/usr/lib/python2.7/dist-packages/ufl/equation.py is in python-ufl 2016.2.0-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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"The Equation class, used to express equations like a == L."
# Copyright (C) 2012-2016 Anders Logg and Martin Sandve Alnæs
#
# This file is part of UFL.
#
# UFL is free software: you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# UFL is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with UFL. If not, see <http://www.gnu.org/licenses/>.
from ufl.log import error
from ufl.utils.py23 import as_native_str
from ufl.utils.py23 import as_native_strings
# Export list for ufl.classes
__all_classes__ = as_native_strings(["Equation"])
class Equation(object):
"""This class is used to represent equations expressed by the "=="
operator. Examples include a == L and F == 0 where a, L and F are
Form objects."""
def __init__(self, lhs, rhs):
"Create equation lhs == rhs"
self.lhs = lhs
self.rhs = rhs
def __bool__(self):
"""Evaluate bool(lhs_form == rhs_form).
This will not trigger when setting 'equation = a == L',
but when e.g. running 'if equation:'.
"""
# NB!: pep8 will say you should use isinstance here, but we do
# actually want to compare the exact types in this case.
# Not equal if types are not identical (i.e. not accepting
# subclasses)
if type(self.lhs) != type(self.rhs): # noqa: E721
return False
# Try to delegate to equals function
if hasattr(self.lhs, "equals"):
return self.lhs.equals(self.rhs)
elif hasattr(self.rhs, "equals"):
return self.rhs.equals(self.lhs)
else:
error("Either lhs or rhs of Equation must implement self.equals(other).")
__nonzero__ = __bool__
def __eq__(self, other):
"Compare two equations by comparing lhs and rhs."
return isinstance(other, Equation) and \
bool(self.lhs == other.lhs) and \
bool(self.rhs == other.rhs)
def __hash__(self):
return hash((hash(self.lhs), hash(self.rhs)))
def __repr__(self):
r = "Equation(%s, %s)" % (repr(self.lhs), repr(self.rhs))
return as_native_str(r)
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