src/mylib/ConfigFile.cpp

// ConfigFile.cpp

#include "ConfigFile.h"

using std::string;

ConfigFile::ConfigFile( string filename, string delimiter,
                        string comment, string sentry )
        : myDelimiter(delimiter), myComment(comment), mySentry(sentry)
{
        // Construct a ConfigFile, getting keys and values from given file
        
        std::ifstream in( filename.c_str() );
        
        if( !in ) throw file_not_found( filename ); 
        
        in >> (*this);
}


ConfigFile::ConfigFile()
        : myDelimiter( string(1,'=') ), myComment( string(1,'#') )
{
        // Construct a ConfigFile without a file; empty
}


void ConfigFile::remove( const string& key )
{
        // Remove key and its value
        myContents.erase( myContents.find( key ) );
        return;
}


bool ConfigFile::keyExists( const string& key ) const
{
        // Indicate whether key is found
        mapci p = myContents.find( key );
        return ( p != myContents.end() );
}


/* static */
void ConfigFile::trim( string& s )
{
        // Remove leading and trailing whitespace
        static const char whitespace[] = " \n\t\v\r\f";
        s.erase( 0, s.find_first_not_of(whitespace) );
        s.erase( s.find_last_not_of(whitespace) + 1U );
}


std::ostream& operator<<( std::ostream& os, const ConfigFile& cf )
{
        // Save a ConfigFile to os
        for( ConfigFile::mapci p = cf.myContents.begin();
             p != cf.myContents.end();
                 ++p )
        {
                os << p->first << " " << cf.myDelimiter << " ";
                os << p->second << std::endl;
        }
        return os;
}


std::istream& operator>>( std::istream& is, ConfigFile& cf )
{
        // Load a ConfigFile from is
        // Read in keys and values, keeping internal whitespace
        typedef string::size_type pos;
        const string& delim  = cf.myDelimiter;  // separator
        const string& comm   = cf.myComment;    // comment
        const string& sentry = cf.mySentry;     // end of file sentry
        const pos skip = delim.length();        // length of separator
        
        string nextline = "";  // might need to read ahead to see where value ends
        
        while( is || nextline.length() > 0 )
        {
                // Read an entire line at a time
                string line;
                if( nextline.length() > 0 )
                {
                        line = nextline;  // we read ahead; use it now
                        nextline = "";
                }
                else
                {
                        std::getline( is, line );
                }
                
                // Ignore comments
                line = line.substr( 0, line.find(comm) );
                
                // Check for end of file sentry
                if( sentry != "" && line.find(sentry) != string::npos ) return is;
                
                // Parse the line if it contains a delimiter
                pos delimPos = line.find( delim );
                if( delimPos < string::npos )
                {
                        // Extract the key
                        string key = line.substr( 0, delimPos );
                        line.replace( 0, delimPos+skip, "" );
                        
                        // See if value continues on the next line
                        // Stop at blank line, next line with a key, end of stream,
                        // or end of file sentry
                        bool terminate = false;
                        while( !terminate && is )
                        {
                                std::getline( is, nextline );
                                terminate = true;
                                
                                string nlcopy = nextline;
                                ConfigFile::trim(nlcopy);
                                if( nlcopy == "" ) continue;
                                
                                nextline = nextline.substr( 0, nextline.find(comm) );
                                if( nextline.find(delim) != string::npos )
                                        continue;
                                if( sentry != "" && nextline.find(sentry) != string::npos )
                                        continue;
                                
                                nlcopy = nextline;
                                ConfigFile::trim(nlcopy);
                                if( nlcopy != "" ) line += "\n";
                                line += nextline;
                                terminate = false;
                        }
                        
                        // Store key and value
                        ConfigFile::trim(key);
                        ConfigFile::trim(line);
                        cf.myContents[key] = line;  // overwrites if key is repeated
                }
        }
        
        return is;
}