def _canonical_expression(self, e):
e_ = None
if e.__class__ is EXPR._EqualityExpression:
if e._args[1].is_fixed():
_e = (e._args[1], e._args[0])
#
# The first argument of an equality is never fixed
#
#elif e._args[0].is_fixed():
# _e = (e._args[0], e._args[1])
else:
with EXPR.bypass_clone_check():
_e = (ZeroConstant, e._args[0] - e._args[1])
elif e.__class__ is EXPR._InequalityExpression:
if len(e._args) == 3:
_e = (e._args[0], e._args[1], e._args[2])
else:
if e._args[1].is_fixed():
_e = (None, e._args[0], e._args[1])
elif e._args[0].is_fixed():
_e = (e._args[0], e._args[1], None)
else:
with EXPR.bypass_clone_check():
_e = (ZeroConstant, e._args[1] - e._args[0], None)
else:
_e = (None, e, None)
return _e
def set_value(self, expr):
"""Set the expression on this constraint."""
if expr is None:
self._body = None
self._lower = None
self._upper = None
self._equality = False
return
_expr_type = expr.__class__
if _expr_type is tuple: # or expr_type is list:
#
# Form equality expression
#
if len(expr) == 2:
arg0 = expr[0]
if arg0 is not None:
arg0 = as_numeric(arg0)
arg1 = expr[1]
if arg1 is not None:
arg1 = as_numeric(arg1)
self._equality = True
if arg1 is None or (not arg1._potentially_variable()):
self._lower = self._upper = arg1
self._body = arg0
elif arg0 is None or (not arg0._potentially_variable()):
self._lower = self._upper = arg0
self._body = arg1
else:
with EXPR.bypass_clone_check():
self._lower = self._upper = ZeroConstant
self._body = arg0
self._body -= arg1
#self._body = EXPR.generate_expression_bypassCloneCheck(
# _sub, arg0, arg1)
#
# Form inequality expression
#
elif len(expr) == 3:
arg0 = expr[0]
if arg0 is not None:
arg0 = as_numeric(arg0)
if arg0._potentially_variable():
raise ValueError(
"Constraint '%s' found a 3-tuple (lower,"
" expression, upper) but the lower "
"value was not data or an expression "
"restricted to storage of data." % (self.name))
arg1 = expr[1]
if arg1 is not None:
arg1 = as_numeric(arg1)
arg2 = expr[2]
if arg2 is not None:
arg2 = as_numeric(arg2)
if arg2._potentially_variable():
raise ValueError(
"Constraint '%s' found a 3-tuple (lower,"
" expression, upper) but the upper "
"value was not data or an expression "
"restricted to storage of data." % (self.name))
self._lower = arg0
self._body = arg1
self._upper = arg2
else:
raise ValueError(
"Constructor rule for constraint '%s' returned "
"a tuple of length %d. Expecting a tuple of "
"length 2 or 3:\n"
"Equality: (left, right)\n"
"Inequality: (lower, expression, upper)" %
(self.name, len(expr)))
relational_expr = False
else:
try:
relational_expr = expr.is_relational()
if not relational_expr:
raise ValueError(
"Constraint '%s' does not have a proper "
"value. Found '%s'\nExpecting a tuple or "
"equation. Examples:"
"\n summation(model.costs) == model.income"
"\n (0, model.price[item], 50)" %
(self.name, str(expr)))
except AttributeError:
msg = ("Constraint '%s' does not have a proper "
"value. Found '%s'\nExpecting a tuple or "
"equation. Examples:"
"\n summation(model.costs) == model.income"
"\n (0, model.price[item], 50)" %
(self.name, str(expr)))
if type(expr) is bool:
msg += ("\nNote: constant Boolean expressions "
"are not valid constraint expressions. "
"Some apparently non-constant compound "
"inequalities (e.g. 'expr >= 0 <= 1') "
"can return boolean values; the proper "
"form for compound inequalities is "
"always 'lb <= expr <= ub'.")
raise ValueError(msg)
#
# Special check for chainedInequality errors like "if var <
# 1:" within rules. Catching them here allows us to provide
# the user with better (and more immediate) debugging
# information. We don't want to check earlier because we
# want to provide a specific debugging message if the
# construction rule returned True/False; for example, if the
# user did ( var < 1 > 0 ) (which also results in a non-None
# chainedInequality value)
#
if EXPR.generate_relational_expression.chainedInequality is not None:
raise TypeError(EXPR.chainedInequalityErrorMessage())
#
# Process relational expressions
# (i.e. explicit '==', '<', and '<=')
#
if relational_expr:
if _expr_type is EXPR._EqualityExpression:
# Equality expression: only 2 arguments!
self._equality = True
_args = expr._args
# Explicitly dereference the original arglist (otherwise
# this runs afoul of the getrefcount logic)
expr._args = []
if not _args[1]._potentially_variable():
self._lower = self._upper = _args[1]
self._body = _args[0]
elif not _args[0]._potentially_variable():
self._lower = self._upper = _args[0]
self._body = _args[1]
else:
with EXPR.bypass_clone_check():
self._lower = self._upper = ZeroConstant
self._body = _args[0]
self._body -= _args[1]
#self._body = EXPR.generate_expression_bypassCloneCheck(
# _sub, _args[0], _args[1] )
else:
# Inequality expression: 2 or 3 arguments
if expr._strict:
try:
_strict = any(expr._strict)
except:
_strict = True
if _strict:
#
# We can relax this when:
# (a) we have a need for this
# (b) we have problem writer that
# explicitly handles this
# (c) we make sure that all problem writers
# that don't handle this make it known
# to the user through an error or
# warning
#
raise ValueError(
"Constraint '%s' encountered a strict "
"inequality expression ('>' or '<'). All"
" constraints must be formulated using "
"using '<=', '>=', or '=='." % (self.name))
_args = expr._args
# Explicitly dereference the original arglist (otherwise
# this runs afoul of the getrefcount logic)
expr._args = []
if len(_args) == 3:
if _args[0]._potentially_variable():
raise ValueError(
"Constraint '%s' found a double-sided "
"inequality expression (lower <= "
"expression <= upper) but the lower "
"bound was not data or an expression "
"restricted to storage of data." % (self.name))
if _args[2]._potentially_variable():
raise ValueError(
"Constraint '%s' found a double-sided "\
"inequality expression (lower <= "
"expression <= upper) but the upper "
"bound was not data or an expression "
"restricted to storage of data."
% (self.name))
self._lower = _args[0]
self._body = _args[1]
self._upper = _args[2]
else:
if not _args[1]._potentially_variable():
self._lower = None
self._body = _args[0]
self._upper = _args[1]
elif not _args[0]._potentially_variable():
self._lower = _args[0]
self._body = _args[1]
self._upper = None
else:
with EXPR.bypass_clone_check():
self._lower = None
self._body = _args[0]
self._body -= _args[1]
self._upper = ZeroConstant
#self._body = EXPR.generate_expression_bypassCloneCheck(
# _sub, _args[0], _args[1])
#
# Replace numeric bound values with a NumericConstant object,
# and reset the values to 'None' if they are 'infinite'
#
if (self._lower is not None) and is_constant(self._lower):
val = self._lower()
if not pyutilib.math.is_finite(val):
if val > 0:
raise ValueError(
"Constraint '%s' created with a +Inf lower "
"bound." % (self.name))
self._lower = None
elif bool(val > 0) == bool(val <= 0):
raise ValueError("Constraint '%s' created with a non-numeric "
"lower bound." % (self.name))
if (self._upper is not None) and is_constant(self._upper):
val = self._upper()
if not pyutilib.math.is_finite(val):
if val < 0:
raise ValueError(
"Constraint '%s' created with a -Inf upper "
"bound." % (self.name))
self._upper = None
elif bool(val > 0) == bool(val <= 0):
raise ValueError("Constraint '%s' created with a non-numeric "
"upper bound." % (self.name))
#
# Error check, to ensure that we don't have a constraint that
# doesn't depend on any variables / parameters.
#
# Error check, to ensure that we don't have an equality
# constraint with 'infinite' RHS
#
if self._equality:
if self._lower is None:
raise ValueError("Equality constraint '%s' defined with "
"non-finite term." % (self.name))
assert self._lower is self._upper