public TokensTape ExecuteMostPriorityOperation(TokensTape tokensTape)
{
var @operator = FindMostPriorityOperator(tokensTape);
if (@operator.Previous == null ||
@operator.Next == null)
{
throw new Exception("Wrong tokens input!");
}
var left = (Number)@operator.Previous.Value;
var right = (Number)@operator.Next.Value;
var mathOperation = (IMathOperation)@operator.Value;
var result = mathOperation.ExecuteBinary(left, right);
var replacement = new[]
{
@operator.Previous,
@operator.Next,
@operator
};
var newTokens = Replace(replacement, result, tokensTape);
var newTape = new TokensTape(newTokens);
return(newTape);
}
private LinkedListNode <IToken> FindMostPriorityOperator(TokensTape tokensTape)
{
var operators = tokensTape.Enumerate()
.Where(x => x.Value is IMathOperation)
.ToArray();
var maxPriority = operators.Max(x => x.Value.Priority);
return(operators
.First(o => o.Value.Priority == maxPriority));
}
private IEnumerable <IToken> Replace(LinkedListNode <IToken>[] replacement, IToken result, TokensTape tokensTape)
{
foreach (var token in tokensTape.Enumerate())
{
if (token == replacement.First())
{
yield return(result);
}
if (replacement.Any(r => r == token))
{
continue;
}
yield return(token.Value);
}
}
