/// <summary>
/// Get corresponding Z3 formula of a MSF row.
/// </summary>
/// <param name="rid">The MSF row id</param>
private ArithExpr MkGoalRow(int rid)
{
// Start with the 0 term
List <ArithExpr> row = new List <ArithExpr>();
// Now, add all the entries of this row
foreach (LinearEntry entry in GetRowEntries(rid))
{
// Get the variable and constant in the row
ArithExpr e = _solver.GetVariable(entry.Index);
if (!entry.Value.IsOne)
{
e = _solver.Context.MkMul(_solver.GetNumeral(entry.Value, e.Sort), e);
}
row.Add(e);
}
switch (row.Count)
{
case 0: return(_solver.GetNumeral(new Rational()));
case 1: return(row[0]);
default: return(_solver.Context.MkAdd(row.ToArray()));
}
}
private ArithExpr MkTerm(int rid)
{
var context = _solver.Context;
if (IsConstant(rid))
{
Rational lower, upper;
GetBounds(rid, out lower, out upper);
Debug.Assert(lower == upper);
return(_solver.GetNumeral(lower));
}
else if (IsOperation(rid))
{
ArithExpr[] operands;
TermModelOperation op = GetOperation(rid);
switch (op)
{
case TermModelOperation.And:
case TermModelOperation.Or:
case TermModelOperation.Not:
case TermModelOperation.Unequal:
case TermModelOperation.Greater:
case TermModelOperation.Less:
case TermModelOperation.GreaterEqual:
case TermModelOperation.LessEqual:
case TermModelOperation.Equal:
return(MkBoolToArith(MkBool(rid)));
case TermModelOperation.If:
Debug.Assert(GetOperandCount(rid) == 3, "If is ternary.");
BoolExpr b = MkBool(GetOperand(rid, 0));
Expr x1 = MkTerm(GetOperand(rid, 1));
Expr x2 = MkTerm(GetOperand(rid, 2));
return((ArithExpr)context.MkITE(b, x1, x2));
case TermModelOperation.Plus:
Debug.Assert(GetOperandCount(rid) >= 2, "Plus takes at least two operands.");
operands = (GetOperands(rid)).Select(x => MkTerm(x)).ToArray();
return(context.MkAdd(operands));
case TermModelOperation.Minus:
Debug.Assert(GetOperandCount(rid) == 1, "Minus takes exactly one operand.");
return(context.MkUnaryMinus(MkTerm(GetOperand(rid, 0))));
case TermModelOperation.Times:
Debug.Assert(GetOperandCount(rid) >= 2, "Times requires at least two operands.");
operands = (GetOperands(rid)).Select(x => MkTerm(x)).ToArray();
return(context.MkMul(operands));
case TermModelOperation.Identity:
Debug.Assert(GetOperandCount(rid) == 1, "Identity takes exactly one operand.");
return(MkTerm(GetOperand(rid, 0)));
case TermModelOperation.Abs:
Debug.Assert(GetOperandCount(rid) == 1, "Abs takes exactly one operand.");
ArithExpr e = MkTerm(GetOperand(rid, 0));
ArithExpr minusE = context.MkUnaryMinus(e);
ArithExpr zero = _solver.GetNumeral(Rational.Zero);
return((ArithExpr)context.MkITE(context.MkGe(e, zero), e, minusE));
default:
Console.Error.WriteLine("{0} operation isn't supported.", op);
throw new NotSupportedException();
}
}
else
{
return(_solver.GetVariable(rid));
}
}
