Source code for ufl.equation

"""The Equation class, used to express equations like a == L."""
# Copyright (C) 2012-2016 Anders Logg and Martin Sandve Aln├Žs
#
# This file is part of UFL (https://www.fenicsproject.org)
#
# SPDX-License-Identifier:    LGPL-3.0-or-later

# Export list for ufl.classes
__all_classes__ = ["Equation"]


[docs]class Equation(object): """Equation. 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: raise ValueError("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 self.lhs == other.lhs and self.rhs == other.rhs def __hash__(self): """Hash.""" return hash((hash(self.lhs), hash(self.rhs))) def __repr__(self): """Representation.""" return f"Equation({self.lhs!r}, {self.rhs!r})"