[bytes] fix bytesFindIndex and bytesFindLastIndex (denoland/deno_std#381)

Original: https://github.com/denoland/deno_std/commit/87142529163ea047066a2991f51cb2cf3001df74

2 files changed, 22 insertions, 7 deletions

diff --git a/bytes/bytes.ts b/bytes/bytes.ts
index 080ec4445..a79a9ed56 100644
--- a/bytes/bytes.ts
+++ b/bytes/bytes.ts
@@ -6,10 +6,11 @@ export function bytesFindIndex(a: Uint8Array, pat: Uint8Array): number {
   for (let i = 0; i < a.length; i++) {
     if (a[i] !== s) continue;
     const pin = i;
-    let matched = 1;
+    let matched = 1,
+      j = i;
     while (matched < pat.length) {
-      i++;
-      if (a[i] !== pat[i - pin]) {
+      j++;
+      if (a[j] !== pat[j - pin]) {
         break;
       }
       matched++;
@@ -27,10 +28,11 @@ export function bytesFindLastIndex(a: Uint8Array, pat: Uint8Array): number {
   for (let i = a.length - 1; i >= 0; i--) {
     if (a[i] !== e) continue;
     const pin = i;
-    let matched = 1;
+    let matched = 1,
+      j = i;
     while (matched < pat.length) {
-      i--;
-      if (a[i] !== pat[pat.length - 1 - (pin - i)]) {
+      j--;
+      if (a[j] !== pat[pat.length - 1 - (pin - j)]) {
         break;
       }
       matched++;
diff --git a/bytes/bytes_test.ts b/bytes/bytes_test.ts
index c0aa1519d..9d4754a39 100644
--- a/bytes/bytes_test.ts
+++ b/bytes/bytes_test.ts
@@ -7,7 +7,7 @@ import {
 import { test } from "../testing/mod.ts";
 import { assertEquals } from "../testing/asserts.ts";
 
-test(function bytesBytesFindIndex(): void {
+test(function bytesBytesFindIndex1(): void {
   const i = bytesFindIndex(
     new Uint8Array([1, 2, 0, 1, 2, 0, 1, 2, 0, 1, 3]),
     new Uint8Array([0, 1, 2])
@@ -15,6 +15,11 @@ test(function bytesBytesFindIndex(): void {
   assertEquals(i, 2);
 });
 
+test(function bytesBytesFindIndex2(): void {
+  const i = bytesFindIndex(new Uint8Array([0, 0, 1]), new Uint8Array([0, 1]));
+  assertEquals(i, 1);
+});
+
 test(function bytesBytesFindLastIndex1(): void {
   const i = bytesFindLastIndex(
     new Uint8Array([0, 1, 2, 0, 1, 2, 0, 1, 3]),
@@ -23,6 +28,14 @@ test(function bytesBytesFindLastIndex1(): void {
   assertEquals(i, 3);
 });
 
+test(function bytesBytesFindLastIndex2(): void {
+  const i = bytesFindLastIndex(
+    new Uint8Array([0, 1, 1]),
+    new Uint8Array([0, 1])
+  );
+  assertEquals(i, 0);
+});
+
 test(function bytesBytesBytesEqual(): void {
   const v = bytesEqual(
     new Uint8Array([0, 1, 2, 3]),