cppcheck/preprocessor.cpp

/*
 * c++check - c/c++ syntax checking
 * Copyright (C) 2007 Daniel Marjamäki
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/
 */


#include "preprocessor.h"

#include <algorithm>
#include <list>
#include <sstream>

/**
 * Get all possible configurations. By looking at the ifdefs and ifndefs in filedata
 */
static std::list<std::string> getcfgs( const std::string &filedata );

/**
 * Get preprocessed code for a given configuration
 */
static std::string getcode(const std::string &filedata, std::string cfg);


/**
 * Extract the code for each configuration
 * \param istr The (file/string) stream to read from.
 * \param result The map that will get the results
 */
void preprocess(std::istream &istr, std::map<std::string, std::string> &result)
{
    // Get filedata from stream.. remove all comments
    std::ostringstream code;
    for (char ch = (char)istr.get(); !istr.eof(); ch = (char)istr.get())
    {
        if ( ch == '/' )
        {
            char chNext = (char)istr.get();

            if ( chNext == '/' )
            {
                while (!istr.eof() && ch!='\n')
                    ch = (char)istr.get();
                code << "\n";
            }

            else if ( chNext == '*' )
            {
                char chPrev = 0;
                while (!istr.eof() && (chPrev!='*' || ch!='/'))
                {
                    chPrev = ch;
                    ch = (char)istr.get();
                    if (ch == '\n')
                        code << "\n";
                }
            }

            else
            {
                code << std::string(1,ch) << std::string(1,chNext);
            }
        }

        else if ( ch == '\"' )
        {
            do
            {
                code << std::string(1,ch);
                ch = (char)istr.get();
                if ( ch == '\\' )
                {
                    code << "\\";
                    ch = (char)istr.get();
                }
            } while ( !istr.eof() && ch != '\"' );
            code << std::string(1, ch);
        }

        else if ( ch == '\'' )
        {
            do
            {
                code << std::string(1, ch);
                ch = (char)istr.get();
                if ( ch == '\\' )
                {
                    code << "\\";
                    ch = (char)istr.get();
                }
            } while ( !istr.eof() && ch != '\'' );
            code << std::string(1, ch);
        }

        else
        {
            code << std::string(1, ch);
        }
    }

    std::string codestr( code.str() );

    // Get all possible configurations..
    std::list<std::string> cfgs = getcfgs( codestr );

    // Extract the code for each possible configuration..
    result.clear();
    for ( std::list<std::string>::const_iterator it = cfgs.begin(); it != cfgs.end(); ++it )
    {
        result[ *it ] = getcode( codestr, *it );
    }
}



static std::list<std::string> getcfgs( const std::string &filedata )
{
    std::list<std::string> ret;
    ret.push_back("");

    std::istringstream istr(filedata);
    std::string line;
    while ( getline(istr, line) )
    {
        if ( line.find("#ifdef ")==0 || line.find("#ifndef ")==0 )
        {
            std::string def( line.substr(line.find(" ") + 1) );
            if (std::find(ret.begin(), ret.end(), def) == ret.end())
                ret.push_back( def );
        }
    }

    return ret;
}




static std::string getcode(const std::string &filedata, std::string cfg)
{
    std::ostringstream ret;

    std::list<bool> matching_ifdef;

    std::istringstream istr(filedata);
    std::string line;
    while ( getline(istr, line) )
    {
        if ( line.find("#ifdef ") == 0 )
            matching_ifdef.push_back( !cfg.empty() && line.find(cfg) != std::string::npos );

        else if ( line.find("#ifndef ") == 0 )
            matching_ifdef.push_back( cfg.empty() || line.find(cfg) == std::string::npos );

        else if ( line.find("#else") == 0)
            matching_ifdef.back() = ! matching_ifdef.back();

        else if ( line.find("#endif") == 0 )
            matching_ifdef.pop_back();

        if ( !matching_ifdef.empty() && !matching_ifdef.back() )
            line = "";

        if ( line.find("#") == 0 )
            line = "";

        ret << line << "\n";
    }

    return ret.str();
}