fixed-merkle-tree/lib/BaseTree.js

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"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
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* @param elements elements of tree
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* @param element An element to find
* @param comparator A function that checks leaf value equality
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* @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
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* @returns {number} Index if element is found, otherwise -1
*/
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static indexOf(elements, element, fromIndex, comparator) {
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if (comparator) {
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return elements.findIndex((el) => comparator(element, el));
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}
else {
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return elements.indexOf(element, fromIndex);
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}
}
/**
* 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;