private bool TryNumber(char lastChar)
{
bool isNumber = NumberExpression.IsNumber(_currentChar);
// only negative when last char is group start or symbol
bool isNegative = NumberExpression.IsNegativeSign(_currentChar) &&
(lastChar == '\0' || OperatorExpression.IsSymbol(lastChar));
if (!isNumber && !isNegative)
{
return(false);
}
_buffer.Length = 0;
_buffer.Append(_currentChar);
char p = (char)_expressionReader.Peek();
while (NumberExpression.IsNumber(p))
{
_currentChar = (char)_expressionReader.Read();
_buffer.Append(_currentChar);
p = (char)_expressionReader.Peek();
}
if (!(double.TryParse(_buffer.ToString(), out double value)))
{
throw new ParseException(Resources.InvalidNumberFormat + _buffer);
}
NumberExpression expression = new NumberExpression(value);
_expressionQueue.Enqueue(expression);
return(true);
}
private bool TryString()
{
if (!char.IsLetter(_currentChar))
{
return(false);
}
_buffer.Length = 0;
_buffer.Append(_currentChar);
char p = (char)_expressionReader.Peek();
while (char.IsLetter(p) || char.IsNumber(p))
{
_buffer.Append((char)_expressionReader.Read());
p = (char)_expressionReader.Peek();
}
if (_variables.ContainsKey(_buffer.ToString()))
{
double value = _variables[_buffer.ToString()];
NumberExpression expression = new NumberExpression(value);
_expressionQueue.Enqueue(expression);
return(true);
}
throw new ParseException(Resources.InvalidVariableEncountered + _buffer);
}