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