add shiftEdge method

This commit is contained in:
Sergei SMART 2022-03-02 14:33:04 +10:00
parent e0817b8389
commit 5ebbf81959
2 changed files with 52 additions and 2 deletions

@ -60,6 +60,14 @@ export class PartialMerkleTree {
return this._layers[this.levels][0] ?? this._zeros[this.levels]
}
get edgeIndex(): number {
return this._edgeLeaf.index
}
get edgeElement(): Element {
return this._edgeLeaf.data
}
private _buildTree(): void {
const edgeLeafIndex = this._edgeLeaf.index
this._leaves = [...Array.from({ length: edgeLeafIndex }, () => null), ...this._leavesAfterEdge]
@ -69,7 +77,6 @@ export class PartialMerkleTree {
this._layers = [this._leaves]
this._buildZeros()
this._buildHashes()
}
private _buildZeros() {
@ -210,6 +217,25 @@ export class PartialMerkleTree {
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 ${elements.length}`)
}
this._edgeLeafProof = edge.edgePath
this._edgeLeaf = { index: edge.edgeIndex, data: edge.edgeElement }
this._leavesAfterEdge = [...elements, ...this._leavesAfterEdge]
this._buildTree()
}
serialize(): SerializedPartialTreeState {
const leaves = this.layers[0].slice(this._edgeLeaf.index)
return {

@ -224,7 +224,31 @@ describe('PartialMerkleTree', () => {
should().throw(call, 'Index 2 is below the edge: 4')
})
})
describe('#shiftEdge', () => {
it('should work', () => {
const levels = 20
const elements: Element[] = Array.from({ length: levels ** 2 }, (_, i) => i)
const tree = new MerkleTree(levels, elements)
const edge1 = tree.getTreeEdge(200)
const edge2 = tree.getTreeEdge(100)
const partialTree1 = new PartialMerkleTree(levels, edge1, elements.slice(edge1.edgeIndex), tree.root)
const partialTree2 = new PartialMerkleTree(levels, edge2, elements.slice(edge2.edgeIndex), tree.root)
partialTree1.shiftEdge(edge2, elements.slice(edge2.edgeIndex, partialTree1.edgeIndex))
assert.deepEqual(partialTree1.path(105), partialTree2.path(105))
})
it('should fail if new edge index is over current edge', () => {
const { fullTree, partialTree } = getTestTrees(10, [1, 2, 3, 4, 5, 6, 7, 8, 9], 5)
const newEdge = fullTree.getTreeEdge(6)
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], 5)
const newEdge = fullTree.getTreeEdge(4)
const call = () => partialTree.shiftEdge(newEdge, [1, 2])
should().throw(call, 'Elements length should be 2')
})
})
describe('#serialize', () => {
it('should work', () => {
const { partialTree } = getTestTrees(5, [1, 2, 3, 4, 5, 6, 7, 8, 9], 6)