Provides a wrapper for ANTLR CharStreams that applies case transformation strategies (e.g., lower, upper, invert) on-the-fly during parsing. Enables case-insensitive preview of grammars without modifying the original grammar, demonstrating a non-obvious solution for handling case sensitivity in language previews.

Implements a token stream that returns only tokens within a specified character range, enabling efficient incremental parsing for editor features like live preview and error checking. Correctly handles token boundaries and state, showcasing expertise in adapting ANTLR's streaming model for interactive environments.

Monitors ANTLR lexer execution in a background thread with timeout protection to prevent UI hangs caused by problematic lexer rules (e.g., left recursion). Demonstrates a robust pattern for isolating potentially blocking operations in interactive language tools.

Contains utility methods for performing grammar refactorings (rule extraction, inlining, literal rule generation) while maintaining grammatical correctness. Handles complex AST modifications and symbol updates, offering a reusable domain-specific library for ANTLR grammar manipulation.