/// <summary>
/// Subtracts the right operand from the left one.
/// </summary>
/// <param name="Left">Left operand.</param>
/// <param name="Right">Right operand.</param>
/// <param name="Node">Node performing the operation.</param>
/// <returns>Result</returns>
public static IElement EvaluateSubtraction(IElement Left, IElement Right, ScriptNode Node)
{
IElement Result;
IGroupElement Temp;
if (Left is IGroupElement LE && Right is IGroupElement RE)
{
Temp = RE.Negate();
if (!(Temp is null))
{
Result = LE.AddRight(Temp);
if (!(Result is null))
{
return(Result);
}
Result = Temp.AddLeft(LE);
if (!(Result is null))
{
return(Result);
}
}
}
if (Left.IsScalar)
{
if (Right.IsScalar)
{
ISet LeftSet = Left.AssociatedSet;
ISet RightSet = Right.AssociatedSet;
if (!LeftSet.Equals(RightSet))
{
if (!Expression.UpgradeField(ref Left, ref LeftSet, ref Right, ref RightSet, Node))
{
throw new ScriptRuntimeException("Incompatible operands.", Node);
}
LE = Left as IGroupElement;
RE = Right as IGroupElement;
if (!(LE is null) && !(RE is null))
{
Temp = RE.Negate();
if (!(Temp is null))
{
Result = LE.AddRight(Temp);
if (!(Result is null))
{
return(Result);
}
Result = Temp.AddLeft(LE);
if (!(Result is null))
{
return(Result);
}
}
}
}
throw new ScriptRuntimeException("Operands cannot be subtracted.", Node);
}
else
{
LinkedList <IElement> Elements = new LinkedList <IElement>();
foreach (IElement RightChild in Right.ChildElements)
{
Elements.AddLast(EvaluateSubtraction(Left, RightChild, Node));
}
return(Right.Encapsulate(Elements, Node));
}
}
else
{
if (Right.IsScalar)
{
LinkedList <IElement> Elements = new LinkedList <IElement>();
foreach (IElement LeftChild in Left.ChildElements)
{
Elements.AddLast(EvaluateSubtraction(LeftChild, Right, Node));
}
return(Left.Encapsulate(Elements, Node));
}
else
{
ICollection <IElement> LeftChildren = Left.ChildElements;
ICollection <IElement> RightChildren = Right.ChildElements;
if (LeftChildren.Count == RightChildren.Count)
{
LinkedList <IElement> Elements = new LinkedList <IElement>();
IEnumerator <IElement> eLeft = LeftChildren.GetEnumerator();
IEnumerator <IElement> eRight = RightChildren.GetEnumerator();
try
{
while (eLeft.MoveNext() && eRight.MoveNext())
{
Elements.AddLast(EvaluateSubtraction(eLeft.Current, eRight.Current, Node));
}
}
finally
{
eLeft.Dispose();
eRight.Dispose();
}
return(Left.Encapsulate(Elements, Node));
}
else
{
LinkedList <IElement> LeftResult = new LinkedList <IElement>();
foreach (IElement LeftChild in LeftChildren)
{
LinkedList <IElement> RightResult = new LinkedList <IElement>();
foreach (IElement RightChild in RightChildren)
{
RightResult.AddLast(EvaluateSubtraction(LeftChild, RightChild, Node));
}
LeftResult.AddLast(Right.Encapsulate(RightResult, Node));
}
return(Left.Encapsulate(LeftResult, Node));
}
}
}
}
