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#ifndef BOKF_FORMULA_H
#define BOKF_FORMULA_H
#include <stddef.h>
#include <stdint.h>
/* Tiny, deterministic expression evaluator for voucher templates.
Grammar: expr := term (('+'|'-') term)*
term := factor (('*'|'/') factor)*
factor := ('+'|'-') factor | primary
primary := number | 'x' | '(' expr ')'
Values are kronor as double; x is the template variable in kronor. */
struct template_row {
const char *account; /* account number */
const char *formula;
const char *description; /* optional */
};
struct resolved_row {
char account[16];
int64_t debit_ore;
int64_t credit_ore;
char description[128];
};
/* Returns 0 on success and stores the value in *out_kr. On error returns
-1 and writes a message to errbuf. */
int formula_eval(const char *formula, double x, double *out_kr, char *errbuf,
size_t errlen);
/* Evaluates all rows with x, rounds to whole öre, drops zero rows, and
assigns the rounding remainder to the largest row so debit equals credit.
Returns 0 on success and sets *out_n. Errors (bad formula, too few
rows) are reported in errbuf. */
int formula_resolve_rows(const struct template_row *rows, size_t nrows,
double x, struct resolved_row *out, size_t *out_n,
char *errbuf, size_t errlen);
/* True when the formula parses (evaluated with x = 1). */
int formula_valid(const char *formula);
#endif
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