C--

// map-macro: recursive macros (https://github.com/swansontec/map-macro)
// (you can implement these yourself pretty easily)
// ((so it's not particularly interesting))
#include "map.h"

// static casting from subclass to superclass
// really?
#define as .

// used for pasting macro name and parentheses without ##
// is needed to make the macro actually expand after
#define FAKE_CAT2_(X, ...) X __VA_ARGS__
#define FAKE_CAT2(...)     FAKE_CAT2_(__VA_ARGS__)

// token concatenation/2
#define CAT2_(X, ...) X ## __VA_ARGS__
#define CAT2(...)     CAT2_(__VA_ARGS__)

// token concatenation/3
#define CAT3_(X, Y, ...) X ## Y ## __VA_ARGS__
#define CAT3(...)        CAT3_(__VA_ARGS__)

// outer generation (top level) of method selectors
// (this expands to normal class-named functions with class name argument)
#define OUTER_METHOD_(...) __VA_ARGS__)
#define OUTER_METHOD(Class, Method, Return, ...) \
    Return CAT3(Class, _, Method)(Class OUTER_METHOD_ __VA_ARGS__
#define OUTER0_method(...) OUTER_METHOD
#define OUTER1_method(...) __VA_ARGS__

// outer generation of property selectors
// (this expands to nothing)
#define OUTER_PROPERTY(...)
#define OUTER0_property(...) OUTER_PROPERTY
#define OUTER1_property(...) __VA_ARGS__

// selector for outer generation
// first gets selector macro args by forming OUTER1_method or OUTER1_property
// then wraps class name with args in parens and forms OUTER0_method/property
// FAKE_CAT2 is needed to make this actually expand
#define CLASS0_(Selector, ...) FAKE_CAT2(OUTER0_ ## Selector, (__VA_ARGS__, OUTER1_ ## Selector))

// implements inheritance
// simply makes fields with the same name as the class (Foo Foo;)
#define EXTENDS_(...) __VA_ARGS__ __VA_ARGS__;
#define CLASS1_(...)  MAP(EXTENDS_, __VA_ARGS__)

// inner generation (inside struct) of method selectors
// (this expands to nothing)
#define INNER_method(...)

// inner generation of property selectors
// expands to simple struct fields (Foo foo;)
#define INNER_property(Property, ...) __VA_ARGS__ Property;

// selector for inner generation
// has no need for class name, so simpler than outer (only pasting)
#define CLASS2_(...) INNER_ ## __VA_ARGS__

// actual class definition with name, inheritance list, and selectors
// 1. predeclares class for inner usage
// 2. defines the class with the inheritance list expanded by CLASS1_...
// 3. ...and the fields expanded by CLASS2_
// 4. defines methods as free functions with CLASS0_
// (can be easily extended to predeclare all functions so order doesn't matter)
// ((can be easily extended to have actual vtables (maybe "virtual" selector?)))
#define class(Class, EXTENDS, ...) \
    typedef struct Class Class; \
    struct Class { CLASS1_ EXTENDS MAP(CLASS2_, __VA_ARGS__) }; \
    MAP_UD(CLASS0_, Class, __VA_ARGS__);

// implements dynamic casting from superclass to subclass
// basically glorified container_of macro
// but staged to have type list be separate from parameters
#define DYNAMIC_CAST_(...) __VA_ARGS__)))
#define dynamic_cast(From, To) \
    ((To *)(-offsetof(To, From) + (char *)(DYNAMIC_CAST_