Refactor `StringPart` into `StringSegment`

DiscordChatExporter.Core/Markdown/Parsing/AggregateMatcher.cs

@@ -16,7 +16,7 @@ internal class AggregateMatcher<T> : IMatcher<T>
     {
     }
 
-    public ParsedMatch<T>? TryMatch(StringPart stringPart)
+    public ParsedMatch<T>? TryMatch(StringSegment segment)
     {
         ParsedMatch<T>? earliestMatch = null;
 
@@ -24,19 +24,19 @@ internal class AggregateMatcher<T> : IMatcher<T>
         foreach (var matcher in _matchers)
         {
             // Try to match
-            var match = matcher.TryMatch(stringPart);
+            var match = matcher.TryMatch(segment);
 
             // If there's no match - continue
             if (match is null)
                 continue;
 
             // If this match is earlier than previous earliest - replace
-            if (earliestMatch is null || match.StringPart.StartIndex < earliestMatch.StringPart.StartIndex)
+            if (earliestMatch is null || match.Segment.StartIndex < earliestMatch.Segment.StartIndex)
                 earliestMatch = match;
 
             // If the earliest match starts at the very beginning - break,
             // because it's impossible to find a match earlier than that
-            if (earliestMatch.StringPart.StartIndex == stringPart.StartIndex)
+            if (earliestMatch.Segment.StartIndex == segment.StartIndex)
                 break;
         }
 

DiscordChatExporter.Core/Markdown/Parsing/IMatcher.cs

@@ -5,44 +5,57 @@ namespace DiscordChatExporter.Core.Markdown.Parsing;
 
 internal interface IMatcher<T>
 {
-    ParsedMatch<T>? TryMatch(StringPart stringPart);
+    ParsedMatch<T>? TryMatch(StringSegment segment);
 }
 
 internal static class MatcherExtensions
 {
-    public static IEnumerable<ParsedMatch<T>> MatchAll<T>(this IMatcher<T> matcher,
-        StringPart stringPart, Func<StringPart, T> transformFallback)
+    public static IEnumerable<ParsedMatch<T>> MatchAll<T>(
+        this IMatcher<T> matcher,
+        StringSegment segment,
+        Func<StringSegment, T> transformFallback)
     {
         // Loop through segments divided by individual matches
-        var currentIndex = stringPart.StartIndex;
-        while (currentIndex < stringPart.EndIndex)
+        var currentIndex = segment.StartIndex;
+        while (currentIndex < segment.EndIndex)
         {
             // Find a match within this segment
-            var match = matcher.TryMatch(stringPart.Slice(currentIndex, stringPart.EndIndex - currentIndex));
+            var match = matcher.TryMatch(
+                segment.Relocate(
+                    currentIndex,
+                    segment.EndIndex - currentIndex
+                )
+            );
 
-            // If there's no match - break
             if (match is null)
                 break;
 
-            // If this match doesn't start immediately at current index - transform and yield fallback first
-            if (match.StringPart.StartIndex > currentIndex)
+            // If this match doesn't start immediately at the current position - transform and yield fallback first
+            if (match.Segment.StartIndex > currentIndex)
             {
-                var fallbackPart = stringPart.Slice(currentIndex, match.StringPart.StartIndex - currentIndex);
-                yield return new ParsedMatch<T>(fallbackPart, transformFallback(fallbackPart));
+                var fallbackSegment = segment.Relocate(
+                    currentIndex,
+                    match.Segment.StartIndex - currentIndex
+                );
+
+                yield return new ParsedMatch<T>(fallbackSegment, transformFallback(fallbackSegment));
             }
 
-            // Yield match
             yield return match;
 
             // Shift current index to the end of the match
-            currentIndex = match.StringPart.StartIndex + match.StringPart.Length;
+            currentIndex = match.Segment.StartIndex + match.Segment.Length;
         }
 
-        // If EOL wasn't reached - transform and yield remaining part as fallback
-        if (currentIndex < stringPart.EndIndex)
+        // If EOL hasn't been reached - transform and yield remaining part as fallback
+        if (currentIndex < segment.EndIndex)
         {
-            var fallbackPart = stringPart.Slice(currentIndex);
-            yield return new ParsedMatch<T>(fallbackPart, transformFallback(fallbackPart));
+            var fallbackSegment = segment.Relocate(
+                currentIndex,
+                segment.EndIndex - currentIndex
+            );
+
+            yield return new ParsedMatch<T>(fallbackSegment, transformFallback(fallbackSegment));
         }
     }
 }

DiscordChatExporter.Core/Markdown/Parsing/MarkdownParser.cs

@@ -23,7 +23,7 @@ internal static partial class MarkdownParser
     // Capture any character until the earliest double asterisk not followed by an asterisk
     private static readonly IMatcher<MarkdownNode> BoldFormattingNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("\\*\\*(.+?)\\*\\*(?!\\*)", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Bold, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Bold, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Capture any character until the earliest single asterisk not preceded or followed by an asterisk
@@ -31,54 +31,54 @@ internal static partial class MarkdownParser
     // Closing asterisk must not be preceded by whitespace
     private static readonly IMatcher<MarkdownNode> ItalicFormattingNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("\\*(?!\\s)(.+?)(?<!\\s|\\*)\\*(?!\\*)", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Italic, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Italic, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Capture any character until the earliest triple asterisk not followed by an asterisk
     private static readonly IMatcher<MarkdownNode> ItalicBoldFormattingNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("\\*(\\*\\*.+?\\*\\*)\\*(?!\\*)", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Italic, Parse(p.Slice(m.Groups[1]), BoldFormattingNodeMatcher))
+        (s, m) => new FormattingNode(FormattingKind.Italic, Parse(s.Relocate(m.Groups[1]), BoldFormattingNodeMatcher))
     );
 
     // Capture any character except underscore until an underscore
     // Closing underscore must not be followed by a word character
     private static readonly IMatcher<MarkdownNode> ItalicAltFormattingNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("_([^_]+)_(?!\\w)", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Italic, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Italic, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Capture any character until the earliest double underscore not followed by an underscore
     private static readonly IMatcher<MarkdownNode> UnderlineFormattingNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("__(.+?)__(?!_)", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Underline, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Underline, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Capture any character until the earliest triple underscore not followed by an underscore
     private static readonly IMatcher<MarkdownNode> ItalicUnderlineFormattingNodeMatcher =
         new RegexMatcher<MarkdownNode>(
             new Regex("_(__.+?__)_(?!_)", DefaultRegexOptions | RegexOptions.Singleline),
-            (p, m) => new FormattingNode(FormattingKind.Italic,
-                Parse(p.Slice(m.Groups[1]), UnderlineFormattingNodeMatcher))
+            (s, m) => new FormattingNode(FormattingKind.Italic,
+                Parse(s.Relocate(m.Groups[1]), UnderlineFormattingNodeMatcher))
         );
 
     // Capture any character until the earliest double tilde
     private static readonly IMatcher<MarkdownNode> StrikethroughFormattingNodeMatcher =
         new RegexMatcher<MarkdownNode>(
             new Regex("~~(.+?)~~", DefaultRegexOptions | RegexOptions.Singleline),
-            (p, m) => new FormattingNode(FormattingKind.Strikethrough, Parse(p.Slice(m.Groups[1])))
+            (s, m) => new FormattingNode(FormattingKind.Strikethrough, Parse(s.Relocate(m.Groups[1])))
         );
 
     // Capture any character until the earliest double pipe
     private static readonly IMatcher<MarkdownNode> SpoilerFormattingNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("\\|\\|(.+?)\\|\\|", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Spoiler, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Spoiler, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Capture any character until the end of the line
     // Opening 'greater than' character must be followed by whitespace
     private static readonly IMatcher<MarkdownNode> SingleLineQuoteNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("^>\\s(.+\n?)", DefaultRegexOptions),
-        (p, m) => new FormattingNode(FormattingKind.Quote, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Quote, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Repeatedly capture any character until the end of the line
@@ -97,7 +97,7 @@ internal static partial class MarkdownParser
     // Opening 'greater than' characters must be followed by whitespace
     private static readonly IMatcher<MarkdownNode> MultiLineQuoteNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("^>>>\\s(.+)", DefaultRegexOptions | RegexOptions.Singleline),
-        (p, m) => new FormattingNode(FormattingKind.Quote, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new FormattingNode(FormattingKind.Quote, Parse(s.Relocate(m.Groups[1])))
     );
 
     /* Code blocks */
@@ -185,7 +185,7 @@ internal static partial class MarkdownParser
     // Capture [title](link)
     private static readonly IMatcher<MarkdownNode> TitledLinkNodeMatcher = new RegexMatcher<MarkdownNode>(
         new Regex("\\[(.+?)\\]\\((.+?)\\)", DefaultRegexOptions),
-        (p, m) => new LinkNode(m.Groups[2].Value, Parse(p.Slice(m.Groups[1])))
+        (s, m) => new LinkNode(m.Groups[2].Value, Parse(s.Relocate(m.Groups[1])))
     );
 
     // Capture any non-whitespace character after http:// or https://
@@ -207,7 +207,7 @@ internal static partial class MarkdownParser
     // This escapes it from matching for formatting
     private static readonly IMatcher<MarkdownNode> ShrugTextNodeMatcher = new StringMatcher<MarkdownNode>(
         @"¯\_(ツ)_/¯",
-        p => new TextNode(p.ToString())
+        s => new TextNode(s.ToString())
     );
 
     // Capture some specific emoji that don't get rendered
@@ -323,24 +323,24 @@ internal static partial class MarkdownParser
         UnixTimestampNodeMatcher
     );
 
-    private static IReadOnlyList<MarkdownNode> Parse(StringPart stringPart, IMatcher<MarkdownNode> matcher) =>
+    private static IReadOnlyList<MarkdownNode> Parse(StringSegment segment, IMatcher<MarkdownNode> matcher) =>
         matcher
-            .MatchAll(stringPart, p => new TextNode(p.ToString()))
+            .MatchAll(segment, s => new TextNode(s.ToString()))
             .Select(r => r.Value)
             .ToArray();
 }
 
 internal static partial class MarkdownParser
 {
-    private static IReadOnlyList<MarkdownNode> Parse(StringPart stringPart) =>
-        Parse(stringPart, AggregateNodeMatcher);
+    private static IReadOnlyList<MarkdownNode> Parse(StringSegment segment) =>
+        Parse(segment, AggregateNodeMatcher);
 
-    private static IReadOnlyList<MarkdownNode> ParseMinimal(StringPart stringPart) =>
-        Parse(stringPart, MinimalAggregateNodeMatcher);
+    private static IReadOnlyList<MarkdownNode> ParseMinimal(StringSegment segment) =>
+        Parse(segment, MinimalAggregateNodeMatcher);
 
     public static IReadOnlyList<MarkdownNode> Parse(string input) =>
-        Parse(new StringPart(input));
+        Parse(new StringSegment(input));
 
     public static IReadOnlyList<MarkdownNode> ParseMinimal(string input) =>
-        ParseMinimal(new StringPart(input));
+        ParseMinimal(new StringSegment(input));
 }

DiscordChatExporter.Core/Markdown/Parsing/ParsedMatch.cs

@@ -2,13 +2,13 @@
 
 internal class ParsedMatch<T>
 {
-    public StringPart StringPart { get; }
+    public StringSegment Segment { get; }
 
     public T Value { get; }
 
-    public ParsedMatch(StringPart stringPart, T value)
+    public ParsedMatch(StringSegment segment, T value)
     {
-        StringPart = stringPart;
+        Segment = segment;
         Value = value;
     }
 }

DiscordChatExporter.Core/Markdown/Parsing/RegexMatcher.cs

@@ -6,17 +6,17 @@ namespace DiscordChatExporter.Core.Markdown.Parsing;
 internal class RegexMatcher<T> : IMatcher<T>
 {
     private readonly Regex _regex;
-    private readonly Func<StringPart, Match, T?> _transform;
+    private readonly Func<StringSegment, Match, T?> _transform;
 
-    public RegexMatcher(Regex regex, Func<StringPart, Match, T?> transform)
+    public RegexMatcher(Regex regex, Func<StringSegment, Match, T?> transform)
     {
         _regex = regex;
         _transform = transform;
     }
 
-    public ParsedMatch<T>? TryMatch(StringPart stringPart)
+    public ParsedMatch<T>? TryMatch(StringSegment segment)
     {
-        var match = _regex.Match(stringPart.Target, stringPart.StartIndex, stringPart.Length);
+        var match = _regex.Match(segment.Source, segment.StartIndex, segment.Length);
         if (!match.Success)
             return null;
 
@@ -25,14 +25,14 @@ internal class RegexMatcher<T> : IMatcher<T>
         // Which is super weird because regex.Match(string, int) takes the whole input in context.
         // So in order to properly account for ^/$ regex tokens, we need to make sure that
         // the expression also matches on the bigger part of the input.
-        if (!_regex.IsMatch(stringPart.Target[..stringPart.EndIndex], stringPart.StartIndex))
+        if (!_regex.IsMatch(segment.Source[..segment.EndIndex], segment.StartIndex))
             return null;
 
-        var stringPartMatch = stringPart.Slice(match.Index, match.Length);
-        var value = _transform(stringPartMatch, match);
+        var segmentMatch = segment.Relocate(match);
+        var value = _transform(segmentMatch, match);
 
         return value is not null
-            ? new ParsedMatch<T>(stringPartMatch, value)
+            ? new ParsedMatch<T>(segmentMatch, value)
             : null;
     }
 }

DiscordChatExporter.Core/Markdown/Parsing/StringMatcher.cs

@@ -6,31 +6,31 @@ internal class StringMatcher<T> : IMatcher<T>
 {
     private readonly string _needle;
     private readonly StringComparison _comparison;
-    private readonly Func<StringPart, T?> _transform;
+    private readonly Func<StringSegment, T?> _transform;
 
-    public StringMatcher(string needle, StringComparison comparison, Func<StringPart, T?> transform)
+    public StringMatcher(string needle, StringComparison comparison, Func<StringSegment, T?> transform)
     {
         _needle = needle;
         _comparison = comparison;
         _transform = transform;
     }
 
-    public StringMatcher(string needle, Func<StringPart, T> transform)
+    public StringMatcher(string needle, Func<StringSegment, T> transform)
         : this(needle, StringComparison.Ordinal, transform)
     {
     }
 
-    public ParsedMatch<T>? TryMatch(StringPart stringPart)
+    public ParsedMatch<T>? TryMatch(StringSegment segment)
     {
-        var index = stringPart.Target.IndexOf(_needle, stringPart.StartIndex, stringPart.Length, _comparison);
+        var index = segment.Source.IndexOf(_needle, segment.StartIndex, segment.Length, _comparison);
         if (index < 0)
             return null;
 
-        var stringPartMatch = stringPart.Slice(index, _needle.Length);
-        var value = _transform(stringPartMatch);
+        var segmentMatch = segment.Relocate(index, _needle.Length);
+        var value = _transform(segmentMatch);
 
         return value is not null
-            ? new ParsedMatch<T>(stringPartMatch, value)
+            ? new ParsedMatch<T>(segmentMatch, value)
             : null;
     }
 }

DiscordChatExporter.Core/Markdown/Parsing/StringPart.cs

@@ -1,21 +0,0 @@
-using System.Text.RegularExpressions;
-
-namespace DiscordChatExporter.Core.Markdown.Parsing;
-
-internal readonly record struct StringPart(string Target, int StartIndex, int Length)
-{
-    public int EndIndex => StartIndex + Length;
-
-    public StringPart(string target)
-        : this(target, 0, target.Length)
-    {
-    }
-
-    public StringPart Slice(int newStartIndex, int newLength) => new(Target, newStartIndex, newLength);
-
-    public StringPart Slice(int newStartIndex) => Slice(newStartIndex, EndIndex - newStartIndex);
-
-    public StringPart Slice(Capture capture) => Slice(capture.Index, capture.Length);
-
-    public override string ToString() => Target.Substring(StartIndex, Length);
-}

DiscordChatExporter.Core/Markdown/Parsing/StringSegment.cs

@@ -0,0 +1,19 @@
+using System.Text.RegularExpressions;
+
+namespace DiscordChatExporter.Core.Markdown.Parsing;
+
+internal readonly record struct StringSegment(string Source, int StartIndex, int Length)
+{
+    public int EndIndex => StartIndex + Length;
+
+    public StringSegment(string target)
+        : this(target, 0, target.Length)
+    {
+    }
+
+    public StringSegment Relocate(int newStartIndex, int newLength) => new(Source, newStartIndex, newLength);
+
+    public StringSegment Relocate(Capture capture) => Relocate(capture.Index, capture.Length);
+
+    public override string ToString() => Source.Substring(StartIndex, Length);
+}