Improve performance of JSONDecoder and JSONEncoder for large apps

Author: ChrisBenua

Sources/FoundationEssentials/JSON/JSONDecoder.swift

@@ -610,8 +610,13 @@ extension JSONDecoderImpl: Decoder {
         if type == Decimal.self {
             return try self.unwrapDecimal(from: mapValue, for: codingPathNode, additionalKey) as! T
         }
-        if T.self is _JSONStringDictionaryDecodableMarker.Type {
-            return try self.unwrapDictionary(from: mapValue, as: type, for: codingPathNode, additionalKey)
+        switch options.keyDecodingStrategy {
+        case .useDefaultKeys:
+            break
+        case .convertFromSnakeCase, .custom:
+            if T.self is _JSONStringDictionaryDecodableMarker.Type {
+                return try self.unwrapDictionary(from: mapValue, as: type, for: codingPathNode, additionalKey)
+            }
         }
 
         return try self.with(value: mapValue, path: codingPathNode.appending(additionalKey)) {

Sources/FoundationEssentials/JSON/JSONEncoder.swift

@@ -1214,7 +1214,7 @@ private extension __JSONEncoder {
             return self.wrap(url.absoluteString)
         } else if let decimal = value as? Decimal {
             return .number(decimal.description)
-        } else if let encodable = value as? _JSONStringDictionaryEncodableMarker {
+        } else if !options.keyEncodingStrategy.isDefault, let encodable = value as? _JSONStringDictionaryEncodableMarker {
             return try self.wrap(encodable as! [String:Encodable], for: additionalKey)
         } else if let array = value as? _JSONDirectArrayEncodable {
             if options.outputFormatting.contains(.prettyPrinted) {
@@ -1466,3 +1466,14 @@ extension Array : _JSONDirectArrayEncodable where Element: _JSONSimpleValueArray
         return (writer.bytes, lengths: byteLengths)
     }
 }
+
+private extension JSONEncoder.KeyEncodingStrategy {
+    var isDefault: Bool {
+        switch self {
+        case .useDefaultKeys:
+            return true
+        case .custom, .convertToSnakeCase:
+            return false
+        }
+    }
+}