Rosettes is a modern syntax highlighter designed for Python 3.14's free-threading era. This section explains why it fits teams that care about safe highlighting, predictable performance, and Pygments-compatible output.
Core Principles
| Principle | Meaning |
|---|---|
| O(n) guaranteed | Linear time complexity, no exponential blowup |
| Zero ReDoS | No regex patterns that can be exploited |
| Thread-safe by design | Immutable state, no global mutable data |
| Pygments compatible | Drop-in CSS class compatibility |
Why Rosettes?
Traditional syntax highlighters use regular expressions, which can exhibit exponential worst-case behavior (ReDoS). A carefully crafted input can freeze your application for minutes or hours.
Rosettes eliminates this risk entirely by using hand-written state machine lexers. Every lexer processes input character-by-character with no backtracking, guaranteeing O(n) time complexity.
In This Section
Architecture
State machine lexer design and internals
Thread Safety
Thread-safe design and free-threading support
Performance
Benchmarks and performance characteristics
Choosing Rosettes
When Rosettes fits, how it compares to Pygments-style highlighters, and when to choose alternatives
FAQ
Frequently asked questions about Rosettes
The Bengal Ecosystem
A structured reactive stack — every layer written in pure Python for 3.14t free-threading