Squashed 'apollo-ios/' changes from e46fb72f..89e8b1af

89e8b1af Add mutateIfFulfilled functions (#608)

git-subtree-dir: apollo-ios
git-subtree-split: 89e8b1afa0241a191ef066b1a998ecbca386e1e7

Author: gh-action-runner

Sources/ApolloAPI/LocalCacheMutation.swift

@@ -42,4 +42,64 @@ public extension MutableSelectionSet where Fragments: FragmentContainer {
   }
 }
 
+public extension MutableSelectionSet where Self: InlineFragment {
+
+  /// Function for mutating a conditional inline fragment on a mutable selection set.
+  ///
+  /// This function is the only supported way to mutate an inline fragment. Because setting the
+  /// value for an inline fragment that was not already present would result in fatal data
+  /// inconsistencies, inline fragments properties are get-only. However, mutating the properties of
+  /// an inline fragment that has been fulfilled is allowed. This function enables the described
+  /// functionality by checking if the fragment is fulfilled and, if so, calling the mutation body.
+  ///
+  /// - Parameters:
+  ///   - keyPath: The `KeyPath` to the inline fragment to mutate the properties of
+  ///   - transform: A closure used to apply mutations to the inline fragment's properties.
+  /// - Returns: A `Bool` indicating if the fragment was fulfilled.
+  ///   If this returns `false`, the `transform` block will not be called.
+  @discardableResult
+  mutating func mutateIfFulfilled<T: InlineFragment>(
+    _ keyPath: KeyPath<Self, T?>,
+    _ transform: (inout T) -> Void
+  ) -> Bool where T.RootEntityType == Self.RootEntityType {
+    guard var fragment = self[keyPath: keyPath] else {
+      return false
+    }
+
+    transform(&fragment)
+    self.__data = fragment.__data
+    return true
+  }
+}
+
 public protocol MutableRootSelectionSet: RootSelectionSet, MutableSelectionSet {}
+
+public extension MutableRootSelectionSet {
+  
+  /// Function for mutating a conditional inline fragment on a mutable selection set.
+  ///
+  /// This function is the only supported way to mutate an inline fragment. Because setting the
+  /// value for an inline fragment that was not already present would result in fatal data
+  /// inconsistencies, inline fragments properties are get-only. However, mutating the properties of
+  /// an inline fragment that has been fulfilled is allowed. This function enables the described
+  /// functionality by checking if the fragment is fulfilled and, if so, calling the mutation body.
+  ///
+  /// - Parameters:
+  ///   - keyPath: The `KeyPath` to the inline fragment to mutate the properties of
+  ///   - transform: A closure used to apply mutations to the inline fragment's properties.
+  /// - Returns: A `Bool` indicating if the fragment was fulfilled.
+  ///   If this returns `false`, the `transform` block will not be called.
+  @discardableResult
+  mutating func mutateIfFulfilled<T: InlineFragment>(
+    _ keyPath: KeyPath<Self, T?>,
+    _ transform: (inout T) -> Void
+  ) -> Bool where T.RootEntityType == Self {
+    guard var fragment = self[keyPath: keyPath] else {
+      return false
+    }
+
+    transform(&fragment)
+    self.__data = fragment.__data
+    return true
+  }
+}