Source code for sympy.printing.precedence

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

from sympy import S
from sympy.core.function import _coeff_isneg

# Default precedence values for some basic types
PRECEDENCE = {
    "Lambda":1,
    "Relational":20,
    "Or":20,
    "And":30,
    "Add":40,
    "Mul":50,
    "Pow":60,
    "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 = {
    "Or" : PRECEDENCE["Or"],
    "And" : PRECEDENCE["And"],
    "Add" : PRECEDENCE["Add"],
    "Pow" : PRECEDENCE["Pow"],
    "Relational" : PRECEDENCE["Relational"],
    "Sub" : PRECEDENCE["Add"],
    "Not": PRECEDENCE["Not"],
    "factorial": PRECEDENCE["Pow"],
    "factorial2": PRECEDENCE["Pow"],
    "NegativeInfinity": PRECEDENCE["Add"],
}

# 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"]

PRECEDENCE_FUNCTIONS = {
    "Integer" : precedence_Integer,
    "Mul" : precedence_Mul,
    "Rational" : precedence_Rational,
    "Float": precedence_Float,
}


[docs]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"]