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import sys
import globals
def toString (node):
if node == None:
return ''
chars = '('
if type(node.left) == type(0):
chars += "%d"%node.left
else:
chars += toString(node.left)
chars += node.op
if type(node.right) == type(0):
chars += "%d"%node.right
else:
chars += toString(node.right)
chars += ")"
return chars
class Node(object):
def __init__ (self):
self.left = None
self.right = None
self.parent = None
self.op = None
class ExpParser(object):
def __init__ (self, tokens):
self.tokens = tokens
def jumpToRoot (self):
while self.ptr.parent != None:
self.ptr = self.ptr.parent
def build (self):
self.ptr = Node()
for token in self.tokens:
if token in '+-':
if self.ptr.left == None:
raise globals.ParseError ('')
if self.ptr.right == None:
self.ptr.op = token
else:
self.jumpToRoot()
self.ptr.parent = Node()
self.ptr.parent.left = self.ptr
self.ptr = self.ptr.parent
self.ptr.op = token
elif token in '*/':
if self.ptr.left == None:
raise globals.ParseError ('')
elif self.ptr.right == None:
self.ptr.op = token
else:
num = self.ptr.right
self.ptr.right = Node()
self.ptr.right.parent = self.ptr
self.ptr.right.left = num
self.ptr.right.op = token
self.ptr = self.ptr.right
elif token == '(':
if self.ptr.left == None:
self.ptr.left = Node()
self.ptr.left.parent = self.ptr
self.ptr = self.ptr.left
elif self.ptr.right == None:
self.ptr.right = Node()
self.ptr.right.parent = self.ptr
self.ptr = self.ptr.right
else:
raise globals.ParseError ('')
elif token == ')':
if self.ptr.left == None:
raise globals.ParseError ('')
elif self.ptr.right == None:
raise globals.ParseError ('')
elif self.ptr.parent == None:
pass
else:
self.ptr = self.ptr.parent
else:
num = int(token)
if self.ptr.left == None:
self.ptr.left = num
elif self.ptr.right == None:
self.ptr.right = num
else:
raise globals.ParseError ('')
def dumpTree (self):
self.jumpToRoot()
print toString(self.ptr)
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