Fix replace with

Author: cherylEnkidu

Firestore/Source/API/FIRPipelineBridge.mm

@@ -625,7 +625,6 @@ - (id)initWithOrderings:(NSArray<id> *)orderings {
 
 @implementation FIRReplaceWithStageBridge {
   FIRExprBridge *_expr;
-  NSString *_fieldName;
   Boolean isUserDataRead;
   std::shared_ptr<ReplaceWith> cpp_replace_with;
 }
@@ -634,29 +633,14 @@ - (id)initWithExpr:(FIRExprBridge *)expr {
   self = [super init];
   if (self) {
     _expr = expr;
-    _fieldName = nil;
-    isUserDataRead = NO;
-  }
-  return self;
-}
-
-- (id)initWithFieldName:(NSString *)fieldName {
-  self = [super init];
-  if (self) {
-    _fieldName = fieldName;
-    _expr = nil;
     isUserDataRead = NO;
   }
   return self;
 }
 
 - (std::shared_ptr<api::Stage>)cppStageWithReader:(FSTUserDataReader *)reader {
   if (!isUserDataRead) {
-    if (_expr) {
-      cpp_replace_with = std::make_shared<ReplaceWith>([_expr cppExprWithReader:reader]);
-    } else {
-      cpp_replace_with = std::make_shared<ReplaceWith>(MakeString(_fieldName));
-    }
+    cpp_replace_with = std::make_shared<ReplaceWith>([_expr cppExprWithReader:reader]);
   }
 
   isUserDataRead = YES;

Firestore/Source/Public/FirebaseFirestore/FIRPipelineBridge.h

@@ -173,7 +173,6 @@ NS_SWIFT_SENDABLE
 NS_SWIFT_NAME(ReplaceWithStageBridge)
 @interface FIRReplaceWithStageBridge : FIRStageBridge
 - (id)initWithExpr:(FIRExprBridge *)expr;
-- (id)initWithFieldName:(NSString *)fieldName;
 @end
 
 NS_SWIFT_SENDABLE

Firestore/Swift/Source/SwiftAPI/Pipeline/Pipeline.swift

@@ -581,7 +581,7 @@ public struct Pipeline: @unchecked Sendable {
   /// - Parameter fieldName: The name of the field containing the nested map.
   /// - Returns: A new `Pipeline` object with this stage appended.
   public func replace(with fieldName: String) -> Pipeline {
-    return Pipeline(stages: stages + [ReplaceWith(fieldName: fieldName)], db: db)
+    return Pipeline(stages: stages + [ReplaceWith(expr: Field(fieldName))], db: db)
   }
 
   /// Performs pseudo-random sampling of input documents, returning a specific count.

Firestore/Swift/Source/SwiftAPI/Stages.swift

@@ -256,20 +256,12 @@ class Sort: Stage {
 class ReplaceWith: Stage {
   var name: String = "replaceWith"
   var bridge: StageBridge
-  private var expr: Expr?
-  private var fieldName: String?
+  private var expr: Expr
 
   init(expr: Expr) {
     self.expr = expr
-    fieldName = nil
     bridge = ReplaceWithStageBridge(expr: expr.toBridge())
   }
-
-  init(fieldName: String) {
-    self.fieldName = fieldName
-    expr = nil
-    bridge = ReplaceWithStageBridge(fieldName: fieldName)
-  }
 }
 
 class Sample: Stage {

Firestore/core/src/api/stages.cc

@@ -312,24 +312,15 @@ google_firestore_v1_Pipeline_Stage ReplaceWith::to_proto() const {
 
   result.args_count = 1;
   result.args = nanopb::MakeArray<google_firestore_v1_Value>(1);
-  if (expr_) {
-    result.args[0] = expr_->to_proto();
-  } else {
-    result.args[0].which_value_type =
-        google_firestore_v1_Value_string_value_tag;
-    result.args[0].string_value = nanopb::MakeBytesArray(field_name_.value());
-  }
+  result.args[0] = expr_->to_proto();
 
   result.options_count = 0;
   result.options = nullptr;
   return result;
 }
 
 ReplaceWith::ReplaceWith(std::shared_ptr<Expr> expr)
-    : expr_(std::move(expr)), field_name_(absl::nullopt) {
-}
-ReplaceWith::ReplaceWith(std::string field_name)
-    : expr_(nullptr), field_name_(std::move(field_name)) {
+    : expr_(std::move(expr)) {
 }
 
 Sample::Sample(std::string type, int64_t count, double percentage)

Firestore/core/src/api/stages.h

@@ -253,13 +253,11 @@ class RemoveFieldsStage : public Stage {
 class ReplaceWith : public Stage {
  public:
   explicit ReplaceWith(std::shared_ptr<Expr> expr);
-  explicit ReplaceWith(std::string field_name);
   ~ReplaceWith() override = default;
   google_firestore_v1_Pipeline_Stage to_proto() const override;
 
  private:
   std::shared_ptr<Expr> expr_;
-  absl::optional<std::string> field_name_;
 };
 
 class Sample : public Stage {