parser.py

#! /usr/env/bin python
# -*- coding;utf-8 -*-

import sys

class Parser():
	def __init__(self):
		self.s = ""
		self.ptr = 0
		self.mem = [ 0 for x in range(0, 100) ]
		self.blist = {} 

	def __del__(self):
		del self;
	
	def start(self, str):
		self.s = str
		self.bsearch()
		self.process()
#		print(self.blist)
	
	def process(self, index = 0):
		while(index < len(self.s)):
			if self.s[index] == '+':
				self.mem[self.ptr] += 1 
				if self.mem[self.ptr] > 255:
					self.mem[self.ptr] = 0 
				index += 1
			elif self.s[index] == '-':
				self.mem[self.ptr] -= 1 
				if self.mem[self.ptr] < 0:
					self.mem[self.ptr] = 255
				index += 1
			elif self.s[index] == '>':
				self.ptr += 1 if self.ptr + 1 < len(self.mem) else 0
				index += 1
			elif self.s[index] == '<':
				self.ptr -= 1 if self.ptr > 0 else 0
				index += 1
			elif self.s[index] == '[':
				if self.mem[self.ptr] == 0:
					index = self.blist[index] + 1
				else:
					index += 1
			elif self.s[index] == ']':
				index = self.blist[index]
			elif self.s[index] == '.':
				sys.stdout.write(chr(self.mem[self.ptr]))
				index += 1
			elif self.s[index] == ',':
				try:
					ch = sys.stdin.read(1)
					self.mem[self.ptr] = ord(ch)
					index += 1
				except:
					print("Illegal Input")
					break
			else:
				index += 1
#			print(index)
#			if index < len(self.s):
#				self.debug(index)
		else:
			print()

	def bsearch(self):
		"""
		文中のカッコの位置を特定

		return : bracke position list[(first, second), ...]
		"""
		lb = []
		for index, c in enumerate(self.s):
			if c == '[':
				lb.append(index)
			elif c == ']':
				self.blist[lb[-1]] = index
				self.blist[index] = lb[-1]
				lb.pop(-1)
	
	def debug(self, index):
		print("Case :" + str(index))
		print(self.s[index])
		print(self.mem)
		print(self.blist)