public override string ToString()
{
if (Function is ArithmeticBinaryFunction)
{
return($"{LeftBracket.GetInstance()}{_terms[0]}{Function}{_terms[1]}{RightBracket.GetInstance()}");
}
return($"{Function}{LeftBracket.GetInstance()}{string.Join<Term>(Comma.GetInstance().ToString(), _terms)}{RightBracket.GetInstance()}");
}
public override string ToString()
{
if (Predicate is ArithmeticPredicate)
{
return($"{LeftBracket.GetInstance()}{_terms[0]}{Predicate}{_terms[1]}{RightBracket.GetInstance()}");
}
return($"{Predicate}{LeftBracket.GetInstance()}{string.Join<Term>(Comma.GetInstance().ToString(), _terms)}{RightBracket.GetInstance()}");
}
private static IEnumerable <Symbol> ToSymbols(string str)
{
var index = 0;
var isLastForUnaryMinus = true;
while (index < str.Length)
{
switch (str[index])
{
case ' ':
++index;
continue;
case '(':
yield return(LeftBracket.GetInstance());
isLastForUnaryMinus = true;
++index;
continue;
case ')':
yield return(RightBracket.GetInstance());
isLastForUnaryMinus = false;
++index;
continue;
case ',':
yield return(Comma.GetInstance());
isLastForUnaryMinus = true;
++index;
continue;
case '\\':
yield return(SpecialSymbol(str, ref index));
isLastForUnaryMinus = true;
continue;
}
if (char.IsLetter(str[index]))
{
yield return(LetterSymbol(str, ref index));
isLastForUnaryMinus = false;
continue;
}
if (char.IsDigit(str[index]))
{
yield return(DigitSymbol(str, ref index));
isLastForUnaryMinus = false;
continue;
}
if (IsArithmeticPredicate(str[index]))
{
yield return(ArithmeticPredicateSymbol(str, ref index));
isLastForUnaryMinus = true;
continue;
}
if (str[index] == '-')
{
if (isLastForUnaryMinus)
{
yield return(UnaryMinus.GetInstance());
++index;
continue;
}
}
if (IsArithmeticBinaryFunction(str[index]))
{
yield return(ArithmeticBinaryFunctionSymbol(str, ref index));
isLastForUnaryMinus = true;
continue;
}
throw new ArgumentException($"the symbol {str[index]} with the number {index} is unexpected");
}
}