Add missing expressions

Firestore/Swift/Source/ExpressionImplementation.swift

@@ -523,6 +523,14 @@ public extension Expression {
     return FunctionExpression(functionName: "array_get", args: [self, offsetExpression])
   }
 
+  func arrayMaximum() -> FunctionExpression {
+    return FunctionExpression(functionName: "maximum", args: [self])
+  }
+
+  func arrayMinimum() -> FunctionExpression {
+    return FunctionExpression(functionName: "minimum", args: [self])
+  }
+
   func greaterThan(_ other: Expression) -> BooleanExpression {
     return BooleanExpression(functionName: "greater_than", args: [self, other])
   }
@@ -622,6 +630,14 @@ public extension Expression {
     return FunctionExpression(functionName: "join", args: [self, Constant(delimiter)])
   }
 
+  func split(delimiter: String) -> FunctionExpression {
+    return FunctionExpression(functionName: "split", args: [self, Constant(delimiter)])
+  }
+
+  func split(delimiter: Expression) -> FunctionExpression {
+    return FunctionExpression(functionName: "split", args: [self, delimiter])
+  }
+
   func length() -> FunctionExpression {
     return FunctionExpression(functionName: "length", args: [self])
   }
@@ -709,6 +725,10 @@ public extension Expression {
     return FunctionExpression(functionName: "trim", args: [self, value])
   }
 
+  func trim() -> FunctionExpression {
+    return FunctionExpression(functionName: "trim", args: [self])
+  }
+
   func stringConcat(_ strings: [Expression]) -> FunctionExpression {
     return FunctionExpression(functionName: "string_concat", args: [self] + strings)
   }
@@ -773,20 +793,6 @@ public extension Expression {
     return FunctionExpression(functionName: "map_merge", args: [self] + maps)
   }
 
-  func mapSet(key: Expression, value: Sendable) -> FunctionExpression {
-    return FunctionExpression(
-      functionName: "map_set",
-      args: [self, key, Helper.sendableToExpr(value)]
-    )
-  }
-
-  func mapSet(key: String, value: Sendable) -> FunctionExpression {
-    return FunctionExpression(
-      functionName: "map_set",
-      args: [self, Helper.sendableToExpr(key), Helper.sendableToExpr(value)]
-    )
-  }
-
   // --- Added Aggregate Operations (on Expr) ---
 
   func countDistinct() -> AggregateFunction {
@@ -919,7 +925,7 @@ public extension Expression {
     return FunctionExpression(functionName: "timestamp_to_unix_seconds", args: [self])
   }
 
-  func timestampTruncate(granularity: TimeUnit) -> FunctionExpression {
+  func timestampTruncate(granularity: TimeGranularity) -> FunctionExpression {
     return FunctionExpression(
       functionName: "timestamp_trunc",
       args: [self, Helper.sendableToExpr(granularity.rawValue)]
@@ -1001,4 +1007,8 @@ public extension Expression {
     let exprs = [self] + values.map { Helper.sendableToExpr($0) }
     return FunctionExpression(functionName: "concat", args: exprs)
   }
+
+  func type() -> FunctionExpression {
+    return FunctionExpression(functionName: "type", args: [self])
+  }
 }

Firestore/Swift/Source/Stages.swift

@@ -26,7 +26,8 @@ import Foundation
 protocol Stage {
   var name: String { get }
   var bridge: StageBridge { get }
-  /// The `errorMessage` defaults to `nil`. Errors during stage construction are captured and thrown later when `execute()` is called.
+  /// The `errorMessage` defaults to `nil`. Errors during stage construction are captured and thrown
+  /// later when `execute()` is called.
   var errorMessage: String? { get }
 }
 

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

@@ -461,6 +461,30 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the "arrayGet" operation.
   func arrayGet(_ offsetExpression: Expression) -> FunctionExpression
 
+  /// Creates an expression that returns the maximum element of an array.
+  ///
+  /// Assumes `self` evaluates to an array.
+  ///
+  /// ```swift
+  /// // Get the maximum value in the "scores" array.
+  /// Field("scores").arrayMaximum()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the maximum element of the array.
+  func arrayMaximum() -> FunctionExpression
+
+  /// Creates an expression that returns the minimum element of an array.
+  ///
+  /// Assumes `self` evaluates to an array.
+  ///
+  /// ```swift
+  /// // Get the minimum value in the "scores" array.
+  /// Field("scores").arrayMinimum()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the minimum element of the array.
+  func arrayMinimum() -> FunctionExpression
+
   /// Creates a `BooleanExpression` that returns `true` if this expression is greater
   /// than the given expression.
   ///
@@ -681,6 +705,18 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the joined string.
   func join(delimiter: String) -> FunctionExpression
 
+  /// Creates an expression that splits a string into an array of substrings based on a delimiter.
+  ///
+  /// - Parameter delimiter: The string to split on.
+  /// - Returns: A new `FunctionExpression` representing the array of substrings.
+  func split(delimiter: String) -> FunctionExpression
+
+  /// Creates an expression that splits a string into an array of substrings based on a delimiter.
+  ///
+  /// - Parameter delimiter: An expression that evaluates to a string or bytes to split on.
+  /// - Returns: A new `FunctionExpression` representing the array of substrings.
+  func split(delimiter: Expression) -> FunctionExpression
+
   /// Creates an expression that returns the length of a string.
   ///
   /// ```swift
@@ -886,6 +922,18 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the uppercase string.
   func toUpper() -> FunctionExpression
 
+  /// Creates an expression that removes leading and trailing whitespace from a string.
+  ///
+  /// Assumes `self` evaluates to a string.
+  ///
+  /// ```swift
+  /// // Trim leading/trailing whitespace from the "comment" field.
+  /// Field("comment").trim()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the trimmed string.
+  func trim() -> FunctionExpression
+
   /// Creates an expression that removes leading and trailing occurrences of specified characters
   /// from a string (from `self`).
   /// Assumes `self` evaluates to a string, and `value` evaluates to a string.
@@ -961,8 +1009,8 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the reversed string.
   func stringReverse() -> FunctionExpression
 
-  /// Creates an expression that calculates the length of this expression in bytes.
-  /// Assumes `self` evaluates to a string.
+  /// Creates an expression that calculates the length of this string or bytes expression in bytes.
+  /// Assumes `self` evaluates to a string or bytes.
   ///
   /// ```swift
   /// // Calculate the length of the "myString" field in bytes.
@@ -975,9 +1023,9 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the length in bytes.
   func byteLength() -> FunctionExpression
 
-  /// Creates an expression that returns a substring of this expression using
+  /// Creates an expression that returns a substring of this expression (String or Bytes) using
   /// literal integers for position and optional length.
-  /// Indexing is 0-based. Assumes `self` evaluates to a string.
+  /// Indexing is 0-based. Assumes `self` evaluates to a string or bytes.
   ///
   /// ```swift
   /// // Get substring from index 5 with length 10
@@ -992,9 +1040,9 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the substring.
   func substring(position: Int, length: Int?) -> FunctionExpression
 
-  /// Creates an expression that returns a substring of this expression using
+  /// Creates an expression that returns a substring of this expression (String or Bytes) using
   /// expressions for position and optional length.
-  /// Indexing is 0-based. Assumes `self` evaluates to a string, and parameters evaluate to
+  /// Indexing is 0-based. Assumes `self` evaluates to a string or bytes, and parameters evaluate to
   /// integers.
   ///
   /// ```swift
@@ -1080,34 +1128,6 @@ public protocol Expression: Sendable {
   /// - Returns: A new `FunctionExpression` representing the "map_merge" operation.
   func mapMerge(_ maps: [Expression]) -> FunctionExpression
 
-  /// Creates an expression that adds or updates a specified field in a map.
-  /// Assumes `self` evaluates to a Map, `key` evaluates to a string, and `value` can be
-  /// any type.
-  ///
-  /// ```swift
-  /// // Set a field using a key from another field
-  /// Field("config").mapSet(key: Field("keyName"), value: Field("keyValue"))
-  /// ```
-  ///
-  /// - Parameter key: An `Expression` (evaluating to a string) representing the key of
-  /// the field to set or update.
-  /// - Parameter value: The `Expression` representing the value to set for the field.
-  /// - Returns: A new `FunctionExpression` representing the map with the updated field.
-  func mapSet(key: Expression, value: Sendable) -> FunctionExpression
-
-  /// Creates an expression that adds or updates a specified field in a map.
-  /// Assumes `self` evaluates to a Map.
-  ///
-  /// ```swift
-  /// // Set the "status" field to "active" in the "order" map
-  /// Field("order").mapSet(key: "status", value: "active")
-  /// ```
-  ///
-  /// - Parameter key: The literal string key of the field to set or update.
-  /// - Parameter value: The `Sendable` literal value to set for the field.
-  /// - Returns: A new `FunctionExpression` representing the map with the updated field.
-  func mapSet(key: String, value: Sendable) -> FunctionExpression
-
   // MARK: Aggregations
 
   /// Creates an aggregation that counts the number of distinct values of this expression.
@@ -1429,19 +1449,23 @@ public protocol Expression: Sendable {
   /// Field("timestamp").timestampTruncate(granularity: .day)
   /// ```
   ///
-  /// - Parameter granularity: A `TimeUnit` enum representing the truncation unit.
+  /// - Parameter granularity: A `TimeGranularity` representing the truncation unit.
   /// - Returns: A new `FunctionExpression` representing the truncated timestamp.
-  func timestampTruncate(granularity: TimeUnit) -> FunctionExpression
+  func timestampTruncate(granularity: TimeGranularity) -> FunctionExpression
 
   /// Creates an expression that truncates a timestamp to a specified granularity.
-  /// Assumes `self` evaluates to a Timestamp, and `granularity` is a literal string.
+  /// Assumes `self` evaluates to a Timestamp.
   ///
   /// ```swift
   /// // Truncate "timestamp" field to the nearest day using a literal string.
   /// Field("timestamp").timestampTruncate(granularity: "day")
+  ///
+  /// // Truncate "timestamp" field to the nearest day using an expression.
+  /// Field("timestamp").timestampTruncate(granularity: Field("granularity_field"))
   /// ```
   ///
-  /// - Parameter granularity: A `Sendable` literal string specifying the truncation unit.
+  /// - Parameter granularity: A `Sendable` literal string or an `Expression` that evaluates to a
+  /// string, specifying the truncation unit.
   /// - Returns: A new `FunctionExpression` representing the truncated timestamp.
   func timestampTruncate(granularity: Sendable) -> FunctionExpression
 
@@ -1596,4 +1620,14 @@ public protocol Expression: Sendable {
   /// - Parameter values: The values to concatenate.
   /// - Returns: A new `FunctionExpression` representing the concatenated result.
   func concat(_ values: [Sendable]) -> FunctionExpression
+
+  /// Creates an expression that returns the type of the expression.
+  ///
+  /// ```swift
+  /// // Get the type of the "rating" field.
+  /// Field("rating").type()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the type of the expression as a string.
+  func type() -> FunctionExpression
 }

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

@@ -103,6 +103,17 @@ public struct Pipeline: @unchecked Sendable {
     }
   }
 
+  /// Creates a new `Pipeline` instance in a faulted state.
+  ///
+  /// This function is used to propagate an error through the pipeline chain. When a stage
+  /// fails to initialize or if a preceding stage has already failed, this method is called
+  /// to create a new pipeline that holds the error message. The `stages` array is cleared,
+  /// and the `errorMessage` is set.
+  ///
+  /// The stored error is eventually thrown by the `execute()` method.
+  ///
+  /// - Parameter message: The error message to store in the pipeline.
+  /// - Returns: A new `Pipeline` instance with the specified error message.
   private func withError(_ message: String) -> Pipeline {
     return Pipeline(stages: [], db: db, errorMessage: message)
   }
@@ -127,7 +138,7 @@ public struct Pipeline: @unchecked Sendable {
   /// - Throws: An error if the pipeline execution fails on the backend.
   /// - Returns: A `Pipeline.Snapshot` containing the result of the pipeline execution.
   public func execute() async throws -> Pipeline.Snapshot {
-    // Check if any Error exist during Stage contruction
+    // Check if any errors occurred during stage construction.
     if let errorMessage = errorMessage {
       throw NSError(
         domain: "com.google.firebase.firestore",

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

@@ -0,0 +1,82 @@
+// Copyright 2025 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+public struct TimeGranularity: Sendable, Equatable, Hashable {
+  enum Kind: String {
+    case microsecond
+    case millisecond
+    case second
+    case minute
+    case hour
+    case day
+    case week
+    case weekMonday = "week(monday)"
+    case weekTuesday = "week(tuesday)"
+    case weekWednesday = "week(wednesday)"
+    case weekThursday = "week(thursday)"
+    case weekFriday = "week(friday)"
+    case weekSaturday = "week(saturday)"
+    case weekSunday = "week(sunday)"
+    case isoweek
+    case month
+    case quarter
+    case year
+    case isoyear
+  }
+
+  public static let microsecond = TimeGranularity(kind: .microsecond)
+  public static let millisecond = TimeGranularity(kind: .millisecond)
+  public static let second = TimeGranularity(kind: .second)
+  public static let minute = TimeGranularity(kind: .minute)
+  public static let hour = TimeGranularity(kind: .hour)
+  /// The day in the Gregorian calendar year that contains the value to truncate.
+  public static let day = TimeGranularity(kind: .day)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Sundays. WEEK is
+  /// equivalent to WEEK(SUNDAY).
+  public static let week = TimeGranularity(kind: .week)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Monday.
+  public static let weekMonday = TimeGranularity(kind: .weekMonday)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Tuesday.
+  public static let weekTuesday = TimeGranularity(kind: .weekTuesday)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Wednesday.
+  public static let weekWednesday = TimeGranularity(kind: .weekWednesday)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Thursday.
+  public static let weekThursday = TimeGranularity(kind: .weekThursday)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Friday.
+  public static let weekFriday = TimeGranularity(kind: .weekFriday)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Saturday.
+  public static let weekSaturday = TimeGranularity(kind: .weekSaturday)
+  /// The first day in the week that contains the value to truncate. Weeks begin on Sunday.
+  public static let weekSunday = TimeGranularity(kind: .weekSunday)
+  /// The first day in the ISO 8601 week that contains the value to truncate. The ISO week begins on
+  /// Monday. The first ISO week of each ISO year contains the first Thursday of the corresponding
+  /// Gregorian calendar year.
+  public static let isoweek = TimeGranularity(kind: .isoweek)
+  /// The first day in the month that contains the value to truncate.
+  public static let month = TimeGranularity(kind: .month)
+  /// The first day in the quarter that contains the value to truncate.
+  public static let quarter = TimeGranularity(kind: .quarter)
+  /// The first day in the year that contains the value to truncate.
+  public static let year = TimeGranularity(kind: .year)
+  /// The first day in the ISO 8601 week-numbering year that contains the value to truncate. The ISO
+  /// year is the Monday of the first week where Thursday belongs to the corresponding Gregorian
+  /// calendar year.
+  public static let isoyear = TimeGranularity(kind: .isoyear)
+
+  public let rawValue: String
+
+  init(kind: Kind) {
+    rawValue = kind.rawValue
+  }
+}