/// <summary>
/// Evaluates expression with variable equal to var's lowerbound or upperbound.
/// </summary>
/// <param name="expr"></param>
/// <param name="var"></param>
/// <param name="intv"></param>
/// <returns></returns>
TInterval EvalWithExtremes(TExpr expr, TVar var, TInterval intv)
{
var evaluator = new EvaluateExpressionVisitor <IntervalEnvironmentBase <TVar, TExpr, TInterval, TNumeric>, TVar, TExpr, TInterval, TNumeric> (Decoder);
var envLowerBound = With(var, Context.For(intv.LowerBound));
// replace current intv with it's only lowerbound
var withLowerBound = evaluator.Visit(expr, new Counter <IntervalEnvironmentBase <TVar, TExpr, TInterval, TNumeric> > (envLowerBound));
var envUpperBound = With(var, Context.For(intv.UpperBound));
// replace current intv with it's only upperBound
var withUpperBound = evaluator.Visit(expr, new Counter <IntervalEnvironmentBase <TVar, TExpr, TInterval, TNumeric> > (envUpperBound));
return(withLowerBound.Join(withUpperBound));
}
public TInterval Eval(TExpr expr)
{
int intValue;
if (Decoder.IsConstantInt(expr, out intValue))
{
return(Context.For(intValue));
}
var evaluator = new EvaluateExpressionVisitor <IntervalEnvironmentBase <TVar, TExpr, TInterval, TNumeric>, TVar, TExpr, TInterval, TNumeric> (Decoder);
var interval = evaluator.Visit(expr, new Counter <IntervalEnvironmentBase <TVar, TExpr, TInterval, TNumeric> > (this));
if (evaluator.DuplicatedOccurences.Length() >= 1)
{
var noDuplicates = true;
TInterval result = null;
foreach (var var in evaluator.DuplicatedOccurences.AsEnumerable())
{
TInterval intv;
if (TryGetValue(var, out intv) && intv.IsFinite &&
Context.IsGreaterEqualThanZero(intv.LowerBound))
{
var extreme = EvalWithExtremes(expr, var, intv);
if (noDuplicates)
{
noDuplicates = false;
result = extreme;
}
else
{
result = result.Join(extreme);
}
}
}
if (!noDuplicates)
{
interval = result;
}
}
return(interval);
}