/// <summary>
/// Reads an operator from the given string expression, starting at the given position.
/// </summary>
/// <param name="expr">The expression to read the operator from.</param>
/// <param name="pos">The position to start reading at.</param>
/// <returns>The result of the read.</returns>
internal ReadResult ReadOperator(string expr, int pos)
{
ReadResult result = new ReadResult() { Position = pos };
char c = expr[pos];
if (!char.IsWhiteSpace(c))
{
IOperationProvider provider = this.providerFactory.GetProvider(c);
if (provider != null)
{
result.Token = provider.CreateOperator(c);
result.Position = pos + 1;
result.Success = true;
}
}
return result;
}
internal ReadResult ReadOperand(string expr, int pos)
{
ReadResult result = new ReadResult() { Position = pos };
StringBuilder sb = new StringBuilder();
bool hasPeriod = false;
char c;
do
{
c = expr[pos];
if (char.IsDigit(c))
{
sb.Append(c);
pos++;
}
else if (c == '.')
{
if (!hasPeriod)
{
sb.Append(c);
pos++;
hasPeriod = true;
}
else
{
break;
}
}
else
{
break;
}
}
while (pos < expr.Length);
if (sb.Length > 0)
{
try
{
if (hasPeriod)
{
result.Token = new Operand(double.Parse(sb.ToString(), CultureInfo.InvariantCulture));
}
else
{
result.Token = new Operand(long.Parse(sb.ToString(), CultureInfo.InvariantCulture));
}
result.Position = pos;
result.Success = true;
}
catch (FormatException)
{
}
catch (OverflowException)
{
}
}
return result;
}