add inline shortcut for Markdig

.gitignore

@@ -57,4 +57,5 @@ src/docfx.website.themes/default/fonts/
 #    deploy   #
 ###############
 tools/Deployment/.vscode/
-tools/Deployment/out/
+tools/Deployment/out/
+/package_version_temp.txt

src/Microsoft.DocAsCode.Dfm/DfmEngineBuilder.cs

@@ -42,13 +42,14 @@ public DfmEngineBuilder(Options options, string baseDir, string templateDir, IRe
             {
                 throw new ArgumentException("MarkdownLinkInlineRule should exist!");
             }
+
             inlineRules.Insert(index + 1, new DfmXrefShortcutInlineRule());
             inlineRules.Insert(index + 1, new DfmEmailInlineRule());
             inlineRules.Insert(index + 1, new DfmFencesInlineRule());
+            inlineRules.Insert(index + 1, new DfmIncludeInlineShortcutRule());
 
             // xref link inline rule must be before MarkdownLinkInlineRule
             inlineRules.Insert(index, new DfmIncludeInlineRule());
-            inlineRules.Insert(index, new DfmIncludeInlineShortcutRule());
 
             Replace<MarkdownTextInlineRule, DfmTextInlineRule>(inlineRules);
 

src/Microsoft.DocAsCode.Dfm/Rules/DfmIncludeInlineShortcutRule.cs

@@ -14,7 +14,7 @@ namespace Microsoft.DocAsCode.Dfm
     public class DfmIncludeInlineShortcutRule : IMarkdownRule
     {
         public virtual string Name => "DfmIncludeInlineShortcut";
-        private static readonly Regex _inlineIncludeRegex = new Regex(@"@@(?<identifier>\w+)", RegexOptions.Compiled | RegexOptions.IgnoreCase, TimeSpan.FromSeconds(10));
+        internal static readonly Regex _inlineIncludeRegex = new Regex(@"@@(?<identifier>\w+)", RegexOptions.Compiled | RegexOptions.IgnoreCase, TimeSpan.FromSeconds(10));
         public virtual Regex Include => _inlineIncludeRegex;
 
         public IMarkdownToken TryMatch(IMarkdownParser parser, IMarkdownParsingContext context)

src/Microsoft.DocAsCode.MarkdigEngine.Extensions/Inclusion/InclusionExtension.cs

@@ -25,6 +25,10 @@ public void Setup(MarkdownPipelineBuilder pipeline)
         {
             pipeline.BlockParsers.AddIfNotAlready<InclusionBlockParser>();
             pipeline.InlineParsers.InsertBefore<LinkInlineParser>(new InclusionInlineParser());
+
+            var inlineShortcut = new InclusionInlineShortcutParser();
+            pipeline.InlineParsers.InsertBefore<XrefInlineShortParser>(inlineShortcut);
+            pipeline.InlineParsers.AddIfNotAlready(inlineShortcut);
         }
 
         public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
@@ -38,6 +42,13 @@ public void Setup(MarkdownPipeline pipeline, IMarkdownRenderer renderer)
                     htmlRenderer.ObjectRenderers.Insert(0, new HtmlInclusionInlineRenderer(_context, inlinePipeline));
                 }
 
+                if (!htmlRenderer.ObjectRenderers.Contains<HtmlInclusionInlineShortcutRenderer>())
+                {
+                    var inlinePipeline = LazyInitializer.EnsureInitialized(ref _inlinePipeline, () => CreateInlineOnlyPipeline(pipeline));
+
+                    htmlRenderer.ObjectRenderers.Insert(0, new HtmlInclusionInlineShortcutRenderer(_context, inlinePipeline));
+                }
+
                 if (!htmlRenderer.ObjectRenderers.Contains<HtmlInclusionBlockRenderer>())
                 {
                     htmlRenderer.ObjectRenderers.Insert(0, new HtmlInclusionBlockRenderer(_context, pipeline));

src/Microsoft.DocAsCode.MarkdigEngine.Extensions/Inclusion/InclusionInlineShortcut/HtmlInclusionInlineRenderer.cs

@@ -0,0 +1,46 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.DocAsCode.MarkdigEngine.Extensions
+{
+    using Markdig;
+    using Markdig.Renderers;
+    using Markdig.Renderers.Html;
+    using System.Linq;
+
+    public class HtmlInclusionInlineShortcutRenderer : HtmlObjectRenderer<InclusionInlineShortcut>
+    {
+        private readonly MarkdownContext _context;
+        private readonly MarkdownPipeline _inlinePipeline;
+
+        public HtmlInclusionInlineShortcutRenderer(MarkdownContext context, MarkdownPipeline inlinePipeline)
+        {
+            _context = context;
+            _inlinePipeline = inlinePipeline;
+        }
+
+        protected override void Write(HtmlRenderer renderer, InclusionInlineShortcut inclusion)
+        {
+            var (content, includeFilePath) = _context.ReadFile(inclusion.IncludedFilePath, inclusion);
+
+            if (content == null)
+            {
+                _context.LogWarning("include-not-found", $"Cannot resolve '{inclusion.IncludedFilePath}' relative to '{InclusionContext.File}'.", inclusion);
+                renderer.Write(inclusion.GetRawToken());
+                return;
+            }
+
+            if (InclusionContext.IsCircularReference(includeFilePath, out var dependencyChain))
+            {
+                _context.LogWarning("circular-reference", $"Build has identified file(s) referencing each other: {string.Join(" --> ", dependencyChain.Select(file => $"'{file}'"))} --> '{includeFilePath}'", inclusion);
+                renderer.Write(inclusion.GetRawToken());
+                return;
+            }
+
+            using (InclusionContext.PushInclusion(includeFilePath))
+            {
+                renderer.Write(Markdown.ToHtml(content, _inlinePipeline));
+            }
+        }
+    }
+}

src/Microsoft.DocAsCode.MarkdigEngine.Extensions/Inclusion/InclusionInlineShortcut/InclusionInlineShortcut.cs

@@ -0,0 +1,18 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.DocAsCode.MarkdigEngine.Extensions
+{
+    using Markdig.Syntax.Inlines;
+
+    public class InclusionInlineShortcut : ContainerInline
+    {
+        public string RawFilename { get; set; }
+
+        public string IncludedFilePath { get; set; }
+
+        public object ResolvedFilePath { get; set; }
+
+        public string GetRawToken() => $"@@{RawFilename}";
+    }
+}

src/Microsoft.DocAsCode.MarkdigEngine.Extensions/Inclusion/InclusionInlineShortcut/InclusionInlineShortcutParser.cs

@@ -0,0 +1,63 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+namespace Microsoft.DocAsCode.MarkdigEngine.Extensions
+{
+    using Markdig.Helpers;
+    using Markdig.Parsers;
+    using Markdig.Syntax;
+
+    public class InclusionInlineShortcutParser : InlineParser
+    {
+        private const string StartString = "@@";
+
+        public InclusionInlineShortcutParser()
+        {
+            OpeningCharacters = new[] { '@' };
+        }
+
+        public override bool Match(InlineProcessor processor, ref StringSlice slice)
+        {
+            var startPosition = processor.GetSourcePosition(slice.Start, out var line, out var column);
+
+            if (!ExtensionsHelper.MatchStart(ref slice, StartString, false))
+            {
+                return false;
+            }
+
+            var str = StringBuilderCache.Local();
+
+            str.Append(slice.CurrentChar);
+
+            var c = slice.NextChar();
+            while (c.IsAlphaNumeric())
+            {
+                str.Append(c);
+                c = slice.NextChar();
+            }
+
+            if (str.Length == 0)
+            {
+                return false;
+            }
+
+            string symbol = str.ToString();
+            if (string.IsNullOrWhiteSpace(symbol))
+            {
+                return false;
+            }
+
+            processor.Inline = new InclusionInlineShortcut
+            {
+                RawFilename = symbol,
+                IncludedFilePath = $"~/includes/{symbol}.md",
+                Line = line,
+                Column = column,
+                Span = new SourceSpan(startPosition, processor.GetSourcePosition(slice.Start - 1)),
+                IsClosed = true,
+            };
+
+            return true;
+        }
+    }
+}