217 lines
5.8 KiB
Python
217 lines
5.8 KiB
Python
#!/usr/bin/env python
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# encoding: utf-8
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from .generic import Stack, flatten_list, expand_list, isNumber, isOperator
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from .render import txt, tex
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from .str2tokens import str2tokens
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__all__ = ['Expression']
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class Expression(object):
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"""A calculus expression. Today it can andle only expression with numbers later it will be able to manipulate unknown"""
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STR_RENDER = tex
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def __init__(self, exp):
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""" Initiate the expression
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:param exp: the expression. It can be a string or a list of postfix tokens.
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"""
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if type(exp) == str:
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#self._exp = exp
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self.postfix_tokens = str2tokens(exp) # les tokens seront alors stockés dans self.tokens temporairement
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elif type(exp) == list:
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self.postfix_tokens = flatten_list([tok.postfix_tokens if self.isExpression(tok) else tok for tok in exp])
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self._isExpression = 1
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def __str__(self):
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"""
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Overload str
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If you want to changer render set Expression.RENDER
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"""
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return self.STR_RENDER(self.postfix_tokens)
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def render(self, render = lambda x:str(x)):
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""" Same as __str__ but accept render as argument
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:param render: function which render the list of token (postfix form) to string
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"""
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# TODO: I don't like the name of this method |ven. janv. 17 12:48:14 CET 2014
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return render(self.postfix_tokens)
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## ---------------------
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## Mechanism functions
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def simplify(self, render=STR_RENDER):
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""" Generator which return steps for computing the expression """
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if not self.can_go_further():
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yield render(self.postfix_tokens)
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else:
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self.compute_exp()
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old_s = ''
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for s in self.steps:
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new_s = render(s)
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# Astuce pour éviter d'avoir deux fois la même étape (par exemple pour la transfo d'une division en fraction)
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if new_s != old_s:
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old_s = new_s
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yield new_s
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for s in self.child.simplify():
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if old_s != s:
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yield s
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def can_go_further(self):
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"""Check whether it's a last step or not. If not create self.child the next expression.
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:returns: 1 if it's not the last step, 0 otherwise
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"""
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if len(self.postfix_tokens) == 1:
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return 0
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else:
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return 1
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def compute_exp(self):
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""" Create self.child with self.steps to go up to it """
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self.steps = [self.postfix_tokens]
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tokenList = self.postfix_tokens.copy()
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tmpTokenList = []
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while len(tokenList) > 2:
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# on va chercher les motifs du genre A B +, quand l'operateur est d'arité 2, pour les calculer
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if isNumber(tokenList[0]) and isNumber(tokenList[1]) \
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and isOperator(tokenList[2]) and tokenList[2].arity == 2 :
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# S'il y a une opération à faire
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op1 = tokenList[0]
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op2 = tokenList[1]
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operator = tokenList[2]
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res = operator(op1, op2)
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tmpTokenList.append(res)
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# Comme on vient de faire le calcul, on peut détruire aussi les deux prochains termes
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del tokenList[0:3]
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# Et les motifs du gens A -, quand l'operateur est d'arité 1
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elif isNumber(tokenList[0]) \
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and isOperator(tokenList[1]) and tokenList[1].arity == 1:
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# S'il y a une opération à faire
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op1 = tokenList[0]
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operator = tokenList[1]
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res = operator(op1)
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tmpTokenList.append(res)
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# Comme on vient de faire le calcul, on peut détruire aussi les deux prochains termes
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del tokenList[0:2]
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else:
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tmpTokenList.append(tokenList[0])
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del tokenList[0]
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tmpTokenList += tokenList
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steps = expand_list(tmpTokenList)
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if len(steps[:-1]) > 0:
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self.steps += [flatten_list(s) for s in steps[:-1]]
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self.child = Expression(steps[-1])
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def isExpression(self, other):
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try:
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other._isExpression
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except AttributeError:
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return 0
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return 1
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def test(exp):
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a = Expression(exp)
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print(a)
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for i in a.simplify():
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print(i)
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print("\n")
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if __name__ == '__main__':
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Expression.STR_RENDER = txt
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exp1 = "2 ^ 3 * 5"
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test(exp1)
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from pymath.operator import op
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exp = [2, 3, op.pw, 5, op.mul]
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test(exp)
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test([Expression(exp1), Expression(exp), op.add])
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exp = "1 + 3 * 5"
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test(exp)
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#exp = "2 * 3 * 3 * 5"
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#test(exp)
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#exp = "2 * 3 + 3 * 5"
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#test(exp)
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#exp = "2 * ( 3 + 4 ) + 3 * 5"
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#test(exp)
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#exp = "2 * ( 3 + 4 ) + ( 3 - 4 ) * 5"
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#test(exp)
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#
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#exp = "2 * ( 2 - ( 3 + 4 ) ) + ( 3 - 4 ) * 5"
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#test(exp)
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#
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#exp = "2 * ( 2 - ( 3 + 4 ) ) + 5 * ( 3 - 4 )"
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#test(exp)
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#
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#exp = "2 + 5 * ( 3 - 4 )"
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#test(exp)
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#exp = "( 2 + 5 ) * ( 3 - 4 )^4"
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#test(exp)
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#exp = "( 2 + 5 ) * ( 3 * 4 )"
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#test(exp)
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#exp = "( 2 + 5 - 1 ) / ( 3 * 4 )"
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#test(exp)
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#exp = "( 2 + 5 ) / ( 3 * 4 ) + 1 / 12"
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#test(exp)
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#exp = "( 2+ 5 )/( 3 * 4 ) + 1 / 2"
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#test(exp)
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#exp="(-2+5)/(3*4)+1/12+5*5"
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#test(exp)
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#exp="-2*4(12 + 1)(3-12)"
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#test(exp)
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#exp="(-2+5)/(3*4)+1/12+5*5"
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#test(exp)
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# TODO: The next one doesn't work |ven. janv. 17 14:56:58 CET 2014
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#exp="-2*(-a)(12 + 1)(3-12)"
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#e = Expression(exp)
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#print(e)
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## Can't handle it yet!!
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#exp="-(-2)"
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#test(exp)
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#import doctest
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#doctest.testmod()
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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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