boost/boost/log/support/spirit_classic.hpp

/*
 *          Copyright Andrey Semashev 2007 - 2015.
 * 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)
 */
/*!
 * \file   support/spirit_classic.hpp
 * \author Andrey Semashev
 * \date   19.07.2009
 *
 * This header enables Boost.Spirit (classic) support for Boost.Log.
 */

#ifndef BOOST_LOG_SUPPORT_SPIRIT_CLASSIC_HPP_INCLUDED_
#define BOOST_LOG_SUPPORT_SPIRIT_CLASSIC_HPP_INCLUDED_

#include <boost/mpl/bool.hpp>
#include <boost/utility/enable_if.hpp>
#include <boost/log/detail/config.hpp>
#include <boost/log/utility/functional/matches.hpp>

#ifdef BOOST_HAS_PRAGMA_ONCE
#pragma once
#endif

#if !defined(BOOST_LOG_NO_THREADS) && !defined(BOOST_SPIRIT_THREADSAFE) && !defined(BOOST_LOG_DOXYGEN_PASS)
/*
 * As Boost.Log filters may be called in multiple threads concurrently,
 * this may lead to using Boost.Spirit parsers in a multithreaded context.
 * In order to protect parsers properly, BOOST_SPIRIT_THREADSAFE macro should
 * be defined.
 *
 * If we got here, it means that the user did not define that macro and we
 * have to define it ourselves. However, it may also lead to ODR violations
 * or even total ignorance of this macro, if the user has included Boost.Spirit
 * headers before including this header, or uses Boost.Spirit without the macro
 * in other translation units. The only reliable way to settle this problem is to
 * define the macro for the whole project (i.e. all translation units).
 */
#if defined(__GNUC__)
#pragma message "Boost.Log: Boost.Spirit requires BOOST_SPIRIT_THREADSAFE macro to be defined if parsers are used in a multithreaded context. It is strongly recommended to define this macro project-wide."
#elif defined(_MSC_VER)
#pragma message("Boost.Log: Boost.Spirit requires BOOST_SPIRIT_THREADSAFE macro to be defined if parsers are used in a multithreaded context. It is strongly recommended to define this macro project-wide.")
#endif
#define BOOST_SPIRIT_THREADSAFE 1
#endif // !defined(BOOST_LOG_NO_THREADS) && !defined(BOOST_SPIRIT_THREADSAFE)

#include <boost/spirit/include/classic_parser.hpp>

#include <boost/log/detail/header.hpp>

namespace boost {

BOOST_LOG_OPEN_NAMESPACE

namespace aux {

//! This tag type is used if an expression is recognized as a Boost.Spirit.Classic expression
struct boost_spirit_classic_expression_tag;

//! The trait verifies if the type can be converted to a Boost.Spirit (classic) parser
template< typename T >
struct is_spirit_classic_parser
{
private:
    typedef char yes_type;
    struct no_type { char dummy[2]; };

    template< typename U >
    static yes_type check_spirit_classic_parser(spirit::classic::parser< U > const&);
    static no_type check_spirit_classic_parser(...);
    static T& get_T();

public:
    enum { value = sizeof(check_spirit_classic_parser(get_T())) == sizeof(yes_type) };
    typedef mpl::bool_< value > type;
};

//! The metafunction detects the matching expression kind and returns a tag that is used to specialize \c match_traits
template< typename ExpressionT >
struct matching_expression_kind< ExpressionT, typename boost::enable_if_c< is_spirit_classic_parser< ExpressionT >::value >::type >
{
    typedef boost_spirit_classic_expression_tag type;
};

//! The matching function implementation
template< typename ExpressionT >
struct match_traits< ExpressionT, boost_spirit_classic_expression_tag >
{
    typedef ExpressionT compiled_type;
    static compiled_type compile(ExpressionT const& expr) { return expr; }

    template< typename StringT >
    static bool matches(StringT const& str, ExpressionT const& expr)
    {
        typedef typename StringT::const_iterator const_iterator;
        spirit::classic::parse_info< const_iterator > info =
            spirit::classic::parse(str.begin(), str.end(), expr);
        return info.full;
    }
};

} // namespace aux

BOOST_LOG_CLOSE_NAMESPACE // namespace log

} // namespace boost

#include <boost/log/detail/footer.hpp>

#endif // BOOST_LOG_SUPPORT_SPIRIT_CLASSIC_HPP_INCLUDED_