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""" A pure Python Stack implementation modelled after mxStack.
Copyright (c) 2000, Marc-Andre Lemburg; mailto:mal@lemburg.com
Copyright (c) 2000-2010, eGenix.com Software GmbH; mailto:info@egenix.com
See the documentation for further information on copyrights,
or contact the author. All Rights Reserved.
"""
class UserStack:
def __init__(self):
self.stack = ()
def push(self,x):
self.stack = (x,self.stack)
def pop(self):
x, self.stack = self.stack
return x
def not_empty(self):
return len(self.stack) != 0
def top(self):
return self.stack[0]
def __len__(self):
i = 0
s = self.stack
while len(s) != 0:
s = s[1]
i = i + 1
return i
def __repr__(self):
l = []
s = self.stack
while len(s) != 0:
l.append(repr(s[0]))
s = s[1]
return '<UserStack [%s]>' % ', '.join(l)
def __str__(self):
l = []
s = self.stack
while len(s) != 0:
l.append(s[0])
s = s[1]
return 's' + repr(l)
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