/main.cpp

/*
 * PROGRAM:
 *   Brainfuck interpreter
 *
 * AUTHOR:
 *   Théophile BASTIAN (a.k.a. Tobast)
 *
 * CONTACT & WEBSITE:
 *   http://tobast.fr/ (contact feature included)
 *   error-report@tobast.fr (error reporting only)
 *
 * SHORT DESCRIPTION:
 *   See first license line.
 *
 * LICENSE:
 *   This software is (another) classical brainfuck interpreter, with errors handling and support of both stdin and source-file argument.
 *   Copyright (C) 2011  Théophile BASTIAN
 *
 *   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/gpl.txt.
*/

#include <iostream>
#include <vector>
#include <string>
#include <stdexcept>
#include <cstdio>
#include <fstream>

#define DEFAULT_MEM_VALUE 0

using namespace std;

string inputCode(void)
{
	std::string outstr;

	cin.seekg(0, ios::end);

	if(!cin.fail()) // buffer not empty
	{
		cin.seekg(0, ios::beg);
		while(!cin.eof())
			outstr+=cin.get();
		cin.clear();
	}   
	else
	{   
		cin.seekg(0, ios::beg);
		cin.clear();
		while(1)
		{   
			std::string tmp;
			std::cin >> tmp;
			outstr+=tmp;
			if(tmp.find(-1) != std::string::npos || tmp.find('\\') != string::npos) // found a ^D or a backslash 
				break;

		}   
	}   

	return outstr;
}

int main(int argc, char** argv)
{
	string code;
	vector<unsigned char> memtab(10000, DEFAULT_MEM_VALUE);
	unsigned ptr=0, i=0;
	bool quiet=true, inputfile=false;

	if(argc>1)
	{
		ifstream file(argv[1]);
		if(file)
		{
			inputfile=true;

			while(!file.eof())
				code+=file.get();
			file.close();
		}
			
		for(int i=1;i<argc;i++)
		{
			if(string(argv[i]) == "-v")
				quiet=false;
		}
	}
	
	if(!inputfile)
		code=inputCode();

	if(!quiet)
		cout << endl << "Executing...";
	cout << endl;

	try {

		for(i=0;i<code.size();i++)
		{
			int matchcount=0, input=0; // useful only for respectively ( [ & ] ) ; ,
			switch(code[i])
			{
				case '>':
					ptr++;
					if(ptr >= memtab.size())
					{
						if(memtab.size() == memtab.max_size())
							throw out_of_range("Maximal memory array index reached.");
						else if(memtab.size()+1000 > memtab.max_size())
							memtab.resize(memtab.max_size(), DEFAULT_MEM_VALUE);
						memtab.resize(memtab.size()+1000, DEFAULT_MEM_VALUE);
					}
					break;

				case '<':
					if(ptr==0) // will go under 0 (unsigned int must be above 0, either as a vector index).
						throw out_of_range("Minimal memory array index reached.");
					ptr--;
					break;

				case '+':
					memtab[ptr]++;
					break;

				case '-':
					memtab[ptr]--;
					break;

				case '.':
					cout << memtab[ptr];
					break;

				case ',':
					input=getchar();
					if(input < 0 || input > 128)
						throw range_error("Input out of byte range.");
					memtab[ptr]=(unsigned char) input;
					break;

				case '[':
					if(!memtab[ptr]) // jump to next ]
					{
						i++;
						for(;i<code.size();i++)
						{
							if(code[i]=='[')
								matchcount++;
							else if(code[i]==']')
								matchcount--;
							if(matchcount < 0)
								break;
						}
						if(matchcount>=0)
							throw runtime_error("No matching ']' found after '[' token.");
					}
					break;

				case ']':
					if(memtab[ptr]) // jump to previous [
					{
						i--;
						for(; i!=0 ; i--)
						{
							if(code[i]=='[')
								matchcount--;
							else if(code[i]==']')
								matchcount++;
							if(matchcount < 0)
								break;
						}
						if(code[i]=='[')
							matchcount--;

						if(matchcount>=0)
							throw runtime_error("No matching '[' found before ']' token.");
					}
					break;

				default:
					break;
			}
		}

		cout << endl;
		if(!quiet)
			cout << "Done." << endl;

		return 0;
	}
	catch(const range_error &e) {
		cerr << "FATAL: " << e.what() << endl;
	}
	catch(const out_of_range &e) {
		cerr << i+1 << " = " << code[i] << " : " << e.what() << ". Memory table size: 0 -> " << memtab.max_size() << "." << endl;
	}
	catch(const exception &e) {
		cerr << i+1 << " = " << code[i] << " : " << e.what() << endl;
	}

	return 1;
}