pub unsafe trait LmdbOrdKey: FromLmdbBytes + Ord {
// Provided methods
fn ordered_by_bytes() -> bool { ... }
fn ordered_as_integer() -> bool { ... }
}Expand description
Trait describing a value which can be used as an LMDB key by having LMDB
call into the value’s Ord implementation.
§Unsafety
Behaviour is undefined if the FromLmdbBytes or Ord implementations
panic.
Provided Methods§
Sourcefn ordered_by_bytes() -> bool
fn ordered_by_bytes() -> bool
Returns whether the default LMDB byte-by-byte comparison is correct for valid values of this type.
Generally, one should not specifically use
DatabaseOptions::sort_values_as and so forth for types where this is
the case. This function exists to support generic code wishing to avoid
the conversion overhead when the types happen to already be
byte-comparable.
Note that if this returns true, that does not mean that byte
comparison is exactly equivalent to Ord-based comparison. For
example, invalid str instances sort before valid ones and are equal
to each other, but byte comparison will intermingle them. Because of
this, DatabaseOptions::sort_values_as and similar do not make
decisions based on this value; it is the client code’s responsibility
to use this if so desired.
§Example
assert!(<u8 as LmdbOrdKey>::ordered_by_bytes());
assert!(!<i8 as LmdbOrdKey>::ordered_by_bytes());
assert!(<str as LmdbOrdKey>::ordered_by_bytes());
assert!(<[u8] as LmdbOrdKey>::ordered_by_bytes());
assert!(!<[i8] as LmdbOrdKey>::ordered_by_bytes());Sourcefn ordered_as_integer() -> bool
fn ordered_as_integer() -> bool
Returns whether LMDB will correctly handle this value with the
INTEGERKEY or INTEGERDUP flags.
There’s generally no reason to use sort_keys_as and so forth with
values where this is true instead of using the appropriate flags. This
function exists to support generic code which wants to make such
decisions automatically.
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.