boost/spirit/home/support/iterators/detail/split_functor_input_policy.hpp
// Copyright (c) 2001-2011 Hartmut Kaiser
//
// 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)
#if !defined(BOOST_SPIRIT_ITERATOR_SPLIT_FUNCTOR_INPUT_POLICY_JAN_17_2008_0103PM)
#define BOOST_SPIRIT_ITERATOR_SPLIT_FUNCTOR_INPUT_POLICY_JAN_17_2008_0103PM
#include <boost/spirit/home/support/iterators/multi_pass_fwd.hpp>
#include <boost/spirit/home/support/iterators/detail/multi_pass.hpp>
#include <boost/core/invoke_swap.hpp>
#include <boost/assert.hpp>
#include <boost/type_traits/is_empty.hpp>
namespace boost { namespace spirit { namespace iterator_policies
{
namespace split_functor_input_is_valid_test_
{
template <typename Token>
inline bool token_is_valid(Token const&)
{
return true;
}
}
///////////////////////////////////////////////////////////////////////////
// class split_functor_input
// Implementation of the InputPolicy used by multi_pass
// split_functor_input gets tokens from a functor
//
// This policy should be used when the functor holds two parts of data: a
// unique part (unique for each instance of the iterator) and a shared
// part (to be shared between the different copies of the same iterator).
// Using this policy allows to merge the shared part of the functor with
// the shared part of the iterator data, saving one pointer and one
// allocation per iterator instance.
//
// The Functor template parameter of this policy is expected to be a
// std::pair<unique, shared>, where 'unique' and 'shared' represent the
// respective parts of the functor itself.
//
// Note: the unique part of the functor must have a typedef for result_type
// It also must have a static variable of type result_type defined
// to represent EOF that is called eof.
//
///////////////////////////////////////////////////////////////////////////
struct split_functor_input
{
///////////////////////////////////////////////////////////////////////
template <typename Functor
, bool FunctorIsEmpty = is_empty<typename Functor::first_type>::value>
class unique;
// the unique part of the functor is empty, do not include the functor
// as a member at all to avoid unnecessary padding bytes to be included
// into the generated structure
template <typename Functor>
class unique<Functor, true> // : public detail::default_input_policy
{
protected:
typedef typename Functor::first_type functor_type;
typedef typename functor_type::result_type result_type;
public:
typedef result_type value_type;
typedef std::ptrdiff_t difference_type;
typedef std::ptrdiff_t distance_type;
typedef result_type const* pointer;
typedef result_type const& reference;
protected:
unique() {}
explicit unique(Functor const&) {}
public:
void swap(unique&) {}
// get the next token
template <typename MultiPass>
static typename MultiPass::reference get_input(MultiPass& mp)
{
value_type& curtok = mp.shared()->curtok;
using namespace split_functor_input_is_valid_test_;
if (!token_is_valid(curtok))
functor_type::get_next(mp, curtok);
return curtok;
}
template <typename MultiPass>
static void advance_input(MultiPass& mp)
{
functor_type::get_next(mp, mp.shared()->curtok);
}
// test, whether we reached the end of the underlying stream
template <typename MultiPass>
static bool input_at_eof(MultiPass const& mp)
{
return mp.shared()->curtok == functor_type::eof;
}
template <typename MultiPass>
static bool input_is_valid(MultiPass const&, value_type const& t)
{
using namespace split_functor_input_is_valid_test_;
return token_is_valid(t);
}
template <typename MultiPass>
static void destroy(MultiPass& mp)
{
functor_type::destroy(mp);
}
};
// the unique part of the functor is non-empty
template <typename Functor>
class unique<Functor, false> : public unique<Functor, true>
{
protected:
typedef typename Functor::first_type functor_type;
typedef typename functor_type::result_type result_type;
protected:
unique() {}
explicit unique(Functor const& x) : ftor(x.first) {}
void swap(unique& x)
{
boost::core::invoke_swap(ftor, x.ftor);
}
public:
typedef result_type value_type;
typedef std::ptrdiff_t difference_type;
typedef std::ptrdiff_t distance_type;
typedef result_type const* pointer;
typedef result_type const& reference;
public:
// get the next token
template <typename MultiPass>
static typename MultiPass::reference get_input(MultiPass& mp)
{
value_type& curtok = mp.shared()->curtok;
using namespace split_functor_input_is_valid_test_;
if (!token_is_valid(curtok))
functor_type::get_next(mp, curtok);
return curtok;
}
template <typename MultiPass>
static void advance_input(MultiPass& mp)
{
mp.ftor.get_next(mp, mp.shared()->curtok);
}
template <typename MultiPass>
static bool input_is_valid(MultiPass const&, value_type const& t)
{
using namespace split_functor_input_is_valid_test_;
return token_is_valid(t);
}
// test, whether we reached the end of the underlying stream
template <typename MultiPass>
static bool input_at_eof(MultiPass const& mp)
{
return mp.shared()->curtok == mp.ftor.eof;
}
typename Functor::first_type& get_functor() const
{
return ftor;
}
mutable functor_type ftor;
};
///////////////////////////////////////////////////////////////////////
template <typename Functor>
struct shared
{
protected:
typedef typename Functor::first_type functor_type;
typedef typename functor_type::result_type result_type;
public:
explicit shared(Functor const& x) : ftor(x.second), curtok(0) {}
mutable typename Functor::second_type ftor;
result_type curtok;
};
};
}}}
#endif