// Sources/SwiftProtobuf/Decoder.swift - Basic field setting // // Copyright (c) 2014 - 2016 Apple Inc. and the project authors // Licensed under Apache License v2.0 with Runtime Library Exception // // See LICENSE.txt for license information: // https://github.com/apple/swift-protobuf/blob/master/LICENSE.txt // // ----------------------------------------------------------------------------- /// /// In this way, the generated code only knows about schema /// information; the decoder logic knows how to decode particular /// wire types based on that information. /// // ----------------------------------------------------------------------------- import Foundation /// This is the abstract protocol used by the generated code /// to deserialize data. /// /// The generated code looks roughly like this: /// /// ``` /// while fieldNumber = try decoder.nextFieldNumber() { /// switch fieldNumber { /// case 1: decoder.decodeRepeatedInt32Field(value: &_field) /// ... etc ... /// } /// ``` /// /// For performance, this is mostly broken out into a separate method /// for singular/repeated fields of every supported type. Note that /// we don't distinguish "packed" here, since all existing decoders /// treat "packed" the same as "repeated" at this level. (That is, /// even when the serializer distinguishes packed and non-packed /// forms, the deserializer always accepts both.) /// /// Generics come into play at only a few points: `Enum`s and `Message`s /// use a generic type to locate the correct initializer. Maps and /// extensions use generics to avoid the method explosion of having to /// support a separate method for every map and extension type. Maps /// do distinguish `Enum`-valued and `Message`-valued maps to avoid /// polluting the generated `Enum` and `Message` types with all of the /// necessary generic methods to support this. public protocol Decoder { /// Called by a `oneof` when it already has a value and is being asked to /// accept a new value. Some formats require `oneof` decoding to fail in this /// case. mutating func handleConflictingOneOf() throws /// Returns the next field number, or nil when the end of the input is /// reached. /// /// For JSON and text format, the decoder translates the field name to a /// number at this point, based on information it obtained from the message /// when it was initialized. mutating func nextFieldNumber() throws -> Int? // Primitive field decoders mutating func decodeSingularFloatField(value: inout Float) throws mutating func decodeSingularFloatField(value: inout Float?) throws mutating func decodeRepeatedFloatField(value: inout [Float]) throws mutating func decodeSingularDoubleField(value: inout Double) throws mutating func decodeSingularDoubleField(value: inout Double?) throws mutating func decodeRepeatedDoubleField(value: inout [Double]) throws mutating func decodeSingularInt32Field(value: inout Int32) throws mutating func decodeSingularInt32Field(value: inout Int32?) throws mutating func decodeRepeatedInt32Field(value: inout [Int32]) throws mutating func decodeSingularInt64Field(value: inout Int64) throws mutating func decodeSingularInt64Field(value: inout Int64?) throws mutating func decodeRepeatedInt64Field(value: inout [Int64]) throws mutating func decodeSingularUInt32Field(value: inout UInt32) throws mutating func decodeSingularUInt32Field(value: inout UInt32?) throws mutating func decodeRepeatedUInt32Field(value: inout [UInt32]) throws mutating func decodeSingularUInt64Field(value: inout UInt64) throws mutating func decodeSingularUInt64Field(value: inout UInt64?) throws mutating func decodeRepeatedUInt64Field(value: inout [UInt64]) throws mutating func decodeSingularSInt32Field(value: inout Int32) throws mutating func decodeSingularSInt32Field(value: inout Int32?) throws mutating func decodeRepeatedSInt32Field(value: inout [Int32]) throws mutating func decodeSingularSInt64Field(value: inout Int64) throws mutating func decodeSingularSInt64Field(value: inout Int64?) throws mutating func decodeRepeatedSInt64Field(value: inout [Int64]) throws mutating func decodeSingularFixed32Field(value: inout UInt32) throws mutating func decodeSingularFixed32Field(value: inout UInt32?) throws mutating func decodeRepeatedFixed32Field(value: inout [UInt32]) throws mutating func decodeSingularFixed64Field(value: inout UInt64) throws mutating func decodeSingularFixed64Field(value: inout UInt64?) throws mutating func decodeRepeatedFixed64Field(value: inout [UInt64]) throws mutating func decodeSingularSFixed32Field(value: inout Int32) throws mutating func decodeSingularSFixed32Field(value: inout Int32?) throws mutating func decodeRepeatedSFixed32Field(value: inout [Int32]) throws mutating func decodeSingularSFixed64Field(value: inout Int64) throws mutating func decodeSingularSFixed64Field(value: inout Int64?) throws mutating func decodeRepeatedSFixed64Field(value: inout [Int64]) throws mutating func decodeSingularBoolField(value: inout Bool) throws mutating func decodeSingularBoolField(value: inout Bool?) throws mutating func decodeRepeatedBoolField(value: inout [Bool]) throws mutating func decodeSingularStringField(value: inout String) throws mutating func decodeSingularStringField(value: inout String?) throws mutating func decodeRepeatedStringField(value: inout [String]) throws mutating func decodeSingularBytesField(value: inout Data) throws mutating func decodeSingularBytesField(value: inout Data?) throws mutating func decodeRepeatedBytesField(value: inout [Data]) throws // Decode Enum fields mutating func decodeSingularEnumField(value: inout E) throws where E.RawValue == Int mutating func decodeSingularEnumField(value: inout E?) throws where E.RawValue == Int mutating func decodeRepeatedEnumField(value: inout [E]) throws where E.RawValue == Int // Decode Message fields mutating func decodeSingularMessageField(value: inout M?) throws mutating func decodeRepeatedMessageField(value: inout [M]) throws // Decode Group fields mutating func decodeSingularGroupField(value: inout G?) throws mutating func decodeRepeatedGroupField(value: inout [G]) throws // Decode Map fields. // This is broken into separate methods depending on whether the value // type is primitive (_ProtobufMap), enum (_ProtobufEnumMap), or message // (_ProtobufMessageMap) mutating func decodeMapField(fieldType: _ProtobufMap.Type, value: inout _ProtobufMap.BaseType) throws mutating func decodeMapField(fieldType: _ProtobufEnumMap.Type, value: inout _ProtobufEnumMap.BaseType) throws where ValueType.RawValue == Int mutating func decodeMapField(fieldType: _ProtobufMessageMap.Type, value: inout _ProtobufMessageMap.BaseType) throws // Decode extension fields mutating func decodeExtensionField(values: inout ExtensionFieldValueSet, messageType: Message.Type, fieldNumber: Int) throws // Run a decode loop decoding the MessageSet format for Extensions. mutating func decodeExtensionFieldsAsMessageSet(values: inout ExtensionFieldValueSet, messageType: Message.Type) throws } /// Most Decoders won't care about Extension handing as in MessageSet /// format, so provide a default implementation simply looping on the /// fieldNumbers and feeding through to extension decoding. extension Decoder { public mutating func decodeExtensionFieldsAsMessageSet( values: inout ExtensionFieldValueSet, messageType: Message.Type ) throws { while let fieldNumber = try self.nextFieldNumber() { try self.decodeExtensionField(values: &values, messageType: messageType, fieldNumber: fieldNumber) } } }