cpython/Include/internal/pycore_global_objects.h

#ifndef Py_INTERNAL_GLOBAL_OBJECTS_H
#define Py_INTERNAL_GLOBAL_OBJECTS_H
#ifdef __cplusplus
extern "C" {
#endif

#ifndef Py_BUILD_CORE
#  error "this header requires Py_BUILD_CORE define"
#endif

#include "pycore_gc.h"              // PyGC_Head
#include "pycore_global_strings.h"  // struct _Py_global_strings


// These would be in pycore_long.h if it weren't for an include cycle.
#define _PY_NSMALLPOSINTS           257
#define _PY_NSMALLNEGINTS           5


// Only immutable objects should be considered runtime-global.
// All others must be per-interpreter.

#define _Py_GLOBAL_OBJECT(NAME) \
    _PyRuntime.global_objects.NAME
#define _Py_SINGLETON(NAME) \
    _Py_GLOBAL_OBJECT(singletons.NAME)

struct _Py_global_objects {
    struct {
        /* Small integers are preallocated in this array so that they
         * can be shared.
         * The integers that are preallocated are those in the range
         * -_PY_NSMALLNEGINTS (inclusive) to _PY_NSMALLPOSINTS (exclusive).
         */
        PyLongObject small_ints[_PY_NSMALLNEGINTS + _PY_NSMALLPOSINTS];

        PyBytesObject bytes_empty;
        struct {
            PyBytesObject ob;
            char eos;
        } bytes_characters[256];

        struct _Py_global_strings strings;

        _PyGC_Head_UNUSED _tuple_empty_gc_not_used;
        PyTupleObject tuple_empty;
    } singletons;

    PyObject *interned;
};

#define _Py_INTERP_CACHED_OBJECT(interp, NAME) \
    (interp)->cached_objects.NAME

struct _Py_interp_cached_objects {
    int _not_set;
};

#define _Py_INTERP_STATIC_OBJECT(interp, NAME) \
    (interp)->static_objects.NAME
#define _Py_INTERP_SINGLETON(interp, NAME) \
    _Py_INTERP_STATIC_OBJECT(interp, singletons.NAME)

struct _Py_interp_static_objects {
    struct {
        int _not_used;
    } singletons;
};


#ifdef __cplusplus
}
#endif
#endif /* !Py_INTERNAL_GLOBAL_OBJECTS_H */