public void Operate()
{
var expressionParent = (Expression)Parent;
var operatorIndex = expressionParent.Children.IndexOf(this);
var a = expressionParent.Children[operatorIndex - 1];
var b = expressionParent.Children[operatorIndex + 1];
expressionParent.Children.RemoveRange(operatorIndex - 1, 3);
if (a is Units && b is Units)
{
var aUnits = (Units)a;
var bUnits = (Units)b;
var result = new Units(expressionParent) { Amount = (aUnits.Amount * bUnits.Amount), Unit = aUnits.Unit };
expressionParent.Children.Insert(operatorIndex - 1, result);
}
}
internal static bool TryParse(Node parent, Queue<Word> remainingWords, out Units units)
{
int firstDigit;
if (!int.TryParse(remainingWords.Peek().Text.Substring(0,1), out firstDigit))
{
units = null;
return false;
}
var text = remainingWords.Dequeue().Text;
var index = 0;
while (index < text.Length &&
text.Substring(index, 1).IndexOfAny(numericCharacters) >= 0)
{
index++;
}
var amount = Decimal.Parse(text.Substring(0, index));
var unit = text.Substring(index);
units = new Units(parent) { Amount = amount, Unit = unit };
return true;
}