Error handling

Error handling

In case of an error the libraryL provide similar methods for querying the information associated with the error. This information will be in the properties of a ParserError exception object thrown by the parser.

These properties are:

• exception.Message - returns the error message.
• exception.Expr - returns the current formula (if a formula is set)
• exception.Token - returns the token associated with the error (if applicable)
• exception.Pos - returns the current formula position (if applicable)
• exception.Code - returns the error code.

The following table lists the parser error codes. The first column contains the enumeration values as defined in the enumeration ErrorCodes. The second column lists their numeric code and the third column contains the error description.

Enumeration name	Value	Description
UNEXPECTED_OPERATOR	0	Unexpected binary operator found
UNASSIGNABLE_TOKEN	1	Token cant be identified
UNEXPECTED_EOF	2	Unexpected end of formula. (Example: "2+sin(")
UNEXPECTED_ARG_SEP	3	An unexpected argument separator has been found. (Example: "1,23")
UNEXPECTED_ARG	4	An unexpected argument has been found
UNEXPECTED_VAL	5	An unexpected value token has been found
UNEXPECTED_VAR	6	An unexpected variable token has been found
UNEXPECTED_PARENS	7	Unexpected parenthesis, opening or closing
UNEXPECTED_STR	8	A string has been found at an inapropriate position
STRING_EXPECTED	9	A string function has been called with a different type of argument
VAL_EXPECTED	10	A numerical function has been called with a non value type of argument
MISSING_PARENS	11	Missing parens. (Example: "3*sin(3")
UNEXPECTED_FUN	12	Unexpected function found. (Example: "sin(8)cos(9)")
UNTERMINATED_STRING	13	unterminated string constant. (Example: "3*valueof("hello)")
TOO_MANY_PARAMS	14	Too many function parameters
TOO_FEW_PARAMS	15	Too few function parameters. (Example: "ite(1<2,2)")
OPRT_TYPE_CONFLICT	16	binary operators may only be applied to value items of the same type
STR_RESULT	17	result is a string
INVALID_NAME	18	Invalid function, variable or constant name.
INVALID_BINOP_IDENT	19	Invalid binary operator identifier.
INVALID_INFIX_IDENT	20	Invalid infix operator identifier.
INVALID_POSTFIX_IDENT	21	Invalid postfix operator identifier.
BUILTIN_OVERLOAD	22	Trying to overload builtin operator
INVALID_FUN_PTR	23	Invalid callback function pointer
INVALID_VAR_PTR	24	Invalid variable pointer
EMPTY_EXPRESSION	25	The expression string is empty
NAME_CONFLICT	26	Name conflict
OPT_PRI	27	Invalid operator priority
DOMAIN_ERROR	28	catch division by zero, sqrt(-1), log(0) (currently unused)
DIV_BY_ZERO	29	Division by zero (currently unused)
GENERIC	30	Error that does not fit any other code but is not an internal error
LOCALE	31	Conflict with current locale
UNEXPECTED_CONDITIONAL	32	Unexpected if then else operator
MISSING_ELSE_CLAUSE	33	Missing else clause
MISPLACED_COLON	34	Misplaced colon
INTERNAL_ERROR	35	Internal error of any kind.

In case of an error the parser raises an exception of type ParserError. This class provides you with several member functions that allow querying the exact cause as well as additional information for the error.

try
{
    ...
    parser.Eval();
    ...
}
catch(ParserError e)
{
    Console.WriteLine(e.Message);
    Console.WriteLine(e.Expr);
    Console.WriteLine(e.Pos);
    Console.WriteLine(e.Token);
    Console.WriteLine(e.Code);
}