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///////////////////////////////////////////////////////////////////////////////
// optional_matcher.hpp
//
// Copyright 2008 Eric Niebler. 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_XPRESSIVE_DETAIL_CORE_MATCHER_OPTIONAL_MATCHER_HPP_EAN_10_04_2005
#define BOOST_XPRESSIVE_DETAIL_CORE_MATCHER_OPTIONAL_MATCHER_HPP_EAN_10_04_2005
// MS compatible compilers support #pragma once
#if defined(_MSC_VER)
# pragma once
#endif
#include <boost/mpl/bool.hpp>
#include <boost/xpressive/detail/detail_fwd.hpp>
#include <boost/xpressive/detail/core/quant_style.hpp>
#include <boost/xpressive/detail/core/state.hpp>
namespace boost { namespace xpressive { namespace detail
{
///////////////////////////////////////////////////////////////////////////////
// optional_matcher
template<typename Xpr, typename Greedy>
struct optional_matcher
: quant_style<quant_variable_width, unknown_width::value, Xpr::pure>
{
Xpr xpr_;
explicit optional_matcher(Xpr const &xpr)
: xpr_(xpr)
{
}
template<typename BidiIter, typename Next>
bool match(match_state<BidiIter> &state, Next const &next) const
{
return this->match_(state, next, Greedy());
}
private:
template<typename BidiIter, typename Next>
bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const // Greedy
{
return this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state)
|| next.match(state);
}
template<typename BidiIter, typename Next>
bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const // Non-greedy
{
return next.match(state)
|| this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state);
}
optional_matcher &operator =(optional_matcher const &);
};
///////////////////////////////////////////////////////////////////////////////
// optional_mark_matcher
template<typename BidiIter, typename Next>
inline bool match_next(match_state<BidiIter> &state, Next const &next, int mark_number)
{
sub_match_impl<BidiIter> &br = state.sub_match(mark_number);
bool old_matched = br.matched;
br.matched = false;
if(next.match(state))
{
return true;
}
br.matched = old_matched;
return false;
}
///////////////////////////////////////////////////////////////////////////////
// optional_mark_matcher
template<typename Xpr, typename Greedy>
struct optional_mark_matcher
: quant_style<quant_variable_width, unknown_width::value, Xpr::pure>
{
Xpr xpr_;
int mark_number_;
explicit optional_mark_matcher(Xpr const &xpr, int mark_number)
: xpr_(xpr)
, mark_number_(mark_number)
{
}
template<typename BidiIter, typename Next>
bool match(match_state<BidiIter> &state, Next const &next) const
{
return this->match_(state, next, Greedy());
}
private:
template<typename BidiIter, typename Next>
bool match_(match_state<BidiIter> &state, Next const &next, mpl::true_) const // Greedy
{
return this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state)
|| match_next(state, next, this->mark_number_);
}
template<typename BidiIter, typename Next>
bool match_(match_state<BidiIter> &state, Next const &next, mpl::false_) const // Non-greedy
{
return match_next(state, next, this->mark_number_)
|| this->xpr_.BOOST_NESTED_TEMPLATE push_match<Next>(state);
}
optional_mark_matcher &operator =(optional_mark_matcher const &);
};
}}}
#endif
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