Support substitutions in directive titles (admonitions, tabs)

docs/syntax/_snippets/reusable-snippet.md

@@ -1,4 +1,4 @@
-This is a snippet included on "{{page_title}}".
+This is a snippet included on "{{context.page_title}}".
 
 :::{tip}
 This is a snippet

docs/testing/nested/index.md

@@ -1,8 +1,9 @@
 ---
 sub:
   x: "Variable"
+navigation_title: "Testing nesting and {{x}}"
 ---
-# Testing Nesting
+# Testing Nesting and {{x}}
 
 The files in this directory are used for testing purposes. Do not edit these files unless you are working on tests.
 

src/Elastic.Markdown/Helpers/Interpolation.cs

@@ -2,7 +2,9 @@
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
 
+using System.Diagnostics.CodeAnalysis;
 using System.Text.RegularExpressions;
+using Elastic.Markdown.Myst;
 
 namespace Elastic.Markdown.Helpers;
 
@@ -14,22 +16,60 @@ internal static partial class InterpolationRegex
 
 public static class Interpolation
 {
-	public static bool ReplaceSubstitutions(this ReadOnlySpan<char> span, IReadOnlyDictionary<string, string>? properties, out string? replacement)
+	public static string ReplaceSubstitutions(
+		this string input,
+		ParserContext context
+	)
+	{
+		var span = input.AsSpan();
+		if (span.ReplaceSubstitutions([context.Substitutions, context.ContextSubstitutions], out var replacement))
+			return replacement;
+		return input;
+	}
+
+
+	public static bool ReplaceSubstitutions(
+		this ReadOnlySpan<char> span,
+		ParserContext context,
+		[NotNullWhen(true)] out string? replacement
+	) =>
+		span.ReplaceSubstitutions([context.Substitutions, context.ContextSubstitutions], out replacement);
+
+	public static bool ReplaceSubstitutions(
+		this ReadOnlySpan<char> span,
+		IReadOnlyDictionary<string, string>? properties,
+		[NotNullWhen(true)] out string? replacement
+	)
 	{
 		replacement = null;
+		if (properties is null || properties.Count == 0)
+			return false;
+
 		if (span.IndexOf("}}") < 0)
 			return false;
 
-		if (properties is null || properties.Count == 0)
+		return span.ReplaceSubstitutions([properties], out replacement);
+	}
+
+	public static bool ReplaceSubstitutions(
+		this ReadOnlySpan<char> span,
+		IReadOnlyDictionary<string, string>[] properties,
+		[NotNullWhen(true)] out string? replacement
+	)
+	{
+		replacement = null;
+		if (span.IndexOf("}}") < 0)
 			return false;
 
-		var substitutions = properties as Dictionary<string, string>
-							?? new Dictionary<string, string>(properties, StringComparer.OrdinalIgnoreCase);
-		if (substitutions.Count == 0)
+		if (properties.Length == 0 || properties.Sum(p => p.Count) == 0)
 			return false;
 
+		var lookups = properties
+			.Select(p => p as Dictionary<string, string> ?? new Dictionary<string, string>(p, StringComparer.OrdinalIgnoreCase))
+			.Select(d => d.GetAlternateLookup<ReadOnlySpan<char>>())
+			.ToArray();
+
 		var matchSubs = InterpolationRegex.MatchSubstitutions().EnumerateMatches(span);
-		var lookup = substitutions.GetAlternateLookup<ReadOnlySpan<char>>();
 
 		var replaced = false;
 		foreach (var match in matchSubs)
@@ -39,14 +79,15 @@ public static bool ReplaceSubstitutions(this ReadOnlySpan<char> span, IReadOnlyD
 
 			var spanMatch = span.Slice(match.Index, match.Length);
 			var key = spanMatch.Trim(['{', '}']);
+			foreach (var lookup in lookups)
+			{
+				if (!lookup.TryGetValue(key, out var value))
+					continue;
 
-			if (!lookup.TryGetValue(key, out var value))
-				continue;
-
-			replacement ??= span.ToString();
-			replacement = replacement.Replace(spanMatch.ToString(), value);
-			replaced = true;
-
+				replacement ??= span.ToString();
+				replacement = replacement.Replace(spanMatch.ToString(), value);
+				replaced = true;
+			}
 		}
 
 		return replaced;

src/Elastic.Markdown/Myst/Directives/AdmonitionBlock.cs

@@ -1,6 +1,9 @@
 // Licensed to Elasticsearch B.V under one or more agreements.
 // Elasticsearch B.V licenses this file to you under the Apache 2.0 License.
 // See the LICENSE file in the project root for more information
+
+using Elastic.Markdown.Helpers;
+
 namespace Elastic.Markdown.Myst.Directives;
 
 public class DropdownBlock(DirectiveBlockParser parser, ParserContext context) : AdmonitionBlock(parser, "dropdown", context);
@@ -14,6 +17,11 @@ public AdmonitionBlock(DirectiveBlockParser parser, string admonition, ParserCon
 		_admonition = admonition;
 		if (_admonition is "admonition")
 			Classes = "plain";
+
+		var t = Admonition;
+		var title = Thread.CurrentThread.CurrentCulture.TextInfo.ToTitleCase(t);
+		Title = title;
+
 	}
 
 	public string Admonition => _admonition;
@@ -23,26 +31,20 @@ public AdmonitionBlock(DirectiveBlockParser parser, string admonition, ParserCon
 	public string? Classes { get; protected set; }
 	public bool? DropdownOpen { get; private set; }
 
-	public string Title
-	{
-		get
-		{
-			var t = Admonition;
-			var title = Thread.CurrentThread.CurrentCulture.TextInfo.ToTitleCase(t);
-			if (_admonition is "admonition" or "dropdown" && !string.IsNullOrEmpty(Arguments))
-				title = Arguments;
-			else if (!string.IsNullOrEmpty(Arguments))
-				title += $" {Arguments}";
-			return title;
-		}
-	}
+	public string Title { get; private set; }
 
 	public override void FinalizeAndValidate(ParserContext context)
 	{
 		CrossReferenceName = Prop("name");
 		DropdownOpen = TryPropBool("open");
 		if (DropdownOpen.HasValue)
 			Classes = "dropdown";
+
+		if (_admonition is "admonition" or "dropdown" && !string.IsNullOrEmpty(Arguments))
+			Title = Arguments;
+		else if (!string.IsNullOrEmpty(Arguments))
+			Title += $" {Arguments}";
+		Title = Title.ReplaceSubstitutions(context);
 	}
 }
 

src/Elastic.Markdown/Myst/Directives/TabSetBlock.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information
 
 using Elastic.Markdown.Diagnostics;
+using Elastic.Markdown.Helpers;
 using Elastic.Markdown.Slices.Directives;
 
 namespace Elastic.Markdown.Myst.Directives;
@@ -44,7 +45,7 @@ public override void FinalizeAndValidate(ParserContext context)
 		if (string.IsNullOrWhiteSpace(Arguments))
 			this.EmitError("{tab-item} requires an argument to name the tab.");
 
-		Title = Arguments ?? "{undefined}";
+		Title = (Arguments ?? "{undefined}").ReplaceSubstitutions(context);
 		Index = Parent!.IndexOf(this);
 
 		var tabSet = Parent as TabSetBlock;

src/Elastic.Markdown/Myst/ParserContext.cs

@@ -44,23 +44,29 @@ public ParserContext(
 		Build = context;
 		Configuration = configuration;
 
-		foreach (var (key, value) in configuration.Substitutions)
-			Properties[key.ToLowerInvariant()] = value;
-
-		if (frontMatter?.Properties is { } props)
+		if (frontMatter?.Properties is not { Count: > 0 })
+			Substitutions = configuration.Substitutions;
+		else
 		{
-			foreach (var (k, value) in props)
+			var subs = new Dictionary<string, string>(configuration.Substitutions);
+			foreach (var (k, value) in frontMatter.Properties)
 			{
 				var key = k.ToLowerInvariant();
 				if (configuration.Substitutions.TryGetValue(key, out _))
 					this.EmitError($"{{{key}}} can not be redeclared in front matter as its a global substitution");
 				else
-					Properties[key] = value;
+					subs[key] = value;
 			}
+
+			Substitutions = subs;
 		}
 
+		var contextSubs = new Dictionary<string, string>();
+
 		if (frontMatter?.Title is { } title)
-			Properties["page_title"] = title;
+			contextSubs["context.page_title"] = title;
+
+		ContextSubstitutions = contextSubs;
 	}
 
 	public ConfigurationFile Configuration { get; }
@@ -70,4 +76,7 @@ public ParserContext(
 	public BuildContext Build { get; }
 	public bool SkipValidation { get; init; }
 	public Func<IFileInfo, DocumentationFile?>? GetDocumentationFile { get; init; }
+	public IReadOnlyDictionary<string, string> Substitutions { get; }
+	public IReadOnlyDictionary<string, string> ContextSubstitutions { get; }
+
 }

src/Elastic.Markdown/Myst/Substitution/SubstitutionParser.cs

@@ -6,6 +6,7 @@
 using System.Net.Mime;
 using System.Runtime.CompilerServices;
 using Elastic.Markdown.Diagnostics;
+using Markdig;
 using Markdig.Helpers;
 using Markdig.Parsers;
 using Markdig.Renderers;
@@ -98,6 +99,9 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
 		if (slice.PeekCharExtra(1) != match)
 			return false;
 
+		if (processor.Context is not ParserContext context)
+			return false;
+
 		Debug.Assert(match is not ('\r' or '\n'));
 
 		// Match the opened sticks
@@ -140,10 +144,15 @@ public override bool Match(InlineProcessor processor, ref StringSlice slice)
 		var key = content.ToString().Trim(['{', '}']).ToLowerInvariant();
 		var found = false;
 		var replacement = string.Empty;
-		if (processor.Context?.Properties.TryGetValue(key, out var value) ?? false)
+		if (context.Substitutions.TryGetValue(key, out var value))
+		{
+			found = true;
+			replacement = value;
+		}
+		else if (context.ContextSubstitutions.TryGetValue(key, out value))
 		{
 			found = true;
-			replacement = value.ToString() ?? string.Empty;
+			replacement = value;
 		}
 
 		var start = processor.GetSourcePosition(startPosition, out var line, out var column);