Coverage for sympy/printing/precedence.py : 37%

"""A module providing information about the necessity of brackets""" 

from __future__ import print_function, division 

from sympy.core.function import _coeff_isneg 

# Default precedence values for some basic types 

PRECEDENCE = { 

"Lambda": 1, 

"Xor": 10, 

"Or": 20, 

"And": 30, 

"Relational": 35, 

"Add": 40, 

"Mul": 50, 

"Pow": 60, 

"Func": 70, 

"Not": 100, 

"Atom": 1000 

} 

# A dictionary assigning precedence values to certain classes. These values are 

# treated like they were inherited, so not every single class has to be named 

# here. 

PRECEDENCE_VALUES = { 

"Equivalent": PRECEDENCE["Xor"], 

"Xor": PRECEDENCE["Xor"], 

"Implies": PRECEDENCE["Xor"], 

"Or": PRECEDENCE["Or"], 

"And": PRECEDENCE["And"], 

"Add": PRECEDENCE["Add"], 

"Pow": PRECEDENCE["Pow"], 

"Relational": PRECEDENCE["Relational"], 

"Sub": PRECEDENCE["Add"], 

"Not": PRECEDENCE["Not"], 

"Function" : PRECEDENCE["Func"], 

"NegativeInfinity": PRECEDENCE["Add"], 

"MatAdd": PRECEDENCE["Add"], 

"MatMul": PRECEDENCE["Mul"], 

"MatPow": PRECEDENCE["Pow"], 

"HadamardProduct": PRECEDENCE["Mul"] 

} 

# Sometimes it's not enough to assign a fixed precedence value to a 

# class. Then a function can be inserted in this dictionary that takes 

# an instance of this class as argument and returns the appropriate 

# precedence value. 

# Precedence functions 

def precedence_Mul(item): 

if _coeff_isneg(item): 

return PRECEDENCE["Add"] 

return PRECEDENCE["Mul"] 

def precedence_Rational(item): 

if item.p < 0: 

return PRECEDENCE["Add"] 

return PRECEDENCE["Mul"] 

def precedence_Integer(item): 

if item.p < 0: 

return PRECEDENCE["Add"] 

return PRECEDENCE["Atom"] 

def precedence_Float(item): 

if item < 0: 

return PRECEDENCE["Add"] 

return PRECEDENCE["Atom"] 

def precedence_PolyElement(item): 

if item.is_generator: 

return PRECEDENCE["Atom"] 

elif item.is_ground: 

return precedence(item.coeff(1)) 

elif item.is_term: 

return PRECEDENCE["Mul"] 

else: 

return PRECEDENCE["Add"] 

def precedence_FracElement(item): 

if item.denom == 1: 

return precedence_PolyElement(item.numer) 

else: 

return PRECEDENCE["Mul"] 

PRECEDENCE_FUNCTIONS = { 

"Integer": precedence_Integer, 

"Mul": precedence_Mul, 

"Rational": precedence_Rational, 

"Float": precedence_Float, 

"PolyElement": precedence_PolyElement, 

"FracElement": precedence_FracElement, 

} 

def precedence(item): 

""" 

Returns the precedence of a given object. 

""" 

if hasattr(item, "precedence"): 

return item.precedence 

try: 

mro = item.__class__.__mro__ 

except AttributeError: 

return PRECEDENCE["Atom"] 

for i in mro: 

n = i.__name__ 

if n in PRECEDENCE_FUNCTIONS: 

return PRECEDENCE_FUNCTIONS[n](item) 

elif n in PRECEDENCE_VALUES: 

return PRECEDENCE_VALUES[n] 

return PRECEDENCE["Atom"] 

def precedence_traditional(item): 

""" 

Returns the precedence of a given object according to the traditional rules 

of mathematics. This is the precedence for the LaTeX and pretty printer. 

""" 

# Integral, Sum, Product, Limit have the precedence of Mul in LaTeX, 

# the precedence of Atom for other printers: 

from sympy import Integral, Sum, Product, Limit, Derivative 

if isinstance(item, (Integral, Sum, Product, Limit, Derivative)): 

return PRECEDENCE["Mul"] 

else: 

return precedence(item)