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#ifndef NETDATA_EVAL_H
#define NETDATA_EVAL_H
#define EVAL_MAX_VARIABLE_NAME_LENGTH 300
typedef struct eval_variable {
char *name;
uint32_t hash;
struct rrdvar *rrdvar;
struct eval_variable *next;
} EVAL_VARIABLE;
typedef struct eval_expression {
const char *source;
const char *parsed_as;
RRDCALC_STATUS *status;
calculated_number *this;
time_t *after;
time_t *before;
calculated_number result;
int error;
BUFFER *error_msg;
// hidden EVAL_NODE *
void *nodes;
// custom data to be used for looking up variables
struct rrdcalc *rrdcalc;
} EVAL_EXPRESSION;
#define EVAL_VALUE_INVALID 0
#define EVAL_VALUE_NUMBER 1
#define EVAL_VALUE_VARIABLE 2
#define EVAL_VALUE_EXPRESSION 3
// parsing and evaluation
#define EVAL_ERROR_OK 0
// parsing errors
#define EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION 1
#define EVAL_ERROR_UNKNOWN_OPERAND 2
#define EVAL_ERROR_MISSING_OPERAND 3
#define EVAL_ERROR_MISSING_OPERATOR 4
#define EVAL_ERROR_REMAINING_GARBAGE 5
#define EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE 6
// evaluation errors
#define EVAL_ERROR_INVALID_VALUE 101
#define EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS 102
#define EVAL_ERROR_VALUE_IS_NAN 103
#define EVAL_ERROR_VALUE_IS_INFINITE 104
#define EVAL_ERROR_UNKNOWN_VARIABLE 105
// parse the given string as an expression and return:
// a pointer to an expression if it parsed OK
// NULL in which case the pointer to error has the error code
extern EVAL_EXPRESSION *expression_parse(const char *string, const char **failed_at, int *error);
// free all resources allocated for an expression
extern void expression_free(EVAL_EXPRESSION *op);
// convert an error code to a message
extern const char *expression_strerror(int error);
// evaluate an expression and return
// 1 = OK, the result is in: expression->result
// 2 = FAILED, the error message is in: buffer_tostring(expression->error_msg)
extern int expression_evaluate(EVAL_EXPRESSION *expression);
#endif //NETDATA_EVAL_H
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