private bool IsUnaryPrefix(StringToken token, Operator[] possibleOperators)
{
if (!possibleOperators.Any(x => x.Arity == Arity.Unary && x.Fixity == Fixity.Prefix))
{
return(false);
}
var isPrecededByOpenBracket = token.Previous != default &&
grammarService.OpenPriorityBracket.Denotations.Contains(token.Previous);
var isFollowedByOpenBracket = token.Next != default &&
grammarService.OpenPriorityBracket.Denotations.Contains(token.Next);
// like -1 - 2
// ^
var isPrefixCase1 = grammarService.IsOperand(token.Next) &&
token.Previous == StringToken.NonExistingOperator;
// like !a && !b
// ^
var isPrefixCase2 = grammarService.IsOperand(token.Next) &&
grammarService.IsOperator(token.Previous) &&
grammarService.IsUniqueByArity(token.Previous, Arity.Unary);
// like -(1 - 2)
// ^
var isPrefixCase3 = isFollowedByOpenBracket &&
token.Previous == StringToken.NonExistingOperator;
// like ( -(1 - 2))
// ^
var isPrefixCase4 = isPrecededByOpenBracket &&
grammarService.IsOperator(token.Current) &&
isFollowedByOpenBracket;
// like (-5)
// ^
var isPrefixCase5 = isPrecededByOpenBracket &&
grammarService.IsOperator(token.Current) &&
grammarService.IsOperand(token.Next);
return(isPrefixCase1 ||
isPrefixCase2 ||
isPrefixCase3 ||
isPrefixCase4 ||
isPrefixCase5);
}
