Replace levelup+memdown with level-mem 3.0.1 and upgrade level-ws to 1.0.0

.travis.yml

@@ -1,11 +1,9 @@
 language: node_js
 node_js:
-  - "4"
-  - "5"
   - "6"
-  - "7"
   - "8"
   - "9"
+  - "10"
 env:
   - CXX=g++-4.8
 addons:
@@ -35,5 +33,3 @@ matrix:
       env: CXX=g++-4.8 TEST_SUITE=test:browser
 script: npm run $TEST_SUITE
 
-notifications:
-  irc: "chat.freenode.net#ethereumjs"

README.md

@@ -1,4 +1,4 @@
-# SYNOPSIS 
+# SYNOPSIS
 [![NPM Package](https://img.shields.io/npm/v/merkle-patricia-tree.svg?style=flat-square)](https://www.npmjs.org/package/merkle-patricia-tree)
 [![Build Status](https://img.shields.io/travis/ethereumjs/merkle-patricia-tree.svg?branch=master&style=flat-square)](https://travis-ci.org/ethereumjs/merkle-patricia-tree)
 [![Coverage Status](https://img.shields.io/coveralls/ethereumjs/merkle-patricia-tree.svg?style=flat-square)](https://coveralls.io/r/ethereumjs/merkle-patricia-tree)
@@ -22,9 +22,9 @@ The only backing store supported is LevelDB through the ```levelup``` module.
 
 ```javascript
 var Trie = require('merkle-patricia-tree'),
-levelup = require('levelup'),
-db = levelup('./testdb'),
-trie = new Trie(db); 
+level = require('level'),
+db = level('./testdb'),
+trie = new Trie(db);
 
 trie.put('test', 'one', function () {
   trie.get('test', function (err, value) {
@@ -49,19 +49,19 @@ Trie.prove(trie, 'test', function (err, prove) {
 ## Read stream on Geth DB
 
 ```javascript
-var levelup = require('levelup')
+var level = require('level')
 var Trie = require('./secure')
 
 var stateRoot = "0xd7f8974fb5ac78d9ac099b9ad5018bedc2ce0a72dad1827a1709da30580f0544" // Block #222
 
-var db = levelup('YOUR_PATH_TO_THE_GETH_CHAIN_DB')
+var db = level('YOUR_PATH_TO_THE_GETH_CHAIN_DB')
 var trie = new Trie(db, stateRoot)
 
 trie.createReadStream()
   .on('data', function (data) {
     console.log(data)
   })
-  .on('end', function() { 
+  .on('end', function() {
     console.log('End.')
   })
 ```

baseTrie.js

@@ -1,6 +1,5 @@
 const assert = require('assert')
-const levelup = require('levelup')
-const memdown = require('memdown')
+const level = require('level-mem')
 const async = require('async')
 const rlp = require('rlp')
 const ethUtil = require('ethereumjs-util')
@@ -19,7 +18,7 @@ module.exports = Trie
  * Use `require('merkel-patricia-tree')` for the base interface. In Ethereum applications stick with the Secure Trie Overlay `require('merkel-patricia-tree/secure')`. The API for the raw and the secure interface are about the same
  * @class Trie
  * @param {Object} [db] An instance of [levelup](https://github.com/rvagg/node-levelup/) or a compatible API. If the db is `null` or left undefined, then the trie will be stored in memory via [memdown](https://github.com/rvagg/memdown)
- * @param {Buffer|String} [root]` A hex `String` or `Buffer` for the root of a previously stored trie
+ * @param {Buffer|String} [root] A hex `String` or `Buffer` for the root of a previously stored trie
  * @prop {Buffer} root The current root of the `trie`
  * @prop {Boolean} isCheckpoint  determines if you are saving to a checkpoint or directly to the db
  * @prop {Buffer} EMPTY_TRIE_ROOT the Root for an empty trie
@@ -30,10 +29,7 @@ function Trie (db, root) {
   this.sem = semaphore(1)
 
   // setup dbs
-  this.db = db ||
-    levelup('', {
-      db: memdown
-    })
+  this.db = db || level()
 
   this._getDBs = [this.db]
   this._putDBs = [this.db]

checkpoint-interface.js

@@ -1,9 +1,8 @@
-const levelup = require('levelup')
-const memdown = require('memdown')
+const level = require('level-mem')
 const async = require('async')
 const inherits = require('util').inherits
 const Readable = require('readable-stream').Readable
-const levelws = require('level-ws')
+const WriteStream = require('level-ws')
 const callTogether = require('./util').callTogether
 
 module.exports = checkpointInterface
@@ -90,9 +89,7 @@ function revert (cb) {
 
 // enter into checkpoint mode
 function _enterCpMode () {
-  this._scratch = levelup('', {
-    db: memdown
-  })
+  this._scratch = level()
   this._getDBs = [this._scratch].concat(this._getDBs)
   this.__putDBs = this._putDBs
   this._putDBs = [this._scratch]
@@ -110,12 +107,8 @@ function _exitCpMode (commitState, cb) {
   this.putRaw = this._putRaw
 
   function flushScratch (db, cb) {
-    if (!db.createWriteStream) {
-      db = levelws(db)
-    }
-
     self.createScratchReadStream(scratch)
-      .pipe(db.createWriteStream())
+      .pipe(WriteStream(db))
       .on('close', cb)
   }