Add support for left bracket escaping in the regex.

.github/workflows/RunTests.yml

@@ -25,7 +25,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: '6.0.101'
+        dotnet-version: '6.0.425'
     - name: Test
       run: |
         cd Sources

Sources/SynKit/Libraries/Lexer.Generator/RegExParser.cs

@@ -117,6 +117,7 @@ private char ParseLiteralRangeAtom()
             var ch = this.Consume();
             var escaped = Escape(ch);
             if (ch == '-') return ch;
+            if (ch == '[') return ch;
             if (ch == ']') return ch;
             if (escaped == null) throw new FormatException($"invalid escape \\{ch} in grouping (position {this.index - 2})");
             return escaped.Value;

Sources/SynKit/Tests/Lexer.Tests/AdvancedLexerGeneratorTests.cs

@@ -18,6 +18,8 @@ public enum TokenType
         [End] End,
 
         [Regex("[\\-]")] MinusInRegexGroup,
+        [Regex("[\\[]")] LeftBracketInRegexGroup,
+        [Regex("[\\]]")] RightBracketInRegexGroup,
     }
 
     [Lexer(typeof(TokenType))]
@@ -32,4 +34,20 @@ public void AdvancedRulesSequence()
         Assert.Equal(Token("-", TokenType.MinusInRegexGroup, Range((0, 0), 1)), lexer.Next());
         Assert.Equal(Token(string.Empty, TokenType.End, Range((0, 1), 0)), lexer.Next());
     }
+
+    [Fact]
+    public void LeftBracketInRegex()
+    {
+        var lexer = new AdvancedLexer("[");
+        Assert.Equal(Token("[", TokenType.LeftBracketInRegexGroup, Range((0, 0), 1)), lexer.Next());
+        Assert.Equal(Token(string.Empty, TokenType.End, Range((0, 1), 0)), lexer.Next());
+    }
+
+    [Fact]
+    public void RightBracketInRegex()
+    {
+        var lexer = new AdvancedLexer("]");
+        Assert.Equal(Token("]", TokenType.RightBracketInRegexGroup, Range((0, 0), 1)), lexer.Next());
+        Assert.Equal(Token(string.Empty, TokenType.End, Range((0, 1), 0)), lexer.Next());
+    }
 }