Compiler Construction - Lista 1.

Obrazki, ktore może narysuje w weekend.

Nie pisemnie

zmieniamy funkcje nexttoken na nastepujaca i w definicji klasy token, zmieniamy liste unsigned intów na signed

int chartoint( char c )
{                      
        switch (c)     
        {              
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                case '0':
                        return c - '0';
                case 'a':              
                case 'A':              
                        return 10;     
                case 'b':              
                case 'B':              
                        return 11;     
                case 'c':              
                case 'C':              
                        return 12;     
                case 'd':              
                case 'D':              
                        return 13;     
                case 'e':              
                case 'E':              
                        return 14;     
                case 'f':              
                case 'F':              
                        return 15;     
                default:               
                        return 17;     
        }                              
}                                      

token nexttoken( reader& r )
{                           
        if( r. lookahead == EOF )
                return token::token( tkn_eof );

        int val,sign;

        //hexadecimal number with initial '$'
        if( r. lookahead == '$' )            
        {                                    
                r. moveforward( );           
                val = 0;                     

                if( chartoint(r.lookahead) == 17 )
                        goto err;                 

                while( chartoint(r.lookahead) != 17 )
                {                                    
                        val *= 16;                   
                        val += chartoint( r.lookahead );
                        r.moveforward();                
                }                                       
                token th = tkn_int;                     
                th.intattr.push_back( val );            
                return th;                              

        }


        //decimal integer with possible initial '+' or '-'
        if( r. lookahead == '-' )                         
        {                                                 
                r.moveforward( );                         
                sign = -1;                                
                val = 0;                                  
        }                                                 
        else if( r.lookahead == '+' )                     
        {                                                 
                r.moveforward( );                         
                sign = 1;                                 
                val = 0;                                  
        }                                                 
        else if( r.lookahead >= '0' && r.lookahead <= '9' )
        {                                                  
                sign = 1;                                  
                val = 0;                                   
        }                                                  
        else                                               
        {                                                  
                goto err;                                  
        }                                                  

        if( r.lookahead < '0' || r.lookahead > '9' )
                goto err;                           

        {
                while( r.lookahead >= '0' && r.lookahead <= '9' )
                {                                                
                        val *= 10;                               
                        val += r.lookahead - '0';                
                        r.moveforward();                         
                }                                                
                token t = tkn_int;                               
                t.intattr.push_back( sign*val );                 
                return t;                                        
        }                                                        

        err:

                token te = tkn_error;

                te. stringattr. push_back( std::string( ));
                te. stringattr. back( ) += r. lookahead;   
                                                           
                r. moveforward( );                         
                return te;                                 
}