Fix circular dependency between user_data_reader and expressions

Author: MarkDuckworth

packages/firestore/src/lite-api/expressions.ts

@@ -25,6 +25,7 @@ import { Value as ProtoValue } from '../protos/firestore_proto_api';
 import {
   JsonProtoSerializer,
   ProtoSerializable,
+  ProtoValueSerializable,
   toMapValue,
   toStringValue,
   UserData
@@ -129,14 +130,15 @@ function fieldOfOrExpr(value: any): Expr {
  * The `Expr` class provides a fluent API for building expressions. You can chain together
  * method calls to create complex expressions.
  */
-export abstract class Expr implements ProtoSerializable<ProtoValue>, UserData {
+export abstract class Expr implements ProtoValueSerializable, UserData {
   abstract exprType: ExprType;
 
   /**
    * @private
    * @internal
    */
   abstract _toProto(serializer: JsonProtoSerializer): ProtoValue;
+  _protoValueType = 'ProtoValue' as const;
 
   /**
    * @private
@@ -2088,20 +2090,12 @@ export interface Selectable {
   readonly expr: Expr;
 }
 
-export function _isSelectable(value: any): value is Selectable {
-  return value.selectable &&
-    typeof value.alias === 'string' &&
-    value.expr instanceof Expr;
-}
-
 /**
  * @beta
  *
  * A class that represents an aggregate function.
  */
-export class AggregateFunction
-  implements ProtoSerializable<ProtoValue>, UserData
-{
+export class AggregateFunction implements ProtoValueSerializable, UserData {
   exprType: ExprType = 'AggregateFunction';
 
   constructor(private name: string, private params: Expr[]) {}
@@ -2137,6 +2131,8 @@ export class AggregateFunction
     };
   }
 
+  _protoValueType = 'ProtoValue' as const;
+
   /**
    * @private
    * @internal

packages/firestore/src/lite-api/user_data_reader.ts

@@ -56,7 +56,8 @@ import {
   JsonProtoSerializer,
   toBytes,
   toResourceName,
-  toTimestamp
+  toTimestamp,
+  isProtoValueSerializable
 } from '../remote/serializer';
 import { debugAssert, fail } from '../util/assert';
 import { Code, FirestoreError } from '../util/error';
@@ -65,7 +66,6 @@ import { Dict, forEach, isEmpty } from '../util/obj';
 
 import { Bytes } from './bytes';
 import { Firestore } from './database';
-import { AggregateFunction, Expr } from './expressions';
 import { FieldPath } from './field_path';
 import { FieldValue } from './field_value';
 import { GeoPoint } from './geo_point';
@@ -910,9 +910,7 @@ export function parseScalarValue(
     };
   } else if (value instanceof VectorValue) {
     return parseVectorValue(value, context);
-  } else if (value instanceof Expr) {
-    return value._toProto(context.serializer);
-  } else if (value instanceof AggregateFunction) {
+  } else if (isProtoValueSerializable(value)) {
     return value._toProto(context.serializer);
   } else {
     throw context.createError(
@@ -972,8 +970,7 @@ export function looksLikeJsonObject(input: unknown): boolean {
     !(input instanceof DocumentReference) &&
     !(input instanceof FieldValue) &&
     !(input instanceof VectorValue) &&
-    !(input instanceof Expr) &&
-    !(input instanceof AggregateFunction)
+    !isProtoValueSerializable(input)
   );
 }
 

packages/firestore/src/remote/serializer.ts

@@ -1434,6 +1434,21 @@ export interface ProtoSerializable<ProtoType> {
   _toProto(serializer: JsonProtoSerializer): ProtoType;
 }
 
+export interface ProtoValueSerializable extends ProtoSerializable<ProtoValue> {
+  // Supports runtime identification of the ProtoSerializable<ProtoValue> type.
+  _protoValueType: 'ProtoValue';
+}
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export function isProtoValueSerializable(
+  value: any
+): value is ProtoValueSerializable {
+  return (
+    typeof value._toProto === 'function' &&
+    value._protoValueType === 'ProtoValue'
+  );
+}
+
 export interface UserData {
   _readUserData(dataReader: UserDataReader): void;
 }