| # ************************************************************* |
| # |
| # Licensed to the Apache Software Foundation (ASF) under one |
| # or more contributor license agreements. See the NOTICE file |
| # distributed with this work for additional information |
| # regarding copyright ownership. The ASF licenses this file |
| # to you under the Apache License, Version 2.0 (the |
| # "License"); you may not use this file except in compliance |
| # with the License. You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, |
| # software distributed under the License is distributed on an |
| # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| # KIND, either express or implied. See the License for the |
| # specific language governing permissions and limitations |
| # under the License. |
| # |
| # ************************************************************* |
| |
| |
| 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)) |