Fix keySearch

Author: sirtimid

packages/kernel/src/utils/key-search.test.ts

@@ -13,8 +13,8 @@ describe('keySearch', () => {
   it('returns the index of the first key greater than the search key', () => {
     const arr = ['a', 'c', 'e', 'g', 'i'];
     expect(keySearch(arr, 'b')).toBe(1);
-    expect(keySearch(arr, 'd')).toBe(1);
-    expect(keySearch(arr, 'f')).toBe(-1);
+    expect(keySearch(arr, 'd')).toBe(2);
+    expect(keySearch(arr, 'f')).toBe(3);
   });
 
   it('returns 0 when the search key is less than the first element', () => {
@@ -71,7 +71,7 @@ describe('keySearch', () => {
     const arr = ['a', 'bb', 'ccc', 'dddd', 'eeeee'];
     expect(keySearch(arr, 'bb')).toBe(1);
     expect(keySearch(arr, 'b')).toBe(1);
-    expect(keySearch(arr, 'cc')).toBe(1);
+    expect(keySearch(arr, 'cc')).toBe(2);
   });
 
   it('preserves lexicographic ordering', () => {

packages/kernel/src/utils/key-search.ts

@@ -12,31 +12,43 @@
  *   `key`, or -1 if no such key exists.
  */
 export function keySearch(arr: string[], key: string): number {
-  if (arr === null) {
-    // This shouldn't happen, but just in case...
+  if (arr === null || arr.length === 0) {
     return -1;
   }
+
   let beg = 0;
   let end = arr.length - 1;
-  if (key < (arr[beg] as string)) {
-    return beg;
+
+  // Key is less than first element
+  if (key < (arr[0] as string)) {
+    return 0;
   }
-  if ((arr[end] as string) < key) {
+
+  // Key is greater than last element
+  if (key > (arr[arr.length - 1] as string)) {
     return -1;
   }
-  while (beg <= end) {
+
+  // Exact match with first element
+  if (key === arr[0]) {
+    return 0;
+  }
+
+  // Binary search algorithm
+  while (beg < end) {
     const mid = Math.floor((beg + end) / 2);
+
+    // Exact match
     if (arr[mid] === key) {
       return mid;
     }
+
     if (key < (arr[mid] as string)) {
-      end = mid - 1;
+      end = mid;
     } else {
       beg = mid + 1;
     }
-    if (beg === end) {
-      return beg;
-    }
   }
-  return -1;
+
+  return beg;
 }

vitest.config.ts

@@ -88,10 +88,10 @@ export default defineConfig({
           lines: 81.03,
         },
         'packages/kernel/**': {
-          statements: 85.18,
+          statements: 85.02,
           functions: 91.46,
-          branches: 71.54,
-          lines: 85.3,
+          branches: 71.45,
+          lines: 85.13,
         },
         'packages/nodejs/**': {
           statements: 72.91,