/* * BFI.cpp * An almost total rewrite of BFI.c Copyright (C) 2003 Thomas Cort * Changes Copyright (C) 2004, 2005 Ernest S. Pazera * * This source 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 2 of the License, or * (at your option) any later version. * * This source 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 source; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */#include #include #include #include #include using namespace std;//data sizeconst size_t DATA_SIZE=32768;//shorthand command structurestruct command_t{	char token;//the token	union 	{		size_t count;//repeat count for the token(all but [ and ])		size_t position;//position after opposing token ([ and ] only)	};	size_t byte_position;//byte position within the file};//check for a valid sourcesize_t source_is_valid(const string& source_string){	size_t error_position=(size_t)-1;	//keep track of the nested level of [ and ]	size_t nested_level=0;	//loop through the source	for(std::string::const_iterator source_iterator=source_string.begin();source_iterator!=source_string.end();source_iterator++)	{		//look for [ or ]		switch(*source_iterator)		{		case '['://found start of loop			{				//increase nested level				nested_level++;			}break;		case ']'://found end of loop			{				//check for zero nested level				if(nested_level==0)				{					//zero nested level, ERROR!					//source is not valid					error_position=source_iterator-source_string.begin();					return(error_position);				}				else				{					//subtract one from the nested level					nested_level--;				}			}break;		}	}	//return validity	return(error_position);}int main(int argument_count, char **argument_list) {	//don't skip the whitespace	cin.unsetf(ios_base::skipws);	//check argument count	if(argument_count<2)	{		//show syntax		cout<<"Usage:\n\tbfi.exe Source1 [Source2]*\n"<	}	else	{		//at least one argument		//loop through arguments		for(int argument=1;argument		{			//message that source is loading			cout << "Now loading: \t\n" << argument_list[argument] << "...\n" << endl;			//open the file			fstream input_file(argument_list[argument]);			//read the file into a string			string source=string((istreambuf_iterator<char>(input_file)),(istreambuf_iterator<char>()));			//close the input file			input_file.close();			//validate source			size_t error_position=source_is_valid(source);			//if an error is detected, report it and skip to next file			if(error_position!=((size_t)-1))			{				//source is invalid				cout << "Mismatched ] at byte " << (unsigned int)error_position << "." << endl;				continue;			}			//the program			vector program;			//clear the program			program.clear();			//initialize command			command_t command;			command.token=0;			command.count=0;			//loop through the source			for(string::iterator source_iterator=source.begin();source_iterator!=source.end();source_iterator++)			{				//which token are we on?				switch(*source_iterator)				{				case '['://begin loop				case ']'://end loop					{						//do not run-length encode loops						command.token=(*source_iterator);						command.count=0;						command.byte_position=(size_t)(source_iterator-source.begin());						//add to program						program.push_back(command);					}break;				case '.'://output				case ','://input				case '>'://increment pointer				case '<'://decrement pointer				case '+'://increment byte				case '-'://decrement byte					{						//if the program is not empty and the token is the same as the last token...						if(!program.empty()&&program[program.size()-1].token==(*source_iterator))						{							//add to the count of the token							program[program.size()-1].count++;						}						else						{							//new token							command.token=(*source_iterator);							command.count=1;							command.byte_position=(size_t)(source_iterator-source.begin());							//add to program							program.push_back(command);						}					}break;				}			}			//program iterator			vector::iterator program_iterator;			//loop through program			for(program_iterator=program.begin();program_iterator!=program.end();program_iterator++)			{				//check for a start of loop				if((*program_iterator).token=='[')				{					//make a note of the position					size_t start_position=program_iterator-program.begin();					//start keeping track of the nested level					size_t nested_level=0;					//use a temporary iterator					vector::iterator temp=program_iterator;					//find the end of the loop					do					{						//adjust the nested level						nested_level+=(((*temp).token=='[')-((*temp).token==']'));						//if nested level, move to next token						if(nested_level)							temp++;					}while(nested_level);					//make note of the end position					size_t end_position=temp-program.begin();					//tell start position about the end position					(*program_iterator).position=end_position;					//tell end position about the start position					(*temp).position=start_position;				}				//check for increment or decrement byte				else if((*program_iterator).token=='+' && (*program_iterator).token=='-')				{					//it's a byte, so modulo 256					(*program_iterator).count%=256;				}			}			//go to start of program			program_iterator=program.begin();			//create a string to represent the data			string data(DATA_SIZE,0);			//point to the front of the data			string::iterator data_iterator=data.begin();			//reset error position			error_position=(size_t)(-1);			string error_message="";			//interpret until the source iterator reaches the end or there is an error			while(program_iterator!=program.end() && error_message.empty())			{				//what is the current instruction?				switch((*program_iterator).token)				{				case '+'://increase byte at data pointer					{						(*data_iterator)+=(*program_iterator).count;					}break;				case '-'://decrease byte at data pointer					{						(*data_iterator)-=(*program_iterator).count;					}break;				case '>'://increase data pointer 					{						//check for overflow						if((data.end()-data_iterator)>(*program_iterator).count)						{							//no overflow							data_iterator+=(*program_iterator).count;						}						else						{							//overflow							error_message="Data iterator overflow!";							error_position=(*program_iterator).byte_position;						}					}break;				case '<'://decrease data pointer					{						//check for underflow						if((data_iterator-data.begin())>=(*program_iterator).count)						{							//no underflow							data_iterator-=(*program_iterator).count;						}						else						{							//underflow							error_message="Data iterator underflow!";							error_position=(*program_iterator).byte_position;						}					}break;				case ','://read character from console					{						for(size_t i=0;i<(*program_iterator).count;i++)							cin>>(*data_iterator);					}break;				case '.'://write character to console					{						for(size_t i=0;i<(*program_iterator).count;i++)							cout<<(*data_iterator);					}break;				case '['://begin loop					{						//if byte is zero...						if(!(*data_iterator))						{							//move to stored position of the end of the loop							program_iterator=program.begin()+(*program_iterator).position;						}					}break;				case ']'://end loop					{						//if byte is non-zero						if(*data_iterator)						{							//move to stored position of the beginning of the loop							program_iterator=program.begin()+(*program_iterator).position;						}					}break;				}				//move to next instruction				program_iterator++;			}			//check for successful run			if(error_message.empty())			{				//success				cout << "\nSuccess!" << endl;			}			else			{				//error				cout << "\nRun-time error:" << endl;				cout << "\tError Message: " << error_message << endl;				cout << "\tLocation(Approximate): " << (unsigned int)error_position << endl;			}		}	}	//this is the one line I didn't change	return 0;}