boost_1_45_0/libs/wave/samples/emit_custom_line_directives/emit_custom_line_directives.hpp

/*=============================================================================
    Boost.Wave: A Standard compliant C++ preprocessor library
    http://www.boost.org/

    Copyright (c) 2001-2010 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_WAVE_emit_custom_line_directives_HOOKS_INCLUDED)
#define BOOST_WAVE_emit_custom_line_directives_HOOKS_INCLUDED

#include <cstdio>
#include <ostream>
#include <string>
#include <algorithm>

#include <boost/assert.hpp>
#include <boost/config.hpp>

#include <boost/wave/token_ids.hpp>
#include <boost/wave/util/macro_helpers.hpp>
#include <boost/wave/preprocessing_hooks.hpp>

///////////////////////////////////////////////////////////////////////////////
//  
//  The emit_custom_line_directives_hooks policy class is used to register some
//  of the more advanced (and probably more rarely used hooks with the Wave
//  library.
//
//  This policy type is used as a template parameter to the boost::wave::context<>
//  object.
//
///////////////////////////////////////////////////////////////////////////////
class emit_custom_line_directives_hooks
:   public boost::wave::context_policies::default_preprocessing_hooks
{
public:
    ///////////////////////////////////////////////////////////////////////////
    //
    //  The function 'emit_line_directive' is called whenever a #line directive
    //  has to be emitted into the generated output.
    //
    //  The parameter 'ctx' is a reference to the context object used for 
    //  instantiating the preprocessing iterators by the user.
    //
    //  The parameter 'pending' may be used to push tokens back into the input 
    //  stream, which are to be used instead of the default output generated
    //  for the #line directive.
    //
    //  The parameter 'act_token' contains the actual #pragma token, which may 
    //  be used for error output. The line number stored in this token can be
    //  used as the line number emitted as part of the #line directive.
    //
    //  If the return value is 'false', a default #line directive is emitted
    //  by the library. A return value of 'true' will inhibit any further 
    //  actions, the tokens contained in 'pending' will be copied verbatim 
    //  to the output.
    //
    ///////////////////////////////////////////////////////////////////////////
    template <typename ContextT, typename ContainerT>
    bool 
    emit_line_directive(ContextT const& ctx, ContainerT &pending, 
        typename ContextT::token_type const& act_token)
    {
    // emit a #line directive showing the relative filename instead
    typename ContextT::position_type pos = act_token.get_position();
    unsigned int column = 1;

        typedef typename ContextT::token_type result_type;
        using namespace boost::wave;

        pos.set_column(column);
        pending.push_back(result_type(T_POUND, "#", pos));

        pos.set_column(++column);      // account for '#'
        pending.push_back(result_type(T_SPACE, " ", pos));

    // 21 is the max required size for a 64 bit integer represented as a 
    // string
    char buffer[22];

        using namespace std;    // for some systems sprintf is in namespace std
        sprintf (buffer, "%d", pos.get_line());

        pos.set_column(++column);                 // account for ' '
        pending.push_back(result_type(T_INTLIT, buffer, pos));
        pos.set_column(column += (unsigned int)strlen(buffer)); // account for <number>
        pending.push_back(result_type(T_SPACE, " ", pos));
        pos.set_column(++column);                 // account for ' '

    std::string file("\"");
    boost::filesystem::path filename(
        boost::wave::util::create_path(ctx.get_current_relative_filename().c_str()));

        using boost::wave::util::impl::escape_lit;
        file += escape_lit(boost::wave::util::native_file_string(filename)) + "\"";

        pending.push_back(result_type(T_STRINGLIT, file.c_str(), pos));
        pos.set_column(column += (unsigned int)file.size());    // account for filename
        pending.push_back(result_type(T_GENERATEDNEWLINE, "\n", pos));

        return true;
    }
};

#endif // !defined(BOOST_WAVE_ADVANCED_PREPROCESSING_HOOKS_INCLUDED)