- Befunge 98 with concurrency and file io!

README.md

@@ -1,6 +1,5 @@
 # Befunge
-[Befunge](https://en.wikipedia.org/wiki/Befunge) interpreter and debugger for Befunge 93,
+[Befunge](https://en.wikipedia.org/wiki/Befunge) interpreter and debugger for Befunge 93/98: [Funges](https://github.com/catseye/Funge-98/blob/master/doc/funge98.markdown#Whatis).
-the first of the [Funges](https://web.archive.org/web/20041225010717/http://quadium.net/funge/spec98.html).
 
 ## Installation
 `pip install befunge@git+https://github.com/wimpomp/befunge.git`
@@ -9,4 +8,4 @@ the first of the [Funges](https://web.archive.org/web/20041225010717/http://quad
 `befunge --help`
 
 ## Examples
-`befunge examples/factorial0.bf -i 20 -d 0.05`
+`befunge examples/factorial0.bf 20 -d 0.05`

befunge/__init__.py

@@ -1,35 +1,19 @@
-from enum import Enum
+import os
+import sys
+import re
+import curses
 from random import randint
 from argparse import ArgumentParser
 from pathlib import Path
 from time import sleep
 from io import StringIO
-from itertools import chain
+from itertools import chain, takewhile, dropwhile
-from curses import wrapper
+from datetime import datetime
+from ._version import __version__
 
 
-class OperatorException(Exception):
+class StopExecution(Exception):
-    def __init__(self, op):
+    pass
-        super().__init__(f'Could not parse operator {op}')
-
-
-class Direction(Enum):
-    RIGHT = 0
-    UP = 1
-    LEFT = 2
-    DOWN = 3
-
-    def __add__(self, other):
-        return Direction((self.value + other) % len(Direction))
-
-    def __radd__(self, other):
-        return self + other
-
-    def __sub__(self, other):
-        return Direction((self.value - other) % len(Direction))
-
-    def __rsub__(self, other):
-        return self - other
 
 
 class Input(list):
@@ -37,49 +21,441 @@ class Input(list):
         return self.pop(0)
 
 
-class Grid(dict):
+class Stack(list):
-    def __init__(self, code=None, version=None):
+    def copy(self):
-        self.version = version or 'b93'
+        return __class__(super().copy())
-        self.cursor = True
+
-        if self.version == 'b93':
+    def pop(self, *args, **kwargs):
-            self.shape = 80, 25
+        try:
+            return super().pop()
+        except IndexError:
+            return 0
+
+    def push(self, value):
+        self.append(value)
+
+
+class StackStack(list):
+    def __repr__(self):
+        return '\n'.join(str(stack) for stack in self[::-1])
+
+    def copy(self):
+        return __class__(stack.copy() for stack in self)
+
+    def push(self, value):
+        self.append(value)
+
+
+class IP:
+    def __init__(self, funge, stackstack=None, position=(0, 0), delta=(1, 0), offset=(0, 0), version=982):
+        self.funge = funge
+        self.id = len([ip.id for ip in self.funge.ips]) if hasattr(self.funge, 'ip') else 0
+        self.stackstack = stackstack or StackStack([Stack()])
+        self.position = position
+        self.delta = delta
+        self.offset = offset
+        self.version = version
+        self.string = False
+        self.fingerprint_ops = {}
+        if self.op in (ord(' '), ord(';')):
+            self.advance()
+
+    @property
+    def stack(self):
+        if not self.stackstack:
+            self.stackstack.append(Stack())
+        return self.stackstack[-1]
+
+    @stack.setter
+    def stack(self, stack):
+        if self.stackstack:
+            self.stackstack[-1] = stack
         else:
-            self.shape = None
+            self.stackstack.append(stack)
-        self._ip = [0, 0]
+
-        self.direction = Direction.RIGHT
+    @property
+    def op(self):
+        return self.funge[self.position]
+
+    def copy(self):
+        return __class__(self.funge, self.stackstack.copy(), self.position, self.delta)
+
+    def reverse(self):
+        self.delta = -self.delta[0], -self.delta[1]
+
+    def turn_right(self):
+        self.delta = -self.delta[1], self.delta[0]
+
+    def turn_left(self):
+        self.delta = self.delta[1], -self.delta[0]
+
+    def read_string(self):
+        string = ''
+        while True:
+            f = self.stack.pop()
+            if f == 0:
+                return string
+            else:
+                string += chr(f)
+
+    def read_fingerprint(self):
+        n = self.stack.pop()
+        t = 0
+        for _ in range(n):
+            t *= 256
+            t += self.stack.pop()
+        return t
+
+    def not_implemented(self):
+        print(f'operator {self.op} at {self.position} not implemented', file=self.funge.output)
+        self.reverse()
+
+    def get_info(self, n):
+        time = datetime.now()
+        match n:
+            case 1:
+                yield 15
+            case 2:
+                yield 2**1024  # as much as the memory can hold
+            case 3:
+                yield sum([256 ** i * ord(char) for i, char in enumerate('wpfunge')])
+            case 4:
+                yield __version__.replace('.', '')
+            case 5:
+                yield 1
+            case 6:
+                yield ord(os.path.sep)
+            case 7:
+                yield 2
+            case 8:
+                yield self.id
+            case 9:
+                yield 0
+            case 10:
+                yield from self.position
+            case 11:
+                yield from self.delta
+            case 12:
+                yield from self.offset
+            case 13:
+                yield from self.funge.extent[::2]
+            case 14:
+                yield from self.funge.extent[1::2]
+            case 15:
+                yield (time.year - 1900) * 256 * 256 + time.month * 256 + time.day
+            case 16:
+                yield time.hour * 256 * 256 + time.minute * 256 + time.second
+            case 17:
+                yield len(self.stackstack)
+            case 18:
+                yield from (len(stack) for stack in self.stackstack[::-1])
+            case 19:
+                yield 0
+                yield from [ord(char) for arg in sys.argv[2:] for char in f'{arg}\x00'][::-1]
+                yield 0
+                yield from [ord(char) for char in Path(sys.argv[1]).name][::-1]
+            case 20:
+                yield 0
+                yield from [ord(char) for key, value in os.environ.items() for char in f'{key}={value}\x00'][::-1]
+            case i:
+                i -= 20
+                yield self.stack[-i] if len(self.stack) >= i else 0
+
+    def step(self, k=False):
+        if self.string:
+            match chr(self.op):
+                case '"':
+                    self.string = False
+                case s:
+                    self.stack.push(ord(s))
+        elif self.op in self.fingerprint_ops:
+            try:
+                self.fingerprint_ops[self.op]()
+            except Exception:
+                self.reverse()
+        elif 0 <= self.op < 255:
+            match chr(self.op):
+                case '+':
+                    self.stack.push(self.stack.pop() + self.stack.pop())
+                case '-':
+                    b, a = self.stack.pop(), self.stack.pop()
+                    self.stack.push(a - b)
+                case '*':
+                    self.stack.push(self.stack.pop() * self.stack.pop())
+                case '/':
+                    b, a = self.stack.pop(), self.stack.pop()
+                    self.stack.push(a // b)
+                case '%':
+                    b, a = self.stack.pop(), self.stack.pop()
+                    self.stack.push(a % b)
+                case '!':
+                    self.stack.push(int(not self.stack.pop()))
+                case '`':
+                    self.stack.push(int(self.stack.pop() < self.stack.pop()))
+                case '>':
+                    self.delta = 1, 0
+                case '<':
+                    self.delta = -1, 0
+                case '^':
+                    self.delta = 0, -1
+                case 'v':
+                    self.delta = 0, 1
+                case '?':
+                    self.delta = ((-1, 0), (1, 0), (0, -1), (0, 1))[randint(0, 3)]
+                case '_':
+                    self.delta = ((1, 0), (-1, 0))[bool(self.stack.pop())]
+                case '|':
+                    self.delta = ((0, 1), (0, -1))[bool(self.stack.pop())]
+                case '"':
+                    self.string = True
+                case ':':
+                    a = self.stack.pop()
+                    self.stack.push(a)
+                    self.stack.push(a)
+                case '\\':
+                    b, a = self.stack.pop(), self.stack.pop()
+                    self.stack.push(b)
+                    self.stack.push(a)
+                case '$':
+                    self.stack.pop()
+                case '.':
+                    print(str(self.stack.pop()) + ' ', end='', file=self.funge.output)
+                case ',':
+                    print(chr(self.stack.pop()), end='', file=self.funge.output)
+                case '#':
+                    self.move()
+                case 'p':
+                    y, x, a = self.stack.pop(), self.stack.pop(), self.stack.pop()
+                    self.funge[x + self.offset[0], y + self.offset[1]] = a
+                case 'g':
+                    y, x = self.stack.pop(), self.stack.pop()
+                    self.stack.push(self.funge[x + self.offset[0], y + self.offset[1]])
+                case '&':
+                    try:
+                        self.stack.push(int(''.join(
+                            takewhile(lambda i: i.isdigit(), dropwhile(lambda i: not i.isdigit(), self.funge.input())))))
+                    except Exception:
+                        self.delta = -self.delta[0], -self.delta[1]
+                case '~':
+                    try:
+                        self.stack.push(ord(self.funge.input()))
+                    except Exception:
+                        self.reverse()
+                case '@':
+                    return
+                case ' ':
+                    self.advance()
+                    yield self.step()
+                    return
+                # 98 from here
+                case '[':
+                    self.turn_left()
+                case ']':
+                    self.turn_right()
+                case '\'':
+                    self.move()
+                    self.stack.push(self.op)
+                case '{':
+                    n = self.stack.pop()
+                    cells = -n * [0] if n < 0 else self.stack[-n:][::-1]
+                    for coordinate in self.offset:
+                        self.stack.push(coordinate)
+                    self.stackstack.push(Stack())
+                    for cell in cells:
+                        self.stack.push(cell)
+                    self.offset = self.next_pos
+                case '}':
+                    n = self.stack.pop()
+                    cells = -n * [0] if n < 0 else [self.stack.pop() for _ in range(n)][::-1]
+                    self.stackstack.pop()
+                    y, x = self.stack.pop(), self.stack.pop()
+                    self.offset = x, y
+                    for cell in cells:
+                        self.stack.push(cell)
+                case '=':
+                    self.stack.push(os.system(self.read_string()))
+                case '(':
+                    # no fingerprints are implemented
+                    self.read_fingerprint()
+                    # self.fingerprint_ops[] = lambda i: i
+                    self.reverse()
+                case ')':
+                    self.read_fingerprint()
+                    # self.fingerprint_ops.pop()
+                case 'i':
+                    file = Path(self.read_string())
+                    flags, y0, x0 = self.stack.pop(), self.stack.pop(), self.stack.pop()
+                    try:
+                        text = file.read_text()
+                        if flags % 2:
+                            width, height = len(text), 1
+                            for x, char in enumerate(text, x0):
+                                self.funge[x, y0] = char
+                        else:
+                            text = text.splitlines()
+                            height = len(text)
+                            width = max([len(line) for line in text])
+                            self.funge.insert_code([line + ' ' * (width - len(line)) for line in text], x0, y0)
+                    except Exception:
+                        width, height = 0, 0
+                    self.stack.push(x0)
+                    self.stack.push(y0)
+                    self.stack.push(width)
+                    self.stack.push(height)
+                case 'j':
+                    for _ in range(self.stack.pop()):
+                        self.move()
+                case 'k':
+                    self.advance()
+                    ips = [self]
+                    for n in range(self.stack.pop()):
+                        ips = [i for ip in ips for i in ip.step(True)]
+                    yield from ips
+                    return
+                case 'n':
+                    self.stack = Stack()
+                case 'o':
+                    file = Path(self.read_string())
+                    flags, x0, y0, width, height = (self.stack.pop() for _ in range(5))
+                    try:
+                        if flags % 2:
+                            text = '\n'.join([''.join([chr(self.funge[x, y]) for x in range(x0, x0 + width)]).rstrip(' ')
+                                              for y in range(y0, y0 + height)]).rstrip('\n')
+                        else:
+                            text = '\n'.join([''.join([chr(self.funge[x, y]) for x in range(x0, x0 + width)])
+                                              for y in range(y0, y0 + height)])
+                        file.write_text(text)
+                    except Exception:
+                        self.reverse()
+                case 'q':
+                    raise StopExecution()
+                case 'r':
+                    self.reverse()
+                case 's':
+                    self.move()
+                    self.funge[self.position] = self.stack.pop()
+                case 't':
+                    new = self.copy()
+                    new.reverse()
+                    yield new.advance()
+                case 'u':
+                    if len(self.stackstack) > 1:
+                        n = self.stack.pop()
+                        for _ in range(abs(n)):
+                            toss = self.stackstack.pop()
+                            toss.push(self.stack.pop())
+                            self.stackstack.push(toss)
+                    else:
+                        self.reverse()
+                case 'w':
+                    b, a = self.stack.pop(), self.stack.pop()
+                    if a < b:
+                        self.turn_left()
+                    elif a > b:
+                        self.turn_right()
+                case 'x':
+                    dy, dx = self.stack.pop(), self.stack.pop()
+                    self.delta = dx, dy
+                case 'y':
+                    n = self.stack.pop()
+                    if n <= 0:
+                        for j in range(1, 21):
+                            for i in self.get_info(j):
+                                self.stack.push(i)
+                    else:
+                        for i in self.get_info(n):
+                            self.stack.push(i)
+                case 'z':
+                    pass
+                case d:
+                    if d in '1234567890':
+                        self.stack.push(int(d))
+                    elif d in 'abcdef':
+                        self.stack.push(ord(d) - 87)
+                    else:
+                        self.not_implemented()
+        else:
+            self.not_implemented()
+        if not k:
+            self.advance()
+        yield self
+
+    @property
+    def next_pos(self):
+        pos = tuple(p + d for p, d in zip(self.position, self.delta))
+        # TODO: analytic solution
+        if not all(a <= p < b for p, a, b in zip(pos, self.funge.extent[::2], self.funge.extent[1::2])):
+            while True:
+                pos = tuple(p - d for p, d in zip(pos, self.delta))
+                if not all(a <= p < b for p, a, b in zip(pos, self.funge.extent[::2], self.funge.extent[1::2])):
+                    break
+            pos = tuple(p + d for p, d in zip(pos, self.delta))
+        return pos
+
+    def move(self):
+        self.position = self.next_pos
+
+    def advance(self):
+        """ move the ip to the next valid instruction """
+        if self.string:
+            if self.op == ord(' ') and self.version // 10 > 93:
+                while self.op == ord(' '):
+                    self.move()
+            else:
+                self.move()
+        else:
+            while True:
+                if self.op != ord(';'):
+                    self.move()
+                if self.op == ord(';'):
+                    self.move()
+                    while self.op != ord(';'):
+                        self.move()
+                    self.move()
+                while self.op == ord(' '):
+                    self.move()
+                if self.op != ord(';'):
+                    break
+        return self
+
+
+class Befunge(dict):
+    def __init__(self, code=None, inputs=None):
         super().__init__()
-        for y, line in enumerate(code.splitlines()):
+        self.extent = [0, 0, 0, 0]  # xl, xr, yt, yb
-            for x, char in enumerate(line):
+        if code.startswith(r'#!/usr/bin/env befunge') or code.startswith(r'#!/usr/bin/env -S befunge'):
-                self[(x, y)] = char
+            code = '\n'.join(code.splitlines()[1:])
-
+        self.insert_code(code)
-    def wrap(self, value, dim):
+        self.output = None
-        if self.shape is None:
+        if inputs is None:
-            return value
+            self.input = input
         else:
-            return value % self.shape[dim]
+            self.input = Input(inputs)
+        self.string = False
+        self.steps = 0
+        self.terminated = False
+        self.ips = [IP(self)]
 
-    @property
+    def insert_code(self, code, x0=0, y0=0):
-    def x(self):
+        if isinstance(code, str):
-        return self._ip[0]
+            code = code.splitlines()
-
+        for y, line in enumerate(code, y0):
-    @x.setter
+            for x, char in enumerate(line, x0):
-    def x(self, value):
+                self[x, y] = char
-        self._ip[0] = self.wrap(value, 0)
-
-    @property
-    def y(self):
-        return self._ip[1]
-
-    @y.setter
-    def y(self, value):
-        self._ip[1] = self.wrap(value, 1)
 
     def __getitem__(self, key):
         return self.get(key, ord(' '))
 
     def __setitem__(self, key, value):
-        super().__setitem__(tuple(self.wrap(k, i) for i, k in enumerate(key)),
+        if key[0] < self.extent[0]:
-                            ord(value) if isinstance(value, str) else value)
+            self.extent[0] = key[0]
+        if key[0] >= self.extent[1]:
+            self.extent[1] = key[0] + 1
+        if key[1] < self.extent[2]:
+            self.extent[2] = key[2]
+        if key[1] >= self.extent[3]:
+            self.extent[3] = key[1] + 1
+        super().__setitem__(key, ord(value) if isinstance(value, str) else value)
 
     def __repr__(self):
         lines = []
@@ -89,70 +465,16 @@ class Grid(dict):
             while len(lines[y]) <= x:
                 lines[y].append(' ')
             lines[y][x] = chr(value) if 32 <= value <= 126 or 161 <= value <= 255 else chr(164)
-        lines = [''.join(line) for line in lines]
-        if self.cursor:
-            return '\n'.join(lines[:self.y] +
-                             [lines[self.y][:self.x] +
-                              '\x1b[37m\x1b[40m' + lines[self.y][self.x] + '\033[0m' +
-                              lines[self.y][self.x + 1:]] +
-                             lines[self.y + 1:])
-        else:
-            return '\n'.join(lines)
 
-    @property
+        for ip in self.ips:
-    def op(self):
+            lines[ip.position[1]][ip.position[0]] = f'\x1b[37m\x1b[40m{lines[ip.position[1]][ip.position[0]]}\033[0m'
-        return self[self.x, self.y]
+        return 'grid:\n' + '\n'.join([''.join(line) for line in lines]) + '\n\n' + \
-
+               'stacks:\n' + '\n-\n'.join(str(ip.stackstack) for ip in self.ips)
-    def advance(self):
-        match self.direction:
-            case Direction.RIGHT:
-                self.x += 1
-            case Direction.UP:
-                self.y -= 1
-            case Direction.LEFT:
-                self.x -= 1
-            case Direction.DOWN:
-                self.y += 1
-
-
-class Stack(list):
-    def pop(self, index=-1):
-        try:
-            return super().pop(index)
-        except IndexError:
-            return 0
-
-    def push(self, value):
-        self.append(value)
-
-
-class Befunge(Grid):
-    def __init__(self, code=None, version=None, inputs=None):
-        super().__init__(code, version)
-        self.output = None
-        if inputs is None:
-            self.input = input
-        else:
-            self.input = Input(inputs)
-        self.stack = Stack()
-        self.string = False
-        self.steps = 0
-        self.terminated = False
-        self.operations = {'b93': '+-*/%!`><^v?_|":\\$.,#pg&~@ 1234567890'}[self.version]
 
     @staticmethod
-    def from_file(file, version=None, inputs=None):
+    def from_file(file, inputs=None):
         file = Path(file)
-        if version is None:
+        return Befunge(file.read_text(), inputs)
-            match file.suffix:
-                case '.bf':
-                    version = 'b93'
-                case suffix:
-                    version = suffix.strip('.')
-        return Befunge(file.read_text(), version, inputs)
-
-    def __repr__(self):
-        return f'grid:\n{super().__repr__()}\n\nstack:\n{self.stack}'
 
     def __iter__(self):
         return self
@@ -166,146 +488,84 @@ class Befunge(Grid):
         for _ in self:
             pass
 
-    def debug(self, time_step):
+    def debug(self, time_step=None):
         def fun(stdscr):
             def scr_input():
                 height, width = stdscr.getmaxyx()
                 stdscr.move(height - 1, 0)
                 stdscr.clrtoeol()
-                stdscr.addstr(height - 1, 0, 'input?')
+                stdscr.addstr(height - 1, 0, 'input?'[:width])
-                stdscr.move(self.y + 1, self.x)
                 stdscr.refresh()
                 return stdscr.getstr()
 
+            curses.curs_set(False)
+            curses.init_pair(1, curses.COLOR_BLACK, curses.COLOR_WHITE)
+            pattern = re.compile(r'\x1b\[[\d;]+m')
             self.output = StringIO()
-            self.cursor = False
             if not isinstance(self.input, Input):
                 self.input = scr_input
             stdscr.clear()
             stdscr.refresh()
 
-            for b in chain((self,), self):
+            for b in chain((self,), self, (self,)):
                 height, width = stdscr.getmaxyx()
                 stdscr.clear()
-                stdscr.addstr(f'{b}\n\noutput:\n{b.output.getvalue()}\n\nstep:\n{b.steps}')
+                b_str = re.sub(pattern, '', str(b))
-                if time_step > 0:
+                for y, line in enumerate(f'{b_str}\n\noutput:\n{b.output.getvalue()}\n\nstep:\n{b.steps}'.splitlines()):
-                    stdscr.move(b.y + 1, b.x)
+                    if y >= height:
+                        break
+                    stdscr.addstr(y, 0, line[:width])
+
+                for ip in b.ips:
+                    x, y = ip.position
+                    if x < width and y < height:
+                        stdscr.addstr(y + 1, x, b_str.splitlines()[y + 1][x], curses.color_pair(1))
+                if b.terminated:
+                    stdscr.addstr(height - 1, 0, 'Press any key to quit.'[:width])
+                    stdscr.refresh()
+                    stdscr.getch()
+                elif time_step is None:
+                    stdscr.addstr(height - 1, 0, 'Press any key to continue.'[:width])
+                    stdscr.refresh()
+                    stdscr.getch()
+                else:
                     stdscr.refresh()
                     sleep(time_step)
-                else:
-                    stdscr.addstr(height - 1, 0, 'Press any key to continue.')
-                    stdscr.move(b.y + 1, b.x)
-                    stdscr.refresh()
-                    stdscr.getch()
-
-            height, width = stdscr.getmaxyx()
-            stdscr.move(height - 1, 0)
-            stdscr.clrtoeol()
-            stdscr.addstr(height - 1, 0, 'Press any key to quit.')
-            stdscr.move(self.y + 1, self.x)
-            stdscr.getch()
 
         try:
-            wrapper(fun)
+            curses.wrapper(fun)
         except KeyboardInterrupt:
             pass
 
     def step(self, n=1):
-        m = 0
+        for i in range(n):
-        while m < n:
-            if self.string:
-                if self.op == ord('"'):
-                    self.string = False
-                else:
-                    self.stack.push(self.op)
-            elif chr(self.op) in self.operations:
-                match chr(self.op):
-                    case '+':
-                        self.stack.push(self.stack.pop() + self.stack.pop())
-                    case '-':
-                        self.stack.push(self.stack.pop(-2) - self.stack.pop())
-                    case '*':
-                        self.stack.push(self.stack.pop() * self.stack.pop())
-                    case '/':
-                        self.stack.push(self.stack.pop(-2) // self.stack.pop())
-                    case '%':
-                        self.stack.push(self.stack.pop(-2) % self.stack.pop())
-                    case '!':
-                        self.stack.push(int(not self.stack.pop()))
-                    case '`':
-                        self.stack.push(int(self.stack.pop() < self.stack.pop()))
-                    case '>':
-                        self.direction = Direction.RIGHT
-                    case '<':
-                        self.direction = Direction.LEFT
-                    case '^':
-                        self.direction = Direction.UP
-                    case 'v':
-                        self.direction = Direction.DOWN
-                    case '?':
-                        self.direction = Direction(randint(0, 3))
-                    case '_':
-                        self.direction = Direction(2 * bool(self.stack.pop()))
-                    case '|':
-                        self.direction = Direction(3 - 2 * bool(self.stack.pop()))
-                    case '[':
-                        self.direction += 1
-                    case ']':
-                        self.direction -= 1
-                    case '"':
-                        self.string = True
-                    case ':':
-                        if len(self.stack):
-                            self.stack.push(self.stack[-1])
-                    case '\\':
-                        if len(self.stack) > 1:
-                            self.stack.push(self.stack.pop(-2))
-                    case '$':
-                        self.stack.pop()
-                    case '.':
-                        print(str(self.stack.pop()) + ' ', end='', file=self.output)
-                    case ',':
-                        print(chr(self.stack.pop()), end='', file=self.output)
-                    case '#':
-                        self.advance()
-                    case 'p':
-                        self[self.stack.pop(-2), self.stack.pop()] = self.stack.pop(-3)
-                    case 'g':
-                        self.stack.push(self[self.stack.pop(-2), self.stack.pop()])
-                    case '&':
-                        self.stack.push(int(self.input()))
-                    case '~':
-                        self.stack.push(ord(self.input()))
-                    case '@':
-                        self.terminated = True
-                    case ' ':
-                        pass
-                    case op:
-                        self.stack.append(int(op))
-            else:
-                raise OperatorException(self.op)
-            self.advance()
-            if not (not self.string and self.op == ord(' ')):
-                m += 1
             self.steps += 1
+            try:
+                self.ips = [i for ip in self.ips for i in ip.step()]
+            except StopExecution:
+                self.ips = []
+            if not self.ips:
+                self.terminated = True
+                return self
         return self
 
 
 def main():
-    parser = ArgumentParser(description='Display info and save as tif')
+    parser = ArgumentParser(description='Funge interpreter and debugger')
-    group = parser.add_mutually_exclusive_group()
+    parser.add_argument('input', help='funge code file or string')
-    group.add_argument('file', help='funge code file', nargs='?')
+    parser.add_argument('args', help='arguments to the funge (& or ~)', nargs='*')
-    group.add_argument('-s', '--string', help='funge code string', default=None)
+    parser.add_argument('-v', '--version', help='show interpreter\'s version number and exit',
-    parser.add_argument('-v', '--version', help='funge version: b93, b98', type=str, default=None)
+                        action='version', version=__version__)
-    parser.add_argument('-d', '--debug', help='debug, steps / second, 0: continue on key press', type=float, default=-1)
+    parser.add_argument('-d', '--debug', help='debug, step on key press or steps / second',
-    parser.add_argument('-i', '--inputs', help='inputs for when befunge asks for it', nargs='*')
+                        type=float, default=False, nargs='?')
     args = parser.parse_args()
-    if args.file:
-        befunge = Befunge.from_file(args.file, args.version, args.inputs)
-    else:
-        befunge = Befunge(args.string, args.version, args.inputs)
 
-    if args.debug < 0:
+    if Path(args.input).exists():
+        befunge = Befunge.from_file(args.input, args.args or None)
+    else:
+        befunge = Befunge(args.input, args.args or None)
+
+    if args.debug is False:
         befunge.run()
     else:
         befunge.debug(args.debug)

examples/99.bf

@@ -0,0 +1,12 @@
+#!/usr/bin/env befunge
+992+*: v:                                                                      <
+v" ".:<_091+".reeb fo selttob erom on ,llaw eht no reeb fo selttob erom oN">:v
+,v"Go to the store and buy some more, 99 bottles of beer on the wall."+910<^,_v
+ >:#,_@>:101-*+v                  >$0" ,llaw eht no reeb fo ">:#,_$:.1v   ^  $<
+>0\ >> ^      v_0"elttob">:#,_$\:!|   >091+".reeb fo ">:#,_$  v
+              >0"selttob"^        >1-!|                               >" ",\v
+>$2\ ^\2<," ".<                       >091+:".llaw eht no reeb fo "v
+^_v  >  ^     |:<    v!:<"Take one down and pass it around, "0< v!:<
+ !,v ^          ^:-1$_, ^                                     v$_>,^
+>^  ^                                                                       <
+^:<"no more "0<                                               >                ^

examples/cat_v.bf

@@ -0,0 +1,4 @@
+#!/usr/bin/env befunge
+ w4110'vin10
+"<v"
+ >>#,:#<_@

examples/concurrent.bf

@@ -0,0 +1,3 @@
+#!/usr/bin/env befunge
+    v
+@000_1t111@

examples/dna.bf

@@ -0,0 +1,9 @@
+#!/usr/bin/env befunge
+7^DN>vA
+v_#v? v
+7^<""""
+3  ACGT
+90!""""
+4*:>>>v
++8^-1,<
+> ,+,@)

examples/factorial0.bf

@@ -1,5 +1,5 @@
+#!/usr/bin/env befunge
 v
-0
 &
 >>:1v
  |:-<

examples/factorial_eso.bf

@@ -0,0 +1,3 @@
+#!/usr/bin/env befunge
+&>:1-:v v *_$.@
+ ^    _$>\:^

examples/factorial_heap.bf

@@ -1,2 +1,3 @@
+#!/usr/bin/env befunge
 &:>00p1-::v
   ^ *g00  _g.25*,@

examples/fibonacci.bf

@@ -0,0 +1,2 @@
+#!/usr/bin/env befunge
+j1\:b0p+:.' 1

examples/guess.bf

@@ -0,0 +1,25 @@
+#!/usr/bin/env befunge
+vv  <      <
+    2
+    ^  v<
+ v1<?>3v4
+    ^   ^
+>  >?>  ?>5^
+    v   v
+ v9<?>7v6
+    v  v<
+    8
+    >  >   ^
+ vv  <      <
+     2
+     ^  v<
+  v1<?>3v4
+     ^   ^
+ >  >?>  ?>5^
+     v   v      v          ,*25         <<
+  v9<?>7v6                              ,,
+     v  v<                              ""
+     8                                  ><
+     >  >   ^                           ""v
+  >*: >0"!rebmun tupnI">:#,_$25*,:&:99p`|^<       _0"!niw uoY">:#,_$25*,@
+      ^         <                       >:99g01-*+^

examples/guess2.bf

@@ -0,0 +1,16 @@
+#!/usr/bin/env befunge
+v>>> > v>>> > v
+ 012 3  012 3
+ ^?^    ^?^
+>>?#v?4>>?#v?4v
+ v?v    v?v
+ 98765  98765
+ >>>>> ^>>>>> v
+v 0 + * + : 5 <
+>"!sseuG">:#,_v
+0v_v#:-&:,+:5$<
+, v>0"!niw uoY"
++0>:#,_$5:+,@
+:>`0\"!"\v
+ v"small"_"gib"
+^>" ooT">:#,_$5

examples/hello_b98.bf

@@ -0,0 +1,2 @@
+#!/usr/bin/env befunge
+<>:#,_# @#"Hello, World!"

examples/mill.bf

@@ -0,0 +1,9 @@
+#!/usr/bin/env befunge
+ ]   v
+    >v
+v?t1?
+ 1  t
+ t  1
+ ?1t?v
+v<   <
+>29*y.@

examples/pi.bf

@@ -0,0 +1,4 @@
+#!/usr/bin/env befunge
+"^a&EPm=kY}t/qYC+i9wHye$m N@~x+"v
+"|DsY<"-"z6n<[Yo2x|UP5VD:">:#v_@>
+-:19+/"0"+,19+%"0"+,      ^  >39*

examples/quine1.bf

@@ -0,0 +1,2 @@
+#!/usr/bin/env befunge
+01->1# +# :# 0# g# ,# :# 5# 8# *# 4# +# -# _@

examples/random_n.bf

@@ -0,0 +1,6 @@
+#!/usr/bin/env befunge
+& :v>00g2/.@
+v00_^#!`/2g00:<
+>0p:1>>:10p` !|
+>+00p^?<*2g01:<
+^ g00:<

examples/sieve.bf

@@ -0,0 +1,5 @@
+#!/usr/bin/env befunge
+2>:3g" "-!v\  g30          <
+ |!`"O":+1_:.:03p>03g+:"O"`|
+ @               ^  p3\" ":<
+2 234567890123456789012345678901234567890123456789012345678901234567890123456789

examples/soup.bf

@@ -0,0 +1,23 @@
+#!/usr/bin/env befunge
+      060p070                                                           p'O80v
+    pb2*90p4$4>                                                         $4$>v>
+  v4$>4$>4$>4$>#                                                        ARGH>!
+ <{[BEFUNGE_97]}>                                                       FUNGE!
+ ##:-:##   #####*         4$*>4$      >060p>    60g80g -!#v_  60g1+     60p60v
+ #vOOGAH               **>4$>^!!eg    nufeB^    $4$4$4 $4<v#<<v-*2a::   v7-1g<
+ #>70g>90g-!          #@_^Befunge!!   123456    123456 VvVv!#!>Weird!   >0ggv*
+  ^$4$4p07+1g07      ,a<$4<   <$4$4<  <$4$4<    <$4$4< <<#<*-=-=-=-=-*  -=-=v*
+   ::48*-#v_>,4$>    4$4$4     $4$4$  4$4$4$    4$4$4$ 4$^*!*   XXXXXX   XXX>
+     BOINK>$60g1-7  0g+d2*     %'A+,1 $1$1$1    $1$1$1 $>^<$     HAR!!!  8888
+        Befunge_is  such_a     pretty langua    ge,_is n't_i     t?_It_  8888
+           looks_so much_l     ike_li ne_noi    se_and it's_     STILL_  ‘88’
+Turing-     Complet e!_Cam     ouflag e_your    code!! Confu     se_the
+hell_out   of_every one_re     ading_ your_co  de._Oh, AND_y     ou.:-) ,o88o.
+ Once_this_thing_i   s_code   d,_rea  ding_it_back_ver ges_on   the_imp 888888
+  ossible._Obfusc     ate_the_obfus    cated!_Befunge_ debuggers_are__  888888
+   your_friends!       By:_Alexios     Chouchou las... X-X-X-X-X-X-X!   888888
+      -=*##*=-           \*****/         9797*  -=97=- !@-*=  *****     ‘"88P’
+                                                       *!@-*
+                                                       =*!@-
+                                                       -=*!@
+                                                       @-=*!

examples/test.bf

@@ -0,0 +1,2 @@
+#!/usr/bin/env befunge
+45*1-y>>#,:#<_$:w@

examples/v

@@ -0,0 +1 @@
+Hello world!