1 // Copyright Cromwell D. Enage 2013.
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
6 #ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_INC_BINARY_SEQ_HPP
7 #define BOOST_PARAMETER_AUX_PREPROCESSOR_INC_BINARY_SEQ_HPP
9 #include <boost/preprocessor/seq/push_back.hpp>
11 // This macro keeps the rest of the sequence if carry == 0.
12 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_0(seq, element) \
13 (BOOST_PP_SEQ_PUSH_BACK(seq, element), 0)
16 #include <boost/preprocessor/control/iif.hpp>
18 // This macro updates the rest of the sequence if carry == 1.
19 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_1(seq, element) \
20 (BOOST_PP_SEQ_PUSH_BACK(seq, BOOST_PP_IIF(element, 0, 1)), element)
23 #include <boost/preprocessor/tuple/elem.hpp>
24 #include <boost/preprocessor/cat.hpp>
26 // This macro maintains a tuple (seq, carry), where seq is the intermediate
27 // result and carry is a flag that will unset upon finding an element == 0.
28 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_OP(s, result_tuple, element) \
30 BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_ \
31 , BOOST_PP_TUPLE_ELEM(2, 1, result_tuple) \
32 )(BOOST_PP_TUPLE_ELEM(2, 0, result_tuple), element)
35 // This macro keeps the sequence at its original length if carry == 0.
36 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_0(seq) seq
39 // This macro appends a zero to seq if carry == 1.
40 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_1(seq) \
41 BOOST_PP_SEQ_PUSH_BACK(seq, 0)
44 // This macro takes in the tuple (seq, carry), with carry indicating whether
45 // or not seq originally contained all 1s. If so, then seq now contains all
46 // 0s, and this macro pushes an extra 0 before expanding to the new sequence.
47 // Otherwise, this macro expands to seq as is.
48 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL(seq_and_carry) \
50 BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_ \
51 , BOOST_PP_TUPLE_ELEM(2, 1, seq_and_carry) \
52 )(BOOST_PP_TUPLE_ELEM(2, 0, seq_and_carry))
55 #include <boost/preprocessor/seq/seq.hpp>
56 #include <boost/preprocessor/seq/fold_left.hpp>
58 // This macro treats the specified sequence of 1s and 0s like a binary number
59 // in reverse and expands to a sequence representing the next value up.
60 // However, if the input sequence contains all 1s, then the output sequence
61 // will contain one more element but all 0s.
64 // seq = (1)(0)(1)(0) --> return (0)(1)(1)(0)
65 // seq = (1)(1)(1)(0) --> return (0)(0)(0)(1)
66 // seq = (1)(1)(1)(1) --> return (0)(0)(0)(0)(0)
67 #define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ(seq) \
68 BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL( \
69 BOOST_PP_SEQ_FOLD_LEFT( \
70 BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_OP \
71 , (BOOST_PP_SEQ_NIL, 1) \
77 #endif // include guard