Merge branch 'PreetamSing-task/binary-search-leaf'

src/Base.ts

@@ -10,7 +10,7 @@ export class Base {
    *tree.print()
    *```
    */
-  print ():void {
+  print (): void {
     Base.print(this)
   }
 
@@ -26,9 +26,103 @@ export class Base {
    *const index = tree.bufferIndexOf(haystack, needle)
    *```
    */
-  protected _bufferIndexOf (array: Buffer[], element: Buffer):number {
+  protected _bufferIndexOf (
+    array: Buffer[],
+    element: Buffer,
+    isSorted: boolean = false
+  ): number {
+    if (isSorted) {
+      return this.binarySearch(array, element, Buffer.compare)
+    }
+
+    const eqChecker = (buffer1, buffer2) => buffer1.equals(buffer2)
+    return this.linearSearch(array, element, eqChecker)
+  }
+
+  /**
+   * binarySearch
+   * @desc Returns the first index of which given item is found in array using binary search.
+   * @param {Buffer[]} array - Array of items.
+   * @param {Buffer} element - Item to find.
+   * @param {Function} compareFunction
+   * @return {Number} - Index number
+   *
+   * @example
+   * ```js
+   *const index = MerkleTree.binarySearch(array, element, Buffer.compare)
+   *```
+   */
+  static binarySearch (
+    array: Buffer[],
+    element: Buffer,
+    compareFunction: (a: unknown, b: unknown) => number
+  ): number {
+    let start = 0
+    let end = array.length - 1
+
+    // Iterate while start not meets end
+    while (start <= end) {
+      // Find the mid index
+      const mid = Math.floor((start + end) / 2)
+
+      // Check if the mid value is greater than, equal to, or less than search element.
+      const ordering = compareFunction(array[mid], element)
+
+      // If element is present at mid, start iterating for searching first appearance.
+      if (ordering === 0) {
+        // Linear reverse iteration until the first matching item index is found.
+        for (let i = mid - 1; i >= 0; i--) {
+          if (compareFunction(array[i], element) === 0) continue
+          return i + 1
+        }
+        return 0
+      } /* Else look in left or right half accordingly */ else if (ordering < 0) {
+        start = mid + 1
+      } else {
+        end = mid - 1
+      }
+    }
+
+    return -1
+  }
+
+  /**
+   * binarySearch
+   * @desc Returns the first index of which given item is found in array using binary search.
+   * @param {Buffer[]} array - Array of items.
+   * @param {Buffer} element - Item to find.
+   * @param {Function} compareFunction
+   * @return {Number} - Index number
+   *
+   * @example
+   * ```js
+   *const index = tree.binarySearch(array, element, Buffer.compare)
+   *```
+   */
+  binarySearch (
+    array: Buffer[],
+    element: Buffer,
+    compareFunction: (a: unknown, b: unknown) => number
+  ): number {
+    return Base.binarySearch(array, element, compareFunction)
+  }
+
+  /**
+   * linearSearch
+   * @desc Returns the first index of which given item is found in array using linear search.
+   * @param {Buffer[]} array - Array of items.
+   * @param {Buffer} element - Item to find.
+   * @param {Function} eqChecker
+   * @return {Number} - Index number
+   *
+   * @example
+   * ```js
+   *const index = MerkleTree.linearSearch(array, element, (a, b) => a === b)
+   *```
+   */
+  static linearSearch (array: Buffer[], element: Buffer, eqChecker: (a: unknown, b: unknown) => boolean):number {
     for (let i = 0; i < array.length; i++) {
-      if (element.equals(array[i])) {
+      if (eqChecker(array[i], element)) {
         return i
       }
     }
@@ -36,6 +130,23 @@ export class Base {
     return -1
   }
 
+  /**
+   * linearSearch
+   * @desc Returns the first index of which given item is found in array using linear search.
+   * @param {Buffer[]} array - Array of items.
+   * @param {Buffer} element - Item to find.
+   * @param {Function} eqChecker
+   * @return {Number} - Index number
+   *
+   * @example
+   * ```js
+   *const index = tree.linearSearch(array, element, (a, b) => a === b)
+   *```
+   */
+  linearSearch (array: Buffer[], element: Buffer, eqChecker: (a: unknown, b: unknown) => boolean):number {
+    return Base.linearSearch(array, element, eqChecker)
+  }
+
   /**
    * bufferify
    * @desc Returns a buffer type for the given value.
@@ -47,7 +158,7 @@ export class Base {
    *const buf = MerkleTree.bufferify('0x1234')
    *```
    */
-  static bufferify (value: any):Buffer {
+  static bufferify (value: any): Buffer {
     if (!Buffer.isBuffer(value)) {
       // crypto-js support
       if (typeof value === 'object' && value.words) {
@@ -81,8 +192,8 @@ export class Base {
    *console.log(MerkleTree.isHexString('0x1234'))
    *```
    */
-  static isHexString (v: string):boolean {
+  static isHexString (v: string): boolean {
-    return (typeof v === 'string' && /^(0x)?[0-9A-Fa-f]*$/.test(v))
+    return typeof v === 'string' && /^(0x)?[0-9A-Fa-f]*$/.test(v)
   }
 
   /**
@@ -95,7 +206,7 @@ export class Base {
    *MerkleTree.print(tree)
    *```
    */
-  static print (tree: any):void {
+  static print (tree: any): void {
     console.log(tree.toString())
   }
 
@@ -109,7 +220,7 @@ export class Base {
    *const hexStr = tree.bufferToHex(Buffer.from('A'))
    *```
    */
-  bufferToHex (value: Buffer, withPrefix: boolean = true):string {
+  bufferToHex (value: Buffer, withPrefix: boolean = true): string {
     return Base.bufferToHex(value, withPrefix)
   }
 
@@ -123,8 +234,10 @@ export class Base {
    *const hexStr = MerkleTree.bufferToHex(Buffer.from('A'))
    *```
    */
-  static bufferToHex (value: Buffer, withPrefix: boolean = true):string {
+  static bufferToHex (value: Buffer, withPrefix: boolean = true): string {
-    return `${withPrefix ? '0x' : ''}${(value || Buffer.alloc(0)).toString('hex')}`
+    return `${withPrefix ? '0x' : ''}${(value || Buffer.alloc(0)).toString(
+      'hex'
+    )}`
   }
 
   /**
@@ -138,7 +251,7 @@ export class Base {
    *const buf = tree.bufferify('0x1234')
    *```
    */
-  bufferify (value: any):Buffer {
+  bufferify (value: any): Buffer {
     return Base.bufferify(value)
   }
 
@@ -153,7 +266,7 @@ export class Base {
    *const fn = tree.bufferifyFn((value) => sha256(value))
    *```
    */
-  bufferifyFn (f: any):any {
+  bufferifyFn (f: any): any {
     return (value: any): Buffer => {
       const v = f(value)
       if (Buffer.isBuffer(v)) {
@@ -173,7 +286,12 @@ export class Base {
       }
 
       // crypto-js support
-      return Buffer.from(f(CryptoJS.enc.Hex.parse(value.toString('hex'))).toString(CryptoJS.enc.Hex), 'hex')
+      return Buffer.from(
+        f(CryptoJS.enc.Hex.parse(value.toString('hex'))).toString(
+          CryptoJS.enc.Hex
+        ),
+        'hex'
+      )
     }
   }
 
@@ -188,7 +306,7 @@ export class Base {
    *console.log(MerkleTree.isHexString('0x1234'))
    *```
    */
-  protected _isHexString (value: string):boolean {
+  protected _isHexString (value: string): boolean {
     return Base.isHexString(value)
   }
 
@@ -198,7 +316,7 @@ export class Base {
    * @param {Number} value
    * @return {Number}
    */
-  protected _log2 (n: number):number {
+  protected _log2 (n: number): number {
     return n === 1 ? 0 : 1 + this._log2((n / 2) | 0)
   }
 
@@ -215,7 +333,7 @@ export class Base {
    *console.log(zipped) // [ [ 'a', 'A' ], [ 'b', 'B' ] ]
    *```
    */
-  protected _zip (a: any[], b: any[]):any[][] {
+  protected _zip (a: any[], b: any[]): any[][] {
     return a.map((e, i) => [e, b[i]])
   }
 }

src/MerkleTree.ts

@@ -256,7 +256,7 @@ export class MerkleTree extends Base {
         }
       }
 
-      return this.leaves.filter(leaf => this._bufferIndexOf(values, leaf) !== -1)
+      return this.leaves.filter(leaf => this._bufferIndexOf(values, leaf, this.sortLeaves) !== -1)
     }
 
     return this.leaves
@@ -518,13 +518,7 @@ export class MerkleTree extends Base {
     const proof = []
 
     if (!Number.isInteger(index)) {
-      index = -1
+      index = this._bufferIndexOf(this.leaves, leaf, this.sortLeaves)
-
-      for (let i = 0; i < this.leaves.length; i++) {
-        if (Buffer.compare(leaf, this.leaves[i]) === 0) {
-          index = i
-        }
-      }
     }
 
     if (index <= -1) {
@@ -870,7 +864,7 @@ export class MerkleTree extends Base {
         els = els.sort(Buffer.compare)
       }
 
-      let ids = els.map((el) => this._bufferIndexOf(this.leaves, el)).sort((a, b) => a === b ? 0 : a > b ? 1 : -1)
+      let ids = els.map((el) => this._bufferIndexOf(this.leaves, el, this.sortLeaves)).sort((a, b) => a === b ? 0 : a > b ? 1 : -1)
       if (!ids.every((idx) => idx !== -1)) {
         throw new Error('Element does not exist in Merkle tree')
       }
@@ -993,7 +987,7 @@ export class MerkleTree extends Base {
     if (leaves.every(Number.isInteger)) {
       ids = [...leaves].sort((a, b) => a === b ? 0 : a > b ? 1 : -1) // Indices where passed
     } else {
-      ids = leaves.map((el) => this._bufferIndexOf(this.leaves, el)).sort((a, b) => a === b ? 0 : a > b ? 1 : -1)
+      ids = leaves.map((el) => this._bufferIndexOf(this.leaves, el, this.sortLeaves)).sort((a, b) => a === b ? 0 : a > b ? 1 : -1)
     }
 
     if (!ids.every((idx: number) => idx !== -1)) {

test/Base.test.js

@@ -20,3 +20,17 @@ test('bufferifyFn', t => {
   t.deepEqual(fn('0x123'), Buffer.from('123', 'hex'))
   t.deepEqual(fn('XYZ'), Buffer.from('XYZ'))
 })
+
+test('binarySearch', t => {
+  t.plan(3)
+
+  const base = new Base()
+  const compareFunction = (a, b) => {
+    if (a === b) return 0
+    else if (a < b) return -1
+    else return 1
+  }
+  t.equal(base.binarySearch([2, 2, 3, 3, 3, 4, 4, 4, 4], 3, compareFunction), 2)
+  t.equal(base.binarySearch([3, 3, 3, 3, 3, 4, 4, 4, 4], 3, compareFunction), 0)
+  t.equal(base.binarySearch([2, 2, 3, 3, 3, 4, 4, 4, 4], 1, compareFunction), -1)
+})