karma/binary/padding.hpp

0001 //  Copyright (c) 2001-2011 Hartmut Kaiser
0002 //
0003 //  Distributed under the Boost Software License, Version 1.0. (See accompanying
0004 //  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
0005
0006 #if !defined(BOOST_SPIRIT_KARMA_PADDING_MAY_06_2008_0436PM)
0007 #define BOOST_SPIRIT_KARMA_PADDING_MAY_06_2008_0436PM
0008
0009 #if defined(_MSC_VER)
0010 #pragma once
0011 #endif
0012
0013 #include <boost/spirit/home/support/common_terminals.hpp>
0014 #include <boost/spirit/home/support/info.hpp>
0015
0016 #include <boost/spirit/home/karma/domain.hpp>
0017 #include <boost/spirit/home/karma/meta_compiler.hpp>
0018 #include <boost/spirit/home/karma/delimit_out.hpp>
0019 #include <boost/spirit/home/karma/auxiliary/lazy.hpp>
0020 #include <boost/spirit/home/karma/detail/generate_to.hpp>
0021 #include <boost/spirit/home/support/unused.hpp>
0022 #include <boost/fusion/include/at.hpp>
0023 #include <boost/fusion/include/vector.hpp>
0024
0025 ///////////////////////////////////////////////////////////////////////////////
0026 namespace boost { namespace spirit
0027 {
0028     ///////////////////////////////////////////////////////////////////////////
0029     // Enablers
0030     ///////////////////////////////////////////////////////////////////////////
0031
0032     // enables pad(...)
0033     template <typename A0>
0034     struct use_terminal<karma::domain
0035         , terminal_ex<tag::pad, fusion::vector1<A0> > >
0036       : mpl::true_ {};
0037
0038     // enables lazy pad(...)
0039     template <>
0040     struct use_lazy_terminal<karma::domain, tag::pad, 1>
0041       : mpl::true_ {};
0042
0043 }}
0044
0045 ///////////////////////////////////////////////////////////////////////////////
0046 namespace boost { namespace spirit { namespace karma
0047 {
0048 #ifndef BOOST_SPIRIT_NO_PREDEFINED_TERMINALS
0049     using boost::spirit::pad;
0050 #endif
0051     using boost::spirit::pad_type;
0052
0053     struct binary_padding_generator
0054       : primitive_generator<binary_padding_generator>
0055     {
0056         typedef mpl::int_<generator_properties::tracking> properties;
0057
0058         template <typename Context, typename Unused>
0059         struct attribute
0060         {
0061             typedef unused_type type;
0062         };
0063
0064         binary_padding_generator(int numpadbytes)
0065           : numpadbytes_(numpadbytes)
0066         {}
0067
0068         template <
0069             typename OutputIterator, typename Context, typename Delimiter
0070           , typename Attribute>
0071         bool generate(OutputIterator& sink, Context&, Delimiter const& d
0072           , Attribute const& /*attr*/) const
0073         {
0074             std::size_t count = sink.get_out_count() % numpadbytes_;
0075             if (count)
0076                 count = numpadbytes_ - count;
0077
0078             bool result = true;
0079             while (result && count-- != 0)
0080                 result = detail::generate_to(sink, '\0');
0081
0082             if (result)
0083                 result = karma::delimit_out(sink, d);  // always do post-delimiting
0084             return result;
0085         }
0086
0087         template <typename Context>
0088         static info what(Context const&)
0089         {
0090             return info("pad");
0091         }
0092
0093         int numpadbytes_;
0094     };
0095
0096     ///////////////////////////////////////////////////////////////////////////
0097     // Generator generators: make_xxx function (objects)
0098     ///////////////////////////////////////////////////////////////////////////
0099     template <typename Modifiers, typename A0>
0100     struct make_primitive<
0101         terminal_ex<tag::pad, fusion::vector1<A0> >
0102       , Modifiers>
0103     {
0104         typedef binary_padding_generator result_type;
0105
0106         template <typename Terminal>
0107         result_type operator()(Terminal const& term, unused_type) const
0108         {
0109             return result_type(fusion::at_c<0>(term.args));
0110         }
0111     };
0112
0113 }}}
0114
0115 #endif