private void UpdateRange(CardVar cvar, CardRange newRange)
{
Contract.Requires(newRange.Lower != Cardinality.Infinity);
MutableTuple <CardRange> range;
if (solverState.Peek().TryFindValue(cvar, out range))
{
range.Item1 = newRange;
}
else
{
solverState.Peek().Add(cvar, new MutableTuple <CardRange>(newRange));
}
}
public bool TryIntersect(CardRange r, out CardRange intersection)
{
var min = Cardinality.Max(lower, r.lower);
var max = Cardinality.Min(upper, r.upper);
if (max < min)
{
intersection = all;
return(false);
}
else
{
intersection = new CardRange(min, max);
return(true);
}
}
private bool Propagate(CardVar cvar)
{
Cardinality cd;
CardRange lhs, rhs;
CardRange intr, intrp;
CardConstraint con;
var stack = new Stack <CardConstraint>();
EnqueueConstraints(cvar, stack);
while (stack.Count > 0)
{
con = stack.Pop();
lhs = GetRange(con.Lhs);
rhs = Eval(con.Rhs);
con.IsQueued = false;
switch (con.Op)
{
case CardConstraint.OpKind.LEq:
if ((cd = Cardinality.Min(lhs.Upper, rhs.Upper)) != lhs.Upper)
{
if (cd < lhs.Lower)
{
return(false);
}
UpdateRange(con.Lhs, lhs = new CardRange(lhs.Lower, cd));
EnqueueConstraints(con.Lhs, stack);
}
if (rhs.Lower < lhs.Lower)
{
foreach (var rhsvar in con.RhsVars)
{
rhs = GetRange(rhsvar);
if (Eval(con.Rhs, rhsvar, rhs.Lower, false) >= lhs.Lower)
{
continue;
}
intr = new CardRange(rhs.Lower, Cardinality.Min(lhs.Lower, rhs.Upper));
while (intr.Lower + 1 < intr.Upper)
{
intrp = intr.Bisect(true);
if (Eval(con.Rhs, rhsvar, intrp.Lower, false) >= lhs.Lower)
{
intr = new CardRange(intr.Lower, intrp.Lower);
}
else
{
intr = new CardRange(intrp.Lower, intr.Upper);
}
}
if (Eval(con.Rhs, rhsvar, intr.Lower, false) >= lhs.Lower)
{
if (intr.Lower > rhs.Lower)
{
UpdateRange(rhsvar, new CardRange(intr.Lower, rhs.Upper));
EnqueueConstraints(rhsvar, stack);
continue;
}
}
else if (Eval(con.Rhs, rhsvar, intr.Upper, false) >= lhs.Lower)
{
if (intr.Upper > rhs.Lower)
{
UpdateRange(rhsvar, new CardRange(intr.Upper, rhs.Upper));
EnqueueConstraints(rhsvar, stack);
continue;
}
}
else
{
return(false);
}
}
}
break;
case CardConstraint.OpKind.GEq:
if ((cd = Cardinality.Max(lhs.Lower, rhs.Lower)) != lhs.Lower)
{
if (cd > lhs.Upper)
{
return(false);
}
UpdateRange(con.Lhs, lhs = new CardRange(cd, lhs.Upper));
EnqueueConstraints(con.Lhs, stack);
}
if (rhs.Upper > lhs.Upper)
{
foreach (var rhsvar in con.RhsVars)
{
rhs = GetRange(rhsvar);
if (Eval(con.Rhs, rhsvar, rhs.Upper, true) <= lhs.Upper)
{
continue;
}
intr = new CardRange(rhs.Lower, Cardinality.Min(rhs.Upper, lhs.Upper));
while (intr.Lower + 1 < intr.Upper)
{
intrp = intr.Bisect(false);
if (Eval(con.Rhs, rhsvar, intrp.Upper, true) <= lhs.Upper)
{
intr = new CardRange(intrp.Upper, intr.Upper);
}
else
{
intr = new CardRange(intr.Lower, intrp.Upper);
}
}
if (Eval(con.Rhs, rhsvar, intr.Upper, true) <= lhs.Upper)
{
if (intr.Upper < rhs.Upper)
{
UpdateRange(rhsvar, new CardRange(rhs.Lower, intr.Upper));
EnqueueConstraints(rhsvar, stack);
continue;
}
}
else if (Eval(con.Rhs, rhsvar, intr.Lower, true) <= lhs.Upper)
{
if (intr.Lower < rhs.Upper)
{
UpdateRange(rhsvar, new CardRange(rhs.Lower, intr.Lower));
EnqueueConstraints(rhsvar, stack);
continue;
}
}
else
{
return(false);
}
}
}
break;
default:
throw new NotImplementedException();
}
}
return(true);
}