pub struct BoundedBTreeMap<K, V, S>(_, _);
Expand description

A bounded map based on a B-Tree.

B-Trees represent a fundamental compromise between cache-efficiency and actually minimizing the amount of work performed in a search. See BTreeMap for more details.

Unlike a standard BTreeMap, there is an enforced upper limit to the number of items in the map. All internal operations ensure this bound is respected.

Implementations§

Get the bound of the type in usize.

Examples found in repository?
src/bounded/bounded_btree_map.rs (line 94)
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	pub fn into_inner(self) -> BTreeMap<K, V> {
		debug_assert!(self.0.len() <= Self::bound());
		self.0
	}

	/// Consumes self and mutates self via the given `mutate` function.
	///
	/// If the outcome of mutation is within bounds, `Some(Self)` is returned. Else, `None` is
	/// returned.
	///
	/// This is essentially a *consuming* shorthand [`Self::into_inner`] -> `...` ->
	/// [`Self::try_from`].
	pub fn try_mutate(mut self, mut mutate: impl FnMut(&mut BTreeMap<K, V>)) -> Option<Self> {
		mutate(&mut self.0);
		(self.0.len() <= Self::bound()).then(move || self)
	}

	/// Clears the map, removing all elements.
	pub fn clear(&mut self) {
		self.0.clear()
	}

	/// Return a mutable reference to the value corresponding to the key.
	///
	/// The key may be any borrowed form of the map's key type, but the ordering on the borrowed
	/// form _must_ match the ordering on the key type.
	pub fn get_mut<Q>(&mut self, key: &Q) -> Option<&mut V>
	where
		K: Borrow<Q>,
		Q: Ord + ?Sized,
	{
		self.0.get_mut(key)
	}

	/// Exactly the same semantics as [`BTreeMap::insert`], but returns an `Err` (and is a noop) if
	/// the new length of the map exceeds `S`.
	///
	/// In the `Err` case, returns the inserted pair so it can be further used without cloning.
	pub fn try_insert(&mut self, key: K, value: V) -> Result<Option<V>, (K, V)> {
		if self.len() < Self::bound() || self.0.contains_key(&key) {
			Ok(self.0.insert(key, value))
		} else {
			Err((key, value))
		}
	}

	/// Remove a key from the map, returning the value at the key if the key was previously in the
	/// map.
	///
	/// The key may be any borrowed form of the map's key type, but the ordering on the borrowed
	/// form _must_ match the ordering on the key type.
	pub fn remove<Q>(&mut self, key: &Q) -> Option<V>
	where
		K: Borrow<Q>,
		Q: Ord + ?Sized,
	{
		self.0.remove(key)
	}

	/// Remove a key from the map, returning the value at the key if the key was previously in the
	/// map.
	///
	/// The key may be any borrowed form of the map's key type, but the ordering on the borrowed
	/// form _must_ match the ordering on the key type.
	pub fn remove_entry<Q>(&mut self, key: &Q) -> Option<(K, V)>
	where
		K: Borrow<Q>,
		Q: Ord + ?Sized,
	{
		self.0.remove_entry(key)
	}

	/// Gets a mutable iterator over the entries of the map, sorted by key.
	///
	/// See [`BTreeMap::iter_mut`] for more information.
	pub fn iter_mut(&mut self) -> sp_std::collections::btree_map::IterMut<K, V> {
		self.0.iter_mut()
	}

	/// Consume the map, applying `f` to each of it's values and returning a new map.
	pub fn map<T, F>(self, mut f: F) -> BoundedBTreeMap<K, T, S>
	where
		F: FnMut((&K, V)) -> T,
	{
		BoundedBTreeMap::<K, T, S>::unchecked_from(
			self.0
				.into_iter()
				.map(|(k, v)| {
					let t = f((&k, v));
					(k, t)
				})
				.collect(),
		)
	}

	/// Consume the map, applying `f` to each of it's values as long as it returns successfully. If
	/// an `Err(E)` is ever encountered, the mapping is short circuited and the error is returned;
	/// otherwise, a new map is returned in the contained `Ok` value.
	pub fn try_map<T, E, F>(self, mut f: F) -> Result<BoundedBTreeMap<K, T, S>, E>
	where
		F: FnMut((&K, V)) -> Result<T, E>,
	{
		Ok(BoundedBTreeMap::<K, T, S>::unchecked_from(
			self.0
				.into_iter()
				.map(|(k, v)| (f((&k, v)).map(|t| (k, t))))
				.collect::<Result<BTreeMap<_, _>, _>>()?,
		))
	}
}

impl<K, V, S> Default for BoundedBTreeMap<K, V, S>
where
	K: Ord,
	S: Get<u32>,
{
	fn default() -> Self {
		Self::new()
	}
}

impl<K, V, S> Clone for BoundedBTreeMap<K, V, S>
where
	BTreeMap<K, V>: Clone,
{
	fn clone(&self) -> Self {
		BoundedBTreeMap(self.0.clone(), PhantomData)
	}
}

impl<K, V, S> sp_std::fmt::Debug for BoundedBTreeMap<K, V, S>
where
	BTreeMap<K, V>: sp_std::fmt::Debug,
	S: Get<u32>,
{
	fn fmt(&self, f: &mut sp_std::fmt::Formatter<'_>) -> sp_std::fmt::Result {
		f.debug_tuple("BoundedBTreeMap").field(&self.0).field(&Self::bound()).finish()
	}
}

impl<K, V, S1, S2> PartialEq<BoundedBTreeMap<K, V, S1>> for BoundedBTreeMap<K, V, S2>
where
	BTreeMap<K, V>: PartialEq,
	S1: Get<u32>,
	S2: Get<u32>,
{
	fn eq(&self, other: &BoundedBTreeMap<K, V, S1>) -> bool {
		S1::get() == S2::get() && self.0 == other.0
	}
}

impl<K, V, S> Eq for BoundedBTreeMap<K, V, S>
where
	BTreeMap<K, V>: Eq,
	S: Get<u32>,
{
}

impl<K, V, S> PartialEq<BTreeMap<K, V>> for BoundedBTreeMap<K, V, S>
where
	BTreeMap<K, V>: PartialEq,
{
	fn eq(&self, other: &BTreeMap<K, V>) -> bool {
		self.0 == *other
	}
}

impl<K, V, S> PartialOrd for BoundedBTreeMap<K, V, S>
where
	BTreeMap<K, V>: PartialOrd,
	S: Get<u32>,
{
	fn partial_cmp(&self, other: &Self) -> Option<sp_std::cmp::Ordering> {
		self.0.partial_cmp(&other.0)
	}
}

impl<K, V, S> Ord for BoundedBTreeMap<K, V, S>
where
	BTreeMap<K, V>: Ord,
	S: Get<u32>,
{
	fn cmp(&self, other: &Self) -> sp_std::cmp::Ordering {
		self.0.cmp(&other.0)
	}
}

impl<K, V, S> IntoIterator for BoundedBTreeMap<K, V, S> {
	type Item = (K, V);
	type IntoIter = sp_std::collections::btree_map::IntoIter<K, V>;

	fn into_iter(self) -> Self::IntoIter {
		self.0.into_iter()
	}
}

impl<'a, K, V, S> IntoIterator for &'a BoundedBTreeMap<K, V, S> {
	type Item = (&'a K, &'a V);
	type IntoIter = sp_std::collections::btree_map::Iter<'a, K, V>;

	fn into_iter(self) -> Self::IntoIter {
		self.0.iter()
	}
}

impl<'a, K, V, S> IntoIterator for &'a mut BoundedBTreeMap<K, V, S> {
	type Item = (&'a K, &'a mut V);
	type IntoIter = sp_std::collections::btree_map::IterMut<'a, K, V>;

	fn into_iter(self) -> Self::IntoIter {
		self.0.iter_mut()
	}
}

impl<K, V, S> MaxEncodedLen for BoundedBTreeMap<K, V, S>
where
	K: MaxEncodedLen,
	V: MaxEncodedLen,
	S: Get<u32>,
{
	fn max_encoded_len() -> usize {
		Self::bound()
			.saturating_mul(K::max_encoded_len().saturating_add(V::max_encoded_len()))
			.saturating_add(codec::Compact(S::get()).encoded_size())
	}
}

impl<K, V, S> Deref for BoundedBTreeMap<K, V, S>
where
	K: Ord,
{
	type Target = BTreeMap<K, V>;

	fn deref(&self) -> &Self::Target {
		&self.0
	}
}

impl<K, V, S> AsRef<BTreeMap<K, V>> for BoundedBTreeMap<K, V, S>
where
	K: Ord,
{
	fn as_ref(&self) -> &BTreeMap<K, V> {
		&self.0
	}
}

impl<K, V, S> From<BoundedBTreeMap<K, V, S>> for BTreeMap<K, V>
where
	K: Ord,
{
	fn from(map: BoundedBTreeMap<K, V, S>) -> Self {
		map.0
	}
}

impl<K, V, S> TryFrom<BTreeMap<K, V>> for BoundedBTreeMap<K, V, S>
where
	K: Ord,
	S: Get<u32>,
{
	type Error = ();

	fn try_from(value: BTreeMap<K, V>) -> Result<Self, Self::Error> {
		(value.len() <= Self::bound())
			.then(move || BoundedBTreeMap(value, PhantomData))
			.ok_or(())
	}

Exactly the same semantics as BTreeMap::retain.

The is a safe &mut self borrow because retain can only ever decrease the length of the inner map.

Create a new BoundedBTreeMap.

Does not allocate.

Examples found in repository?
src/bounded/bounded_btree_map.rs (line 210)
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	fn default() -> Self {
		Self::new()
	}

Consume self, and return the inner BTreeMap.

This is useful when a mutating API of the inner type is desired, and closure-based mutation such as provided by try_mutate is inconvenient.

Consumes self and mutates self via the given mutate function.

If the outcome of mutation is within bounds, Some(Self) is returned. Else, None is returned.

This is essentially a consuming shorthand Self::into_inner -> ... -> Self::try_from.

Clears the map, removing all elements.

Return a mutable reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Exactly the same semantics as BTreeMap::insert, but returns an Err (and is a noop) if the new length of the map exceeds S.

In the Err case, returns the inserted pair so it can be further used without cloning.

Remove a key from the map, returning the value at the key if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

source

pub fn remove_entry<Q>(&mut self, key: &Q) -> Option<(K, V)>where
    K: Borrow<Q>,
    Q: Ord + ?Sized,

Remove a key from the map, returning the value at the key if the key was previously in the map.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Gets a mutable iterator over the entries of the map, sorted by key.

See BTreeMap::iter_mut for more information.

Consume the map, applying f to each of it’s values and returning a new map.

Consume the map, applying f to each of it’s values as long as it returns successfully. If an Err(E) is ever encountered, the mapping is short circuited and the error is returned; otherwise, a new map is returned in the contained Ok value.

Methods from Deref<Target = BTreeMap<K, V>>§

Returns a reference to the value corresponding to the key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "a");
assert_eq!(map.get(&1), Some(&"a"));
assert_eq!(map.get(&2), None);

Returns the key-value pair corresponding to the supplied key.

The supplied key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples
use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "a");
assert_eq!(map.get_key_value(&1), Some((&1, &"a")));
assert_eq!(map.get_key_value(&2), None);

Returns the first key-value pair in the map. The key in this pair is the minimum key in the map.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
assert_eq!(map.first_key_value(), None);
map.insert(1, "b");
map.insert(2, "a");
assert_eq!(map.first_key_value(), Some((&1, &"b")));

Returns the last key-value pair in the map. The key in this pair is the maximum key in the map.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "b");
map.insert(2, "a");
assert_eq!(map.last_key_value(), Some((&2, &"a")));

Returns true if the map contains a value for the specified key.

The key may be any borrowed form of the map’s key type, but the ordering on the borrowed form must match the ordering on the key type.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.insert(1, "a");
assert_eq!(map.contains_key(&1), true);
assert_eq!(map.contains_key(&2), false);

Constructs a double-ended iterator over a sub-range of elements in the map. The simplest way is to use the range syntax min..max, thus range(min..max) will yield elements from min (inclusive) to max (exclusive). The range may also be entered as (Bound<T>, Bound<T>), so for example range((Excluded(4), Included(10))) will yield a left-exclusive, right-inclusive range from 4 to 10.

Panics

Panics if range start > end. Panics if range start == end and both bounds are Excluded.

Examples

Basic usage:

use std::collections::BTreeMap;
use std::ops::Bound::Included;

let mut map = BTreeMap::new();
map.insert(3, "a");
map.insert(5, "b");
map.insert(8, "c");
for (&key, &value) in map.range((Included(&4), Included(&8))) {
    println!("{key}: {value}");
}
assert_eq!(Some((&5, &"b")), map.range(4..).next());

Gets an iterator over the entries of the map, sorted by key.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut map = BTreeMap::new();
map.insert(3, "c");
map.insert(2, "b");
map.insert(1, "a");

for (key, value) in map.iter() {
    println!("{key}: {value}");
}

let (first_key, first_value) = map.iter().next().unwrap();
assert_eq!((*first_key, *first_value), (1, "a"));

Gets an iterator over the keys of the map, in sorted order.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut a = BTreeMap::new();
a.insert(2, "b");
a.insert(1, "a");

let keys: Vec<_> = a.keys().cloned().collect();
assert_eq!(keys, [1, 2]);

Gets an iterator over the values of the map, in order by key.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut a = BTreeMap::new();
a.insert(1, "hello");
a.insert(2, "goodbye");

let values: Vec<&str> = a.values().cloned().collect();
assert_eq!(values, ["hello", "goodbye"]);

Returns the number of elements in the map.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut a = BTreeMap::new();
assert_eq!(a.len(), 0);
a.insert(1, "a");
assert_eq!(a.len(), 1);

Returns true if the map contains no elements.

Examples

Basic usage:

use std::collections::BTreeMap;

let mut a = BTreeMap::new();
assert!(a.is_empty());
a.insert(1, "a");
assert!(!a.is_empty());

Trait Implementations§

Converts this type into a shared reference of the (usually inferred) input type.
Returns a copy of the value. Read more
Performs copy-assignment from source. Read more
Formats the value using the given formatter. Read more
Attempt to deserialise the value from input.
Attempt to skip the encoded value from input. Read more
Returns the fixed encoded size of the type. Read more
Return the number of elements in self_encoded.
Returns the “default value” for a type. Read more
The resulting type after dereferencing.
Dereferences the value.
Convert self to a slice and append it to the destination.
If possible give a hint of expected size of the encoding. Read more
Convert self to an owned vector.
Convert self to a slice and then invoke the given closure with it.
Calculates the encoded size. Read more
Converts to this type from the input type.
The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value. Read more
The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value. Read more
The type of the elements being iterated over.
Which kind of iterator are we turning this into?
Creates an iterator from a value. Read more
Upper bound, in bytes, of the maximum encoded size of this item.
This method returns an Ordering between self and other. Read more
Compares and returns the maximum of two values. Read more
Compares and returns the minimum of two values. Read more
Restrict a value to a certain interval. Read more
This method tests for self and other values to be equal, and is used by ==.
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
This method tests for self and other values to be equal, and is used by ==.
This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <= operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more
The error type that gets returned when a collection can’t be made from self.
Consume self and try to collect the results into C. Read more
The type returned in the event of a conversion error.
Performs the conversion.
The type identifying for which type info is provided. Read more
Returns the static type identifier for Self.

Auto Trait Implementations§

Blanket Implementations§

Gets the TypeId of self. Read more
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
Decode Self and consume all of the given input data. Read more
Decode Self and consume all of the given input data. Read more
Decode Self with the given maximum recursion depth and advance input by the number of bytes consumed. Read more
Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait.
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Compare self to key and return true if they are equal.

Returns the argument unchanged.

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Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Get a reference to the inner from the outer.

Get a mutable reference to the inner from the outer.

Return an encoding of Self prepended by given slice.
Should always be Self
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Performs the conversion.
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