Chris@16: /*=============================================================================
Chris@16:     Boost.Wave: A Standard compliant C++ preprocessor library
Chris@16: 
Chris@16:     http://www.boost.org/
Chris@16: 
Chris@16:     Copyright (c) 2001-2012 Hartmut Kaiser. Distributed under the Boost
Chris@16:     Software License, Version 1.0. (See accompanying file
Chris@16:     LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
Chris@16: =============================================================================*/
Chris@16: 
Chris@16: #if !defined(FUNCTOR_INPUT_HPP_ED3A4C21_8F8A_453F_B438_08214FAC106A_INCLUDED)
Chris@16: #define FUNCTOR_INPUT_HPP_ED3A4C21_8F8A_453F_B438_08214FAC106A_INCLUDED
Chris@16: 
Chris@16: #include <boost/assert.hpp>
Chris@16: #include <boost/spirit/include/classic_multi_pass.hpp>
Chris@16: #include <boost/wave/wave_config.hpp>
Chris@16: 
Chris@16: // this must occur after all of the includes and before any code appears
Chris@16: #ifdef BOOST_HAS_ABI_HEADERS
Chris@16: #include BOOST_ABI_PREFIX
Chris@16: #endif
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: namespace boost {
Chris@16: namespace wave {
Chris@16: namespace util {
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: // 
Chris@16: //  class functor_input
Chris@16: // 
Chris@16: //      Implementation of the InputPolicy used by multi_pass 
Chris@16: //      functor_input gets tokens from a functor
Chris@16: //      Note: the functor must have a typedef for result_type
Chris@16: //            It also must have a static variable of type result_type defined 
Chris@16: //            to represent eof that is called eof.
Chris@16: //
Chris@16: //      This functor input policy template is essentially the same as the 
Chris@16: //      predefined multi_pass functor_input policy. The difference is, 
Chris@16: //      that the first token is not read at initialization time, but only 
Chris@16: //      just before returning the first token. Additionally it does not
Chris@16: //      call operator new() twice but only once.
Chris@16: //
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: struct functor_input {
Chris@16: 
Chris@16:     template <typename FunctorT>
Chris@16:     class inner {
Chris@16:     private:
Chris@16:         typedef typename FunctorT::result_type result_type;
Chris@16: 
Chris@16:     public:
Chris@16:         typedef result_type value_type;
Chris@16: 
Chris@16:     private:
Chris@16:         struct Data {
Chris@16:             Data(FunctorT const &ftor_) 
Chris@16:             :   ftor(ftor_), was_initialized(false)
Chris@16:             {}
Chris@16:             
Chris@16:             FunctorT ftor;
Chris@16:             value_type curtok;
Chris@16:             bool was_initialized;
Chris@16:         };
Chris@16: 
Chris@16:        // Needed by compilers not implementing the resolution to DR45. For
Chris@16:        // reference, see
Chris@16:        // http://www.open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#45.
Chris@16: 
Chris@16:        friend struct Data;
Chris@16: 
Chris@16:     public:
Chris@16:         typedef std::ptrdiff_t difference_type;
Chris@16:         typedef result_type *pointer;
Chris@16:         typedef result_type &reference;
Chris@16: 
Chris@16:     protected:
Chris@16:         inner()
Chris@16:         :   data(0)
Chris@16:         {}
Chris@16: 
Chris@16:         inner(FunctorT const &x)
Chris@16:         :   data(new Data(x))
Chris@16:         {}
Chris@16: 
Chris@16:         inner(inner const &x)
Chris@16:         :   data(x.data)
Chris@16:         {}
Chris@16: 
Chris@16:         void destroy()
Chris@16:         {
Chris@16:             delete data;
Chris@16:             data = 0;
Chris@16:         }
Chris@16: 
Chris@16:         bool same_input(inner const &x) const
Chris@16:         {
Chris@16:             return data == x.data;
Chris@16:         }
Chris@16: 
Chris@16:         void swap(inner &x)
Chris@16:         {
Chris@16:             boost::spirit::classic::impl::mp_swap(data, x.data);
Chris@16:         }
Chris@16: 
Chris@16:         void ensure_initialized() const
Chris@16:         {
Chris@16:             if (data && !data->was_initialized) {
Chris@16:                 data->curtok = (data->ftor)();    // get the first token
Chris@16:                 data->was_initialized = true;
Chris@16:             }
Chris@16:         }
Chris@16: 
Chris@16:     public:
Chris@16:         reference get_input() const
Chris@16:         {
Chris@16:             ensure_initialized();
Chris@16:             return data->curtok;
Chris@16:         }
Chris@16: 
Chris@16:         void advance_input()
Chris@16:         {
Chris@16:             BOOST_ASSERT(0 != data);
Chris@16:             data->curtok = (data->ftor)();
Chris@16:             data->was_initialized = true;
Chris@16:         }
Chris@16: 
Chris@16:         bool input_at_eof() const
Chris@16:         {
Chris@16:             ensure_initialized();
Chris@16:             return !data || data->curtok == data->ftor.eof;
Chris@16:         }
Chris@16: 
Chris@16:         FunctorT& get_functor() const
Chris@16:         {
Chris@16:             BOOST_ASSERT(0 != data);
Chris@16:             return data->ftor;
Chris@16:         }
Chris@16: 
Chris@16:     private:
Chris@16:         mutable Data *data;
Chris@16:     };
Chris@16: };
Chris@16: 
Chris@16: ///////////////////////////////////////////////////////////////////////////////
Chris@16: }   // namespace util
Chris@16: }   // namespace wave
Chris@16: }   // namespace boost 
Chris@16: 
Chris@16: // the suffix header occurs after all of the code
Chris@16: #ifdef BOOST_HAS_ABI_HEADERS
Chris@16: #include BOOST_ABI_SUFFIX
Chris@16: #endif
Chris@16: 
Chris@16: #endif // !defined(FUNCTOR_INPUT_HPP_ED3A4C21_8F8A_453F_B438_08214FAC106A_INCLUDED)