56 lines
2.0 KiB
Rust
56 lines
2.0 KiB
Rust
// Copyright 2015-2018 Parity Technologies (UK) Ltd.
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// This file is part of Parity.
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// Parity is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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// Parity is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with Parity. If not, see <http://www.gnu.org/licenses/>.
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//! Generic trait for trie node encoding/decoding. Takes a `hashdb::Hasher`
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//! to parametrize the hashes used in the codec.
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use hashdb::Hasher;
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use node::Node;
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use ChildReference;
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use elastic_array::{ElasticArray128};
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/// Trait for trie node encoding/decoding
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pub trait NodeCodec<H: Hasher>: Sized {
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/// Encoding error type
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type Error: ::std::error::Error;
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/// Null node type
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const HASHED_NULL_NODE: H::Out;
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/// Decode bytes to a `Node`. Returns `Self::E` on failure.
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fn decode(data: &[u8]) -> Result<Node, Self::Error>;
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/// Decode bytes to the `Hasher`s output type. Returns `None` on failure.
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fn try_decode_hash(data: &[u8]) -> Option<H::Out>;
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/// Check if the provided bytes correspond to the codecs "empty" node.
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fn is_empty_node(data: &[u8]) -> bool;
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/// Returns an empty node
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fn empty_node() -> Vec<u8>;
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/// Returns an encoded leaft node
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fn leaf_node(partial: &[u8], value: &[u8]) -> Vec<u8>;
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/// Returns an encoded extension node
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fn ext_node(partial: &[u8], child_ref: ChildReference<H::Out>) -> Vec<u8>;
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/// Returns an encoded branch node. Takes an iterator yielding `ChildReference<H::Out>` and an optional value
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fn branch_node<I>(children: I, value: Option<ElasticArray128<u8>>) -> Vec<u8>
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where I: IntoIterator<Item=Option<ChildReference<H::Out>>>;
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}
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