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Start objecting expression

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Lafrite
2013-11-01 12:42:42 +01:00
parent decffa6d75
commit 4e3f0a9b66
2 changed files with 331 additions and 137 deletions
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277
expression.py
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@@ -8,182 +8,185 @@ class Expression(object):
priority = {"*" : 3, "/": 3, "+": 2, "-":2, "(": 1} priority = {"*" : 3, "/": 3, "+": 2, "-":2, "(": 1}
def __init__(self, exp): def __init__(self, exp):
""" Initiate the expression. """ Initiate the expression
:param exp: the expression. It can be a string or a list of tokens. It can be infix or postfix expression :param exp: the expression. It can be a string or a list of tokens. It can be infix or postfix expression
""" """
self._tokens = {} self._exp = exp
self._strings = {}
if type(exp) == list: def simplify(self):
fix = self.get_fix(exp) """ Generator which return steps for computing the expression """
self._tokens[fix] = exp if self._exp == 0:
elif type(exp) == str: yield "Zero!"
tokens = self.parseExp(exp)
fix = self.get_fix(tokens)
self._tokens[fix] = tokens
self._strings[fix] = exp
else: else:
raise ValueError("The expression needs to be a string or a list of token") self.children = Expression(self._exp - 1)
yield "num: " + str(self._exp)
yield self.children.simplify().next()
# --------------------- ## ---------------------
# String parsing ## String parsing
# @classmethod ???? ## @classmethod ????
def parseExp(self, exp): #def parseExp(self, exp):
""" Parse the expression, ie tranform a string into a list of tokens # """ Parse the expression, ie tranform a string into a list of tokens
:param exp: The expression (a string) # :param exp: The expression (a string)
:returns: list of token # :returns: list of token
""" # """
return exp.split(" ") # return exp.split(" ")
# --------------------- ## ---------------------
# "fix" recognition ## "fix" recognition
def get_fix(self, tokens): #def get_fix(self, tokens):
""" Give the "fix" of an expression # """ Give the "fix" of an expression
infix -> A + B # infix -> A + B
prefix -> + A B # prefix -> + A B
postfix -> A B + # postfix -> A B +
:param exp: the expression (list of token) # :param exp: the expression (list of token)
:returns: the "fix" (infix, postfix, prefix) # :returns: the "fix" (infix, postfix, prefix)
""" # """
if tokens[0] in "+-*/": # if tokens[0] in "+-*/":
return "prefix" # return "prefix"
elif token[0] not in "+-*/" ans token[1] not in "+-*/": # elif token[0] not in "+-*/" ans token[1] not in "+-*/":
return "postfix" # return "postfix"
else: # else:
return "infix" # return "infix"
# ---------------------- ## ----------------------
# Expressions - tokens getters ## Expressions - tokens getters
def tokens(self, fix = "infix"): #def tokens(self, fix = "infix"):
"""Get the list of tokens with the wanted fix # """Get the list of tokens with the wanted fix
:param fix: the fix wanted (infix default) # :param fix: the fix wanted (infix default)
:returns: list of tokens # :returns: list of tokens
""" # """
# Si ce fix n'a pas encore été enregistré # # Si ce fix n'a pas encore été enregistré
if fix not in self._tokens: # if fix not in self._tokens:
# Il peut venir de la version string # # Il peut venir de la version string
if fix in self._string: # if fix in self._string:
self._tokens[fix] = self.parseExp(self._string[fix]) # self._tokens[fix] = self.parseExp(self._string[fix])
# Sinon il faut le calculer à partir d'une autre forme # # Sinon il faut le calculer à partir d'une autre forme
else: # else:
fix_transfo = "to" + fix.capitalize() # fix_transfo = "to" + fix.capitalize()
getattr(self,fix_transfo)() # getattr(self,fix_transfo)()
return self._tokens[fix] # return self._tokens[fix]
##### On en est là,il faudra faire attention à bien vérifier ce que les "to..." enregistre (string ou tokens) ###### On en est là,il faudra faire attention à bien vérifier ce que les "to..." enregistre (string ou tokens)
def string(self, fix = "infix"): #def string(self, fix = "infix"):
"""Get the string with the wanted fix # """Get the string with the wanted fix
:param fix: the fix wanted (infix default) # :param fix: the fix wanted (infix default)
:returns: the string representing the expression # :returns: the string representing the expression
""" # """
# Si ce fix n'a pas encore été enregistré # # Si ce fix n'a pas encore été enregistré
if fix not in self._string: # if fix not in self._string:
# Il peut venir de la version string # # Il peut venir de la version string
if fix in self._tokens: # if fix in self._tokens:
self._string[fix] = self.parseExp(self._string[fix]) # self._string[fix] = self.parseExp(self._string[fix])
# Sinon il faut le calculer à partir d'une autre forme # # Sinon il faut le calculer à partir d'une autre forme
else: # else:
fix_transfo = "to" + fix.capitalize() # fix_transfo = "to" + fix.capitalize()
getattr(self,fix_transfo)() # getattr(self,fix_transfo)()
return self._string[fix] # return self._string[fix]
#
# ---------------------- ## ----------------------
# "fix" tranformations ## "fix" tranformations
def toPostfix(self): #def toPostfix(self):
""" Transorm the expression into postfix form using the infix form""" # """ Transorm the expression into postfix form using the infix form"""
pass # pass
def toInfix(self): #def toInfix(self):
""" Tranform the expression into infix form using postfix form""" # """ Tranform the expression into infix form using postfix form"""
pass # pass
# --------------------- ## ---------------------
# Tools for placing parenthesis in infix notation ## Tools for placing parenthesis in infix notation
def needPar(operande, operator, posi = "after"): #def needPar(operande, operator, posi = "after"):
""" Says whether or not the operande needs parenthesis # """ Says whether or not the operande needs parenthesis
:param operande: the operande # :param operande: the operande
:param operator: the operator # :param operator: the operator
:param posi: "after"(default) if the operande will be after the operator, "before" othewise # :param posi: "after"(default) if the operande will be after the operator, "before" othewise
:returns: bollean # :returns: bollean
""" # """
if isNumber(operande) and "-" in operande: # if isNumber(operande) and "-" in operande:
return 1 # return 1
elif not isNumber(operande): # elif not isNumber(operande):
# Si c'est une grande expression ou un chiffre négatif # # Si c'est une grande expression ou un chiffre négatif
stand_alone = get_main_op(operande) # stand_alone = get_main_op(operande)
# Si la priorité de l'operande est plus faible que celle de l'opérateur # # Si la priorité de l'operande est plus faible que celle de l'opérateur
minor_priority = self.priority[get_main_op(operande)] < self.priority[operator] # minor_priority = self.priority[get_main_op(operande)] < self.priority[operator]
# Si l'opérateur est -/ pour after ou juste / pour before # # Si l'opérateur est -/ pour after ou juste / pour before
special = (operator in "-/" and posi == "after") or (operator in "/" and posi == "before") # special = (operator in "-/" and posi == "after") or (operator in "/" and posi == "before")
return stand_alone and (minor_priority or special) # return stand_alone and (minor_priority or special)
else: # else:
return 0 # return 0
#
# J'aime pas bien cette endroit faudrait que ce soit une méthode qui s'applique uniquement à l'expression en question (self) pas à n'importe quel string, ça serait plus propre. # J'#aime pas bien cette endroit faudrait que ce soit une méthode qui s'applique uniquement à l'expression en question (self) pas à n'importe quel string, ça serait plus propre.
def get_main_op(exp): #def get_main_op(exp):
""" Gives the main operation of the expression # """ Gives the main operation of the expression
:param exp: the expression # :param exp: the expression
:returns: the main operation (+, -, * or /) or 0 if the expression is only one element # :returns: the main operation (+, -, * or /) or 0 if the expression is only one element
""" # """
parStack = Stack() # parStack = Stack()
tokenList = exp.split(" ") # tokenList = exp.split(" ")
if len(tokenList) == 1: # if len(tokenList) == 1:
# Si l'expression n'est qu'un élément # # Si l'expression n'est qu'un élément
return 0 # return 0
main_op = [] # main_op = []
for token in tokenList: # for token in tokenList:
if token == "(": # if token == "(":
parStack.push(token) # parStack.push(token)
elif token == ")": # elif token == ")":
parStack.pop() # parStack.pop()
elif token in "+-*/" and parStack.isEmpty(): # elif token in "+-*/" and parStack.isEmpty():
main_op.append(token) # main_op.append(token)
return min(main_op, key = lambda s: priority[s]) # return min(main_op, key = lambda s: priority[s])
# --------------------- ## ---------------------
# Computing the expression ## Computing the expression
def compute(self): #def compute(self):
""" Recursive method for computing as a student the expression # """ Recursive method for computing as a student the expression
:returns: list of steps needed to reach the result # :returns: list of steps needed to reach the result
""" # """
pass # pass
#
def doMath(op, op1, op2): #def doMath(op, op1, op2):
"""Compute "op1 op op2" # """Compute "op1 op op2"
:param op: operator # :param op: operator
:param op1: first operande # :param op1: first operande
:param op2: second operande # :param op2: second operande
:returns: string representing the result # :returns: string representing the result
""" # """
return str(eval(op1 + op + op2)) # return str(eval(op1 + op + op2))
if __name__ == '__main__':
a = Expression(10)
for i in a.simplify():
print(i)
# ----------------------------- # -----------------------------
# Reglages pour 'vim' # Reglages pour 'vim'

191
expression.py_back Normal file
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@@ -0,0 +1,191 @@
#!/usr/bin/env python
# encoding: utf-8
class Expression(object):
"""A calculus expression. Today it can andle only expression with numbers later it will be able to manipulate unknown"""
priority = {"*" : 3, "/": 3, "+": 2, "-":2, "(": 1}
def __init__(self, exp):
""" Initiate the expression.
:param exp: the expression. It can be a string or a list of tokens. It can be infix or postfix expression
"""
self._tokens = {}
self._strings = {}
if type(exp) == list:
fix = self.get_fix(exp)
self._tokens[fix] = exp
elif type(exp) == str:
tokens = self.parseExp(exp)
fix = self.get_fix(tokens)
self._tokens[fix] = tokens
self._strings[fix] = exp
else:
raise ValueError("The expression needs to be a string or a list of token")
# ---------------------
# String parsing
# @classmethod ????
def parseExp(self, exp):
""" Parse the expression, ie tranform a string into a list of tokens
:param exp: The expression (a string)
:returns: list of token
"""
return exp.split(" ")
# ---------------------
# "fix" recognition
def get_fix(self, tokens):
""" Give the "fix" of an expression
infix -> A + B
prefix -> + A B
postfix -> A B +
:param exp: the expression (list of token)
:returns: the "fix" (infix, postfix, prefix)
"""
if tokens[0] in "+-*/":
return "prefix"
elif token[0] not in "+-*/" ans token[1] not in "+-*/":
return "postfix"
else:
return "infix"
# ----------------------
# Expressions - tokens getters
def tokens(self, fix = "infix"):
"""Get the list of tokens with the wanted fix
:param fix: the fix wanted (infix default)
:returns: list of tokens
"""
# Si ce fix n'a pas encore été enregistré
if fix not in self._tokens:
# Il peut venir de la version string
if fix in self._string:
self._tokens[fix] = self.parseExp(self._string[fix])
# Sinon il faut le calculer à partir d'une autre forme
else:
fix_transfo = "to" + fix.capitalize()
getattr(self,fix_transfo)()
return self._tokens[fix]
##### On en est là,il faudra faire attention à bien vérifier ce que les "to..." enregistre (string ou tokens)
def string(self, fix = "infix"):
"""Get the string with the wanted fix
:param fix: the fix wanted (infix default)
:returns: the string representing the expression
"""
# Si ce fix n'a pas encore été enregistré
if fix not in self._string:
# Il peut venir de la version string
if fix in self._tokens:
self._string[fix] = self.parseExp(self._string[fix])
# Sinon il faut le calculer à partir d'une autre forme
else:
fix_transfo = "to" + fix.capitalize()
getattr(self,fix_transfo)()
return self._string[fix]
# ----------------------
# "fix" tranformations
def toPostfix(self):
""" Transorm the expression into postfix form using the infix form"""
pass
def toInfix(self):
""" Tranform the expression into infix form using postfix form"""
pass
# ---------------------
# Tools for placing parenthesis in infix notation
def needPar(operande, operator, posi = "after"):
""" Says whether or not the operande needs parenthesis
:param operande: the operande
:param operator: the operator
:param posi: "after"(default) if the operande will be after the operator, "before" othewise
:returns: bollean
"""
if isNumber(operande) and "-" in operande:
return 1
elif not isNumber(operande):
# Si c'est une grande expression ou un chiffre négatif
stand_alone = get_main_op(operande)
# Si la priorité de l'operande est plus faible que celle de l'opérateur
minor_priority = self.priority[get_main_op(operande)] < self.priority[operator]
# Si l'opérateur est -/ pour after ou juste / pour before
special = (operator in "-/" and posi == "after") or (operator in "/" and posi == "before")
return stand_alone and (minor_priority or special)
else:
return 0
# J'aime pas bien cette endroit faudrait que ce soit une méthode qui s'applique uniquement à l'expression en question (self) pas à n'importe quel string, ça serait plus propre.
def get_main_op(exp):
""" Gives the main operation of the expression
:param exp: the expression
:returns: the main operation (+, -, * or /) or 0 if the expression is only one element
"""
parStack = Stack()
tokenList = exp.split(" ")
if len(tokenList) == 1:
# Si l'expression n'est qu'un élément
return 0
main_op = []
for token in tokenList:
if token == "(":
parStack.push(token)
elif token == ")":
parStack.pop()
elif token in "+-*/" and parStack.isEmpty():
main_op.append(token)
return min(main_op, key = lambda s: priority[s])
# ---------------------
# Computing the expression
def compute(self):
""" Recursive method for computing as a student the expression
:returns: list of steps needed to reach the result
"""
pass
def doMath(op, op1, op2):
"""Compute "op1 op op2"
:param op: operator
:param op1: first operande
:param op2: second operande
:returns: string representing the result
"""
return str(eval(op1 + op + op2))
# -----------------------------
# Reglages pour 'vim'
# vim:set autoindent expandtab tabstop=4 shiftwidth=4:
# cursor: 16 del