from collections import deque

class FileContext(object):
	def __init__(self, file_):
		self._file = file_
		self._line = 0
		self._column = 0
		self._column_stack = deque()

	def getc(self):
		c = self._file.read(1)
		if(c == "\n"):
			self._line += 1
			self._column_stack.append(self._column)
			self._column = 0
		else:
			self._column += 1

		return c

	def ungetc(self, c):
		self._file.seek(self._file.tell() - 1, 0)
		if(c == "\n"):
			self._line -= 1
			self._column = self._column_stack.pop()
		else:
			self._column -= 1