Struct ReverseKeyCursor 

pub struct ReverseKeyCursor<'a, C: ?Sized, K: ?Sized, V: ?Sized, R: ?Sized> { /* private fields */ }

Cursor that reverses the direction of keys in the underlying cursor.

WARNING: This cursor iterates over keys in descending order, and thus will not work correctly with code that assumes monotonically growing keys.

Implementations

impl<'a, C, K: ?Sized, V: ?Sized, R: ?Sized> ReverseKeyCursor<'a, C, K, V, R>

where C: Cursor<K, V, (), R> + ?Sized,

pub fn new(cursor: &'a mut C) -> Self

Trait Implementations

impl<C, K: ?Sized, V: ?Sized, R: WeightTrait + ?Sized> Cursor<K, V, (), R> for ReverseKeyCursor<'_, C, K, V, R>

where C: Cursor<K, V, (), R> + ?Sized,

fn weight_factory(&self) -> &'static dyn Factory<R>

fn key_valid(&self) -> bool

Indicates if the current key is valid.

fn val_valid(&self) -> bool

Indicates if the current value is valid.

fn key(&self) -> &K

A reference to the current key. Panics if invalid.

fn val(&self) -> &V

A reference to the current value. Panics if invalid.

fn get_key(&self) -> Option<&K>

Returns a reference to the current key, if valid.

fn get_val(&self) -> Option<&V>

Returns a reference to the current value, if valid.

fn map_times(&mut self, logic: &mut dyn FnMut(&(), &R))

Applies logic to each pair of time and difference. Intended for mutation of the closure’s scope.

fn map_times_through(&mut self, upper: &(), logic: &mut dyn FnMut(&(), &R))

Applies logic to each pair of time and difference, restricted to times t <= upper.

fn weight(&mut self) -> &R

Returns the weight associated with the current key/value pair. This concept only makes sense for cursors with unit timestamp type (T=()), since otherwise there is no singular definition of weight. This method is more convenient, and may be more efficient, than the equivalent call to Self::map_times.

fn weight_checked(&mut self) -> &R

Returns the weight associated with the current key/value pair is T is (); panics otherwise.

fn map_values(&mut self, logic: &mut dyn FnMut(&V, &R))

Apply a function to all values associated with the current key.

fn step_key(&mut self)

Advances the cursor to the next key.

fn step_key_reverse(&mut self)

Moves the cursor to the previous key.

fn seek_key(&mut self, key: &K)

Advances the cursor to the specified key. If key itself is not present, advances to the first key greater than key; if there is no such key, the cursor becomes invalid.

fn seek_key_exact(&mut self, _key: &K, _hash: Option<u64>) -> bool

Looks up the specified key and returns true if it is present.

fn seek_key_with(&mut self, predicate: &dyn Fn(&K) -> bool)

Advances the cursor to the first key that satisfies predicate. Assumes that predicate remains true once it turns true.

fn seek_key_with_reverse(&mut self, predicate: &dyn Fn(&K) -> bool)

Move the cursor backward to the first key that satisfies predicate. Assumes that predicate remains true once it turns true.

fn seek_key_reverse(&mut self, key: &K)

Moves the cursor backward to the specified key. If key itself is not present, moves backward to the first key less than key; if there is no such key, the cursor becomes invalid.

fn step_val(&mut self)

Advances the cursor to the next value.

fn step_val_reverse(&mut self)

Moves the cursor to the previous value.

fn seek_val(&mut self, val: &V)

Advances the cursor to the specified value.

fn seek_val_reverse(&mut self, val: &V)

Moves the cursor back to the specified value.

fn seek_val_with(&mut self, predicate: &dyn Fn(&V) -> bool)

Move the cursor to the first value (for the current key) that satisfies predicate. Assumes that predicate remains true once it turns true.

fn seek_val_with_reverse(&mut self, predicate: &dyn Fn(&V) -> bool)

Move the cursor back to the largest value (for the current key) that satisfies predicate. Assumes that predicate remains true once it turns true.

fn rewind_keys(&mut self)

Rewinds the cursor to the first key.

fn fast_forward_keys(&mut self)

Moves the cursor to the last key.

fn rewind_vals(&mut self)

Rewinds the cursor to the first value for current key.

fn fast_forward_vals(&mut self)

Move the cursor to the last value for the current key.

fn position(&self) -> Option<Position>

fn keyval_valid(&self) -> bool

Reports whether the current (key, value) pair is valid. Returns false if the cursor has exhausted all pairs.

fn keyval(&self) -> (&K, &V)

Returns current (key, value) pair. Panics if invalid.

fn step_keyval(&mut self)

Moves the cursor to the next (key, value) pair.

fn step_keyval_reverse(&mut self)

Moves the cursor to the previous (key, value) pair.

fn seek_keyval(&mut self, key: &K, val: &V)

where K: PartialEq,

Advance the cursor to the specified (key, value) pair.

fn seek_keyval_reverse(&mut self, key: &K, val: &V)

where K: PartialEq,

Moves the cursor back to the specified (key, value) pair.