Struct fdb::KeySelector
source · [−]pub struct KeySelector { /* private fields */ }
Expand description
KeySelector
identifies a particular key in the database.
FDB’s lexicographically ordered data model permits finding keys
based on their order (for example, finding the first key in the
database greater than a given key). Key selectors represent a
description of a key in the database that could be resolved to an
actual key by transaction’s get_key
or used directly as the
beginning or end of a range in transaction’s get_range
.
For more about how key selectors work in practive, see the key selector
documentation. Note that the way key selectors are
resolved is somewhat non-intuitive, so users who wish to use a key
selector other than the default ones described below should
probably consult that documentation before proceeding.
Generally one of the following methods should be used to construct
a KeySelector
.
This is an immutable type. The add(i32)
call does not modify
internal state, but returns a new value.
Implementations
sourceimpl KeySelector
impl KeySelector
sourcepub fn new(key: impl Into<Key>, or_equal: bool, offset: i32) -> KeySelector
pub fn new(key: impl Into<Key>, or_equal: bool, offset: i32) -> KeySelector
Create a new KeySelector
from the given parameters.
sourcepub fn add(self, offset: i32) -> KeySelector
pub fn add(self, offset: i32) -> KeySelector
Returns a new KeySelector
offset by a given number of keys
from this one.
sourcepub fn first_greater_or_equal(key: impl Into<Key>) -> KeySelector
pub fn first_greater_or_equal(key: impl Into<Key>) -> KeySelector
Creates a KeySelector
that picks the first key greater
than or equal to the parameter.
sourcepub fn first_greater_than(key: impl Into<Key>) -> KeySelector
pub fn first_greater_than(key: impl Into<Key>) -> KeySelector
Creates a KeySelector
that picks the first key greater
than or equal to the parameter.
sourcepub fn get_key(&self) -> &Key
pub fn get_key(&self) -> &Key
Returns a reference to the key that serves as the anchor for
this KeySelector
.
sourcepub fn get_offset(&self) -> i32
pub fn get_offset(&self) -> i32
Returns the key offset parameter for this KeySelector
.
sourcepub fn last_less_or_equal(key: impl Into<Key>) -> KeySelector
pub fn last_less_or_equal(key: impl Into<Key>) -> KeySelector
Creates a KeySelector
that picks the last key less than or
equal to the parameter.
sourcepub fn last_less_than(key: impl Into<Key>) -> KeySelector
pub fn last_less_than(key: impl Into<Key>) -> KeySelector
Creates a KeySelector
that picks the last key less than the parameter.
Trait Implementations
sourceimpl Clone for KeySelector
impl Clone for KeySelector
sourcefn clone(&self) -> KeySelector
fn clone(&self) -> KeySelector
Returns a copy of the value. Read more
1.0.0 · sourcefn clone_from(&mut self, source: &Self)
fn clone_from(&mut self, source: &Self)
Performs copy-assignment from source
. Read more
Auto Trait Implementations
impl RefUnwindSafe for KeySelector
impl Send for KeySelector
impl Sync for KeySelector
impl Unpin for KeySelector
impl UnwindSafe for KeySelector
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<T> ToOwned for T where
T: Clone,
impl<T> ToOwned for T where
T: Clone,
type Owned = T
type Owned = T
The resulting type after obtaining ownership.
sourcefn clone_into(&self, target: &mut T)
fn clone_into(&self, target: &mut T)
toowned_clone_into
)Uses borrowed data to replace owned data, usually by cloning. Read more