# CEL Reference Documentation
This directory contains comprehensive reference documentation for the Common Expression Language (CEL) as implemented in cel-cxx.
## Core Documentation
- [Basic Concepts and Syntax](01-basic-concepts.md) - Language fundamentals, syntax, types, and operators
- [Standard Library](02-standard-library.md) - Built-in functions and standard operations
- [Optional Values](03-optional.md) - Optional type handling and safe navigation
- [Extensions](04-extensions.md) - Extension libraries and advanced features
## Extension Libraries
The following extensions are available and documented in the [extensions](extensions/) directory:
- [Bindings Extension](extensions/bindings.md) - Variable binding and scoping enhancements
- [Comprehensions Extension](extensions/comprehensions.md) - List and map comprehensions
- [Encoders Extension](extensions/encoders.md) - Base64 and URL encoding/decoding
- [Lists Extension](extensions/lists.md) - Enhanced list operations
- [Math Extension](extensions/math.md) - Mathematical functions and operations
- [Protocol Buffers Extension](extensions/proto.md) - Protobuf message support
- [Regular Expression Extension](extensions/re.md) - Basic regex operations
- [Regex Extension](extensions/regex.md) - Advanced regex support
- [Sets Extension](extensions/sets.md) - Set operations and utilities
- [Strings Extension](extensions/strings.md) - Advanced string manipulation
## Quick Navigation
- **Getting Started**: Start with [Basic Concepts](01-basic-concepts.md) to understand CEL syntax and types
- **Common Operations**: Check [Standard Library](02-standard-library.md) for built-in functions
- **Advanced Features**: Explore [Extensions](04-extensions.md) for additional capabilities
## Related Documentation
- [Main Documentation](../README.md) - Complete cel-cxx documentation
- [Function Registration](../function-registration.md) - How to register custom functions
- [Advanced Features](../advanced-features.md) - Advanced usage patterns