95 lines
2.7 KiB
Python
95 lines
2.7 KiB
Python
#!/usr/bin/env python
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# encoding: utf-8
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def str2tokens(self, exp):
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""" Parse the expression, ie tranform a string into a list of tokens
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/!\ float are not availiable yet!
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:param exp: The expression (a string)
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:returns: list of token
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"""
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tokens = ['']
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for character in exp:
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if character.isdigit():
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# for "big" numbers (like 2345)
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if type(tokens[-1]) == int:
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if tokens[-1] > 0:
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tokens[-1] = tokens[-1]*10 + int(character)
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else:
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tokens[-1] = tokens[-1]*10 - int(character)
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# Special case for "-" at the begining of an expression or before "("
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elif tokens[-1] == "-" and \
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str(tokens[-2]) in " (+-*/:":
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tokens[-1] = - int(character)
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else:
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tokens.append(int(character))
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elif character in "+-*/):^":
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tokens.append(character)
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elif character in "(":
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# If "3(", ")("
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if self.isNumber(tokens[-1]) \
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or tokens[-1] == ")" :
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tokens.append("*")
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tokens.append(character)
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elif character == ".":
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raise ValueError("No float number please")
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elif character != " ":
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raise ValueError("{} is an unvalid character".format(character))
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return tokens[1:]
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def in2post_fix(cls, infix_tokens):
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""" From the infix_tokens list compute the corresponding postfix_tokens list
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@param infix_tokens: the infix list of tokens to transform into postfix form.
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@return: the corresponding postfix list of tokens.
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>>> .in2post_fix(['(', 2, '+', 5, '-', 1, ')', '/', '(', 3, '*', 4, ')'])
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[2, 5, '+', 1, '-', 3, 4, '*', '/']
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"""
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opStack = Stack()
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postfixList = []
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for token in infix_tokens:
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if token == "(":
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opStack.push(token)
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elif token == ")":
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topToken = opStack.pop()
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while topToken != "(":
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postfixList.append(topToken)
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topToken = opStack.pop()
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elif cls.isOperator(token):
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# On doit ajouter la condition == str sinon python ne veut pas tester l'appartenance à la chaine de caractère.
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while (not opStack.isEmpty()) and (cls.PRIORITY[opStack.peek()] >= cls.PRIORITY[token]):
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postfixList.append(opStack.pop())
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opStack.push(token)
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else:
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postfixList.append(token)
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while not opStack.isEmpty():
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postfixList.append(opStack.pop())
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return postfixList
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# -----------------------------
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# Reglages pour 'vim'
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# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
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# cursor: 16 del
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