Here are the classes, structs, unions and interfaces with brief descriptions:

[detail level 1234]

Ncircus
Nerror
Cparser_error	Exception class for parser errors, holding an error type flag and a message
Cparser_reporter	Aggregates and manages parser error messages with support for logging and flushing
Nfilesystem
Creader__	Utility class to read contents from input streams into a string
Ninternal
Cvisitor	Helper struct to combine multiple callable objects into a single visitor
Ntraits
Cexists	Checks if a type Ts exists among a variadic list of types Us
Cis_vector	Trait to determine if a type is a std::vector
Cis_vector< std::vector< T, A > >
Cpair_inspect	Trait to determine if a type is a pair-like structure (has .first and .second)
Cpair_inspect< T, std::void_t< decltype(std::declval< T >().first), decltype(std::declval< T >().second)> >
Nutils
Ndetail
Cexplode	Compile-time recursion to split an unsigned integer into digits
Cexplode< 0, digits... >	Base case for explode recursion when remainder is zero. Inherits from to_chars to produce the final digit string
Cto_chars	Helper template that stores a compile-time char array of digits
Ccxpr_stream	Compile-time concatenation of multiple string_views into a single string_view
Cenum_flag	A utility class for strongly typed enum flags with bitwise operations
Cnum_to_string	Converts a compile-time unsigned integer to a string literal
Ccirc_variable	Represents a variable in Circus serialization
Cdeserializer	Parses structured circus-formatted input and exposes access to the parsed data
Clexer__	Lexer for tokenizing input strings into Circus tokens
Cparser__	Parser for Circus token streams producing nested Circus variables
Cserializer	A flexible serializer for C++ objects, primitives, STL containers, and user-defined types
Ctokens__	Represents a lexical token with type, literal value, and source location