Brainfuck interpreter with lexer and parser slr(1)
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2 changed files with 327 additions and 0 deletions
308
brainfuck.py
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308
brainfuck.py
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#!/usr/bin/env python
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from sys import stdout,stdin,argv
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class State:
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def __init__(self):
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self.data = [0]
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self.ptr = 0
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def prev(self):
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if self.ptr == 0:
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self.data.insert(0,0)
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else:
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self.ptr-=1
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def next(self):
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if self.ptr == len(self.data)-1:
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self.data.append(0)
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self.ptr+=1
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def get(self):
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return self.data[self.ptr]
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def set(self,val):
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self.data[self.ptr] = val
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class Instruction:
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def run(self,state):
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raise NotImplementedError
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def __repr__(self):
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return self.__class__.__name__
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class NextInstruction(Instruction):
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def run(self,state):
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state.next()
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class PrevInstruction(Instruction):
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def run(self,state):
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state.prev()
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class IncInstruction(Instruction):
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def run(self,state):
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state.set(state.get() + 1)
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class DecInstruction(Instruction):
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def run(self,state):
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state.set(state.get() - 1)
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class PutInstruction(Instruction):
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def run(self,state):
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stdout.write(chr(state.get()))
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stdout.flush()
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class GetInstruction(Instruction):
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def run(self,state):
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state.set(ord(stdin.read(1)))
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class BlockInstruction(Instruction):
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def __init__(self):
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self.instructions = []
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def prepend(self, inst):
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self.instructions.insert(0, inst)
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def run(self,state):
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for inst in self.instructions:
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inst.run(state)
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def __repr__(self):
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return ", ".join(map(repr,self.instructions))
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class LoopInstruction(Instruction):
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def __init__(self,block):
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self.block = block
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def run(self,state):
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while state.get() != 0:
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self.block.run(state)
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def __repr__(self):
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return "[ %s ]" % (repr(self.block))
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Inext = NextInstruction()
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Iprev = PrevInstruction()
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Iinc = IncInstruction()
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Idec = DecInstruction()
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Iput = PutInstruction()
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Iget = GetInstruction()
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class Token:
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NEXT = "T_NEXT"
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PREV = "T_PREV"
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INC = "T_INC"
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DEC = "T_DEC"
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PUT = "T_PUT"
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GET = "T_GET"
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LOOP_START = "T_LOOP_START"
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LOOP_END = "T_LOOP_END"
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EOF = "T_EOF"
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def lex(it):
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if type(it) == str:
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it = iter(it)
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END = object()
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c = next(it,END)
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while c != END:
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if c == ">":
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yield Token.NEXT
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elif c == "<":
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yield Token.PREV
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elif c == "+":
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yield Token.INC
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elif c == "-":
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yield Token.DEC
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elif c == ".":
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yield Token.PUT
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elif c == ",":
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yield Token.GET
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elif c == "[":
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yield Token.LOOP_START
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elif c == "]":
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yield Token.LOOP_END
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c = next(it,END)
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yield Token.EOF
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class DefaultDict:
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def __init__(self,value):
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self.value = value
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def __contains__(self,key):
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return True
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def __getitem__(self,key):
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return self.value
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def parse(it):
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NTS_S = object()
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NTS_B = object()
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r = object()
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s = object()
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a = object()
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table = [
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{
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Token.NEXT: (s,5),
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Token.PREV: (s,6),
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Token.INC: (s,7),
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Token.DEC: (s,8),
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Token.PUT: (s,9),
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Token.GET: (s,10),
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Token.LOOP_START: (s,2)
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},
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{
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Token.NEXT: (s,5),
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Token.PREV: (s,6),
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Token.INC: (s,7),
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Token.DEC: (s,8),
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Token.PUT: (s,9),
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Token.GET: (s,10),
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Token.LOOP_START: (s,2),
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Token.LOOP_END: (r,3),
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Token.EOF: (r,3)
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},
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{
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Token.NEXT: (s,5),
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Token.PREV: (s,6),
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Token.INC: (s,7),
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Token.DEC: (s,8),
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Token.PUT: (s,9),
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Token.GET: (s,10),
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Token.LOOP_START: (s,2)
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},
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{
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Token.LOOP_END: (s,4)
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},
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DefaultDict( (r,10) ),
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DefaultDict( (r,4) ),
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DefaultDict( (r,5) ),
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DefaultDict( (r,6) ),
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DefaultDict( (r,7) ),
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DefaultDict( (r,8) ),
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DefaultDict( (r,9) ),
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DefaultDict( (r,2) ),
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DefaultDict( (a,0) )
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]
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goto = [
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{ NTS_S: 12, NTS_B: 1 },
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{ NTS_S: 11, NTS_B: 1 },
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{ NTS_S: 3, NTS_B: 1 },
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{},
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{},
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{},
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{},
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{},
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{},
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{},
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{},
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{},
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{},
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]
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state = [0]
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data = []
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c = next(it)
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while True:
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op, dat = table[state[-1]][c]
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if op == s:
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data.append(c)
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c = next(it)
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state.append(dat)
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elif op == a:
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return data[0]
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elif op == r:
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if dat == 2:
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S = data.pop()
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B = data.pop()
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state.pop()
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state.pop()
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S.prepend(B)
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data.append(S)
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state.append( goto[state[-1]][NTS_S] )
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elif dat == 3:
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B = data.pop()
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state.pop()
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S = BlockInstruction()
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S.prepend(B)
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data.append(S)
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state.append( goto[state[-1]][NTS_S] )
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elif dat == 4:
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data.pop()
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state.pop()
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data.append( Inext )
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state.append( goto[state[-1]][NTS_B] )
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elif dat == 5:
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data.pop()
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state.pop()
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data.append( Iprev )
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state.append( goto[state[-1]][NTS_B] )
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elif dat == 6:
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data.pop()
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state.pop()
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data.append( Iinc )
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state.append( goto[state[-1]][NTS_B] )
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elif dat == 7:
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data.pop()
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state.pop()
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data.append( Idec )
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state.append( goto[state[-1]][NTS_B] )
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elif dat == 8:
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data.pop()
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state.pop()
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data.append( Iput )
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state.append( goto[state[-1]][NTS_B] )
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elif dat == 9:
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data.pop()
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state.pop()
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data.append( Iget )
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state.append( goto[state[-1]][NTS_B] )
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elif dat == 10:
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data.pop()
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S = data.pop()
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data.pop()
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state.pop()
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state.pop()
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state.pop()
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B = LoopInstruction(S)
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data.append(B)
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state.append( goto[state[-1]][NTS_B] )
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if __name__ == '__main__':
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if len(argv) > 1:
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fd = open(argv[1],"r")
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contents = fd.read()
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fd.close()
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else:
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contents = ",[.,]"
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ast = parse(lex(contents))
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state = State()
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ast.run(state)
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19
helloworld.bf
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19
helloworld.bf
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@ -0,0 +1,19 @@
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++++++++++
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[
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>+++++++>++++++++++>+++>+<<<<-
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] Schleife zur Vorbereitung der Textausgabe
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>++. Ausgabe von 'H'
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>+. Ausgabe von 'e'
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+++++++. 'l'
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. 'l'
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+++. 'o'
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>++. Leerzeichen
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<<+++++++++++++++. 'W'
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>. 'o'
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+++. 'r'
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------. 'l'
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--------. 'd'
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>+. '!'
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>. Zeilenvorschub
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+++. Wagenrücklauf
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