66 lines
3.5 KiB
Python
66 lines
3.5 KiB
Python
__author__ = "Jeremy Saklad"
|
|
|
|
from functools import cache, reduce
|
|
|
|
from ortools.sat.python import cp_model
|
|
|
|
class BoneMarketModel(cp_model.CpModel):
|
|
"""A CpModel with additional functions for common constraints and enhanced enforcement literal support."""
|
|
|
|
__slots__ = ()
|
|
|
|
def AddAllowedAssignments(self, variables, tuples_list):
|
|
intermediate_variables, constraints = zip(*(self.NewIntermediateIntVar(variable, f'{repr((variables, tuples_list))}: {variable}') for variable in variables))
|
|
super().AddAllowedAssignments(intermediate_variables, tuples_list)
|
|
return constraints
|
|
|
|
def AddApproximateExponentiationEquality(self, target, var, exp, upto):
|
|
"""Add an approximate exponentiation equality using a lookup table.
|
|
|
|
Set `upto` to a value that is unlikely to come into play.
|
|
|
|
Each parameter is interpreted as a BoundedLinearExpression, and a layer of indirection is applied such that each Constraint in the returned tuple can accept an enforcement literal."""
|
|
return self.AddAllowedAssignments((target, var), ((int(base**exp), base) for base in range(upto + 1)))
|
|
|
|
def AddMultiplicationEquality(self, target, variables):
|
|
"""Adds `target == variables[0] * .. * variables[n]`.
|
|
|
|
Each parameter is interpreted as a BoundedLinearExpression, and a layer of indirection is applied such that each Constraint in the returned tuple can accept an enforcement literal."""
|
|
|
|
superclass = super()
|
|
|
|
def Multiply(end, stack):
|
|
intermediate_variable, variable_constraint = self.NewIntermediateIntVar(stack.pop(), f'{repr(end)} == {"*".join((repr(variable) for variable in stack))}: last variable')
|
|
|
|
partial_target = self.NewIntVar(f'{repr(end)} == {"*".join((repr(variable) for variable in stack))}: partial target')
|
|
recursive_constraints = self.AddMultiplicationEquality(partial_target, stack) if len(stack) > 1 else (self.Add(partial_target == stack.pop()),)
|
|
|
|
intermediate_target, target_constraint = self.NewIntermediateIntVar(end, f'{repr(end)} == {"*".join((repr(variable) for variable in stack))}: target')
|
|
|
|
superclass.AddMultiplicationEquality(intermediate_target, (partial_target, intermediate_variable))
|
|
|
|
return (variable_constraint, *recursive_constraints, target_constraint)
|
|
|
|
# Avoid mutating parameter directly
|
|
return Multiply(target, variables.copy() if isinstance(variables, list) else list(variables))
|
|
|
|
@cache
|
|
def BoolExpression(self, bounded_linear_exp):
|
|
"""Add a fully-reified implication using an intermediate Boolean variable."""
|
|
|
|
intermediate = self.NewBoolVar(str(bounded_linear_exp))
|
|
linear_exp = bounded_linear_exp.Expression()
|
|
domain = cp_model.Domain(*bounded_linear_exp.Bounds())
|
|
self.AddLinearExpressionInDomain(linear_exp, domain).OnlyEnforceIf(intermediate)
|
|
self.AddLinearExpressionInDomain(linear_exp, domain.Complement()).OnlyEnforceIf(intermediate.Not())
|
|
return intermediate
|
|
|
|
def NewIntermediateIntVar(self, linear_exp, name, *, lb = cp_model.INT_MIN//8, ub = cp_model.INT_MAX//8):
|
|
"""Creates an integer variable equivalent to the given expression and returns a tuple consisting of the variable and constraint for use with enforcement literals."""
|
|
|
|
intermediate = super().NewIntVar(lb, ub, name)
|
|
return (intermediate, self.Add(intermediate == linear_exp))
|
|
|
|
def NewIntVar(self, name, *, lb = cp_model.INT32_MIN, ub = cp_model.INT32_MAX):
|
|
return super().NewIntVar(lb, ub, name)
|