Implement Snapshot & Restore modules

Author: foriequal0

util/merkle/Cargo.toml

@@ -8,6 +8,7 @@ elastic-array = "0.10"
 rand = "0.6.1"
 hashdb = {path = "../hashdb" }
 codechain-crypto = { git = "https://github.com/CodeChain-io/rust-codechain-crypto.git", version = "0.1" }
+memorydb = { path = "../memorydb" }
 primitives = { git = "https://github.com/CodeChain-io/rust-codechain-primitives.git", version = "0.4" }
 rlp = {path = "../rlp" }
 rlp_derive = { path = "../rlp_derive" }

util/merkle/src/chunk.rs

@@ -34,10 +34,10 @@ use ccrypto::BLAKE_NULL_RLP;
 use hashdb::{DBValue, HashDB};
 use primitives::H256;
 
-pub mod chunk;
 mod nibbleslice;
 pub mod node;
 mod skewed;
+pub mod snapshot;
 pub mod triedb;
 pub mod triedbmut;
 pub mod triehash;

util/merkle/src/lib.rs

@@ -19,7 +19,7 @@ use std::fmt;
 use elastic_array::ElasticArray36;
 
 
-#[derive(Eq, Ord)]
+#[derive(Eq, Ord, Copy, Clone)]
 pub struct NibbleSlice<'a> {
     pub data: &'a [u8],
     pub offset: usize,

util/merkle/src/nibbleslice.rs

@@ -113,4 +113,11 @@ impl<'a> Node<'a> {
             }
         }
     }
+
+    pub fn mid(self, offset: usize) -> Self {
+        match self {
+            Node::Leaf(partial, value) => Node::Leaf(partial.mid(offset), value),
+            Node::Branch(partial, child) => Node::Branch(partial.mid(offset), child),
+        }
+    }
 }