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use odbc_sys::{NO_TOTAL, NULL_DATA};
/// Indicates existence and length of a value.
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum Indicator {
/// Field does not exist
Null,
/// Field exists, but its length had not be reported by the driver.
NoTotal,
/// Fields exists. Value indicates number of bytes required to store the value. In case of
/// truncated data, this is the true length of the data, before truncation occurred.
Length(usize),
}
impl Indicator {
/// Creates an indicator from an `isize` indicator value returned by ODBC. Users of this crate
/// have likely no need to call this method.
pub fn from_isize(indicator: isize) -> Self {
match indicator {
NULL_DATA => Indicator::Null,
NO_TOTAL => Indicator::NoTotal,
other => Indicator::Length(other.try_into().expect(
"Length indicator must be non-negative. This is not necessarily a programming \
error, in the application. If you are on a 64Bit platfrom and the isize value has \
been returned by the driver there may be a better exlpanation for what went wrong: \
In the past some driver managers and drivers assumed SQLLEN to be 32Bits even on \
64Bit platforms. Please ask your vendor for a version of the driver which is \
correctly build using 64Bits for SQLLEN.",
)),
}
}
/// Creates an indicator value as required by the ODBC C API.
pub fn to_isize(self) -> isize {
match self {
Indicator::Null => NULL_DATA,
Indicator::NoTotal => NO_TOTAL,
Indicator::Length(len) => len.try_into().unwrap(),
}
}
/// Does this indicator imply truncation for a value of the given length?
///
/// `length_in_buffer` is specified in bytes without terminating zeroes.
pub fn is_truncated(self, length_in_buffer: usize) -> bool {
match self {
Indicator::Null => false,
Indicator::NoTotal => true,
Indicator::Length(complete_length) => complete_length > length_in_buffer,
}
}
/// Only `true` if the indicator is the equivalent to [`odbc_sys::NULL_DATA`], indicating a
/// non-existing value.
pub fn is_null(self) -> bool {
match self {
Indicator::Null => true,
Indicator::NoTotal | Indicator::Length(_) => false,
}
}
/// If the indicator is [`Indicator::Length`] this is [`Some`].
pub fn length(self) -> Option<usize> {
if let Indicator::Length(len) = self {
Some(len)
} else {
None
}
}
}