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Diffstat (limited to 'boost/parameter/aux_/preprocessor/inc_binary_seq.hpp')
-rw-r--r-- | boost/parameter/aux_/preprocessor/inc_binary_seq.hpp | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/boost/parameter/aux_/preprocessor/inc_binary_seq.hpp b/boost/parameter/aux_/preprocessor/inc_binary_seq.hpp new file mode 100644 index 0000000000..9796e336a1 --- /dev/null +++ b/boost/parameter/aux_/preprocessor/inc_binary_seq.hpp @@ -0,0 +1,78 @@ +// Copyright Cromwell D. Enage 2013. +// Distributed under the Boost Software License, Version 1.0. +// (See accompanying file LICENSE_1_0.txt or copy at +// http://www.boost.org/LICENSE_1_0.txt) + +#ifndef BOOST_PARAMETER_AUX_PREPROCESSOR_INC_BINARY_SEQ_HPP +#define BOOST_PARAMETER_AUX_PREPROCESSOR_INC_BINARY_SEQ_HPP + +#include <boost/preprocessor/seq/push_back.hpp> + +// This macro keeps the rest of the sequence if carry == 0. +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_0(seq, element) \ + (BOOST_PP_SEQ_PUSH_BACK(seq, element), 0) +/**/ + +#include <boost/preprocessor/control/iif.hpp> + +// This macro updates the rest of the sequence if carry == 1. +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_1(seq, element) \ + (BOOST_PP_SEQ_PUSH_BACK(seq, BOOST_PP_IIF(element, 0, 1)), element) +/**/ + +#include <boost/preprocessor/tuple/elem.hpp> +#include <boost/preprocessor/cat.hpp> + +// This macro maintains a tuple (seq, carry), where seq is the intermediate +// result and carry is a flag that will unset upon finding an element == 0. +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_OP(s, result_tuple, element) \ + BOOST_PP_CAT( \ + BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_ \ + , BOOST_PP_TUPLE_ELEM(2, 1, result_tuple) \ + )(BOOST_PP_TUPLE_ELEM(2, 0, result_tuple), element) +/**/ + +// This macro keeps the sequence at its original length if carry == 0. +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_0(seq) seq +/**/ + +// This macro appends a zero to seq if carry == 1. +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_1(seq) \ + BOOST_PP_SEQ_PUSH_BACK(seq, 0) +/**/ + +// This macro takes in the tuple (seq, carry), with carry indicating whether +// or not seq originally contained all 1s. If so, then seq now contains all +// 0s, and this macro pushes an extra 0 before expanding to the new sequence. +// Otherwise, this macro expands to seq as is. +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL(seq_and_carry) \ + BOOST_PP_CAT( \ + BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL_ \ + , BOOST_PP_TUPLE_ELEM(2, 1, seq_and_carry) \ + )(BOOST_PP_TUPLE_ELEM(2, 0, seq_and_carry)) +/**/ + +#include <boost/preprocessor/seq/seq.hpp> +#include <boost/preprocessor/seq/fold_left.hpp> + +// This macro treats the specified sequence of 1s and 0s like a binary number +// in reverse and expands to a sequence representing the next value up. +// However, if the input sequence contains all 1s, then the output sequence +// will contain one more element but all 0s. +// +// Examples: +// seq = (1)(0)(1)(0) --> return (0)(1)(1)(0) +// seq = (1)(1)(1)(0) --> return (0)(0)(0)(1) +// seq = (1)(1)(1)(1) --> return (0)(0)(0)(0)(0) +#define BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ(seq) \ + BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_IMPL( \ + BOOST_PP_SEQ_FOLD_LEFT( \ + BOOST_PARAMETER_AUX_PP_INC_BINARY_SEQ_OP \ + , (BOOST_PP_SEQ_NIL, 1) \ + , seq \ + ) \ + ) +/**/ + +#endif // include guard + |