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// Copyright 2020 ChainSafe Systems // SPDX-License-Identifier: Apache-2.0, MIT use super::BytesKey; use crate::node::Node; use crate::{Error, Hash, HashAlgorithm, Sha256, DEFAULT_BIT_WIDTH}; use cid::{Cid, Code::Blake2b256}; use ipld_blockstore::BlockStore; use serde::{de::DeserializeOwned, Serialize, Serializer}; use std::borrow::Borrow; use std::error::Error as StdError; use std::marker::PhantomData; /// Implementation of the HAMT data structure for IPLD. /// /// # Examples /// /// ``` /// use ipld_hamt::Hamt; /// /// let store = db::MemoryDB::default(); /// /// let mut map: Hamt<_, _, usize> = Hamt::new(&store); /// map.set(1, "a".to_string()).unwrap(); /// assert_eq!(map.get(&1).unwrap(), Some(&"a".to_string())); /// assert_eq!(map.delete(&1).unwrap(), Some((1, "a".to_string()))); /// assert_eq!(map.get::<_>(&1).unwrap(), None); /// let cid = map.flush().unwrap(); /// ``` #[derive(Debug)] pub struct Hamt<'a, BS, V, K = BytesKey, H = Sha256> { root: Node<K, V, H>, store: &'a BS, bit_width: u32, hash: PhantomData<H>, } impl<BS, V, K, H> Serialize for Hamt<'_, BS, V, K, H> where K: Serialize, V: Serialize, H: HashAlgorithm, { fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer, { self.root.serialize(serializer) } } impl<'a, K: PartialEq, V: PartialEq, S: BlockStore, H: HashAlgorithm> PartialEq for Hamt<'a, S, V, K, H> { fn eq(&self, other: &Self) -> bool { self.root == other.root } } impl<'a, BS, V, K, H> Hamt<'a, BS, V, K, H> where K: Hash + Eq + PartialOrd + Serialize + DeserializeOwned, V: Serialize + DeserializeOwned, BS: BlockStore, H: HashAlgorithm, { pub fn new(store: &'a BS) -> Self { Self::new_with_bit_width(store, DEFAULT_BIT_WIDTH) } /// Construct hamt with a bit width pub fn new_with_bit_width(store: &'a BS, bit_width: u32) -> Self { Self { root: Node::default(), store, bit_width, hash: Default::default(), } } /// Lazily instantiate a hamt from this root Cid. pub fn load(cid: &Cid, store: &'a BS) -> Result<Self, Error> { Self::load_with_bit_width(cid, store, DEFAULT_BIT_WIDTH) } /// Lazily instantiate a hamt from this root Cid with a specified bit width. pub fn load_with_bit_width(cid: &Cid, store: &'a BS, bit_width: u32) -> Result<Self, Error> { match store.get(cid)? { Some(root) => Ok(Self { root, store, bit_width, hash: Default::default(), }), None => Err(Error::CidNotFound(cid.to_string())), } } /// Sets the root based on the Cid of the root node using the Hamt store pub fn set_root(&mut self, cid: &Cid) -> Result<(), Error> { match self.store.get(cid)? { Some(root) => self.root = root, None => return Err(Error::CidNotFound(cid.to_string())), } Ok(()) } /// Returns a reference to the underlying store of the Hamt. pub fn store(&self) -> &'a BS { self.store } /// Inserts a key-value pair into the HAMT. /// /// If the HAMT did not have this key present, `None` is returned. /// /// If the HAMT did have this key present, the value is updated, and the old /// value is returned. The key is not updated, though; /// /// # Examples /// /// ``` /// use ipld_hamt::Hamt; /// /// let store = db::MemoryDB::default(); /// /// let mut map: Hamt<_, _, usize> = Hamt::new(&store); /// map.set(37, "a".to_string()).unwrap(); /// assert_eq!(map.is_empty(), false); /// /// map.set(37, "b".to_string()).unwrap(); /// map.set(37, "c".to_string()).unwrap(); /// ``` pub fn set(&mut self, key: K, value: V) -> Result<(), Error> { self.root.set(key, value, self.store, self.bit_width) } /// Returns a reference to the value corresponding to the key. /// /// The key may be any borrowed form of the map's key type, but /// `Hash` and `Eq` on the borrowed form *must* match those for /// the key type. /// /// # Examples /// /// ``` /// use ipld_hamt::Hamt; /// /// let store = db::MemoryDB::default(); /// /// let mut map: Hamt<_, _, usize> = Hamt::new(&store); /// map.set(1, "a".to_string()).unwrap(); /// assert_eq!(map.get(&1).unwrap(), Some(&"a".to_string())); /// assert_eq!(map.get(&2).unwrap(), None); /// ``` #[inline] pub fn get<Q: ?Sized>(&self, k: &Q) -> Result<Option<&V>, Error> where K: Borrow<Q>, Q: Hash + Eq, V: DeserializeOwned, { match self.root.get(k, self.store, self.bit_width)? { Some(v) => Ok(Some(v)), None => Ok(None), } } /// Returns `true` if a value exists for the given key in the HAMT. /// /// The key may be any borrowed form of the map's key type, but /// `Hash` and `Eq` on the borrowed form *must* match those for /// the key type. /// /// # Examples /// /// ``` /// use ipld_hamt::Hamt; /// /// let store = db::MemoryDB::default(); /// /// let mut map: Hamt<_, _, usize> = Hamt::new(&store); /// map.set(1, "a".to_string()).unwrap(); /// assert_eq!(map.contains_key(&1).unwrap(), true); /// assert_eq!(map.contains_key(&2).unwrap(), false); /// ``` #[inline] pub fn contains_key<Q: ?Sized>(&self, k: &Q) -> Result<bool, Error> where K: Borrow<Q>, Q: Hash + Eq, { Ok(self.root.get(k, self.store, self.bit_width)?.is_some()) } /// Removes a key from the HAMT, returning the value at the key if the key /// was previously in the HAMT. /// /// The key may be any borrowed form of the HAMT's key type, but /// `Hash` and `Eq` on the borrowed form *must* match those for /// the key type. /// /// # Examples /// /// ``` /// use ipld_hamt::Hamt; /// /// let store = db::MemoryDB::default(); /// /// let mut map: Hamt<_, _, usize> = Hamt::new(&store); /// map.set(1, "a".to_string()).unwrap(); /// assert_eq!(map.delete(&1).unwrap(), Some((1, "a".to_string()))); /// assert_eq!(map.delete(&1).unwrap(), None); /// ``` pub fn delete<Q: ?Sized>(&mut self, k: &Q) -> Result<Option<(K, V)>, Error> where K: Borrow<Q>, Q: Hash + Eq, { self.root.remove_entry(k, self.store, self.bit_width) } /// Flush root and return Cid for hamt pub fn flush(&mut self) -> Result<Cid, Error> { self.root.flush(self.store)?; Ok(self.store.put(&self.root, Blake2b256)?) } /// Returns true if the HAMT has no entries pub fn is_empty(&self) -> bool { self.root.is_empty() } /// Iterates over each KV in the Hamt and runs a function on the values. /// /// This function will constrain all values to be of the same type /// /// # Examples /// /// ``` /// use ipld_hamt::Hamt; /// /// let store = db::MemoryDB::default(); /// /// let mut map: Hamt<_, _, usize> = Hamt::new(&store); /// map.set(1, 1).unwrap(); /// map.set(4, 2).unwrap(); /// /// let mut total = 0; /// map.for_each(|_, v: &u64| { /// total += v; /// Ok(()) /// }).unwrap(); /// assert_eq!(total, 3); /// ``` #[inline] pub fn for_each<F>(&self, mut f: F) -> Result<(), Box<dyn StdError>> where V: DeserializeOwned, F: FnMut(&K, &V) -> Result<(), Box<dyn StdError>>, { self.root.for_each(self.store, &mut f) } }