Struct sp_trie::KeySpacedDBMut

pub struct KeySpacedDBMut<'a, DB, H>(_, _, _);

HashDBMut implementation that append a encoded prefix (unique id bytes) in addition to the prefix of every key value.

Mutable variant of KeySpacedDB, see KeySpacedDB.

Methods

impl<'a, DB, H> KeySpacedDBMut<'a, DB, H> where
    H: Hasher, 

pub fn new(db: &'a mut DB, ks: &'a [u8]) -> Self

instantiate new keyspaced db

Trait Implementations

impl<'a, DB, H, T> AsHashDB<H, T> for KeySpacedDBMut<'a, DB, H> where
    DB: HashDB<H, T>,
    H: Hasher,
    T: Default + PartialEq<T> + for<'b> From<&'b [u8]> + Clone + Send + Sync, 

fn as_hash_db(&self) -> &dyn HashDB<H, T>

Perform upcast to HashDB for anything that derives from HashDB.

fn as_hash_db_mut<'b>(&'b mut self) -> &'b mut (dyn HashDB<H, T> + 'b)

Perform mutable upcast to HashDB for anything that derives from HashDB.

impl<'a, DB, H, T> HashDB<H, T> for KeySpacedDBMut<'a, DB, H> where
    DB: HashDB<H, T>,
    H: Hasher,
    T: Default + PartialEq<T> + for<'b> From<&'b [u8]> + Clone + Send + Sync, 

fn get(&self, key: &H::Out, prefix: Prefix) -> Option<T>

Look up a given hash into the bytes that hash to it, returning None if the hash is not known.

fn contains(&self, key: &H::Out, prefix: Prefix) -> bool

Check for the existance of a hash-key.

fn insert(&mut self, prefix: Prefix, value: &[u8]) -> H::Out

Insert a datum item into the DB and return the datum's hash for a later lookup. Insertions are counted and the equivalent number of remove()s must be performed before the data is considered dead.

fn emplace(&mut self, key: H::Out, prefix: Prefix, value: T)

Like insert(), except you provide the key and the data is all moved.

fn remove(&mut self, key: &H::Out, prefix: Prefix)

Remove a datum previously inserted. Insertions can be "owed" such that the same number of insert()s may happen without the data being eventually being inserted into the DB. It can be "owed" more than once.