Limit recursion depth in markdown parser to prevent stack overflow

DiscordChatExporter.Core/Markdown/Parsing/AggregateMatcher.cs

@@ -2,20 +2,22 @@
 
 namespace DiscordChatExporter.Core.Markdown.Parsing;
 
-internal class AggregateMatcher<T>(IReadOnlyList<IMatcher<T>> matchers) : IMatcher<T>
+internal class AggregateMatcher<TContext, TValue>(
+    IReadOnlyList<IMatcher<TContext, TValue>> matchers
+) : IMatcher<TContext, TValue>
 {
-    public AggregateMatcher(params IMatcher<T>[] matchers)
-        : this((IReadOnlyList<IMatcher<T>>)matchers) { }
+    public AggregateMatcher(params IMatcher<TContext, TValue>[] matchers)
+        : this((IReadOnlyList<IMatcher<TContext, TValue>>)matchers) { }
 
-    public ParsedMatch<T>? TryMatch(StringSegment segment)
+    public ParsedMatch<TValue>? TryMatch(TContext context, StringSegment segment)
     {
-        ParsedMatch<T>? earliestMatch = null;
+        ParsedMatch<TValue>? earliestMatch = null;
 
         // Try to match the input with each matcher and get the match with the lowest start index
         foreach (var matcher in matchers)
         {
             // Try to match
-            var match = matcher.TryMatch(segment);
+            var match = matcher.TryMatch(context, segment);
 
             // If there's no match - continue
             if (match is null)

DiscordChatExporter.Core/Markdown/Parsing/IMatcher.cs

@@ -3,17 +3,18 @@
 
 namespace DiscordChatExporter.Core.Markdown.Parsing;
 
-internal interface IMatcher<T>
+internal interface IMatcher<in TContext, TValue>
 {
-    ParsedMatch<T>? TryMatch(StringSegment segment);
+    ParsedMatch<TValue>? TryMatch(TContext context, StringSegment segment);
 }
 
 internal static class MatcherExtensions
 {
-    public static IEnumerable<ParsedMatch<T>> MatchAll<T>(
-        this IMatcher<T> matcher,
+    public static IEnumerable<ParsedMatch<TValue>> MatchAll<TContext, TValue>(
+        this IMatcher<TContext, TValue> matcher,
+        TContext context,
         StringSegment segment,
-        Func<StringSegment, T> transformFallback
+        Func<TContext, StringSegment, TValue> transformFallback
     )
     {
         // Loop through segments divided by individual matches
@@ -22,6 +23,7 @@ Func<StringSegment, T> transformFallback
         {
             // Find a match within this segment
             var match = matcher.TryMatch(
+                context,
                 segment.Relocate(currentIndex, segment.EndIndex - currentIndex)
             );
 
@@ -36,9 +38,9 @@ Func<StringSegment, T> transformFallback
                     match.Segment.StartIndex - currentIndex
                 );
 
-                yield return new ParsedMatch<T>(
+                yield return new ParsedMatch<TValue>(
                     fallbackSegment,
-                    transformFallback(fallbackSegment)
+                    transformFallback(context, fallbackSegment)
                 );
             }
 
@@ -53,7 +55,10 @@ Func<StringSegment, T> transformFallback
         {
             var fallbackSegment = segment.Relocate(currentIndex, segment.EndIndex - currentIndex);
 
-            yield return new ParsedMatch<T>(fallbackSegment, transformFallback(fallbackSegment));
+            yield return new ParsedMatch<TValue>(
+                fallbackSegment,
+                transformFallback(context, fallbackSegment)
+            );
         }
     }
 }

DiscordChatExporter.Core/Markdown/Parsing/MarkdownContext.cs

@@ -0,0 +1,3 @@
+namespace DiscordChatExporter.Core.Markdown.Parsing;
+
+internal readonly record struct MarkdownContext(int Depth = 0);