private FormulaParser(string formula)
{
StringBuilder buffer = new StringBuilder();
foreach (char c in formula)
{
if (char.IsWhiteSpace(c) && buffer.Length == 0)
{
continue;
}
bool canBe1 = FormulaElement.CanBeElement(buffer.ToString(), out FormulaElement elem);
bool canBe2 = FormulaElement.CanBeElement(buffer.ToString() + c);
if (canBe1 && !canBe2)
{
if (elem is object)
{
AddNextElement(elem);
buffer.Clear();
if (!char.IsWhiteSpace(c))
{
buffer.Append(c);
}
}
else
{
throw new ParseException();
}
}
else if (canBe1 && canBe2)
{
buffer.Append(c);
}
else
{
throw new ParseException();
}
}
if (buffer.Length > 0)
{
FormulaElement.CanBeElement(buffer.ToString(), out FormulaElement elem);
if (elem is object)
{
AddNextElement(elem);
}
else
{
throw new ParseException($"Error parse \"{buffer}\" at the end of formula.");
}
}
EndParse();
}
private void AddNext(Bracket bracket)
{
if (bracket.IsOpen)
{
if (_prevElement is Variable || IsCloseBracket(_prevElement))
{
throw new LogicException("Before open bracket can not be variable or close bracket.");
}
_operationsStack.Push(bracket);
}
else
{
if (!(_prevElement is Variable || IsCloseBracket(_prevElement)))
{
throw new LogicException("Before close bracket can be only variable or close bracket.");
}
while (true)
{
if (_operationsStack.Count == 0)
{
throw new LogicException("For close bracket not found open bracket.");
}
FormulaElement next = _operationsStack.Pop();
if (next is Bracket openBracket)
{
if (Bracket.IsPair(openBracket, bracket))
{
break;
}
else
{
throw new LogicException("Wrong brackets arrangement.");
}
}
else if (next is Operation)
{
_resultStack.Push(next);
}
}
}
}
private void AddNextElement(FormulaElement element)
{
switch (element)
{
case BinOp op:
AddNext(op);
break;
case UnaryOp op:
AddNext(op);
break;
case Variable variable:
AddNext(variable);
break;
case Bracket bracket:
AddNext(bracket);
break;
}
_prevElement = element;
}
private void EndParse()
{
if (_prevElement is null)
{
throw new ParseException("Empty formula.");
}
if (_prevElement is BinOp || _prevElement is UnaryOp || IsOpenBracket(_prevElement))
{
throw new LogicException("The last element of formula can not be binary operation, unary operation or open bracket.");
}
while (_operationsStack.Count > 0)
{
FormulaElement next = _operationsStack.Pop();
if (next is Bracket)
{
throw new LogicException("Open bracket without close bracket.");
}
else if (next is Operation)
{
_resultStack.Push(next);
}
}
}
private FormulaTable()
{
m_mapElements = new Dictionary <int, FormulaElement>();
m_emptyItem = new FormulaElement();
m_vecAllElements = new List <FormulaElement>();
}
private bool IsCloseBracket(FormulaElement element)
{
return((element is Bracket bracket) && !bracket.IsOpen);
}
