toolkit/src2xml/source/expression.py

   1
   2 import sys
   3 import globals
   4
   5 def toString (node):
   6
   7     if node == None:
   8         return ''
   9
  10     chars = '('
  11
  12     if type(node.left) == type(0):
  13         chars += "%d"%node.left
  14     else:
  15         chars += toString(node.left)
  16
  17     chars += node.op
  18
  19     if type(node.right) == type(0):
  20         chars += "%d"%node.right
  21     else:
  22         chars += toString(node.right)
  23
  24     chars += ")"
  25
  26     return chars
  27
  28 class Node(object):
  29     def __init__ (self):
  30         self.left = None
  31         self.right = None
  32         self.parent = None
  33         self.op = None
  34
  35 class ExpParser(object):
  36
  37     def __init__ (self, tokens):
  38         self.tokens = tokens
  39
  40     def jumpToRoot (self):
  41         while self.ptr.parent != None:
  42             self.ptr = self.ptr.parent
  43
  44     def build (self):
  45         self.ptr = Node()
  46
  47         for token in self.tokens:
  48
  49             if token in '+-':
  50                 if self.ptr.left == None:
  51                     raise globals.ParseError ('')
  52                 if self.ptr.right == None:
  53                     self.ptr.op = token
  54                 else:
  55                     self.jumpToRoot()
  56                     self.ptr.parent = Node()
  57                     self.ptr.parent.left = self.ptr
  58                     self.ptr = self.ptr.parent
  59                     self.ptr.op = token
  60
  61             elif token in '*/':
  62                 if self.ptr.left == None:
  63                     raise globals.ParseError ('')
  64                 elif self.ptr.right == None:
  65                     self.ptr.op = token
  66                 else:
  67                     num = self.ptr.right
  68                     self.ptr.right = Node()
  69                     self.ptr.right.parent = self.ptr
  70                     self.ptr.right.left = num
  71                     self.ptr.right.op = token
  72                     self.ptr = self.ptr.right
  73
  74             elif token == '(':
  75                 if self.ptr.left == None:
  76                     self.ptr.left = Node()
  77                     self.ptr.left.parent = self.ptr
  78                     self.ptr = self.ptr.left
  79                 elif self.ptr.right == None:
  80                     self.ptr.right = Node()
  81                     self.ptr.right.parent = self.ptr
  82                     self.ptr = self.ptr.right
  83                 else:
  84                     raise globals.ParseError ('')
  85
  86             elif token == ')':
  87                 if self.ptr.left == None:
  88                     raise globals.ParseError ('')
  89                 elif self.ptr.right == None:
  90                     raise globals.ParseError ('')
  91                 elif self.ptr.parent == None:
  92                     pass
  93                 else:
  94                     self.ptr = self.ptr.parent
  95
  96             else:
  97                 num = int(token)
  98                 if self.ptr.left == None:
  99                     self.ptr.left = num
 100                 elif self.ptr.right == None:
 101                     self.ptr.right = num
 102                 else:
 103                     raise globals.ParseError ('')
 104
 105     def dumpTree (self):
 106         self.jumpToRoot()
 107         print toString(self.ptr)
 108
 109
 110
 111