add back the utf-8 string comparison

Author: milaGGL

packages/firestore/src/local/indexeddb_remote_document_cache.ts

@@ -655,5 +655,9 @@ export function dbKeyComparator(l: DocumentKey, r: DocumentKey): number {
     return cmp;
   }
 
+  // TODO(b/329441702): Document IDs should be sorted by UTF-8 encoded byte
+  // order, but IndexedDB sorts strings lexicographically. Document ID
+  // comparison here still relies on primitive comparison to avoid mismatches
+  // observed in snapshot listeners with Unicode characters in documentIds
   return primitiveComparator(left[left.length - 1], right[right.length - 1]);
 }

packages/firestore/src/model/path.ts

@@ -19,6 +19,7 @@ import { Integer } from '@firebase/webchannel-wrapper/bloom-blob';
 
 import { debugAssert, fail } from '../util/assert';
 import { Code, FirestoreError } from '../util/error';
+import { compareUtf8Strings, primitiveComparator } from '../util/misc';
 
 export const DOCUMENT_KEY_NAME = '__name__';
 
@@ -181,7 +182,7 @@ abstract class BasePath<B extends BasePath<B>> {
         return comparison;
       }
     }
-    return Math.sign(p1.length - p2.length);
+    return primitiveComparator(p1.length, p2.length);
   }
 
   private static compareSegments(lhs: string, rhs: string): number {
@@ -201,13 +202,7 @@ abstract class BasePath<B extends BasePath<B>> {
       );
     } else {
       // both non-numeric
-      if (lhs < rhs) {
-        return -1;
-      }
-      if (lhs > rhs) {
-        return 1;
-      }
-      return 0;
+      return compareUtf8Strings(lhs, rhs);
     }
   }
 

packages/firestore/src/model/values.ts

@@ -25,7 +25,11 @@ import {
   Value
 } from '../protos/firestore_proto_api';
 import { fail } from '../util/assert';
-import { arrayEquals, primitiveComparator } from '../util/misc';
+import {
+  arrayEquals,
+  compareUtf8Strings,
+  primitiveComparator
+} from '../util/misc';
 import { forEach, objectSize } from '../util/obj';
 import { isNegativeZero } from '../util/types';
 
@@ -251,7 +255,7 @@ export function valueCompare(left: Value, right: Value): number {
         getLocalWriteTime(right)
       );
     case TypeOrder.StringValue:
-      return primitiveComparator(left.stringValue!, right.stringValue!);
+      return compareUtf8Strings(left.stringValue!, right.stringValue!);
     case TypeOrder.BlobValue:
       return compareBlobs(left.bytesValue!, right.bytesValue!);
     case TypeOrder.RefValue:
@@ -400,7 +404,7 @@ function compareMaps(left: MapValue, right: MapValue): number {
   rightKeys.sort();
 
   for (let i = 0; i < leftKeys.length && i < rightKeys.length; ++i) {
-    const keyCompare = primitiveComparator(leftKeys[i], rightKeys[i]);
+    const keyCompare = compareUtf8Strings(leftKeys[i], rightKeys[i]);
     if (keyCompare !== 0) {
       return keyCompare;
     }

packages/firestore/src/util/misc.ts

@@ -107,7 +107,7 @@ export function compareUtf8Strings(left: string, right: string): number {
     }
 
     // Increment by 2 for surrogate pairs, 1 otherwise
-    i += leftCodePoint > 0xffff ? 2 : 1; 
+    i += leftCodePoint > 0xffff ? 2 : 1;
   }
 
   // Compare lengths if all characters are equal

packages/firestore/test/integration/api/database.test.ts

@@ -2451,7 +2451,7 @@ apiDescribe('Database', persistence => {
         'h': { value: '你好' },
         'i': { value: '你顥' },
         'j': { value: '😁' },
-        'k': { value: '😀' },
+        'k': { value: '😀' }
       };
 
       return withTestCollection(persistence, testDocs, async collectionRef => {