openethereum/util/src/trie/trietraits.rs

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2016-02-05 13:40:41 +01:00
// Copyright 2015, 2016 Ethcore (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
use hash::H256;
use rlp::SHA3_NULL_RLP;
/// A key-value datastore implemented as a database-backed modified Merkle tree.
pub trait Trie {
/// Return the root of the trie.
fn root(&self) -> &H256;
/// Is the trie empty?
fn is_empty(&self) -> bool { *self.root() == SHA3_NULL_RLP }
/// Does the trie contain a given key?
fn contains(&self, key: &[u8]) -> bool;
/// What is the value of the given key in this trie?
fn get<'a, 'key>(&'a self, key: &'key [u8]) -> Option<&'a [u8]> where 'a: 'key;
}
/// A key-value datastore implemented as a database-backed modified Merkle tree.
pub trait TrieMut: Trie {
/// Insert a `key`/`value` pair into the trie. An `empty` value is equivalent to removing
/// `key` from the trie.
fn insert(&mut self, key: &[u8], value: &[u8]);
/// Remove a `key` from the trie. Equivalent to making it equal to the empty
/// value.
fn remove(&mut self, key: &[u8]);
}