handle - at the beginig of expression and after "("

This commit is contained in:
lafrite 2014-01-15 16:41:51 +01:00
parent b52ec78d21
commit 95bc15b917
1 changed files with 8 additions and 1 deletions

View File

@ -125,6 +125,10 @@ class Expression(object):
if character.isdigit():
if type(tokens[-1]) == int:
tokens[-1] = tokens[-1]*10 + int(character)
# Special case for "-" at the begining of an expression or before "("
elif tokens[-1] == "-" and \
str(tokens[-2]) in " (":
tokens[-1] = - int(character)
else:
tokens.append(int(character))
elif character in "+-*/()":
@ -343,7 +347,10 @@ if __name__ == '__main__':
exp = "( 2+ 5 )/( 3 * 4 ) + 1 / 2"
test(exp)
exp="(2+5)/(3*4)+1/12+5*5"
exp="(-2+5)/(3*4)+1/12+5*5"
test(exp)
exp="-2*4*(12 + 1)"
test(exp)
import doctest