObject) where T : MarkdownObject
+        {
+            var block = markdownObject as ContainerBlock;
+            if (block != null)
+            {
+                foreach (var subBlock in block)
+                {
+                    var subBlockT = subBlock as T;
+                    if (subBlockT != null)
+                    {
+                        yield return subBlockT;
+                    }
+
+                    foreach (var sub in subBlock.Descendants<T>())
+                    {
+                        yield return sub;
+                    }
+                }
+            }
+            else if (typeof(Inline).IsAssignableFrom(typeof(T)))
+            {
+                var inline = markdownObject as ContainerInline;
+                if (inline != null)
+                {
+                    var child = inline.FirstChild;
+                    while (child != null)
+                    {
+                        var next = child.NextSibling;
+                        var childT = child as T;
+                        if (childT != null)
+                        {
+                            yield return childT;
+                        }
+
+                        foreach (var sub in child.Descendants<T>())
+                        {
+                            yield return sub;
+                        }
+
+                        child = next;
+                    }
+                }
+            }
+        }
+    }
+}