// Internal helper method to hide the two constants GDBM_INSERT and
// GDBM_REPLACE from the user.
func (db *Database) update(key string, value string, flag C.int) (err error) {
// Convert key and value into libgdbm's `datum` data structure. See the
// C definition at the top for the implementation of C.mk_datum(string).
kcs := C.CString(key)
vcs := C.CString(value)
k := C.mk_datum(kcs)
v := C.mk_datum(vcs)
defer C.free(unsafe.Pointer(kcs))
defer C.free(unsafe.Pointer(vcs))
retv := C.gdbm_store(db.dbf, k, v, flag)
if retv != 0 {
err = lastError()
}
return err
}
// Removes a key-value pair from the database. If the database is opened in "r"
// mode, an error is returned
func (db *Database) Delete(key string) (err error) {
kcs := C.CString(key)
k := C.mk_datum(kcs)
defer C.free(unsafe.Pointer(kcs))
retv := C.gdbm_delete(db.dbf, k)
if retv == -1 && db.mode == C.GDBM_READER {
err = lastError()
}
return err
}
// Returns true or false, depending on whether the specified key exists in the
// database.
func (db *Database) Exists(key string) bool {
kcs := C.CString(key)
k := C.mk_datum(kcs)
defer C.free(unsafe.Pointer(kcs))
e := C.gdbm_exists(db.dbf, k)
if e == 1 {
return true
}
return false
}
// Fetches the value of the given key. If the key is not in the database, an
// error will be returned in err. Otherwise, value will be the value string
// that is keyed by `key`.
func (db *Database) Fetch(key string) (value string, err error) {
kcs := C.CString(key)
k := C.mk_datum(kcs)
defer C.free(unsafe.Pointer(kcs))
vdatum := C.gdbm_fetch(db.dbf, k)
if vdatum.dptr == nil {
return "", lastError()
}
value = C.GoStringN(vdatum.dptr, vdatum.dsize)
defer C.free(unsafe.Pointer(vdatum.dptr))
return value, nil
}