278 lines
7.8 KiB
Python
278 lines
7.8 KiB
Python
#!/usr/bin/env python
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# encoding: utf-8
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from .generic import Stack, isNumber, isPolynom
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from .operator import op
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from decimal import Decimal
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import logging
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# logging.basicConfig(filename='str2tokens_debug.log',level=logging.DEBUG)
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def str2tokens(exp):
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""" Parse the string into tokens then turn it into postfix form
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>>> str2tokens('2+3*4')
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[2, 3, 4, *, +]
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>>> str2tokens('2*3+4')
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[2, 3, *, 4, +]
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>>> str2tokens('2x+4')
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[2, < Polynom x [0, 1]>, *, 4, +]
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"""
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in_tokens = str2in_tokens(exp)
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post_tokens = in2post_fix(in_tokens)
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return post_tokens
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def str2in_tokens(exp):
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""" Parse the expression, ie tranform a string into a list of tokens
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:param exp: The expression (a string)
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:returns: list of token
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>>> str2in_tokens('2+3*4')
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[2, '+', 3, '*', 4]
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>>> str2in_tokens('2*3+4')
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[2, '*', 3, '+', 4]
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>>> str2in_tokens('12*3+4')
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[12, '*', 3, '+', 4]
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>>> str2in_tokens('2.3*3+4')
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[Decimal('2.3'), '*', 3, '+', 4]
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>>> str2in_tokens('a*3+4')
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[< Polynom a [0, 1]>, '*', 3, '+', 4]
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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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tokens += feed_digit(character, tokens.pop(), tokens[-1])
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elif character == "(":
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tokens += hidden_meaning_time(tokens[-1])
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tokens.append("(")
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elif character in op.available_op():
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tokens.append(character)
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elif character == ")":
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tokens.append(character)
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elif character.isalpha():
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tokens += hidden_meaning_time(tokens[-1])
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tokens.append(feed_alpha(character))
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elif character == ".":
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tokens.append(feed_dot(tokens.pop()))
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elif character != " ":
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raise ValueError("{} is an unvalid character".format(character))
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return tokens[2:]
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def feed_digit(character, tok_b, tok_bb):
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""" Feed token when a digit is detected
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:param character: the character
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:param tok_b: the token before
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:param tok_bb: the token before before
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:returns: list of token to replace
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>>> feed_digit(1, '-', 2)
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['-', 1]
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>>> feed_digit(1, '', '')
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['', 1]
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>>> feed_digit(1, 2, '')
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[21]
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>>> feed_digit(1, Decimal(2), '')
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[Decimal('2.1')]
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>>> feed_digit(1, Decimal('2.3'), '')
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[Decimal('2.31')]
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>>> feed_digit(1, -2, '')
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[-21]
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>>> feed_digit(1, Decimal('-2'), '')
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[Decimal('-2.1')]
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>>> feed_digit(1, '-', '')
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[-1]
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>>> feed_digit(1, '-', '+')
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[-1]
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>>> feed_digit(1, '-', '(')
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[-1]
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>>> feed_digit(1, '-', 2)
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['-', 1]
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>>> from mapytex.calculus.polynom import Polynom
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>>> feed_digit(1, '-', Polynom([0,1]))
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['-', 1]
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"""
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if isinstance(tok_b, int):
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return [tok_b * 10 + int(tok_b/abs(tok_b)) * int(character)]
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elif isinstance(tok_b, Decimal):
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return [tok_b + int(tok_b/abs(tok_b)) * int(character) * Decimal('10') ** (tok_b.as_tuple().exponent - 1)]
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# TODO: WTF!!! |sam. févr. 27 17:11:53 EAT 2016
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elif tok_b == "-" and (str(tok_bb) in op.available_op() or str(tok_bb) == ""):
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return [- int(character)]
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else:
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return [tok_b, int(character)]
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def hidden_meaning_time(tok_b):
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""" Return a "*" character if it is hidden meaning
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:param tok_b: the token before
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>>> hidden_meaning_time(4)
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['*']
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>>> hidden_meaning_time(')')
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['*']
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>>> from mapytex.calculus.polynom import Polynom
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>>> hidden_meaning_time(Polynom([0,1]))
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['*']
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>>> hidden_meaning_time("+")
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[]
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>>> hidden_meaning_time("*")
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[]
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"""
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if isNumber(tok_b) \
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or tok_b == ")" \
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or isPolynom(tok_b):
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return ["*"]
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return []
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def feed_alpha(character):
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""" Feed token when an alpha character is detected
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:param character: the alpha character
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:param tok_b: the token before
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:returns: tokens to add
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"""
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from mapytex.calculus.polynom import Polynom
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return Polynom([0, 1], letter=character)
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def feed_dot(tok_b):
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r""" Build Decimal with the previous token
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:param tok_b: the previous token
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:returns: the Decimal
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>>> feed_dot(2)
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Decimal('2')
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>>> feed_dot(Decimal('2.3'))
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Traceback (most recent call last):
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...
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ValueError: A number has 2 points...! We have 2.3 before the dot
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>>> feed_dot('+')
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Traceback (most recent call last):
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...
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ValueError: Try to make decimal but + before the dot
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"""
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if isinstance(tok_b, int):
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return Decimal(tok_b)
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elif isinstance(tok_b, Decimal):
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raise ValueError("A number has 2 points...! We have {} before the dot".format(tok_b))
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else:
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raise ValueError("Try to make decimal but {} before the dot".format(tok_b))
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def in2post_fix(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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>>> in2post_fix(['-', '(', '-', 2, ')'])
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[2, -, -]
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>>> in2post_fix(['-', '(', '-', 2, '+', 3, '*', 4, ')'])
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[2, -, 3, 4, *, +, -]
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"""
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logging.debug("New start with {}".format(infix_tokens))
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# Stack where operator will be stocked
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opStack = Stack()
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# final postfix list of tokens
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postfix_tokens = []
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# stack with the nbr of tokens still to compute in postfix_tokens
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arity_Stack = Stack()
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arity_Stack.push(0)
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for (pos_token, token) in enumerate(infix_tokens):
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logging.debug(str(postfix_tokens) +
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" | " + str(opStack) +
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" | " + str(infix_tokens[(pos_token+1):]) +
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" | " + str(arity_Stack)
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)
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if token == ")":
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next_op = opStack.pop()
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while next_op != op.par:
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postfix_tokens.append(next_op)
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next_op = opStack.pop()
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# Go back to old arity
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arity_Stack.pop()
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# Raise the arity
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arity = arity_Stack.pop()
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arity_Stack.push(arity + 1)
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elif op.can_be_operator(token):
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if token == "(":
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opStack.push(op.get_op(token, 0))
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# Set next arity counter
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arity_Stack.push(0)
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else:
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arity = arity_Stack.pop()
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token_op = op.get_op(token, arity + 1)
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# Reset arity to 0 in case there is other operators (the real
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# operation would be "-op.arity + 1")
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arity_Stack.push(0)
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while (not opStack.isEmpty()) and opStack.peek(
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).priority >= token_op.priority:
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next_op = opStack.pop()
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postfix_tokens.append(next_op)
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opStack.push(token_op)
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logging.debug("--" + token + " -> " + str(arity + 1))
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else:
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postfix_tokens.append(token)
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arity = arity_Stack.pop()
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arity_Stack.push(arity + 1)
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logging.debug(str(postfix_tokens) +
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" | " + str(opStack) +
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" | " + str(infix_tokens[(pos_token+1):]) +
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" | " + str(arity_Stack)
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)
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while not opStack.isEmpty():
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next_op = opStack.pop()
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postfix_tokens.append(next_op)
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logging.debug(str(postfix_tokens) +
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" | " + str(opStack) +
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" | " + str(infix_tokens[(pos_token+1):]) +
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" | " + str(arity_Stack)
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)
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if arity_Stack.peek() != 1:
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raise ValueError(
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"Unvalid expression. The arity Stack is ",
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str(arity_Stack))
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logging.debug("Fini!")
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return postfix_tokens
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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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