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#!/usr/bin/env python
"""
Generates some handy macros for preprocessor metaprogramming.
"""
from __future__ import print_function
import sys
import textwrap
if sys.version_info >= (3, 0, 0):
xrange = range
def generate(limit):
print('#pragma once')
print(textwrap.dedent('''
/// @file va_args.h
///
/// Some handy macros for preprocessor metaprogramming.
'''.rstrip()))
print('')
command = ' '.join(sys.argv)
print('// NOTE: this file has been generated with "{}", do not edit -- use the generator instead'.format(command))
print('')
print('// DO_NOT_STYLE')
print('')
print('#include <util/system/defaults.h>')
print('')
pass_va_args()
count(limit)
get_elem(limit)
map_args(limit)
map_args_n(limit)
map_args_with_last(limit)
map_args_with_last_n(limit)
all_but_last(limit)
last(limit)
impl_dispatcher()
def pass_va_args():
print(textwrap.dedent('''
/**
* Triggers another level of macro expansion, use whenever passing __VA_ARGS__ to another macro.
*
* Used merely for working around an MSVC++ bug.
* See http://stackoverflow.com/questions/5134523/msvc-doesnt-expand-va-args-correctly
*/
'''.rstrip()))
print('#define Y_PASS_VA_ARGS(x) x')
def count(limit):
print(textwrap.dedent('''
/**
* Count number of arguments in `__VA_ARGS__`.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
numbers = ', '.join(map(str, xrange(limit, -1, -1)))
u_numbers = ', '.join(map('_{}'.format, xrange(limit, 0, -1)))
print('#define Y_COUNT_ARGS(...) Y_PASS_VA_ARGS('
'__Y_COUNT_ARGS(__VA_ARGS__, {}))'.format(numbers))
print('#define __Y_COUNT_ARGS({}, N, ...) N'.format(u_numbers))
def get_elem(limit):
print(textwrap.dedent('''
/**
* Get the i-th element from `__VA_ARGS__`.
*/
'''.rstrip()))
print('#define Y_GET_ARG(N, ...) Y_PASS_VA_ARGS(Y_PASS_VA_ARGS(Y_CAT(__Y_GET_ARG_, '
'N))(__VA_ARGS__))')
for i in xrange(0, limit + 1):
args = ', '.join(map('_{}'.format, xrange(i + 1)))
print('#define __Y_GET_ARG_{}({}, ...) _{}'.format(i, args, i))
def map_args(limit):
print(textwrap.dedent('''
/**
* Expands a macro for each of the variable arguments.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
print('#define Y_MAP_ARGS(ACTION, ...) Y_PASS_VA_ARGS(Y_PASS_VA_ARGS(Y_CAT('
'__Y_MAP_ARGS_, Y_COUNT_ARGS(__VA_ARGS__)))(ACTION, __VA_ARGS__))')
print('#define __Y_MAP_ARGS_0(...)')
print('#define __Y_MAP_ARGS_1(ACTION, x, ...) ACTION(x)')
for i in xrange(2, limit + 1):
print('#define __Y_MAP_ARGS_{}(ACTION, x, ...) ACTION(x) Y_PASS_VA_ARGS(__Y_MAP_ARGS_{}('
'ACTION, __VA_ARGS__))'.format(i, i - 1))
def map_args_n(limit):
print(textwrap.dedent('''
/**
* Expands a macro for each of the variable arguments with it's sequence number and value.
* Corresponding sequence numbers will expand in descending order.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
print('#define Y_MAP_ARGS_N(ACTION, ...) Y_PASS_VA_ARGS(Y_PASS_VA_ARGS(Y_CAT('
'__Y_MAP_ARGS_N_, Y_COUNT_ARGS(__VA_ARGS__)))(ACTION, __VA_ARGS__))')
print('#define __Y_MAP_ARGS_N_0(...)')
print('#define __Y_MAP_ARGS_N_1(ACTION, x, ...) ACTION(1, x)')
for i in xrange(2, limit + 1):
print('#define __Y_MAP_ARGS_N_{}(ACTION, x, ...) ACTION({}, x) Y_PASS_VA_ARGS(__Y_MAP_ARGS_N_{}('
'ACTION, __VA_ARGS__))'.format(i, i, i - 1))
def map_args_with_last(limit):
print(textwrap.dedent('''
/**
* Expands a macro for each of the variable arguments.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
print('#define Y_MAP_ARGS_WITH_LAST(ACTION, LAST_ACTION, ...) Y_PASS_VA_ARGS(Y_PASS_VA_ARGS('
'Y_CAT(__Y_MAP_ARGS_WITH_LAST_, Y_COUNT_ARGS(__VA_ARGS__)))(ACTION, LAST_ACTION, '
'__VA_ARGS__))')
print('#define __Y_MAP_ARGS_WITH_LAST_0(...)')
print('#define __Y_MAP_ARGS_WITH_LAST_1(ACTION, LAST_ACTION, x, ...) LAST_ACTION(x)')
for i in xrange(2, limit + 1):
print('#define __Y_MAP_ARGS_WITH_LAST_{}(ACTION, LAST_ACTION, x, ...) ACTION(x) Y_PASS_VA_ARGS('
'__Y_MAP_ARGS_WITH_LAST_{}(ACTION, LAST_ACTION, __VA_ARGS__))'.format(i, i - 1))
def map_args_with_last_n(limit):
print(textwrap.dedent('''
/**
* Expands a macro for each of the variable arguments with it's sequence number and value.
* Corresponding sequence numbers will expand in descending order.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
print('#define Y_MAP_ARGS_WITH_LAST_N(ACTION, LAST_ACTION, ...) Y_PASS_VA_ARGS(Y_PASS_VA_ARGS('
'Y_CAT(__Y_MAP_ARGS_WITH_LAST_N_, Y_COUNT_ARGS(__VA_ARGS__)))(ACTION, LAST_ACTION, '
'__VA_ARGS__))')
print('#define __Y_MAP_ARGS_WITH_LAST_N_0(...)')
print('#define __Y_MAP_ARGS_WITH_LAST_N_1(ACTION, LAST_ACTION, x, ...) LAST_ACTION(1, x)')
for i in xrange(2, limit + 1):
print('#define __Y_MAP_ARGS_WITH_LAST_N_{}(ACTION, LAST_ACTION, x, ...) ACTION({}, x) Y_PASS_VA_ARGS('
'__Y_MAP_ARGS_WITH_LAST_N_{}(ACTION, LAST_ACTION, __VA_ARGS__))'.format(i, i, i - 1))
def all_but_last(limit):
print(textwrap.dedent('''
/**
* Get all elements but the last one from `__VA_ARGS__`.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
print('#define Y_ALL_BUT_LAST(...) Y_PASS_VA_ARGS(Y_PASS_VA_ARGS(Y_CAT(__Y_ALL_BUT_LAST_, '
'Y_COUNT_ARGS(__VA_ARGS__)))(__VA_ARGS__))')
print('#define __Y_ALL_BUT_LAST_0(...)')
print('#define __Y_ALL_BUT_LAST_1(...)')
for i in xrange(2, limit + 1):
args = ', '.join(map('_{}'.format, xrange(i - 1)))
print('#define __Y_ALL_BUT_LAST_{}({}, ...) {}'.format(i, args, args))
def last(limit):
print(textwrap.dedent('''
/**
* Get the last element from `__VA_ARGS__`.
* Doesn't work with empty arguments list.
*/
'''.rstrip()))
print('#define Y_LAST(...) Y_PASS_VA_ARGS('
'Y_GET_ARG(Y_COUNT_ARGS(__VA_ARGS__), , __VA_ARGS__, {}))'.format(',' * limit))
def impl_dispatcher():
print(textwrap.dedent('''
/**
* Macros for implementing overload by number of arguments.
*
* Example usage:
*
* @code{cpp}
* #define I1(arg1) Cout << Y_STRINGIZE(arg1) << Endl;
* #define I2(arg1, arg2) Cout << Y_STRINGIZE(arg1) << ';' << Y_STRINGIZE(arg2) << Endl;
*
* #define Y_PRINT(...) Y_PASS_VA_ARGS(Y_MACRO_IMPL_DISPATCHER_2(__VA_ARGS__, I2, I1)(__VA_ARGS__))
* @endcode
*/
'''.rstrip()))
print('/// @{')
for i in xrange(2, 11):
args = ', '.join(map('_{}'.format, xrange(i)))
print('#define Y_MACRO_IMPL_DISPATCHER_{}({}, IMPL, ...) IMPL'.format(i, args))
print('/// }@')
def main():
if len(sys.argv) > 2:
sys.stderr.write('Usage: {} [limit=50]\n'.format(sys.argv[0]))
sys.exit(1)
limit = 50
if len(sys.argv) == 2:
limit = int(sys.argv[1])
generate(limit)
if __name__ == '__main__':
main()
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