cpython/Include/pymacro.h

#ifndef Py_PYMACRO_H
#define Py_PYMACRO_H

#define Py_MIN(x, y) (((x) > (y)) ? (y) : (x))
#define Py_MAX(x, y) (((x) > (y)) ? (x) : (y))

/* Argument must be a char or an int in [-128, 127] or [0, 255]. */
#define Py_CHARMASK(c) ((unsigned char)((c) & 0xff))


/* Assert a build-time dependency, as an expression.

   Your compile will fail if the condition isn't true, or can't be evaluated
   by the compiler. This can be used in an expression: its value is 0.

   Example:

   #define foo_to_char(foo)  \
       ((char *)(foo)        \
        + Py_BUILD_ASSERT_EXPR(offsetof(struct foo, string) == 0))

   Written by Rusty Russell, public domain, http://ccodearchive.net/ */
#define Py_BUILD_ASSERT_EXPR(cond) \
    (sizeof(char [1 - 2*!(cond)]) - 1)

/* Get the number of elements in a visible array

   This does not work on pointers, or arrays declared as [], or function
   parameters. With correct compiler support, such usage will cause a build
   error (see Py_BUILD_ASSERT_EXPR).

   Written by Rusty Russell, public domain, http://ccodearchive.net/ */
#if defined(__GNUC__)
/* Two gcc extensions.
   &a[0] degrades to a pointer: a different type from an array */
#define Py_ARRAY_LENGTH(array) \
    (sizeof(array) / sizeof((array)[0]) \
     + Py_BUILD_ASSERT_EXPR(!__builtin_types_compatible_p(typeof(array), \
                                                          typeof(&(array)[0]))))
#else
#define Py_ARRAY_LENGTH(array) \
    (sizeof(array) / sizeof((array)[0]))
#endif


/* Define macros for inline documentation. */
#define PyDoc_VAR(name) static char name[]
#define PyDoc_STRVAR(name,str) PyDoc_VAR(name) = PyDoc_STR(str)
#ifdef WITH_DOC_STRINGS
#define PyDoc_STR(str) str
#else
#define PyDoc_STR(str) ""
#endif

#endif /* Py_PYMACRO_H */