/// <summary>
/// Parses and extracts a numeric value at the current position
/// </summary>
/// <param name="parser">TextParser object</param>
/// <returns></returns>
protected string ParseNumberToken(TextParser parser)
{
bool hasDecimal = false;
int start = parser.Position;
while (Char.IsDigit(parser.Peek()) || parser.Peek() == '.')
{
if (parser.Peek() == '.')
{
if (hasDecimal)
{
throw new EvalException(ErrMultipleDecimalPoints, parser.Position);
}
hasDecimal = true;
}
parser.MoveAhead();
}
// Extract token
string token = parser.Extract(start, parser.Position);
if (token == ".")
{
throw new EvalException(ErrInvalidOperand, parser.Position - 1);
}
return(token);
}
/// <summary>
/// Parses and extracts a symbol at the current position
/// </summary>
/// <param name="parser">TextParser object</param>
/// <returns></returns>
protected string ParseSymbolToken(TextParser parser)
{
int start = parser.Position;
while (Char.IsLetterOrDigit(parser.Peek()) || parser.Peek() == '_')
{
parser.MoveAhead();
}
return(parser.Extract(start, parser.Position));
}
/// <summary>
/// Extracts and evaluates a function parameter and returns its value. If an
/// exception occurs, it is caught and the column is adjusted to reflect the
/// position in original string, and the exception is rethrown.
/// </summary>
/// <param name="parser">TextParser object</param>
/// <param name="paramStart">Column where this parameter started</param>
/// <returns></returns>
protected double EvaluateParameter(TextParser parser, int paramStart)
{
try
{
// Extract expression and evaluate it
string expression = parser.Extract(paramStart, parser.Position);
return(Execute(expression));
}
catch (EvalException ex)
{
// Adjust column and rethrow exception
ex.Column += paramStart;
throw ex;
}
}
/// <summary>
/// Extracts and evaluates a function parameter and returns its value. If an
/// exception occurs, it is caught and the column is adjusted to reflect the
/// position in original string, and the exception is rethrown.
/// </summary>
/// <param name="parser">TextParser object</param>
/// <param name="paramStart">Column where this parameter started</param>
/// <returns></returns>
protected double EvaluateParameter(TextParser parser, int paramStart) {
try {
// Extract expression and evaluate it
string expression = parser.Extract(paramStart, parser.Position);
return Execute(expression);
}
catch(EvalException ex) {
// Adjust column and rethrow exception
ex.Column += paramStart;
throw ex;
}
}
/// <summary>
/// Parses and extracts a symbol at the current position
/// </summary>
/// <param name="parser">TextParser object</param>
/// <returns></returns>
protected string ParseSymbolToken(TextParser parser) {
int start = parser.Position;
while(Char.IsLetterOrDigit(parser.Peek()) || parser.Peek() == '_')
parser.MoveAhead();
return parser.Extract(start, parser.Position);
}
/// <summary>
/// Parses and extracts a numeric value at the current position
/// </summary>
/// <param name="parser">TextParser object</param>
/// <returns></returns>
protected string ParseNumberToken(TextParser parser) {
bool hasDecimal = false;
int start = parser.Position;
while(Char.IsDigit(parser.Peek()) || parser.Peek() == '.') {
if(parser.Peek() == '.') {
if(hasDecimal)
throw new EvalException(ErrMultipleDecimalPoints, parser.Position);
hasDecimal = true;
}
parser.MoveAhead();
}
// Extract token
string token = parser.Extract(start, parser.Position);
if(token == ".")
throw new EvalException(ErrInvalidOperand, parser.Position - 1);
return token;
}