public static Tuple <int?, int?> BoundRange(this Functor <int> functor)
{
var binaryExpression = functor?.Expression?.Body as BinaryExpression;
if (binaryExpression == null)
{
return(null);
}
var left = ReduceExpression(binaryExpression.Left);
var right = ReduceExpression(binaryExpression.Right);
if (left == null || right == null)
{
return(null);
}
if (!((left is ParameterExpression || left is ConstantExpression) && (right is ParameterExpression || right is ConstantExpression)))
{
return(null);
}
if (binaryExpression.NodeType == ExpressionType.Equal)
{
var v = ToInt(left.As <ConstantExpression>() ?? right.As <ConstantExpression>());
return(Tuple.Create(v, v + 1));
}
if (binaryExpression.NodeType == ExpressionType.LessThan)
{
var l = ToInt(left.As <ConstantExpression>());
var r = ToInt(right.As <ConstantExpression>());
if (l != null)
{
return(Tuple.Create(l + 1, (int?)null));
}
if (r != null)
{
return(Tuple.Create((int?)null, r));
}
}
if (binaryExpression.NodeType == ExpressionType.LessThanOrEqual)
{
var l = ToInt(left.As <ConstantExpression>());
var r = ToInt(right.As <ConstantExpression>());
if (l != null)
{
return(Tuple.Create(l, (int?)null));
}
if (r != null)
{
return(Tuple.Create((int?)null, r + 1));
}
}
if (binaryExpression.NodeType == ExpressionType.GreaterThan)
{
var l = ToInt(left.As <ConstantExpression>());
var r = ToInt(right.As <ConstantExpression>());
if (l != null)
{
return(Tuple.Create((int?)null, l));
}
if (r != null)
{
return(Tuple.Create(r + 1, (int?)null));
}
}
if (binaryExpression.NodeType == ExpressionType.GreaterThanOrEqual)
{
var l = ToInt(left.As <ConstantExpression>());
var r = ToInt(right.As <ConstantExpression>());
if (l != null)
{
return(Tuple.Create((int?)null, l + 1));
}
if (r != null)
{
return(Tuple.Create(r, (int?)null));
}
}
return(null);
}
public Set(Functor <T> condition) : this(new[] { new[] { condition } })
{
}