add exp()

Author: cherylEnkidu

Firestore/Swift/Source/ExpressionImplementation.swift

@@ -33,6 +33,10 @@ public extension Expression {
     return FunctionExpression("ceil", [self])
   }
 
+  func exp() -> FunctionExpression {
+    return FunctionExpression("exp", [self])
+  }
+
   func add(_ value: Expression) -> FunctionExpression {
     return FunctionExpression("add", [self, value])
   }

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

@@ -36,6 +36,18 @@ public protocol Expression: Sendable {
 
   // --- Added Mathematical Operations ---
 
+  /// Creates an expression that returns e to the power of X.
+  ///
+  /// Returns zero on underflow and nil on overflow.
+  ///
+  /// ```swift
+  /// // Get the exp of the "amount" field.
+  /// Field("amount").exp()
+  /// ```
+  ///
+  /// - Returns: A new `FunctionExpression` representing the exp of the number.
+  func exp() -> FunctionExpression
+
   /// Creates an expression that returns the smallest numeric value that isn't less than the number.
   ///
   /// ```swift

Firestore/Swift/Tests/Integration/PipelineTests.swift

@@ -2052,6 +2052,70 @@ class PipelineIntegrationTests: FSTIntegrationTestCase {
     TestHelper.compare(pipelineSnapshot: snapshot, expected: expectedResults, enforceOrder: true)
   }
 
+  func testExpWorks() async throws {
+    let collRef = collectionRef(withDocuments: [
+      "doc1": ["value": 1],
+      "doc2": ["value": 0],
+      "doc3": ["value": -1],
+    ])
+    let db = collRef.firestore
+
+    let pipeline = db.pipeline()
+      .collection(collRef.path)
+      .select([
+        Field("value").exp().as("expValue"),
+      ])
+      .sort([Field("expValue").ascending()])
+
+    let snapshot = try await pipeline.execute()
+
+    let expectedResults: [[String: Sendable]] = [
+      ["expValue": Foundation.exp(Double(-1))],
+      ["expValue": Foundation.exp(Double(0))],
+      ["expValue": Foundation.exp(Double(1))],
+    ]
+
+    TestHelper.compare(pipelineSnapshot: snapshot, expected: expectedResults, enforceOrder: true)
+  }
+
+  func testExpUnderflow() async throws {
+    let collRef = collectionRef(withDocuments: [
+      "doc1": ["value": -1000],
+    ])
+    let db = collRef.firestore
+
+    let pipeline = db.pipeline()
+      .collection(collRef.path)
+      .select([
+        Field("value").exp().as("expValue"),
+      ])
+
+    let snapshot = try await pipeline.execute()
+
+    let expectedResults: [[String: Sendable]] = [
+      ["expValue": 0],
+    ]
+
+    TestHelper.compare(pipelineSnapshot: snapshot, expected: expectedResults, enforceOrder: true)
+  }
+
+  func testExpOverflow() async throws {
+    let collRef = collectionRef(withDocuments: [
+      "doc1": ["value": 1000],
+    ])
+    let db = collRef.firestore
+    
+    let pipeline = db.pipeline()
+      .collection(collRef.path)
+      .select([
+        Field("value").exp().as("expValue"),
+      ])
+    
+    let snapshot = try await pipeline.execute()
+    XCTAssertEqual(snapshot.results.count, 1)
+    XCTAssertNil(snapshot.results.first!.get("expValue"))
+  }
+
   func testCollectionIdWorks() async throws {
     let collRef = collectionRef()
     let docRef = collRef.document("doc")