FieldExecutionInfo will only merge selections on request

Sources/Apollo/GraphQLExecutor.swift

@@ -46,25 +46,31 @@ fileprivate struct ExecutionInfo { // TODO: Rename?
   }
 }
 
-fileprivate struct FieldSelectionGrouping {
+fileprivate struct FieldSelectionGrouping: Sequence {
   private var fieldInfoList: [String: FieldExecutionInfo] = [:]
 
+  var count: Int { fieldInfoList.count }
+
   mutating func append(field: Selection.Field, withInfo info: ExecutionInfo) {
     let fieldKey = field.responseKey
     if var fieldInfo = fieldInfoList[fieldKey] {
-      fieldInfo.mergeInSelections(of: field)
+      fieldInfo.mergedFields.append(field)
       fieldInfoList[fieldKey] = fieldInfo
     } else {
       fieldInfoList[fieldKey] = FieldExecutionInfo(field: field, info: info)
     }
   }
+
+  func makeIterator() -> Dictionary<String, FieldExecutionInfo>.Iterator {
+    fieldInfoList.makeIterator()
+  }  
 }
 
 struct FieldExecutionInfo {
   let field: Selection.Field
   private let info: ExecutionInfo
 
-  private(set) var selections: [Selection] = []
+  var mergedFields: [Selection.Field]
 
   let responsePath: ResponsePath
   let responseKeyForField: String
@@ -78,12 +84,11 @@ struct FieldExecutionInfo {
   ) {
     self.field = field
     self.info = info
+    mergedFields = [field]
 
     let responseKey = field.responseKey
     responsePath = info.responsePath.appending(responseKey)
     responseKeyForField = responseKey
-
-    mergeInSelections(of: field)
   }
 
   fileprivate mutating func computeCacheKeyAndPath(with variables: [String: JSONEncodable]) throws {
@@ -92,12 +97,12 @@ struct FieldExecutionInfo {
     cacheKeyForField = cacheKey
   }
 
-  fileprivate mutating func mergeInSelections(of field: Selection.Field) {
-    // TODO: Can we do this only for fields of object type?
-    // Hold on to a list of "otherFields" instead of a list of selections, then call a
-    // `mergeSelections()` function during `complete`, which only has to be called on object fields.
-    if case let .object(selectionSet) = field.type.namedType {
-      selections += selectionSet.selections
+  fileprivate func computeMergedSelections() -> [Selection] {
+    return mergedFields.flatMap { field -> [Selection] in
+      guard case let .object(selectionSet) = field.type.namedType else {
+        return []
+      }
+      return selectionSet.selections
     }
   }
 }
@@ -478,7 +483,7 @@ final class GraphQLExecutor {
       let groupedFields = try groupFields(selections, on: object, info: info)
 
       var fieldEntries: [PossiblyDeferred<Accumulator.FieldEntry>] = []
-      fieldEntries.reserveCapacity(groupedFields.keys.count)
+      fieldEntries.reserveCapacity(groupedFields.count)
 
       for (_, fields) in groupedFields {
         let fieldEntry = execute(fields: fields,

Sources/Apollo/GraphQLResponse.swift

@@ -8,7 +8,7 @@ public final class GraphQLResponse<Data: SelectionSet> {
   public let body: JSONObject
 
   private var rootKey: String
-  private var variables: [String: InputValue]?
+  private var variables: [String: JsonE]?
 
   public init<Operation: GraphQLOperation>(operation: Operation, body: JSONObject) where Operation.Data == Data {
     self.body = body