restructured MarkupTokenizer a bit.

src/Spectre.Console/Internal/Text/Markup/MarkupTokenizer.cs

@@ -24,92 +24,10 @@ internal sealed class MarkupTokenizer : IDisposable
         }
 
         var current = _reader.Peek();
-        if (current == '[')
+        return current == '[' ? ReadMarkup() : ReadText();
-        {
-            var position = _reader.Position;
-
-            _reader.Read();
-
-            if (_reader.Eof)
-            {
-                throw new InvalidOperationException($"Encountered malformed markup tag at position {_reader.Position}.");
     }
 
-            current = _reader.Peek();
+    private bool ReadText()
-            if (current == '[')
-            {
-                _reader.Read();
-                Current = new MarkupToken(MarkupTokenKind.Text, "[", position);
-                return true;
-            }
-
-            if (current == '/')
-            {
-                _reader.Read();
-
-                if (_reader.Eof)
-                {
-                    throw new InvalidOperationException($"Encountered malformed markup tag at position {_reader.Position}.");
-                }
-
-                current = _reader.Peek();
-                if (current != ']')
-                {
-                    throw new InvalidOperationException($"Encountered malformed markup tag at position {_reader.Position}.");
-                }
-
-                _reader.Read();
-                Current = new MarkupToken(MarkupTokenKind.Close, string.Empty, position);
-                return true;
-            }
-
-            var builder = new StringBuilder();
-            while (!_reader.Eof)
-            {
-                current = _reader.Read();
-                var next = '\0';
-                if (!_reader.Eof)
-                {
-                    next = _reader.Peek();
-                }
-
-                if (current == ']')
-                {
-                    if (next != ']')
-                    {
-                        break;
-                    }
-
-                    _reader.Read();
-                }
-
-                builder.Append(current);
-
-                if (current != '[')
-                {
-                    continue;
-                }
-
-                if (next == '[')
-                {
-                    _reader.Read();
-                }
-                else
-                {
-                    throw new InvalidOperationException(
-                        $"Encountered malformed markup tag at position {_reader.Position - 1}.");
-                }
-            }
-
-            if (_reader.Eof)
-            {
-                throw new InvalidOperationException($"Encountered malformed markup tag at position {_reader.Position}.");
-            }
-
-            Current = new MarkupToken(MarkupTokenKind.Open, builder.ToString(), position);
-            return true;
-        }
-        else
     {
         var position = _reader.Position;
         var builder = new StringBuilder();
@@ -117,12 +35,15 @@ internal sealed class MarkupTokenizer : IDisposable
         var encounteredClosing = false;
         while (!_reader.Eof)
         {
-                current = _reader.Peek();
+            var current = _reader.Peek();
             if (current == '[')
             {
+                // markup encountered. Stop processing.
                 break;
             }
-                else if (current == ']')
+
+            // If we find a closing tag (']') there must be two of them.
+            if (current == ']')
             {
                 if (encounteredClosing)
                 {
@@ -153,5 +74,104 @@ internal sealed class MarkupTokenizer : IDisposable
         Current = new MarkupToken(MarkupTokenKind.Text, builder.ToString(), position);
         return true;
     }
+
+    private bool ReadMarkup()
+    {
+        var position = _reader.Position;
+
+        _reader.Read();
+
+        if (_reader.Eof)
+        {
+            throw new InvalidOperationException($"Encountered malformed markup tag at position {_reader.Position}.");
+        }
+
+        var current = _reader.Peek();
+        switch (current)
+        {
+            case '[':
+                // No markup but instead escaped markup in text.
+                _reader.Read();
+                Current = new MarkupToken(MarkupTokenKind.Text, "[", position);
+                return true;
+            case '/':
+                // Markup closed.
+                _reader.Read();
+
+                if (_reader.Eof)
+                {
+                    throw new InvalidOperationException(
+                        $"Encountered malformed markup tag at position {_reader.Position}.");
+                }
+
+                current = _reader.Peek();
+                if (current != ']')
+                {
+                    throw new InvalidOperationException(
+                        $"Encountered malformed markup tag at position {_reader.Position}.");
+                }
+
+                _reader.Read();
+                Current = new MarkupToken(MarkupTokenKind.Close, string.Empty, position);
+                return true;
+        }
+
+        // Read the "content" of the markup until we find the end-of-markup
+        var builder = new StringBuilder();
+        var encounteredOpening = false;
+        var encounteredClosing = false;
+        while (!_reader.Eof)
+        {
+            current = _reader.Peek();
+
+            if (current == ']' && !encounteredOpening)
+            {
+                if (encounteredClosing)
+                {
+                    builder.Append(_reader.Read());
+                    encounteredClosing = false;
+                    continue;
+                }
+
+                _reader.Read();
+                encounteredClosing = true;
+                continue;
+            }
+
+            if (current == '[' && !encounteredClosing)
+            {
+                if (encounteredOpening)
+                {
+                    builder.Append(_reader.Read());
+                    encounteredOpening = false;
+                    continue;
+                }
+
+                _reader.Read();
+                encounteredOpening = true;
+                continue;
+            }
+
+            if (encounteredClosing)
+            {
+                break;
+            }
+
+            if (encounteredOpening)
+            {
+                throw new InvalidOperationException(
+                    $"Encountered malformed markup tag at position {_reader.Position - 1}.");
+            }
+
+            builder.Append(_reader.Read());
+        }
+
+        if (_reader.Eof)
+        {
+            throw new InvalidOperationException($"Encountered malformed markup tag at position {_reader.Position}.");
+        }
+
+        Current = new MarkupToken(MarkupTokenKind.Open, builder.ToString(), position);
+        return true;
     }
 }

test/Spectre.Console.Tests/Unit/AnsiConsoleTests.Markup.cs

@@ -141,5 +141,18 @@ public partial class AnsiConsoleTests
             result.ShouldBeOfType<InvalidOperationException>()
                 .Message.ShouldBe("Encountered closing tag when none was expected near position 5.");
         }
+
+        [Fact]
+        public void Should_Not_Get_Confused_When_Mixing_Escaped_And_Unescaped()
+        {
+            // Given
+            var console = new TestConsole();
+
+            // When
+            console.Markup("[grey][[grey]][/][white][[white]][/]");
+
+            // Then
+            console.Output.ShouldBe("[grey][white]");
+        }
     }
 }