Because of C++ code snippets not dealing with multiple +- in sequence (or even negative number) in expressions, I post this, as it is so much easier for me than C/C++.
EDIT: Fixed signs together with '(' issues and '+' at beginning removing without lstrip, removed separate now unused '(' branch from if. Changed name of prev to plusminus.
""" Expression cleanup from spaces and multiple +- """
expr = "--4-+--4-- - - ++-++ ( ++ +-- 4* 6.5 / 4.3e6 )- - -6"
plusminus = new_expr = ''
for c in expr:
if c.isdigit() or c == '(':
# do not put + in front of expression or inside ( in front of first expression
new_expr += c if plusminus == '+' and (not new_expr or new_expr.endswith('(')) else plusminus + c
plusminus = ''
elif c in '+-':
plusminus = '-' if (c == '-' and plusminus != '-') or (c=='+' and plusminus =='-') else '+'
elif c != ' ':
new_expr += c
if plusminus:
raise ValueError("+- not in front of number or '('!")
if plusminus:
raise ValueError("Sign at end of expression!")
else:
print("%s\n%s" % (expr, new_expr))
assert eval(expr) == eval(new_expr)
"""Output:
--4-+--4-- - - ++-++ ( ++ +-- 4* 6.5 / 4.3e6 )- - -6
4-4-(4*6.5/4.3e6)-6
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