Bug in parse expression

[Paul Royik]

Just noticed, that official example works:

from sympy.parsing.sympy_parser import (parse_expr, standard_transformations, implicit_multiplication_application) parse_expr("10sin**2 x**2 + 3xyz + tan theta",transformations=(standard_transformations +(implicit_multiplication_application,)))

But 

parse_expr("10sin**(120*x) x**2 + 3xyz + tan theta",transformations=(standard_transformations +(implicit_multiplication_application,)))

raises exception (see sine exponent):

TypeError: unbound method could_extract_minus_sign() must be called with Symbol instance as first argument (got nothing instead)

[Aaron Meurer]

A simpler example is sin**(2*x) x.

Aaron Meurer

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[David Li]

For Aaron's case the expression is turned into

sin (Symbol )**(Integer (2 )('x' ))*Symbol ('x' )

For the original case the expression is turned into

Integer (10 )*sin (Symbol )**(Integer (120 )('x' ))*Symbol ('x' )**Integer (2 )+Integer (3 )*Symbol ('x' )*Symbol ('y' )*Symbol ('z' )+tan (Symbol ('theta' ))

so the exponent/argument is not being properly captured. IIRC because this works at the token level it only handles the case where the exponent is something simple like just a symbol or integer, and not a product of symbols and integers. This might make sense to reimplement as an AST transformation instead, or otherwise the transformation would have to do some actual parsing of the tokens.

David