/*=============================================================================
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Boost.Wave: A Standard compliant C++ preprocessor library
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http://www.boost.org/
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Copyright (c) 2001-2012 Hartmut Kaiser. Distributed under the Boost
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Software License, Version 1.0. (See accompanying file
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LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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=============================================================================*/
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#if !defined(BOOST_FUNCTOR_INPUT_HPP_ED3A4C21_8F8A_453F_B438_08214FAC106A_INCLUDED)
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#define BOOST_FUNCTOR_INPUT_HPP_ED3A4C21_8F8A_453F_B438_08214FAC106A_INCLUDED
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#include <boost/assert.hpp>
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#include <boost/spirit/include/classic_multi_pass.hpp>
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#include <boost/wave/wave_config.hpp>
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// this must occur after all of the includes and before any code appears
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#ifdef BOOST_HAS_ABI_HEADERS
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#include BOOST_ABI_PREFIX
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#endif
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///////////////////////////////////////////////////////////////////////////////
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namespace boost {
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namespace wave {
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namespace util {
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///////////////////////////////////////////////////////////////////////////////
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//
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// class functor_input
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//
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// Implementation of the InputPolicy used by multi_pass
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// functor_input gets tokens from a functor
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// Note: the functor must have a typedef for result_type
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// It also must have a static variable of type result_type defined
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// to represent eof that is called eof.
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//
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// This functor input policy template is essentially the same as the
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// predefined multi_pass functor_input policy. The difference is,
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// that the first token is not read at initialization time, but only
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// just before returning the first token. Additionally it does not
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// call operator new() twice but only once.
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//
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///////////////////////////////////////////////////////////////////////////////
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struct functor_input {
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template <typename FunctorT>
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class inner {
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private:
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typedef typename FunctorT::result_type result_type;
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public:
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typedef result_type value_type;
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private:
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struct Data {
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Data(FunctorT const &ftor_)
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: ftor(ftor_), was_initialized(false)
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{}
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FunctorT ftor;
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value_type curtok;
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bool was_initialized;
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};
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// Needed by compilers not implementing the resolution to DR45. For
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// reference, see
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// http://www.open-std.org/JTC1/SC22/WG21/docs/cwg_defects.html#45.
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friend struct Data;
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public:
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typedef std::ptrdiff_t difference_type;
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typedef result_type *pointer;
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typedef result_type &reference;
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protected:
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inner()
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: data(0)
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{}
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inner(FunctorT const &x)
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: data(new Data(x))
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{}
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inner(inner const &x)
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: data(x.data)
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{}
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void destroy()
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{
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delete data;
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data = 0;
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}
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bool same_input(inner const &x) const
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{
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return data == x.data;
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}
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void swap(inner &x)
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{
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boost::spirit::classic::impl::mp_swap(data, x.data);
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}
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void ensure_initialized() const
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{
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if (data && !data->was_initialized) {
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data->curtok = (data->ftor)(); // get the first token
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data->was_initialized = true;
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}
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}
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public:
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reference get_input() const
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{
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ensure_initialized();
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return data->curtok;
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}
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void advance_input()
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{
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BOOST_ASSERT(0 != data);
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data->curtok = (data->ftor)();
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data->was_initialized = true;
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}
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bool input_at_eof() const
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{
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ensure_initialized();
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return !data || data->curtok == data->ftor.eof;
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}
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FunctorT& get_functor() const
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{
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BOOST_ASSERT(0 != data);
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return data->ftor;
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}
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private:
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mutable Data *data;
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};
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};
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///////////////////////////////////////////////////////////////////////////////
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} // namespace util
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} // namespace wave
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} // namespace boost
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// the suffix header occurs after all of the code
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#ifdef BOOST_HAS_ABI_HEADERS
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#include BOOST_ABI_SUFFIX
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#endif
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#endif // !defined(BOOST_FUNCTOR_INPUT_HPP_ED3A4C21_8F8A_453F_B438_08214FAC106A_INCLUDED)
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