Prepare package to self-host in Gitea npm registry

Migration to Typescript, add partial tree implementation

.eslintrc

@@ -1,26 +1,57 @@
 {
-  "env": {
-    "node": true,
-    "browser": true,
-    "es6": true,
-    "mocha": true
-  },
-  "extends": "eslint:recommended",
   "globals": {
     "Atomics": "readonly",
     "SharedArrayBuffer": "readonly"
   },
-  "parser": "babel-eslint",
-  "parserOptions": {
-    "ecmaVersion": 2018
-  },
+  "parser": "@typescript-eslint/parser",
+  "plugins": [
+    "@typescript-eslint"
+  ],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "prettier"
+  ],
+  "ignorePatterns": [
+    "test/*.spec.ts",
+    "lib"
+  ],
   "rules": {
-    "indent": ["error", 2],
-    "linebreak-style": ["error", "unix"],
-    "quotes": ["error", "single"],
-    "semi": ["error", "never"],
-    "object-curly-spacing": ["error", "always"],
-    "comma-dangle": ["error", "always-multiline"],
+    "@typescript-eslint/no-unused-vars": "error",
+    "@typescript-eslint/consistent-type-definitions": [
+      "error",
+      "type"
+    ],
+    "indent": [
+      "error",
+      2
+    ],
+    "linebreak-style": [
+      "error",
+      "unix"
+    ],
+    "quotes": [
+      "error",
+      "single"
+    ],
+    "semi": [
+      "error",
+      "never"
+    ],
+    "object-curly-spacing": [
+      "error",
+      "always"
+    ],
+    "comma-dangle": [
+      "error",
+      "always-multiline"
+    ],
     "require-await": "error"
+  },
+  "env": {
+    "browser": true,
+    "es2021": true,
+    "node": true,
+    "mocha": true
   }
 }

.gitignore

@@ -1 +1,6 @@
 node_modules
+build
+yarn-error.log
+.idea
+.nyc_output
+.run

.npmrc

@@ -0,0 +1 @@
+@tornado:registry=https://git.tornado.ws/api/packages/tornado-packages/npm/

.nvmrc

@@ -0,0 +1 @@
+14.23

README.md

@@ -5,27 +5,68 @@ This is a fixed depth merkle tree implementation with sequential inserts
 ## Usage
 
 ```javascript
-const MerkleTree = require('MerkleTree')
+import { MerkleTree, PartialMerkleTree } from 'fixed-merkle-tree'
+
 const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
 tree.insert(6)
 tree.update(3, 42)
-const path = tree.path(tree.indexOf(2))
+const path = tree.proof(3)
 console.log(path)
-
-// output:
+// output
 {
-  pathIndex: [0, 1, 0, 0, 0, 0, 0, 0, 0, 0],
   pathElements: [
-    '42',
-    '19814528709687996974327303300007262407299502847885145507292406548098437687919',
-    '11545490348087423460235196042660837039811055736960842865648632633825765931887',
-    '14506027710748750947258687001455876266559341618222612722926156490737302846427',
-    '4766583705360062980279572762279781527342845808161105063909171241304075622345',
-    '16640205414190175414380077665118269450294358858897019640557533278896634808665',
-    '13024477302430254842915163302704885770955784224100349847438808884122720088412',
-    '11345696205391376769769683860277269518617256738724086786512014734609753488820',
-    '17235543131546745471991808272245772046758360534180976603221801364506032471936',
-    '155962837046691114236524362966874066300454611955781275944230309195800494087'
-  ]
+    42,
+    '4027992409016347597424110157229339967488',
+    '2008015086710634950773855228781840564224',
+    '938972308169430750202858820582946897920',
+    '3743880566844110745576746962917825445888',
+    '2074434463882483178614385966084599578624',
+    '2808856778596740691845240322870189490176',
+    '4986731814143931240516913804278285467648',
+    '1918547053077726613961101558405545328640',
+    '5444383861051812288142814494928935059456'
+  ],
+  pathIndices: [
+      0, 1, 0, 0, 0,
+      0, 0, 0, 0, 0
+    ],
+  pathPositions: [
+      3, 0, 1, 0, 0,
+      0, 0, 0, 0, 0
+    ],
+  pathRoot: '3917789723822252567979048877718291611648'
 }
+
+const treeEdge = tree.getTreeEdge(2)
+const partialTree = new PartialMerkleTree(10, treeEdge, tree.elements.slice(treeEdge.edgeIndex))
+console.log(partialTree.elements)
+//  [<2 empty items >, 3, 42, 5, 6]
+
+const proofPath = partialTree.proof(3)
+console.log(proofPath)
+// output
+{
+  pathElements: [
+    42,
+    '4027992409016347597424110157229339967488',
+    '2008015086710634950773855228781840564224',
+    '938972308169430750202858820582946897920',
+    '3743880566844110745576746962917825445888',
+    '2074434463882483178614385966084599578624',
+    '2808856778596740691845240322870189490176',
+    '4986731814143931240516913804278285467648',
+    '1918547053077726613961101558405545328640',
+    '5444383861051812288142814494928935059456'
+  ],
+  pathIndices: [
+    0, 1, 0, 0, 0,
+    0, 0, 0, 0, 0
+  ],
+  pathPositions: [
+    3, 0, 1, 0, 0,
+    0, 0, 0, 0, 0
+  ],
+  pathRoot: '3917789723822252567979048877718291611648'
+}
+
 ```

lib/BaseTree.d.ts

@@ -0,0 +1,43 @@
+import { Element, HashFunction, ProofPath } from './';
+export declare class BaseTree {
+    levels: number;
+    protected _hashFn: HashFunction<Element>;
+    protected zeroElement: Element;
+    protected _zeros: Element[];
+    protected _layers: Array<Element[]>;
+    get capacity(): number;
+    get layers(): Array<Element[]>;
+    get zeros(): Element[];
+    get elements(): Element[];
+    get root(): Element;
+    /**
+     * Find an element in the tree
+     * @param elements elements of tree
+     * @param element An element to find
+     * @param comparator A function that checks leaf value equality
+     * @param fromIndex The index to start the search at. If the index is greater than or equal to the array's length, -1 is returned
+     * @returns {number} Index if element is found, otherwise -1
+     */
+    static indexOf(elements: Element[], element: Element, fromIndex?: number, comparator?: <T>(arg0: T, arg1: T) => boolean): number;
+    /**
+     * Insert new element into the tree
+     * @param element Element to insert
+     */
+    insert(element: Element): void;
+    bulkInsert(elements: Element[]): void;
+    /**
+     * Change an element in the tree
+     * @param {number} index Index of element to change
+     * @param element Updated element value
+     */
+    update(index: number, element: Element): void;
+    /**
+     * Get merkle path to a leaf
+     * @param {number} index Leaf index to generate path for
+     * @returns {{pathElements: Object[], pathIndex: number[]}} An object containing adjacent elements and left-right index
+     */
+    path(index: number): ProofPath;
+    protected _buildZeros(): void;
+    protected _processNodes(nodes: Element[], layerIndex: number): any[];
+    protected _processUpdate(index: number): void;
+}

lib/BaseTree.js

@@ -0,0 +1,154 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.BaseTree = void 0;
+class BaseTree {
+    get capacity() {
+        return 2 ** this.levels;
+    }
+    get layers() {
+        return this._layers.slice();
+    }
+    get zeros() {
+        return this._zeros.slice();
+    }
+    get elements() {
+        return this._layers[0].slice();
+    }
+    get root() {
+        var _a;
+        return (_a = this._layers[this.levels][0]) !== null && _a !== void 0 ? _a : this._zeros[this.levels];
+    }
+    /**
+     * Find an element in the tree
+     * @param elements elements of tree
+     * @param element An element to find
+     * @param comparator A function that checks leaf value equality
+     * @param fromIndex The index to start the search at. If the index is greater than or equal to the array's length, -1 is returned
+     * @returns {number} Index if element is found, otherwise -1
+     */
+    static indexOf(elements, element, fromIndex, comparator) {
+        if (comparator) {
+            return elements.findIndex((el) => comparator(element, el));
+        }
+        else {
+            return elements.indexOf(element, fromIndex);
+        }
+    }
+    /**
+     * Insert new element into the tree
+     * @param element Element to insert
+     */
+    insert(element) {
+        if (this._layers[0].length >= this.capacity) {
+            throw new Error('Tree is full');
+        }
+        this.update(this._layers[0].length, element);
+    }
+    /*
+     * Insert multiple elements into the tree.
+     * @param {Array} elements Elements to insert
+     */
+    bulkInsert(elements) {
+        if (!elements.length) {
+            return;
+        }
+        if (this._layers[0].length + elements.length > this.capacity) {
+            throw new Error('Tree is full');
+        }
+        // First we insert all elements except the last one
+        // updating only full subtree hashes (all layers where inserted element has odd index)
+        // the last element will update the full path to the root making the tree consistent again
+        for (let i = 0; i < elements.length - 1; i++) {
+            this._layers[0].push(elements[i]);
+            let level = 0;
+            let index = this._layers[0].length - 1;
+            while (index % 2 === 1) {
+                level++;
+                index >>= 1;
+                const left = this._layers[level - 1][index * 2];
+                const right = this._layers[level - 1][index * 2 + 1];
+                this._layers[level][index] = this._hashFn(left, right);
+            }
+        }
+        this.insert(elements[elements.length - 1]);
+    }
+    /**
+     * Change an element in the tree
+     * @param {number} index Index of element to change
+     * @param element Updated element value
+     */
+    update(index, element) {
+        if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
+            throw new Error('Insert index out of bounds: ' + index);
+        }
+        this._layers[0][index] = element;
+        this._processUpdate(index);
+    }
+    /**
+     * Get merkle path to a leaf
+     * @param {number} index Leaf index to generate path for
+     * @returns {{pathElements: Object[], pathIndex: number[]}} An object containing adjacent elements and left-right index
+     */
+    path(index) {
+        if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
+            throw new Error('Index out of bounds: ' + index);
+        }
+        let elIndex = +index;
+        const pathElements = [];
+        const pathIndices = [];
+        const pathPositions = [];
+        for (let level = 0; level < this.levels; level++) {
+            pathIndices[level] = elIndex % 2;
+            const leafIndex = elIndex ^ 1;
+            if (leafIndex < this._layers[level].length) {
+                pathElements[level] = this._layers[level][leafIndex];
+                pathPositions[level] = leafIndex;
+            }
+            else {
+                pathElements[level] = this._zeros[level];
+                pathPositions[level] = 0;
+            }
+            elIndex >>= 1;
+        }
+        return {
+            pathElements,
+            pathIndices,
+            pathPositions,
+            pathRoot: this.root,
+        };
+    }
+    _buildZeros() {
+        this._zeros = [this.zeroElement];
+        for (let i = 1; i <= this.levels; i++) {
+            this._zeros[i] = this._hashFn(this._zeros[i - 1], this._zeros[i - 1]);
+        }
+    }
+    _processNodes(nodes, layerIndex) {
+        const length = nodes.length;
+        let currentLength = Math.ceil(length / 2);
+        const currentLayer = new Array(currentLength);
+        currentLength--;
+        const starFrom = length - ((length % 2) ^ 1);
+        let j = 0;
+        for (let i = starFrom; i >= 0; i -= 2) {
+            if (nodes[i - 1] === undefined)
+                break;
+            const left = nodes[i - 1];
+            const right = (i === starFrom && length % 2 === 1) ? this._zeros[layerIndex - 1] : nodes[i];
+            currentLayer[currentLength - j] = this._hashFn(left, right);
+            j++;
+        }
+        return currentLayer;
+    }
+    _processUpdate(index) {
+        for (let level = 1; level <= this.levels; level++) {
+            index >>= 1;
+            const left = this._layers[level - 1][index * 2];
+            const right = index * 2 + 1 < this._layers[level - 1].length
+                ? this._layers[level - 1][index * 2 + 1]
+                : this._zeros[level - 1];
+            this._layers[level][index] = this._hashFn(left, right);
+        }
+    }
+}
+exports.BaseTree = BaseTree;

lib/FixedMerkleTree.d.ts

@@ -0,0 +1,32 @@
+import { Element, HashFunction, MerkleTreeOptions, ProofPath, SerializedTreeState, TreeEdge, TreeSlice } from './';
+import { BaseTree } from './BaseTree';
+export default class MerkleTree extends BaseTree {
+    constructor(levels: number, elements?: Element[], { hashFunction, zeroElement, }?: MerkleTreeOptions);
+    private _buildHashes;
+    /**
+     * Insert multiple elements into the tree.
+     * @param {Array} elements Elements to insert
+     */
+    bulkInsert(elements: Element[]): void;
+    indexOf(element: Element, comparator?: <T>(arg0: T, arg1: T) => boolean): number;
+    proof(element: Element): ProofPath;
+    getTreeEdge(edgeIndex: number): TreeEdge;
+    /**
+     * 🪓
+     * @param count
+     */
+    getTreeSlices(count?: number): TreeSlice[];
+    /**
+     * Serialize entire tree state including intermediate layers into a plain object
+     * Deserializing it back will not require to recompute any hashes
+     * Elements are not converted to a plain type, this is responsibility of the caller
+     */
+    serialize(): SerializedTreeState;
+    /**
+     * Deserialize data into a MerkleTree instance
+     * Make sure to provide the same hashFunction as was used in the source tree,
+     * otherwise the tree state will be invalid
+     */
+    static deserialize(data: SerializedTreeState, hashFunction?: HashFunction<Element>): MerkleTree;
+    toString(): string;
+}

lib/FixedMerkleTree.js

@@ -0,0 +1,114 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+const simpleHash_1 = __importDefault(require("./simpleHash"));
+const BaseTree_1 = require("./BaseTree");
+class MerkleTree extends BaseTree_1.BaseTree {
+    constructor(levels, elements = [], { hashFunction = simpleHash_1.default, zeroElement = 0, } = {}) {
+        super();
+        this.levels = levels;
+        if (elements.length > this.capacity) {
+            throw new Error('Tree is full');
+        }
+        this._hashFn = hashFunction;
+        this.zeroElement = zeroElement;
+        this._layers = [];
+        const leaves = elements.slice();
+        this._layers = [leaves];
+        this._buildZeros();
+        this._buildHashes();
+    }
+    _buildHashes() {
+        for (let layerIndex = 1; layerIndex <= this.levels; layerIndex++) {
+            const nodes = this._layers[layerIndex - 1];
+            this._layers[layerIndex] = this._processNodes(nodes, layerIndex);
+        }
+    }
+    /**
+     * Insert multiple elements into the tree.
+     * @param {Array} elements Elements to insert
+     */
+    bulkInsert(elements) {
+        if (!elements.length) {
+            return;
+        }
+        if (this._layers[0].length + elements.length > this.capacity) {
+            throw new Error('Tree is full');
+        }
+        // First we insert all elements except the last one
+        // updating only full subtree hashes (all layers where inserted element has odd index)
+        // the last element will update the full path to the root making the tree consistent again
+        for (let i = 0; i < elements.length - 1; i++) {
+            this._layers[0].push(elements[i]);
+            let level = 0;
+            let index = this._layers[0].length - 1;
+            while (index % 2 === 1) {
+                level++;
+                index >>= 1;
+                this._layers[level][index] = this._hashFn(this._layers[level - 1][index * 2], this._layers[level - 1][index * 2 + 1]);
+            }
+        }
+        this.insert(elements[elements.length - 1]);
+    }
+    indexOf(element, comparator) {
+        return BaseTree_1.BaseTree.indexOf(this._layers[0], element, 0, comparator);
+    }
+    proof(element) {
+        const index = this.indexOf(element);
+        return this.path(index);
+    }
+    getTreeEdge(edgeIndex) {
+        const edgeElement = this._layers[0][edgeIndex];
+        if (edgeElement === undefined) {
+            throw new Error('Element not found');
+        }
+        const edgePath = this.path(edgeIndex);
+        return { edgePath, edgeElement, edgeIndex, edgeElementsCount: this._layers[0].length };
+    }
+    /**
+     * 🪓
+     * @param count
+     */
+    getTreeSlices(count = 4) {
+        const length = this._layers[0].length;
+        let size = Math.ceil(length / count);
+        if (size % 2)
+            size++;
+        const slices = [];
+        for (let i = 0; i < length; i += size) {
+            const edgeLeft = i;
+            const edgeRight = i + size;
+            slices.push({ edge: this.getTreeEdge(edgeLeft), elements: this.elements.slice(edgeLeft, edgeRight) });
+        }
+        return slices;
+    }
+    /**
+     * Serialize entire tree state including intermediate layers into a plain object
+     * Deserializing it back will not require to recompute any hashes
+     * Elements are not converted to a plain type, this is responsibility of the caller
+     */
+    serialize() {
+        return {
+            levels: this.levels,
+            _zeros: this._zeros,
+            _layers: this._layers,
+        };
+    }
+    /**
+     * Deserialize data into a MerkleTree instance
+     * Make sure to provide the same hashFunction as was used in the source tree,
+     * otherwise the tree state will be invalid
+     */
+    static deserialize(data, hashFunction) {
+        const instance = Object.assign(Object.create(this.prototype), data);
+        instance._hashFn = hashFunction || simpleHash_1.default;
+        instance.zeroElement = instance._zeros[0];
+        return instance;
+    }
+    toString() {
+        return JSON.stringify(this.serialize());
+    }
+}
+exports.default = MerkleTree;

lib/PartialMerkleTree.d.ts

@@ -0,0 +1,35 @@
+import { Element, HashFunction, MerkleTreeOptions, ProofPath, SerializedPartialTreeState, TreeEdge } from './';
+import { BaseTree } from './BaseTree';
+export declare class PartialMerkleTree extends BaseTree {
+    private _leaves;
+    private _leavesAfterEdge;
+    private _edgeLeaf;
+    private _initialRoot;
+    private _edgeLeafProof;
+    private _proofMap;
+    constructor(levels: number, { edgePath, edgeElement, edgeIndex, edgeElementsCount, }: TreeEdge, leaves: Element[], { hashFunction, zeroElement }?: MerkleTreeOptions);
+    get edgeIndex(): number;
+    get edgeElement(): Element;
+    get edgeLeafProof(): ProofPath;
+    private _createProofMap;
+    private _buildTree;
+    private _buildHashes;
+    /**
+     * Change an element in the tree
+     * @param {number} index Index of element to change
+     * @param element Updated element value
+     */
+    update(index: number, element: Element): void;
+    path(index: number): ProofPath;
+    indexOf(element: Element, comparator?: <T>(arg0: T, arg1: T) => boolean): number;
+    proof(element: Element): ProofPath;
+    /**
+     * Shifts edge of tree to left
+     * @param edge new TreeEdge below current edge
+     * @param elements leaves between old and new edge
+     */
+    shiftEdge(edge: TreeEdge, elements: Element[]): void;
+    serialize(): SerializedPartialTreeState;
+    static deserialize(data: SerializedPartialTreeState, hashFunction?: HashFunction<Element>): PartialMerkleTree;
+    toString(): string;
+}

lib/PartialMerkleTree.js

@@ -0,0 +1,159 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.PartialMerkleTree = void 0;
+const simpleHash_1 = __importDefault(require("./simpleHash"));
+const BaseTree_1 = require("./BaseTree");
+class PartialMerkleTree extends BaseTree_1.BaseTree {
+    constructor(levels, { edgePath, edgeElement, edgeIndex, edgeElementsCount, }, leaves, { hashFunction, zeroElement } = {}) {
+        super();
+        if (edgeIndex + leaves.length !== edgeElementsCount)
+            throw new Error('Invalid number of elements');
+        this._edgeLeafProof = edgePath;
+        this._initialRoot = edgePath.pathRoot;
+        this.zeroElement = zeroElement !== null && zeroElement !== void 0 ? zeroElement : 0;
+        this._edgeLeaf = { data: edgeElement, index: edgeIndex };
+        this._leavesAfterEdge = leaves;
+        this.levels = levels;
+        this._hashFn = hashFunction || simpleHash_1.default;
+        this._createProofMap();
+        this._buildTree();
+    }
+    get edgeIndex() {
+        return this._edgeLeaf.index;
+    }
+    get edgeElement() {
+        return this._edgeLeaf.data;
+    }
+    get edgeLeafProof() {
+        return this._edgeLeafProof;
+    }
+    _createProofMap() {
+        this._proofMap = this.edgeLeafProof.pathPositions.reduce((p, c, i) => {
+            p.set(i, [c, this.edgeLeafProof.pathElements[i]]);
+            return p;
+        }, new Map());
+        this._proofMap.set(this.levels, [0, this.edgeLeafProof.pathRoot]);
+    }
+    _buildTree() {
+        const edgeLeafIndex = this._edgeLeaf.index;
+        this._leaves = Array(edgeLeafIndex).concat(this._leavesAfterEdge);
+        if (this._proofMap.has(0)) {
+            const [proofPos, proofEl] = this._proofMap.get(0);
+            this._leaves[proofPos] = proofEl;
+        }
+        this._layers = [this._leaves];
+        this._buildZeros();
+        this._buildHashes();
+    }
+    _buildHashes() {
+        for (let layerIndex = 1; layerIndex <= this.levels; layerIndex++) {
+            const nodes = this._layers[layerIndex - 1];
+            const currentLayer = this._processNodes(nodes, layerIndex);
+            if (this._proofMap.has(layerIndex)) {
+                const [proofPos, proofEl] = this._proofMap.get(layerIndex);
+                if (!currentLayer[proofPos])
+                    currentLayer[proofPos] = proofEl;
+            }
+            this._layers[layerIndex] = currentLayer;
+        }
+    }
+    /**
+     * Change an element in the tree
+     * @param {number} index Index of element to change
+     * @param element Updated element value
+     */
+    update(index, element) {
+        if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
+            throw new Error('Insert index out of bounds: ' + index);
+        }
+        if (index < this._edgeLeaf.index) {
+            throw new Error(`Index ${index} is below the edge: ${this._edgeLeaf.index}`);
+        }
+        this._layers[0][index] = element;
+        this._processUpdate(index);
+    }
+    path(index) {
+        var _a;
+        if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
+            throw new Error('Index out of bounds: ' + index);
+        }
+        if (index < this._edgeLeaf.index) {
+            throw new Error(`Index ${index} is below the edge: ${this._edgeLeaf.index}`);
+        }
+        let elIndex = Number(index);
+        const pathElements = [];
+        const pathIndices = [];
+        const pathPositions = [];
+        for (let level = 0; level < this.levels; level++) {
+            pathIndices[level] = elIndex % 2;
+            const leafIndex = elIndex ^ 1;
+            if (leafIndex < this._layers[level].length) {
+                pathElements[level] = this._layers[level][leafIndex];
+                pathPositions[level] = leafIndex;
+            }
+            else {
+                pathElements[level] = this._zeros[level];
+                pathPositions[level] = 0;
+            }
+            const [proofPos, proofEl] = this._proofMap.get(level);
+            pathElements[level] = (_a = pathElements[level]) !== null && _a !== void 0 ? _a : (proofPos === leafIndex ? proofEl : this._zeros[level]);
+            elIndex >>= 1;
+        }
+        return {
+            pathElements,
+            pathIndices,
+            pathPositions,
+            pathRoot: this.root,
+        };
+    }
+    indexOf(element, comparator) {
+        return BaseTree_1.BaseTree.indexOf(this._layers[0], element, this.edgeIndex, comparator);
+    }
+    proof(element) {
+        const index = this.indexOf(element);
+        return this.path(index);
+    }
+    /**
+     * Shifts edge of tree to left
+     * @param edge new TreeEdge below current edge
+     * @param elements leaves between old and new edge
+     */
+    shiftEdge(edge, elements) {
+        if (this._edgeLeaf.index <= edge.edgeIndex) {
+            throw new Error(`New edgeIndex should be smaller then ${this._edgeLeaf.index}`);
+        }
+        if (elements.length !== (this._edgeLeaf.index - edge.edgeIndex)) {
+            throw new Error(`Elements length should be ${this._edgeLeaf.index - edge.edgeIndex}`);
+        }
+        this._edgeLeafProof = edge.edgePath;
+        this._edgeLeaf = { index: edge.edgeIndex, data: edge.edgeElement };
+        this._leavesAfterEdge = [...elements, ...this._leavesAfterEdge];
+        this._createProofMap();
+        this._buildTree();
+    }
+    serialize() {
+        return {
+            _edgeLeafProof: this._edgeLeafProof,
+            _edgeLeaf: this._edgeLeaf,
+            _layers: this._layers,
+            _zeros: this._zeros,
+            levels: this.levels,
+        };
+    }
+    static deserialize(data, hashFunction) {
+        const instance = Object.assign(Object.create(this.prototype), data);
+        instance._hashFn = hashFunction || simpleHash_1.default;
+        instance._initialRoot = data._edgeLeafProof.pathRoot;
+        instance.zeroElement = instance._zeros[0];
+        instance._leavesAfterEdge = instance._layers[0].slice(data._edgeLeaf.index);
+        instance._createProofMap();
+        return instance;
+    }
+    toString() {
+        return JSON.stringify(this.serialize());
+    }
+}
+exports.PartialMerkleTree = PartialMerkleTree;

lib/index.d.ts

@@ -0,0 +1,45 @@
+import { default as MerkleTree } from './FixedMerkleTree';
+export { PartialMerkleTree } from './PartialMerkleTree';
+export { simpleHash } from './simpleHash';
+export { MerkleTree };
+export default MerkleTree;
+export type HashFunction<T> = {
+    (left: T, right: T): string;
+};
+export type MerkleTreeOptions = {
+    hashFunction?: HashFunction<Element>;
+    zeroElement?: Element;
+};
+export type Element = string | number;
+export type SerializedTreeState = {
+    levels: number;
+    _zeros: Array<Element>;
+    _layers: Array<Element[]>;
+};
+export type SerializedPartialTreeState = {
+    levels: number;
+    _layers: Element[][];
+    _zeros: Array<Element>;
+    _edgeLeafProof: ProofPath;
+    _edgeLeaf: LeafWithIndex;
+};
+export type ProofPath = {
+    pathElements: Element[];
+    pathIndices: number[];
+    pathPositions: number[];
+    pathRoot: Element;
+};
+export type TreeEdge = {
+    edgeElement: Element;
+    edgePath: ProofPath;
+    edgeIndex: number;
+    edgeElementsCount: number;
+};
+export type TreeSlice = {
+    edge: TreeEdge;
+    elements: Element[];
+};
+export type LeafWithIndex = {
+    index: number;
+    data: Element;
+};

lib/index.js

@@ -0,0 +1,13 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.MerkleTree = exports.simpleHash = exports.PartialMerkleTree = void 0;
+const FixedMerkleTree_1 = __importDefault(require("./FixedMerkleTree"));
+Object.defineProperty(exports, "MerkleTree", { enumerable: true, get: function () { return FixedMerkleTree_1.default; } });
+var PartialMerkleTree_1 = require("./PartialMerkleTree");
+Object.defineProperty(exports, "PartialMerkleTree", { enumerable: true, get: function () { return PartialMerkleTree_1.PartialMerkleTree; } });
+var simpleHash_1 = require("./simpleHash");
+Object.defineProperty(exports, "simpleHash", { enumerable: true, get: function () { return simpleHash_1.simpleHash; } });
+exports.default = FixedMerkleTree_1.default;

lib/simpleHash.d.ts

@@ -0,0 +1,10 @@
+import { Element } from './';
+/***
+ * This is insecure hash function, just for example only
+ * @param data
+ * @param seed
+ * @param hashLength
+ */
+export declare function simpleHash<T>(data: T[], seed?: number, hashLength?: number): string;
+declare const _default: (left: Element, right: Element) => string;
+export default _default;

lib/simpleHash.js

@@ -0,0 +1,21 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.simpleHash = void 0;
+/***
+ * This is insecure hash function, just for example only
+ * @param data
+ * @param seed
+ * @param hashLength
+ */
+function simpleHash(data, seed, hashLength = 40) {
+    const str = data.join('');
+    let i, l, hval = seed !== null && seed !== void 0 ? seed : 0x811c9dcc5;
+    for (i = 0, l = str.length; i < l; i++) {
+        hval ^= str.charCodeAt(i);
+        hval += (hval << 1) + (hval << 4) + (hval << 6) + (hval << 8) + (hval << 24);
+    }
+    const hash = (hval >>> 0).toString(16);
+    return BigInt('0x' + hash.padEnd(hashLength - (hash.length - 1), '0')).toString(10);
+}
+exports.simpleHash = simpleHash;
+exports.default = (left, right) => simpleHash([left, right]);

package.json

@@ -1,12 +1,17 @@
 {
-  "name": "fixed-merkle-tree",
-  "version": "0.6.0",
+  "name": "@tornado/fixed-merkle-tree",
+  "version": "0.7.3",
   "description": "Fixed depth merkle tree implementation with sequential inserts",
-  "repository": "https://github.com/tornadocash/fixed-merkle-tree.git",
-  "main": "src/merkleTree.js",
+  "repository": "https://git.tornado.ws/tornado-packages/fixed-merkle-tree.git",
+  "main": "lib/index.js",
+  "types": "lib/index.d.ts",
   "scripts": {
-    "test": "mocha",
-    "lint": "eslint ."
+    "test": "ts-mocha 'test/*.spec.ts' -s 10",
+    "coverage": "nyc npm run test",
+    "build": "tsc",
+    "clean": "rm -rf lib/",
+    "prepare": "npm run clean && npm run build",
+    "lint": "eslint src"
   },
   "keywords": [
     "merkle",
@@ -16,16 +21,20 @@
   "author": "Roman Semenov <semenov.roma@gmail.com>",
   "license": "ISC",
   "files": [
-    "src/*"
+    "src/*",
+    "lib/*"
   ],
-  "dependencies": {
-    "snarkjs": "git+https://github.com/tornadocash/snarkjs.git#869181cfaf7526fe8972073d31655493a04326d5",
-    "circomlib": "git+https://github.com/tornadocash/circomlib.git#5beb6aee94923052faeecea40135d45b6ce6172c"
-  },
   "devDependencies": {
-    "babel-eslint": "^10.1.0",
+    "@types/expect": "^24.3.0",
+    "@types/mocha": "^9.1.0",
+    "@typescript-eslint/eslint-plugin": "^5.12.0",
+    "@typescript-eslint/parser": "^5.12.0",
     "chai": "^4.2.0",
-    "eslint": "^7.5.0",
-    "mocha": "^8.1.0"
+    "eslint": "^8.9.0",
+    "eslint-config-prettier": "^8.3.0",
+    "mocha": "^9.2.2",
+    "nyc": "^15.1.0",
+    "ts-mocha": "^9.0.2",
+    "typescript": "^4.6.2"
   }
 }

src/BaseTree.ts

@@ -0,0 +1,169 @@
+import { Element, HashFunction, ProofPath } from './'
+
+export class BaseTree {
+  levels: number
+  protected _hashFn: HashFunction<Element>
+  protected zeroElement: Element
+  protected _zeros: Element[]
+  protected _layers: Array<Element[]>
+
+  get capacity() {
+    return 2 ** this.levels
+  }
+
+  get layers(): Array<Element[]> {
+    return this._layers.slice()
+  }
+
+  get zeros(): Element[] {
+    return this._zeros.slice()
+  }
+
+  get elements(): Element[] {
+    return this._layers[0].slice()
+  }
+
+  get root(): Element {
+    return this._layers[this.levels][0] ?? this._zeros[this.levels]
+  }
+
+  /**
+   * Find an element in the tree
+   * @param elements elements of tree
+   * @param element An element to find
+   * @param comparator A function that checks leaf value equality
+   * @param fromIndex The index to start the search at. If the index is greater than or equal to the array's length, -1 is returned
+   * @returns {number} Index if element is found, otherwise -1
+   */
+  static indexOf(elements: Element[], element: Element, fromIndex?: number, comparator?: <T> (arg0: T, arg1: T) => boolean): number {
+    if (comparator) {
+      return elements.findIndex((el) => comparator<Element>(element, el))
+    } else {
+      return elements.indexOf(element, fromIndex)
+    }
+  }
+
+  /**
+   * Insert new element into the tree
+   * @param element Element to insert
+   */
+  insert(element: Element) {
+    if (this._layers[0].length >= this.capacity) {
+      throw new Error('Tree is full')
+    }
+    this.update(this._layers[0].length, element)
+  }
+
+  /*
+   * Insert multiple elements into the tree.
+   * @param {Array} elements Elements to insert
+   */
+  bulkInsert(elements: Element[]): void {
+    if (!elements.length) {
+      return
+    }
+
+    if (this._layers[0].length + elements.length > this.capacity) {
+      throw new Error('Tree is full')
+    }
+    // First we insert all elements except the last one
+    // updating only full subtree hashes (all layers where inserted element has odd index)
+    // the last element will update the full path to the root making the tree consistent again
+    for (let i = 0; i < elements.length - 1; i++) {
+      this._layers[0].push(elements[i])
+      let level = 0
+      let index = this._layers[0].length - 1
+      while (index % 2 === 1) {
+        level++
+        index >>= 1
+        const left = this._layers[level - 1][index * 2]
+        const right = this._layers[level - 1][index * 2 + 1]
+        this._layers[level][index] = this._hashFn(left, right)
+      }
+    }
+    this.insert(elements[elements.length - 1])
+  }
+
+
+  /**
+   * Change an element in the tree
+   * @param {number} index Index of element to change
+   * @param element Updated element value
+   */
+  update(index: number, element: Element) {
+    if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
+      throw new Error('Insert index out of bounds: ' + index)
+    }
+    this._layers[0][index] = element
+    this._processUpdate(index)
+  }
+
+  /**
+   * Get merkle path to a leaf
+   * @param {number} index Leaf index to generate path for
+   * @returns {{pathElements: Object[], pathIndex: number[]}} An object containing adjacent elements and left-right index
+   */
+  path(index: number): ProofPath {
+    if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
+      throw new Error('Index out of bounds: ' + index)
+    }
+    let elIndex = +index
+    const pathElements: Element[] = []
+    const pathIndices: number[] = []
+    const pathPositions: number [] = []
+    for (let level = 0; level < this.levels; level++) {
+      pathIndices[level] = elIndex % 2
+      const leafIndex = elIndex ^ 1
+      if (leafIndex < this._layers[level].length) {
+        pathElements[level] = this._layers[level][leafIndex]
+        pathPositions[level] = leafIndex
+      } else {
+        pathElements[level] = this._zeros[level]
+        pathPositions[level] = 0
+      }
+      elIndex >>= 1
+    }
+    return {
+      pathElements,
+      pathIndices,
+      pathPositions,
+      pathRoot: this.root,
+    }
+  }
+
+  protected _buildZeros() {
+    this._zeros = [this.zeroElement]
+    for (let i = 1; i <= this.levels; i++) {
+      this._zeros[i] = this._hashFn(this._zeros[i - 1], this._zeros[i - 1])
+    }
+  }
+
+  protected _processNodes(nodes: Element[], layerIndex: number) {
+    const length = nodes.length
+    let currentLength = Math.ceil(length / 2)
+    const currentLayer = new Array(currentLength)
+    currentLength--
+    const starFrom = length - ((length % 2) ^ 1)
+    let j = 0
+    for (let i = starFrom; i >= 0; i -= 2) {
+      if (nodes[i - 1] === undefined) break
+      const left = nodes[i - 1]
+      const right = (i === starFrom && length % 2 === 1) ? this._zeros[layerIndex - 1] : nodes[i]
+      currentLayer[currentLength - j] = this._hashFn(left, right)
+      j++
+    }
+    return currentLayer
+  }
+
+  protected _processUpdate(index: number) {
+    for (let level = 1; level <= this.levels; level++) {
+      index >>= 1
+      const left = this._layers[level - 1][index * 2]
+      const right = index * 2 + 1 < this._layers[level - 1].length
+        ? this._layers[level - 1][index * 2 + 1]
+        : this._zeros[level - 1]
+      this._layers[level][index] = this._hashFn(left, right)
+    }
+  }
+
+}

src/FixedMerkleTree.ts

@@ -0,0 +1,128 @@
+import { Element, HashFunction, MerkleTreeOptions, ProofPath, SerializedTreeState, TreeEdge, TreeSlice } from './'
+import defaultHash from './simpleHash'
+import { BaseTree } from './BaseTree'
+
+
+export default class MerkleTree extends BaseTree {
+  constructor(levels: number, elements: Element[] = [], {
+    hashFunction = defaultHash,
+    zeroElement = 0,
+  }: MerkleTreeOptions = {}) {
+    super()
+    this.levels = levels
+    if (elements.length > this.capacity) {
+      throw new Error('Tree is full')
+    }
+    this._hashFn = hashFunction
+    this.zeroElement = zeroElement
+    this._layers = []
+    const leaves = elements.slice()
+    this._layers = [leaves]
+    this._buildZeros()
+    this._buildHashes()
+  }
+
+  private _buildHashes() {
+    for (let layerIndex = 1; layerIndex <= this.levels; layerIndex++) {
+      const nodes = this._layers[layerIndex - 1]
+      this._layers[layerIndex] = this._processNodes(nodes, layerIndex)
+    }
+  }
+
+
+  /**
+   * Insert multiple elements into the tree.
+   * @param {Array} elements Elements to insert
+   */
+  bulkInsert(elements: Element[]): void {
+    if (!elements.length) {
+      return
+    }
+
+    if (this._layers[0].length + elements.length > this.capacity) {
+      throw new Error('Tree is full')
+    }
+    // First we insert all elements except the last one
+    // updating only full subtree hashes (all layers where inserted element has odd index)
+    // the last element will update the full path to the root making the tree consistent again
+    for (let i = 0; i < elements.length - 1; i++) {
+      this._layers[0].push(elements[i])
+      let level = 0
+      let index = this._layers[0].length - 1
+      while (index % 2 === 1) {
+        level++
+        index >>= 1
+        this._layers[level][index] = this._hashFn(
+          this._layers[level - 1][index * 2],
+          this._layers[level - 1][index * 2 + 1],
+        )
+      }
+    }
+    this.insert(elements[elements.length - 1])
+  }
+
+  indexOf(element: Element, comparator?: <T> (arg0: T, arg1: T) => boolean): number {
+    return BaseTree.indexOf(this._layers[0], element, 0, comparator)
+  }
+
+  proof(element: Element): ProofPath {
+    const index = this.indexOf(element)
+    return this.path(index)
+  }
+
+  getTreeEdge(edgeIndex: number): TreeEdge {
+    const edgeElement = this._layers[0][edgeIndex]
+    if (edgeElement === undefined) {
+      throw new Error('Element not found')
+    }
+    const edgePath = this.path(edgeIndex)
+    return { edgePath, edgeElement, edgeIndex, edgeElementsCount: this._layers[0].length }
+  }
+
+  /**
+   * 🪓
+   * @param count
+   */
+  getTreeSlices(count = 4): TreeSlice[] {
+    const length = this._layers[0].length
+    let size = Math.ceil(length / count)
+    if (size % 2) size++
+    const slices: TreeSlice[] = []
+    for (let i = 0; i < length; i += size) {
+      const edgeLeft = i
+      const edgeRight = i + size
+      slices.push({ edge: this.getTreeEdge(edgeLeft), elements: this.elements.slice(edgeLeft, edgeRight) })
+    }
+    return slices
+  }
+
+  /**
+   * Serialize entire tree state including intermediate layers into a plain object
+   * Deserializing it back will not require to recompute any hashes
+   * Elements are not converted to a plain type, this is responsibility of the caller
+   */
+  serialize(): SerializedTreeState {
+    return {
+      levels: this.levels,
+      _zeros: this._zeros,
+      _layers: this._layers,
+    }
+  }
+
+  /**
+   * Deserialize data into a MerkleTree instance
+   * Make sure to provide the same hashFunction as was used in the source tree,
+   * otherwise the tree state will be invalid
+   */
+  static deserialize(data: SerializedTreeState, hashFunction?: HashFunction<Element>): MerkleTree {
+    const instance: MerkleTree = Object.assign(Object.create(this.prototype), data)
+    instance._hashFn = hashFunction || defaultHash
+    instance.zeroElement = instance._zeros[0]
+    return instance
+  }
+
+  toString() {
+    return JSON.stringify(this.serialize())
+  }
+}
+

src/PartialMerkleTree.ts

@@ -0,0 +1,186 @@
+import {
+  Element,
+  HashFunction,
+  LeafWithIndex,
+  MerkleTreeOptions,
+  ProofPath,
+  SerializedPartialTreeState,
+  TreeEdge,
+} from './'
+import defaultHash from './simpleHash'
+import { BaseTree } from './BaseTree'
+
+export class PartialMerkleTree extends BaseTree {
+  private _leaves: Element[]
+  private _leavesAfterEdge: Element[]
+  private _edgeLeaf: LeafWithIndex
+  private _initialRoot: Element
+  private _edgeLeafProof: ProofPath
+  private _proofMap: Map<number, [i: number, el: Element]>
+
+  constructor(levels: number, {
+    edgePath,
+    edgeElement,
+    edgeIndex,
+    edgeElementsCount,
+  }: TreeEdge, leaves: Element[], { hashFunction, zeroElement }: MerkleTreeOptions = {}) {
+    super()
+    if (edgeIndex + leaves.length !== edgeElementsCount) throw new Error('Invalid number of elements')
+    this._edgeLeafProof = edgePath
+    this._initialRoot = edgePath.pathRoot
+    this.zeroElement = zeroElement ?? 0
+    this._edgeLeaf = { data: edgeElement, index: edgeIndex }
+    this._leavesAfterEdge = leaves
+    this.levels = levels
+    this._hashFn = hashFunction || defaultHash
+    this._createProofMap()
+    this._buildTree()
+  }
+
+  get edgeIndex(): number {
+    return this._edgeLeaf.index
+  }
+
+  get edgeElement(): Element {
+    return this._edgeLeaf.data
+  }
+
+  get edgeLeafProof(): ProofPath {
+    return this._edgeLeafProof
+  }
+
+  private _createProofMap() {
+    this._proofMap = this.edgeLeafProof.pathPositions.reduce((p, c, i) => {
+      p.set(i, [c, this.edgeLeafProof.pathElements[i]])
+      return p
+    }, new Map())
+    this._proofMap.set(this.levels, [0, this.edgeLeafProof.pathRoot])
+  }
+
+  private _buildTree(): void {
+    const edgeLeafIndex = this._edgeLeaf.index
+    this._leaves = Array(edgeLeafIndex).concat(this._leavesAfterEdge)
+    if (this._proofMap.has(0)) {
+      const [proofPos, proofEl] = this._proofMap.get(0)
+      this._leaves[proofPos] = proofEl
+    }
+    this._layers = [this._leaves]
+    this._buildZeros()
+    this._buildHashes()
+  }
+
+  private _buildHashes() {
+    for (let layerIndex = 1; layerIndex <= this.levels; layerIndex++) {
+      const nodes = this._layers[layerIndex - 1]
+      const currentLayer = this._processNodes(nodes, layerIndex)
+      if (this._proofMap.has(layerIndex)) {
+        const [proofPos, proofEl] = this._proofMap.get(layerIndex)
+        if (!currentLayer[proofPos]) currentLayer[proofPos] = proofEl
+      }
+      this._layers[layerIndex] = currentLayer
+    }
+  }
+
+
+  /**
+   * Change an element in the tree
+   * @param {number} index Index of element to change
+   * @param element Updated element value
+   */
+  update(index: number, element: Element) {
+    if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
+      throw new Error('Insert index out of bounds: ' + index)
+    }
+    if (index < this._edgeLeaf.index) {
+      throw new Error(`Index ${index} is below the edge: ${this._edgeLeaf.index}`)
+    }
+    this._layers[0][index] = element
+    this._processUpdate(index)
+  }
+
+  path(index: number): ProofPath {
+    if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
+      throw new Error('Index out of bounds: ' + index)
+    }
+    if (index < this._edgeLeaf.index) {
+      throw new Error(`Index ${index} is below the edge: ${this._edgeLeaf.index}`)
+    }
+    let elIndex = Number(index)
+    const pathElements: Element[] = []
+    const pathIndices: number[] = []
+    const pathPositions: number [] = []
+    for (let level = 0; level < this.levels; level++) {
+      pathIndices[level] = elIndex % 2
+      const leafIndex = elIndex ^ 1
+      if (leafIndex < this._layers[level].length) {
+        pathElements[level] = this._layers[level][leafIndex]
+        pathPositions[level] = leafIndex
+      } else {
+        pathElements[level] = this._zeros[level]
+        pathPositions[level] = 0
+      }
+      const [proofPos, proofEl] = this._proofMap.get(level)
+      pathElements[level] = pathElements[level] ?? (proofPos === leafIndex ? proofEl : this._zeros[level])
+      elIndex >>= 1
+    }
+    return {
+      pathElements,
+      pathIndices,
+      pathPositions,
+      pathRoot: this.root,
+    }
+  }
+
+  indexOf(element: Element, comparator?: <T> (arg0: T, arg1: T) => boolean): number {
+    return BaseTree.indexOf(this._layers[0], element, this.edgeIndex, comparator)
+  }
+
+  proof(element: Element): ProofPath {
+    const index = this.indexOf(element)
+    return this.path(index)
+  }
+
+  /**
+   * Shifts edge of tree to left
+   * @param edge new TreeEdge below current edge
+   * @param elements leaves between old and new edge
+   */
+
+  shiftEdge(edge: TreeEdge, elements: Element[]) {
+    if (this._edgeLeaf.index <= edge.edgeIndex) {
+      throw new Error(`New edgeIndex should be smaller then ${this._edgeLeaf.index}`)
+    }
+    if (elements.length !== (this._edgeLeaf.index - edge.edgeIndex)) {
+      throw new Error(`Elements length should be ${this._edgeLeaf.index - edge.edgeIndex}`)
+    }
+    this._edgeLeafProof = edge.edgePath
+    this._edgeLeaf = { index: edge.edgeIndex, data: edge.edgeElement }
+    this._leavesAfterEdge = [...elements, ...this._leavesAfterEdge]
+    this._createProofMap()
+    this._buildTree()
+  }
+
+  serialize(): SerializedPartialTreeState {
+    return {
+      _edgeLeafProof: this._edgeLeafProof,
+      _edgeLeaf: this._edgeLeaf,
+      _layers: this._layers,
+      _zeros: this._zeros,
+      levels: this.levels,
+    }
+  }
+
+  static deserialize(data: SerializedPartialTreeState, hashFunction?: HashFunction<Element>): PartialMerkleTree {
+    const instance: PartialMerkleTree = Object.assign(Object.create(this.prototype), data)
+    instance._hashFn = hashFunction || defaultHash
+    instance._initialRoot = data._edgeLeafProof.pathRoot
+    instance.zeroElement = instance._zeros[0]
+    instance._leavesAfterEdge = instance._layers[0].slice(data._edgeLeaf.index)
+    instance._createProofMap()
+    return instance
+  }
+
+  toString() {
+    return JSON.stringify(this.serialize())
+  }
+}

src/index.ts

@@ -0,0 +1,46 @@
+import { default as MerkleTree } from './FixedMerkleTree'
+export { PartialMerkleTree } from './PartialMerkleTree'
+export { simpleHash } from './simpleHash'
+export { MerkleTree }
+export default MerkleTree
+export type HashFunction<T> = {
+  (left: T, right: T): string
+}
+
+export type MerkleTreeOptions = {
+  hashFunction?: HashFunction<Element>
+  zeroElement?: Element
+}
+
+export type  Element = string | number
+
+export type SerializedTreeState = {
+  levels: number,
+  _zeros: Array<Element>,
+  _layers: Array<Element[]>
+}
+
+export type SerializedPartialTreeState = {
+  levels: number
+  _layers: Element[][]
+  _zeros: Array<Element>
+  _edgeLeafProof: ProofPath
+  _edgeLeaf: LeafWithIndex
+}
+
+export type ProofPath = {
+  pathElements: Element[],
+  pathIndices: number[],
+  pathPositions: number[],
+  pathRoot: Element
+}
+export type TreeEdge = {
+  edgeElement: Element;
+  edgePath: ProofPath;
+  edgeIndex: number;
+  edgeElementsCount: number;
+}
+
+export type TreeSlice = { edge: TreeEdge, elements: Element[] }
+export type LeafWithIndex = { index: number, data: Element }
+

src/merkleTree.js

@@ -1,208 +0,0 @@
-// keccak256("tornado") % BN254_FIELD_SIZE
-const DEFAULT_ZERO = '21663839004416932945382355908790599225266501822907911457504978515578255421292'
-const defaultHash = require('./mimc')
-
-// todo ensure consistent types in tree and inserted elements?
-// todo make sha3 default hasher (and update tests) to get rid of mimc/snarkjs/circomlib dependency
-
-/**
- * @callback hashFunction
- * @param left Left leaf
- * @param right Right leaf
- */
-/**
- * Merkle tree
- */
-class MerkleTree {
-  /**
-   * Constructor
-   * @param {number} levels Number of levels in the tree
-   * @param {Array} [elements] Initial elements
-   * @param {Object} options
-   * @param {hashFunction} [options.hashFunction] Function used to hash 2 leaves
-   * @param [options.zeroElement] Value for non-existent leaves
-   */
-  constructor(levels, elements = [], { hashFunction, zeroElement = DEFAULT_ZERO } = {}) {
-    this.levels = levels
-    this.capacity = 2 ** levels
-    if (elements.length > this.capacity) {
-      throw new Error('Tree is full')
-    }
-    this._hash = hashFunction || defaultHash
-    this.zeroElement = zeroElement
-    this._zeros = []
-    this._zeros[0] = zeroElement
-    for (let i = 1; i <= levels; i++) {
-      this._zeros[i] = this._hash(this._zeros[i - 1], this._zeros[i - 1])
-    }
-    this._layers = []
-    this._layers[0] = elements.slice()
-    this._rebuild()
-  }
-
-  _rebuild() {
-    for (let level = 1; level <= this.levels; level++) {
-      this._layers[level] = []
-      for (let i = 0; i < Math.ceil(this._layers[level - 1].length / 2); i++) {
-        this._layers[level][i] = this._hash(
-          this._layers[level - 1][i * 2],
-          i * 2 + 1 < this._layers[level - 1].length
-            ? this._layers[level - 1][i * 2 + 1]
-            : this._zeros[level - 1],
-        )
-      }
-    }
-  }
-
-  /**
-   * Get tree root
-   * @returns {*}
-   */
-  root() {
-    return this._layers[this.levels].length > 0 ? this._layers[this.levels][0] : this._zeros[this.levels]
-  }
-
-  /**
-   * Insert new element into the tree
-   * @param element Element to insert
-   */
-  insert(element) {
-    if (this._layers[0].length >= this.capacity) {
-      throw new Error('Tree is full')
-    }
-    this.update(this._layers[0].length, element)
-  }
-
-  /**
-   * Insert multiple elements into the tree.
-   * @param {Array} elements Elements to insert
-   */
-  bulkInsert(elements) {
-    if (this._layers[0].length + elements.length > this.capacity) {
-      throw new Error('Tree is full')
-    }
-    // First we insert all elements except the last one
-    // updating only full subtree hashes (all layers where inserted element has odd index)
-    // the last element will update the full path to the root making the tree consistent again
-    for (let i = 0; i < elements.length - 1; i++) {
-      this._layers[0].push(elements[i])
-      let level = 0
-      let index = this._layers[0].length - 1
-      while (index % 2 === 1) {
-        level++
-        index >>= 1
-        this._layers[level][index] = this._hash(
-          this._layers[level - 1][index * 2],
-          this._layers[level - 1][index * 2 + 1],
-        )
-      }
-    }
-    this.insert(elements[elements.length - 1])
-  }
-
-  /**
-   * Change an element in the tree
-   * @param {number} index Index of element to change
-   * @param element Updated element value
-   */
-  update(index, element) {
-    if (isNaN(Number(index)) || index < 0 || index > this._layers[0].length || index >= this.capacity) {
-      throw new Error('Insert index out of bounds: ' + index)
-    }
-    this._layers[0][index] = element
-    for (let level = 1; level <= this.levels; level++) {
-      index >>= 1
-      this._layers[level][index] = this._hash(
-        this._layers[level - 1][index * 2],
-        index * 2 + 1 < this._layers[level - 1].length
-          ? this._layers[level - 1][index * 2 + 1]
-          : this._zeros[level - 1],
-      )
-    }
-  }
-
-  /**
-   * Get merkle path to a leaf
-   * @param {number} index Leaf index to generate path for
-   * @returns {{pathElements: Object[], pathIndex: number[]}} An object containing adjacent elements and left-right index
-   */
-  path(index) {
-    if (isNaN(Number(index)) || index < 0 || index >= this._layers[0].length) {
-      throw new Error('Index out of bounds: ' + index)
-    }
-    const pathElements = []
-    const pathIndices = []
-    for (let level = 0; level < this.levels; level++) {
-      pathIndices[level] = index % 2
-      pathElements[level] =
-        (index ^ 1) < this._layers[level].length ? this._layers[level][index ^ 1] : this._zeros[level]
-      index >>= 1
-    }
-    return {
-      pathElements,
-      pathIndices,
-    }
-  }
-
-  /**
-   * Find an element in the tree
-   * @param element An element to find
-   * @param comparator A function that checks leaf value equality
-   * @returns {number} Index if element is found, otherwise -1
-   */
-  indexOf(element, comparator) {
-    if (comparator) {
-      return this._layers[0].findIndex((el) => comparator(element, el))
-    } else {
-      return this._layers[0].indexOf(element)
-    }
-  }
-
-  /**
-   * Returns a copy of non-zero tree elements
-   * @returns {Object[]}
-   */
-  elements() {
-    return this._layers[0].slice()
-  }
-
-  /**
-   * Returns a copy of n-th zero elements array
-   * @returns {Object[]}
-   */
-  zeros() {
-    return this._zeros.slice()
-  }
-
-  /**
-   * Serialize entire tree state including intermediate layers into a plain object
-   * Deserializing it back will not require to recompute any hashes
-   * Elements are not converted to a plain type, this is responsibility of the caller
-   */
-  serialize() {
-    return {
-      levels: this.levels,
-      _zeros: this._zeros,
-      _layers: this._layers,
-    }
-  }
-
-  /**
-   * Deserialize data into a MerkleTree instance
-   * Make sure to provide the same hashFunction as was used in the source tree,
-   * otherwise the tree state will be invalid
-   *
-   * @param data
-   * @param hashFunction
-   * @returns {MerkleTree}
-   */
-  static deserialize(data, hashFunction) {
-    const instance = Object.assign(Object.create(this.prototype), data)
-    instance._hash = hashFunction || defaultHash
-    instance.capacity = 2 ** instance.levels
-    instance.zeroElement = instance._zeros[0]
-    return instance
-  }
-}
-
-module.exports = MerkleTree

src/mimc.js

@@ -1,3 +0,0 @@
-const { mimcsponge } = require('circomlib')
-const { bigInt } = require('snarkjs')
-module.exports = (left, right) => mimcsponge.multiHash([bigInt(left), bigInt(right)]).toString()

src/simpleHash.ts

@@ -0,0 +1,22 @@
+import { Element } from './'
+
+/***
+ * This is insecure hash function, just for example only
+ * @param data
+ * @param seed
+ * @param hashLength
+ */
+
+export function simpleHash<T>(data: T[], seed?: number, hashLength = 40): string {
+  const str = data.join('')
+  let i, l,
+    hval = seed ?? 0x811c9dcc5
+  for (i = 0, l = str.length; i < l; i++) {
+    hval ^= str.charCodeAt(i)
+    hval += (hval << 1) + (hval << 4) + (hval << 6) + (hval << 8) + (hval << 24)
+  }
+  const hash = (hval >>> 0).toString(16)
+  return BigInt('0x' + hash.padEnd(hashLength - (hash.length - 1), '0')).toString(10)
+}
+
+export default (left: Element, right: Element): string => simpleHash([left, right])

test/fixedMerkleTree.spec.ts

@@ -0,0 +1,428 @@
+import { MerkleTree, PartialMerkleTree, TreeEdge } from '../src'
+import { assert, should } from 'chai'
+import { createHash } from 'crypto'
+import { it } from 'mocha'
+
+const sha256Hash = (left, right) => createHash('sha256').update(`${left}${right}`).digest('hex')
+const ZERO_ELEMENT = '21663839004416932945382355908790599225266501822907911457504978515578255421292'
+
+describe('MerkleTree', () => {
+
+  describe('#constructor', () => {
+
+    it('should have correct zero root', () => {
+      const tree = new MerkleTree(10, [])
+      return should().equal(tree.root, '3060353338620102847451617558650138132480')
+    })
+
+    it('should have correct 1 element root', () => {
+      const tree = new MerkleTree(10, [1])
+      should().equal(tree.root, '4059654748770657324723044385589999697920')
+    })
+
+    it('should have correct even elements root', () => {
+      const tree = new MerkleTree(10, [1, 2])
+      should().equal(tree.root, '3715471817149864798706576217905179918336')
+    })
+
+    it('should have correct odd elements root', () => {
+      const tree = new MerkleTree(10, [1, 2, 3])
+      should().equal(tree.root, '5199180210167621115778229238102210117632')
+    })
+
+    it('should be able to create a full tree', () => {
+      new MerkleTree(2, [1, 2, 3, 4])
+    })
+
+    it('should fail to create tree with too many elements', () => {
+      const call = () => new MerkleTree(2, [1, 2, 3, 4, 5])
+      should().throw(call, 'Tree is full')
+    })
+
+    it('should work with optional hash function and zero element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5, 6], { hashFunction: sha256Hash, zeroElement: 'zero' })
+      should().equal(tree.root, 'a377b9fa0ed41add83e56f7e1d0e2ebdb46550b9d8b26b77dece60cb67283f19')
+    })
+  })
+
+  describe('#insert', () => {
+    it('should insert into empty tree', () => {
+      const tree = new MerkleTree(10)
+      tree.insert(42)
+      should().equal(tree.root, '750572848877730275626358141391262973952')
+    })
+
+    it('should insert into odd tree', () => {
+      const tree = new MerkleTree(10, [1])
+      tree.insert(42)
+      should().equal(tree.root, '5008383558940708447763798816817296703488')
+    })
+
+    it('should insert into even tree', () => {
+      const tree = new MerkleTree(10, [1, 2])
+      tree.insert(42)
+      should().equal(tree.root, '5005864318873356880627322373636156817408')
+    })
+
+    it('should insert last element', () => {
+      const tree = new MerkleTree(2, [1, 2, 3])
+      tree.insert(4)
+    })
+
+    it('should fail to insert when tree is full', () => {
+      const tree = new MerkleTree(2, [1, 2, 3, 4])
+      const call = () => tree.insert(5)
+      should().throw(call, 'Tree is full')
+    })
+  })
+
+  describe('#bulkInsert', () => {
+    it('should work', () => {
+      const tree = new MerkleTree(10, [1, 2, 3])
+      tree.bulkInsert([4, 5, 6])
+      should().equal(tree.root, '4066635800770511602067209448381558554624')
+    })
+
+    it('should give the same result as sequential inserts', () => {
+      const initialArray = [
+        [1],
+        [1, 2],
+        [1, 2, 3],
+        [1, 2, 3, 4],
+      ]
+      const insertedArray = [
+        [11],
+        [11, 12],
+        [11, 12, 13],
+        [11, 12, 13, 14],
+      ]
+      for (const initial of initialArray) {
+        for (const inserted of insertedArray) {
+          const tree1 = new MerkleTree(10, initial)
+          const tree2 = new MerkleTree(10, initial)
+          tree1.bulkInsert(inserted)
+          for (const item of inserted) {
+            tree2.insert(item)
+          }
+          should().equal(tree1.root, tree2.root)
+        }
+      }
+    }).timeout(10000)
+
+    it('should work with max elements', () => {
+      const tree = new MerkleTree(2, [1, 2])
+      tree.bulkInsert([3, 4])
+    })
+
+    it('should fail to insert too many elements', () => {
+      const tree = new MerkleTree(2, [1, 2])
+      const call = () => tree.bulkInsert([3, 4, 5])
+      should().throw(call, 'Tree is full')
+    })
+
+    it('should bypass empty elements', () => {
+      const elements = [1, 2, 3, 4]
+      const tree = new MerkleTree(2, elements)
+      tree.bulkInsert([])
+      assert.deepEqual(tree.elements, elements, 'No elements inserted')
+    })
+  })
+
+  describe('#update', () => {
+    it('should update first element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      tree.update(0, 42)
+      should().equal(tree.root, '3884161948856565981263417078389340635136')
+    })
+
+    it('should update last element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      tree.update(4, 42)
+      should().equal(tree.root, '3564959811529894228734180300843252711424')
+    })
+
+    it('should update odd element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      tree.update(1, 42)
+      should().equal(tree.root, '4576704573778433422699674477203122290688')
+    })
+
+    it('should update even element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      tree.update(2, 42)
+      should().equal(tree.root, '1807994110952186123819489133812038762496')
+    })
+
+    it('should update extra element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4])
+      tree.update(4, 5)
+      should().equal(tree.root, '1099080610107164849381389194938128793600')
+    })
+
+    it('should fail to update incorrect index', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      should().throw((() => tree.update(-1, 42)), 'Insert index out of bounds: -1')
+      should().throw((() => tree.update(6, 42)), 'Insert index out of bounds: 6')
+      // @ts-ignore
+      should().throw((() => tree.update('qwe', 42)), 'Insert index out of bounds: qwe')
+    })
+
+    it('should fail to update over capacity', () => {
+      const tree = new MerkleTree(2, [1, 2, 3, 4])
+      const call = () => tree.update(4, 42)
+      should().throw(call, 'Insert index out of bounds: 4')
+    })
+  })
+
+  describe('#indexOf', () => {
+    it('should find index', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      should().equal(tree.indexOf(3), 2)
+    })
+
+    it('should work with comparator', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      should().equal(tree.indexOf(4, (arg0, arg1) => arg0 === arg1), 3)
+    })
+
+    it('should return -1 for non existent element', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      should().equal(tree.indexOf(42), -1)
+    })
+  })
+
+  describe('#path', () => {
+    it('should work for even index', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      const path = tree.path(2)
+      assert.deepEqual(path.pathIndices, [0, 1, 0, 0, 0, 0, 0, 0, 0, 0])
+      assert.deepEqual(path.pathElements, [
+        4,
+        '4027992409016347597424110157229339967488',
+        '3591172241203040147397382471352592629760',
+        '938972308169430750202858820582946897920',
+        '3743880566844110745576746962917825445888',
+        '2074434463882483178614385966084599578624',
+        '2808856778596740691845240322870189490176',
+        '4986731814143931240516913804278285467648',
+        '1918547053077726613961101558405545328640',
+        '5444383861051812288142814494928935059456',
+
+      ])
+    })
+
+    it('should work for odd index', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      const path = tree.path(3)
+      assert.deepEqual(path.pathIndices, [1, 1, 0, 0, 0, 0, 0, 0, 0, 0])
+      assert.deepEqual(path.pathElements, [
+        3,
+        '4027992409016347597424110157229339967488',
+        '3591172241203040147397382471352592629760',
+        '938972308169430750202858820582946897920',
+        '3743880566844110745576746962917825445888',
+        '2074434463882483178614385966084599578624',
+        '2808856778596740691845240322870189490176',
+        '4986731814143931240516913804278285467648',
+        '1918547053077726613961101558405545328640',
+        '5444383861051812288142814494928935059456',
+      ])
+    })
+
+    it('should fail on incorrect index', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4])
+      should().throw((() => tree.path(-1)), 'Index out of bounds: -1')
+      should().throw((() => tree.path(5)), 'Index out of bounds: 5')
+      // @ts-ignore
+      should().throw((() => tree.path('qwe')), 'Index out of bounds: qwe')
+    })
+
+    it('should work for correct string index', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      // @ts-ignore
+      const path = tree.path('2')
+      assert.deepEqual(path.pathIndices, [0, 1, 0, 0, 0, 0, 0, 0, 0, 0])
+      assert.deepEqual(path.pathElements, [
+        4,
+        '4027992409016347597424110157229339967488',
+        '3591172241203040147397382471352592629760',
+        '938972308169430750202858820582946897920',
+        '3743880566844110745576746962917825445888',
+        '2074434463882483178614385966084599578624',
+        '2808856778596740691845240322870189490176',
+        '4986731814143931240516913804278285467648',
+        '1918547053077726613961101558405545328640',
+        '5444383861051812288142814494928935059456',
+
+      ])
+    })
+  })
+  describe('#proof', () => {
+    it('should return proof for leaf', () => {
+      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
+      assert.deepEqual(tree.proof(4), tree.path(3))
+    })
+  })
+
+  describe('#getTreeEdge', () => {
+    it('should return correct treeEdge', () => {
+      const expectedEdge: TreeEdge = {
+        edgePath: {
+          pathElements: [
+            5,
+            '1390935134112885103361924701261056180224',
+            '1952916572242076545231119328171167580160',
+            '938972308169430750202858820582946897920',
+          ],
+          pathIndices: [0, 0, 1, 0],
+          pathPositions: [5, 0, 0, 0],
+          pathRoot: '3283298202329284319899364273680487022592',
+        },
+        edgeElement: 4,
+        edgeIndex: 4,
+        edgeElementsCount: 6,
+      }
+      const tree = new MerkleTree(4, [0, 1, 2, 3, 4, 5])
+      assert.deepEqual(tree.getTreeEdge(4), expectedEdge)
+    })
+    it('should fail if element not found', () => {
+      const tree = new MerkleTree(4, [0, 1, 2, 3, 4, 5])
+      const call = () => tree.getTreeEdge(6)
+      should().throw(call, 'Element not found')
+    })
+  })
+  describe('#getTreeSlices', () => {
+    let fullTree: MerkleTree
+    before(async () => {
+      const elements = Array.from({ length: 2 ** 10 }, (_, i) => i)
+      fullTree = new MerkleTree(10, elements)
+      return Promise.resolve()
+    })
+    it('should return correct slices count', () => {
+      const count = 4
+      const slicesCount = fullTree.getTreeSlices(4).length
+      should().equal(count, slicesCount)
+    }).timeout(10000)
+
+    it('should be able to create partial tree from last slice', () => {
+      const [, , , lastSlice] = fullTree.getTreeSlices()
+      const partialTree = new PartialMerkleTree(10, lastSlice.edge, lastSlice.elements)
+      assert.deepEqual(fullTree.root, partialTree.root)
+    }).timeout(10000)
+
+    it('should be able to build full tree from slices', () => {
+      const slices = fullTree.getTreeSlices()
+      const lastSlice = slices.pop()
+      const partialTree = new PartialMerkleTree(10, lastSlice.edge, lastSlice.elements)
+      slices.reverse().forEach(({ edge, elements }) => {
+        partialTree.shiftEdge(edge, elements)
+      })
+      assert.deepEqual(fullTree.layers, partialTree.layers)
+    }).timeout(10000)
+
+    it('should return same path', () => {
+      const slices = fullTree.getTreeSlices()
+      const lastSlice = slices.pop()
+      const partialTree = new PartialMerkleTree(10, lastSlice.edge, lastSlice.elements)
+      slices.reverse().forEach(({ edge, elements }) => {
+        partialTree.shiftEdge(edge, elements)
+      })
+      assert.deepEqual(fullTree.path(100), partialTree.path(100))
+    }).timeout(10000)
+
+    it('should throw if invalid number of elements', () => {
+      const [firstSlice] = fullTree.getTreeSlices()
+      const call = () => new PartialMerkleTree(10, firstSlice.edge, firstSlice.elements)
+      should().throw(call, 'Invalid number of elements')
+    }).timeout(10000)
+  })
+  describe('#getters', () => {
+    const elements = [1, 2, 3, 4, 5]
+    const layers = [
+      [1, 2, 3, 4, 5],
+      [
+        '4027992409016347597424110157229339967488',
+        '923221781152860005594997320673730232320',
+        '752191049236692618445397735417537626112',
+
+      ],
+      [
+        '81822854828781486047086122479545722339328',
+        '3591172241203040147397382471352592629760',
+
+      ],
+      ['2729943778107054496417267081388406865920'],
+      ['4562739390655416913642128116127918718976'],
+    ]
+
+    it('should return same elements in array', () => {
+      const tree = new MerkleTree(10, elements)
+      assert.deepEqual(tree.elements, elements)
+    })
+    it('should return copy of elements array', () => {
+      const tree = new MerkleTree(10, elements)
+      const elements1 = tree.elements
+      tree.insert(6)
+      const elements2 = tree.elements
+      should().not.equal(elements1, elements2)
+    })
+
+    it('should return same layers in array', () => {
+      const tree = new MerkleTree(4, elements)
+      assert.deepEqual(tree.layers, layers)
+    })
+    it('should return copy of elements array', () => {
+      const tree = new MerkleTree(4, elements)
+      const layers1 = tree.layers
+      tree.insert(6)
+      const layers2 = tree.layers
+      should().not.equal(layers1, layers2)
+    })
+    it('should return correct zeros array', () => {
+      const zeros = [
+        0,
+        '1390935134112885103361924701261056180224',
+        '3223901263414086620636498663535535980544',
+        '938972308169430750202858820582946897920',
+        '3743880566844110745576746962917825445888',
+      ]
+      const tree = new MerkleTree(4, [])
+      assert.deepEqual(tree.zeros, zeros, 'Not equal')
+    })
+    it('should return copy of zeros array', () => {
+      const tree = new MerkleTree(4, [])
+      const zeros1 = tree.zeros
+      tree.insert(6)
+      const zeros2 = tree.zeros
+      should().not.equal(zeros1, zeros2)
+    })
+  })
+
+  describe('#serialize', () => {
+    it('should work', () => {
+      const src = new MerkleTree(10, [1, 2, 3, 4, 5, 6, 7, 8, 9])
+      const data = src.serialize()
+      const dst = MerkleTree.deserialize(data)
+      should().equal(src.root, dst.root)
+
+      src.insert(10)
+      dst.insert(10)
+
+      should().equal(src.root, dst.root)
+    })
+  })
+  describe('#toString', () => {
+    it('should return correct stringified representation', () => {
+      const src = new MerkleTree(10, [1, 2, 3, 4, 5, 6, 7, 8, 9])
+      const str = src.toString()
+      const dst = MerkleTree.deserialize(JSON.parse(str))
+      should().equal(src.root, dst.root)
+
+      src.insert(10)
+      dst.insert(10)
+
+      should().equal(src.root, dst.root)
+
+    })
+  })
+})

test/merkleTree.test.js

@@ -1,246 +0,0 @@
-const MerkleTree = require('../src/merkleTree')
-require('chai').should()
-
-describe('MerkleTree', () => {
-  describe('#constructor', () => {
-    it('should have correct zero root', () => {
-      const tree = new MerkleTree(10)
-      return tree.root().should.equal('14030416097908897320437553787826300082392928432242046897689557706485311282736')
-    })
-
-    it('should have correct 1 element root', () => {
-      const tree = new MerkleTree(10, [1])
-      tree.root().should.equal('8423266420989796135179818298985240707844287090553672312129988553683991994663')
-    })
-
-    it('should have correct even elements root', () => {
-      const tree = new MerkleTree(10, [1, 2])
-      tree.root().should.equal('6632020347849276860492323008882350357301732786233864934344775324188835172576')
-    })
-
-    it('should have correct odd elements root', () => {
-      const tree = new MerkleTree(10, [1, 2, 3])
-      tree.root().should.equal('13605252518346649016266481317890801910232739395710162921320863289825142055129')
-    })
-
-    it('should be able to create a full tree', () => {
-      new MerkleTree(2, [1, 2, 3, 4])
-    })
-
-    it('should fail to create tree with too many elements', () => {
-      const call = () => new MerkleTree(2, [1, 2, 3, 4, 5])
-      call.should.throw('Tree is full')
-    })
-  })
-
-  describe('#insert', () => {
-    it('should insert into empty tree', () => {
-      const tree = new MerkleTree(10)
-      tree.insert(42)
-      tree.root().should.equal('5305397050004975530787056746976521882221645950652996479084366175595194436378')
-    })
-
-    it('should insert into odd tree', () => {
-      const tree = new MerkleTree(10, [1])
-      tree.insert(42)
-      tree.root().should.equal('4732716818150428188641303198013632061441036732749853605989871103991103096471')
-    })
-
-    it('should insert into even tree', () => {
-      const tree = new MerkleTree(10, [1, 2])
-      tree.insert(42)
-      tree.root().should.equal('6204016789747878948181936326719724987136198810274146408545977300318734508764')
-    })
-
-    it('should insert last element', () => {
-      const tree = new MerkleTree(2, [1, 2, 3])
-      tree.insert(4)
-    })
-
-    it('should fail to insert when tree is full', () => {
-      const tree = new MerkleTree(2, [1, 2, 3, 4])
-      const call = () => tree.insert(5)
-      call.should.throw('Tree is full')
-    })
-  })
-
-  describe('#bulkInsert', () => {
-    it('should work', () => {
-      const tree = new MerkleTree(10, [1, 2, 3])
-      tree.bulkInsert([4, 5, 6])
-      tree.root().should.equal('10132905325673518287563057607527946096399700874345297651940963130460267058606')
-    })
-
-    it('should give the same result as sequental inserts', () => {
-      const initialArray = [
-        [1],
-        [1, 2],
-        [1, 2, 3],
-        [1, 2, 3, 4],
-      ]
-      const insertedArray = [
-        [11],
-        [11, 12],
-        [11, 12, 13],
-        [11, 12, 13, 14],
-      ]
-      for (const initial of initialArray) {
-        for (const inserted of insertedArray) {
-          const tree1 = new MerkleTree(10, initial)
-          const tree2 = new MerkleTree(10, initial)
-          tree1.bulkInsert(inserted)
-          for (const item of inserted) {
-            tree2.insert(item)
-          }
-          tree1.root().should.equal(tree2.root())
-        }
-      }
-    }).timeout(10000)
-
-    it('should work with max elements', () => {
-      const tree = new MerkleTree(2, [1, 2])
-      tree.bulkInsert([3, 4])
-    })
-
-    it('should fail to insert too many elements', () => {
-      const tree = new MerkleTree(2, [1, 2])
-      const call = () => tree.bulkInsert([3, 4, 5])
-      call.should.throw('Tree is full')
-    })
-  })
-
-  describe('#update', () => {
-    it('should update first element', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      tree.update(0, 42)
-      tree.root().should.equal('153077538697962715163231177553585573790587443799974092612333826693999310199')
-    })
-
-    it('should update last element', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      tree.update(4, 42)
-      tree.root().should.equal('1955192134603843666100093417117434845771298375724087600313714421260719033775')
-    })
-
-    it('should update odd element', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      tree.update(1, 42)
-      tree.root().should.equal('6642888742811380760154112624880866754768235565211186414088321870395007150538')
-    })
-
-    it('should update even element', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      tree.update(2, 42)
-      tree.root().should.equal('11739358667442647096377238675718917508981868161724701476635082606510350785683')
-    })
-
-    it('should update extra element', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4])
-      tree.update(4, 5)
-      tree.root().should.equal('6341751103515285836339987888606244815365572869367801108789753151704260302930')
-    })
-
-    it('should fail to update incorrect index', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5]);
-      (() => tree.update(-1, 42)).should.throw('Insert index out of bounds: -1');
-      (() => tree.update(6, 42)).should.throw('Insert index out of bounds: 6');
-      (() => tree.update('qwe', 42)).should.throw('Insert index out of bounds: qwe')
-    })
-
-    it('should fail to update over capacity', () => {
-      const tree = new MerkleTree(2, [1, 2, 3, 4])
-      const call = () => tree.update(4, 42)
-      call.should.throw('Insert index out of bounds: 4')
-    })
-  })
-
-  describe('#indexOf', () => {
-    it('should find index', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      tree.indexOf(3).should.equal(2)
-    })
-
-    it('should return -1 for non existent element', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      tree.indexOf(42).should.equal(-1)
-    })
-  })
-
-  describe('#path', () => {
-    it('should work for even index', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      const path = tree.path(2)
-      path.pathIndices.should.be.deep.equal([0, 1, 0, 0, 0, 0, 0, 0, 0, 0])
-      path.pathElements.should.be.deep.equal([
-        4,
-        '19814528709687996974327303300007262407299502847885145507292406548098437687919',
-        '21305827034995891902714687670641862055126514524916463201449278400604999416145',
-        '14506027710748750947258687001455876266559341618222612722926156490737302846427',
-        '4766583705360062980279572762279781527342845808161105063909171241304075622345',
-        '16640205414190175414380077665118269450294358858897019640557533278896634808665',
-        '13024477302430254842915163302704885770955784224100349847438808884122720088412',
-        '11345696205391376769769683860277269518617256738724086786512014734609753488820',
-        '17235543131546745471991808272245772046758360534180976603221801364506032471936',
-        '155962837046691114236524362966874066300454611955781275944230309195800494087',
-      ])
-    })
-
-    it('should work for odd index', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      const path = tree.path(3)
-      path.pathIndices.should.be.deep.equal([1, 1, 0, 0, 0, 0, 0, 0, 0, 0])
-      path.pathElements.should.be.deep.equal([
-        3,
-        '19814528709687996974327303300007262407299502847885145507292406548098437687919',
-        '21305827034995891902714687670641862055126514524916463201449278400604999416145',
-        '14506027710748750947258687001455876266559341618222612722926156490737302846427',
-        '4766583705360062980279572762279781527342845808161105063909171241304075622345',
-        '16640205414190175414380077665118269450294358858897019640557533278896634808665',
-        '13024477302430254842915163302704885770955784224100349847438808884122720088412',
-        '11345696205391376769769683860277269518617256738724086786512014734609753488820',
-        '17235543131546745471991808272245772046758360534180976603221801364506032471936',
-        '155962837046691114236524362966874066300454611955781275944230309195800494087',
-      ])
-    })
-
-    it('should fail on incorrect index', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4]);
-      (() => tree.path(-1)).should.throw('Index out of bounds: -1');
-      (() => tree.path(5)).should.throw('Index out of bounds: 5');
-      (() => tree.path('qwe')).should.throw('Index out of bounds: qwe')
-    })
-
-    it('should work for correct string index', () => {
-      const tree = new MerkleTree(10, [1, 2, 3, 4, 5])
-      const path = tree.path('2')
-      path.pathIndices.should.be.deep.equal([0, 1, 0, 0, 0, 0, 0, 0, 0, 0])
-      path.pathElements.should.be.deep.equal([
-        4,
-        '19814528709687996974327303300007262407299502847885145507292406548098437687919',
-        '21305827034995891902714687670641862055126514524916463201449278400604999416145',
-        '14506027710748750947258687001455876266559341618222612722926156490737302846427',
-        '4766583705360062980279572762279781527342845808161105063909171241304075622345',
-        '16640205414190175414380077665118269450294358858897019640557533278896634808665',
-        '13024477302430254842915163302704885770955784224100349847438808884122720088412',
-        '11345696205391376769769683860277269518617256738724086786512014734609753488820',
-        '17235543131546745471991808272245772046758360534180976603221801364506032471936',
-        '155962837046691114236524362966874066300454611955781275944230309195800494087',
-      ])
-    })
-  })
-
-  describe('#serialize', () => {
-    it('should work', () => {
-      const src = new MerkleTree(10, [1, 2, 3])
-      const data = src.serialize()
-      const dst = MerkleTree.deserialize(data)
-
-      src.root().should.equal(dst.root())
-
-      src.insert(10)
-      dst.insert(10)
-
-      src.root().should.equal(dst.root())
-    })
-  })
-})

test/partialMerkleTree.spec.ts

@@ -0,0 +1,297 @@
+import { Element, MerkleTree, MerkleTreeOptions, PartialMerkleTree } from '../src'
+import { it } from 'mocha'
+import { should } from 'chai'
+import * as assert from 'assert'
+import { createHash } from 'crypto'
+
+const sha256Hash = (left, right) => createHash('sha256').update(`${left}${right}`).digest('hex')
+
+describe('PartialMerkleTree', () => {
+  const getTestTrees = (levels: number, elements: Element[], edgeIndex: number, treeOptions: MerkleTreeOptions = {}) => {
+    const fullTree = new MerkleTree(levels, elements, treeOptions)
+    const edge = fullTree.getTreeEdge(edgeIndex)
+    const leavesAfterEdge = elements.slice(edge.edgeIndex)
+    const partialTree = new PartialMerkleTree(levels, edge, leavesAfterEdge, treeOptions)
+    return { fullTree, partialTree }
+  }
+  describe('#constructor', () => {
+    const { fullTree, partialTree } = getTestTrees(20, ['0', '1', '2', '3', '4', '5'], 2)
+    it('should initialize merkle tree with same root', () => {
+      should().equal(fullTree.root, partialTree.root)
+    })
+
+    it('should initialize merkle tree with same leaves count', () => {
+      should().equal(fullTree.elements.length, partialTree.elements.length)
+    })
+
+    it('should work with optional hash function and zero element', () => {
+      const { partialTree, fullTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6], 3, {
+        hashFunction: sha256Hash,
+        zeroElement: 'zero',
+      })
+      should().equal(partialTree.root, fullTree.root)
+    })
+  })
+
+  describe('#insert', () => {
+
+    it('should have equal root to full tree after insertion ', () => {
+      const { fullTree, partialTree } = getTestTrees(10, ['0', '1', '2', '3', '4', '5', '6', '7'], 5)
+      fullTree.insert('9')
+      partialTree.insert('9')
+      should().equal(fullTree.root, partialTree.root)
+    })
+
+    it('should fail to insert when tree is full', () => {
+      const { partialTree } = getTestTrees(3, ['0', '1', '2', '3', '4', '5', '6', '7'], 5)
+      const call = () => partialTree.insert('8')
+      should().throw(call, 'Tree is full')
+    })
+  })
+
+  describe('#bulkInsert', () => {
+
+    it('should work like full tree', () => {
+      const { fullTree, partialTree } = getTestTrees(20, [1, 2, 3, 4, 5], 2)
+      partialTree.bulkInsert([6, 7, 8])
+      fullTree.bulkInsert([6, 7, 8])
+      should().equal(fullTree.root, partialTree.root)
+    })
+
+    it('should give the same result as sequential inserts', () => {
+      const initialArray = [
+        [1],
+        [1, 2],
+        [1, 2, 3],
+        [1, 2, 3, 4],
+      ]
+      const insertedArray = [
+        [11],
+        [11, 12],
+        [11, 12, 13],
+        [11, 12, 13, 14],
+      ]
+      for (const initial of initialArray) {
+        for (const inserted of insertedArray) {
+          const { partialTree: tree1 } = getTestTrees(10, initial, initial.length - 1)
+          const { partialTree: tree2 } = getTestTrees(10, initial, initial.length - 1)
+          tree1.bulkInsert(inserted)
+          for (const item of inserted) {
+            tree2.insert(item)
+          }
+          should().equal(tree1.root, tree2.root)
+        }
+      }
+    }).timeout(10000)
+
+    it('should fail to insert too many elements', () => {
+      const { partialTree } = getTestTrees(2, [1, 2, 3, 4], 2)
+      const call = () => partialTree.bulkInsert([5, 6, 7])
+      should().throw(call, 'Tree is full')
+    })
+    it('should bypass empty elements', () => {
+      const elements = [1, 2, 3, 4]
+      const { partialTree } = getTestTrees(2, elements, 2)
+      partialTree.bulkInsert([])
+      should().equal(partialTree.elements.length, elements.length, 'No elements inserted')
+    })
+  })
+  describe('#update', () => {
+    it('should update last element', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      partialTree.update(4, 42)
+      fullTree.update(4, 42)
+      should().equal(partialTree.root, fullTree.root)
+    })
+
+
+    it('should update odd element', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8], 2)
+      partialTree.update(4, 42)
+      fullTree.update(4, 42)
+      should().equal(partialTree.root, fullTree.root)
+    })
+
+    it('should update even element', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8], 2)
+      partialTree.update(3, 42)
+      fullTree.update(3, 42)
+      should().equal(partialTree.root, fullTree.root)
+    })
+
+    it('should update extra element', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      partialTree.update(5, 6)
+      fullTree.update(5, 6)
+      should().equal(fullTree.root, partialTree.root)
+    })
+
+    it('should fail to update incorrect index', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 3)
+      should().throw((() => partialTree.update(-1, 42)), 'Insert index out of bounds: -1')
+      should().throw((() => partialTree.update(6, 42)), 'Insert index out of bounds: 6')
+      should().throw((() => partialTree.update(2, 42)), 'Index 2 is below the edge: 3')
+      // @ts-ignore
+      should().throw((() => partialTree.update('qwe', 42)), 'Insert index out of bounds: qwe')
+    })
+
+    it('should fail to update over capacity', () => {
+      const { partialTree } = getTestTrees(2, [1, 2, 3, 4], 1)
+      const call = () => partialTree.update(4, 42)
+      should().throw(call, 'Insert index out of bounds: 4')
+    })
+  })
+  describe('#indexOf', () => {
+    it('should return same result as full tree', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8], 3)
+      should().equal(partialTree.indexOf(5), fullTree.indexOf(5))
+    })
+
+    it('should find index', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      should().equal(partialTree.indexOf(3), 2)
+    })
+
+    it('should work with comparator', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      should().equal(partialTree.indexOf(4, (arg0, arg1) => arg0 === arg1), 3)
+    })
+
+    it('should return -1 for non existent element', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      should().equal(partialTree.indexOf(42), -1)
+    })
+  })
+
+  describe('#proof', () => {
+    it('should return proof for known leaf', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      assert.deepEqual(partialTree.proof(4), partialTree.path(3))
+    })
+  })
+
+  describe('#getters', () => {
+    it('should return capacity', () => {
+      const levels = 10
+      const capacity = 2 ** levels
+      const { fullTree, partialTree } = getTestTrees(levels, [1, 2, 3, 4, 5], 2)
+      should().equal(fullTree.capacity, capacity)
+      should().equal(partialTree.capacity, capacity)
+    })
+
+    it('should return same elements count as full tree', () => {
+      const levels = 10
+      const capacity = 2 ** levels
+      const elements = Array.from({ length: capacity }, (_, i) => i)
+      const { fullTree, partialTree } = getTestTrees(levels, elements, 200)
+      should().equal(partialTree.elements.length, fullTree.elements.length)
+    })
+
+    it('should return copy of layers', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      const layers = partialTree.layers
+      should().not.equal(layers, partialTree.layers)
+    })
+
+    it('should return copy of zeros', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      const zeros = partialTree.zeros
+      should().not.equal(zeros, partialTree.zeros)
+    })
+
+    it('should return edge leaf', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5], 2)
+      should().equal(partialTree.edgeElement, 3)
+    })
+  })
+
+  describe('#path', () => {
+
+    it('should return path for known nodes', () => {
+      const levels = 10
+      const capacity = 2 ** levels
+      const elements = Array.from({ length: capacity / 2 }, (_, i) => i)
+      const { fullTree, partialTree } = getTestTrees(levels, elements, 250)
+      assert.deepEqual(fullTree.path(251), partialTree.path(251))
+    }).timeout(1000)
+
+    it('should fail on incorrect index', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8, 9], 4)
+      should().throw((() => partialTree.path(-1)), 'Index out of bounds: -1')
+      should().throw((() => partialTree.path(10)), 'Index out of bounds: 10')
+      // @ts-ignore
+      should().throw((() => partialTree.path('qwe')), 'Index out of bounds: qwe')
+    })
+
+    it('should fail if index is below edge', () => {
+      const { partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8, 9], 4)
+      const call = () => partialTree.path(2)
+      should().throw(call, 'Index 2 is below the edge: 4')
+    })
+  })
+  describe('#shiftEdge', () => {
+    const levels = 20
+    const elements: Element[] = Array.from({ length: 2 ** 18 }, (_, i) => i)
+    const tree = new MerkleTree(levels, elements)
+    it('should work', () => {
+      const edge1 = tree.getTreeEdge(200)
+      const edge2 = tree.getTreeEdge(100)
+      const partialTree = new PartialMerkleTree(levels, edge1, elements.slice(edge1.edgeIndex))
+      partialTree.shiftEdge(edge2, elements.slice(edge2.edgeIndex, partialTree.edgeIndex))
+      tree.insert('1111')
+      partialTree.insert('1111')
+      assert.deepEqual(partialTree.path(150), tree.path(150))
+    })
+    it('should be able to build full tree from slices', () => {
+      const slices = tree.getTreeSlices(6)
+      const lastSlice = slices.pop()
+      const partialTree = new PartialMerkleTree(levels, lastSlice.edge, lastSlice.elements)
+      for (let i = slices.length - 1; i >= 0; i--) {
+        partialTree.shiftEdge(slices[i].edge, slices[i].elements)
+      }
+      partialTree.insert('1')
+      tree.insert('1')
+      assert.deepStrictEqual(partialTree.path(432), tree.path(432))
+    }).timeout(10000)
+
+    it('should fail if new edge index is over current edge', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [0, 1, 2, 3, 4, 5, 6, 7, 8, 9], 4)
+      const newEdge = fullTree.getTreeEdge(4)
+      const call = () => partialTree.shiftEdge(newEdge, [1, 2])
+      should().throw(call, 'New edgeIndex should be smaller then 4')
+    })
+    it('should fail if elements length are incorrect', () => {
+      const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8, 9], 4)
+      const newEdge = fullTree.getTreeEdge(3)
+      const call = () => partialTree.shiftEdge(newEdge, [1, 2])
+      should().throw(call, 'Elements length should be 1')
+    })
+  })
+  describe('#serialize', () => {
+    it('should work', () => {
+      const { partialTree } = getTestTrees(5, [1, 2, 3, 4, 5, 6, 7, 8, 9], 5)
+      const data = partialTree.serialize()
+      const dst = PartialMerkleTree.deserialize(data)
+      should().equal(partialTree.root, dst.root)
+
+      partialTree.insert(10)
+      dst.insert(10)
+      assert.deepStrictEqual(partialTree.path(6), dst.path(6))
+      should().equal(partialTree.root, dst.root)
+    })
+  })
+  describe('#toString', () => {
+    it('should return correct stringified representation', () => {
+      const { partialTree } = getTestTrees(5, [1, 2, 3, 4, 5, 6, 7, 8, 9], 5)
+      const str = partialTree.toString()
+      const dst = PartialMerkleTree.deserialize(JSON.parse(str))
+      assert.deepStrictEqual(partialTree.path(6), dst.path(6))
+      partialTree.insert(10)
+      dst.insert(10)
+
+      assert.deepStrictEqual(partialTree.path(6), dst.path(6))
+      assert.deepStrictEqual(partialTree.root, dst.root)
+    })
+  })
+})
+

test/simpleHash.spec.ts

@@ -0,0 +1,18 @@
+import { it } from 'mocha'
+import { should } from 'chai'
+import { simpleHash } from '../src'
+
+describe('SimpleHash', () => {
+  it('should return correct hash string with default params', () => {
+    const hash = simpleHash([1, 2, 3])
+    return should().equal(hash, '3530513397947785053296897142557895557120')
+  })
+  it('should return correct hash string with length param', () => {
+    const hash = simpleHash([1, 2, 3], null, 77)
+    return should().equal(hash, '1259729275322113643079999203492506359813191573070980317691663537897682854338069790720')
+  })
+  it('should return correct hash string with seed param', () => {
+    const hash = simpleHash(['1', '2', '3'], 123)
+    return should().equal(hash, '1371592418687375416654554138100746944512')
+  })
+})

tsconfig.json

@@ -0,0 +1,25 @@
+{
+  "compilerOptions": {
+    "lib": [
+      "es2020"
+    ],
+    "target": "es2017",
+    "module": "CommonJS",
+    "moduleResolution": "Node",
+    "outDir": "./lib",
+    "rootDir": "./src",
+    "esModuleInterop": true,
+    "sourceMap": false,
+    "allowSyntheticDefaultImports": true,
+    "forceConsistentCasingInFileNames": true,
+    "declaration": true
+  },
+  "include": [
+    "src"
+  ],
+  "exclude": [
+    "node_modules",
+    "types",
+    "**/*.spec.ts"
+  ]
+}