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Wave: a Standard conformant C++ preprocessor library

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10 Jan 200413 min read 392.1K   4.4K   81  
Describes a free and fully Standard conformant C++ preprocessor library
/*=============================================================================
    Wave: A Standard compliant C++ preprocessor

    Whitespace eater
    
    Copyright (c) 2003 Paul Mensonides
    Copyright (c) 2001-2003 Hartmut Kaiser
    http://spirit.sourceforge.net/

    Permission to copy, use, modify, sell and distribute this software
    is granted provided this copyright notice appears in all copies.
    This software is provided "as is" without express or implied
    warranty, and with no claim as to its suitability for any purpose.

    See Copyright.txt for full copyright notices and acknowledgements.
=============================================================================*/

#if !defined(EAT_WHITESPACE_HPP_4CE9AD17_F82D_4AB2_A117_555DF0DCC801_INCLUDED)
#define EAT_WHITESPACE_HPP_4CE9AD17_F82D_4AB2_A117_555DF0DCC801_INCLUDED

#include "wave/cpplexer/cpp_token_ids.hpp"   

///////////////////////////////////////////////////////////////////////////////
namespace wave {
namespace util {

template <typename TokenT>
class eat_whitespace {

public:
    eat_whitespace();
    
    bool may_skip (TokenT &token, bool &skipped_newline);
    
private:
    typedef bool state_t(TokenT &token, bool &skipped_newline);
    state_t eat_whitespace::* state;
    state_t general, newline, newline_2nd, whitespace;
};

template <typename TokenT>
inline 
eat_whitespace<TokenT>::eat_whitespace()
:   state(&eat_whitespace::newline) 
{
}

template <typename TokenT>
inline bool 
eat_whitespace<TokenT>::may_skip(TokenT &token, bool &skipped_newline) 
{
    return (this->*state)(token, skipped_newline);
}

template <typename TokenT>
inline bool 
eat_whitespace<TokenT>::general(TokenT &token, bool &skipped_newline) 
{
    using wave::cpplexer::token_id;

    token_id id = token_id(token);
    if (T_NEWLINE == id || T_CPPCOMMENT == id) {
        state = &eat_whitespace::newline;
    }
    else if (T_SPACE == id || T_CCOMMENT == id) {
        state = &eat_whitespace::whitespace;

        if (T_CCOMMENT == id) {
            if (typename TokenT::string_t::npos != 
                token.get_value().find_first_of("\n"))
            {
                skipped_newline = true;
            }
        }

        if (token.get_value().size() > 1)
            token.set_value(" ");   // replace with a single space
    }
    else {
        state = &eat_whitespace::general;
    }
    return false;
}

template <typename TokenT>
inline bool 
eat_whitespace<TokenT>::newline(TokenT &token, bool &skipped_newline) 
{
    using wave::cpplexer::token_id;
    
    token_id id = token_id(token);
    if (T_NEWLINE == id || T_CPPCOMMENT == id) {
//        skipped_newline = true;
        state = &eat_whitespace::newline_2nd;
        return false;
    }
    else if (T_SPACE != id && T_CCOMMENT != id) {
        return general(token, skipped_newline);
    }

    if (T_CCOMMENT == id) {
        if (typename TokenT::string_t::npos != 
            token.get_value().find_first_of("\n"))
        {
            skipped_newline = true;
        }
        return true;
    }
    return true;
}

template <typename TokenT>
inline bool 
eat_whitespace<TokenT>::newline_2nd(TokenT &token, bool &skipped_newline) 
{
    using wave::cpplexer::token_id;
    
    token_id id = token_id(token);
    if (T_SPACE == id)
        return true;
    if (T_CCOMMENT == id) {
        if (typename TokenT::string_t::npos != 
            token.get_value().find_first_of("\n"))
        {
            skipped_newline = true;
        }
        return true;
    }
    if (T_NEWLINE != id && T_CPPCOMMENT != id) 
        return general(token, skipped_newline);

    skipped_newline = true;
    return true;
}

template <typename TokenT>
inline bool 
eat_whitespace<TokenT>::whitespace(TokenT &token, bool &skipped_newline) 
{
    using wave::cpplexer::token_id;
    
    token_id id = token_id(token);
    if (T_SPACE != id && T_CCOMMENT != id) 
        return general(token, skipped_newline);

    if (T_CCOMMENT == id) {
        if (typename TokenT::string_t::npos != 
            token.get_value().find_first_of("\n"))
        {
            skipped_newline = true;
        }
        return true;
    }
    return true;
}

///////////////////////////////////////////////////////////////////////////////
}   // namespace util
}   // namespace wave

#endif // !defined(EAT_WHITESPACE_HPP_4CE9AD17_F82D_4AB2_A117_555DF0DCC801_INCLUDED)

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Written By
United States United States
Actively involved in Boost and the development of the Spirit parser construction framework.

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