Re-implementation of Patricia-Merkle Trie (#203)

* Start of trie-db re-implementation

* WIP commit

* More WIP

* WIP, seems complete, untested

* Ported trie-db operational

* Add Ethereum trie tests

* Use u8aConcat to construct u8a

* Basic RocksDb interface

* Combine engines into DB, expand tests

* Update Trie with transaction wrapper

* LevelDb (sync) interface

* Remove unused (for now) package (compatibility)

* trie-d -> trie-db-old, trie-db-ext -> trie-db

* Version bump

* Skip old trie tests (package to be removed)

* Skip tests (fixed)

* Remove non-used RocksDb spec

* Skip FileFlat tests (deprecated?)

packages/db/src/engines/MemoryDb.ts

@@ -0,0 +1,54 @@
+// Copyright 2017-2018 @polkadot/db authors & contributors
+// This software may be modified and distributed under the terms
+// of the ISC license. See the LICENSE file for details.
+
+import { BaseDb, ProgressCb } from '../types';
+
+// import logger from '@polkadot/util/logger';
+// import u8aToHex from '@polkadot/util/u8a/toHex';
+
+type Storage = {
+  [index: string]: Uint8Array
+};
+
+// const l = logger('db/memory');
+
+export default class MemoryDb implements BaseDb {
+  private storage: Storage;
+
+  constructor () {
+    this.storage = {};
+  }
+
+  close (): void {
+    // noop
+  }
+
+  open (): void {
+    // noop
+  }
+
+  maintain (fn: ProgressCb): void {
+    fn({
+      isCompleted: true,
+      keys: Object.keys(this.storage).length,
+      percent: 100
+    });
+  }
+
+  del (key: Uint8Array): void {
+    delete this.storage[key.toString()];
+  }
+
+  get (key: Uint8Array): Uint8Array | null {
+    // l.debug(() => ['get', u8aToHex(key)]);
+
+    return this.storage[key.toString()] || null;
+  }
+
+  put (key: Uint8Array, value: Uint8Array): void {
+    // l.debug(() => ['put', u8aToHex(key), u8aToHex(value)]);
+
+    this.storage[key.toString()] = value;
+  }
+}