swift-protobuf/Sources/SwiftProtobuf/ExtensionFields.swift

// Sources/SwiftProtobuf/ExtensionFields.swift - Extension support
//
// 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/main/LICENSE.txt
//
// -----------------------------------------------------------------------------
///
/// Core protocols implemented by generated extensions.
///
// -----------------------------------------------------------------------------

//
// Type-erased Extension field implementation.
// Note that it has no "self or associated type" references, so can
// be used as a protocol type.  (In particular, although it does have
// a hashValue property, it cannot be Hashable.)
//
// This can encode, decode, return a hashValue and test for
// equality with some other extension field; but it's type-sealed
// so you can't actually access the contained value itself.
//
@preconcurrency
public protocol AnyExtensionField: Sendable, CustomDebugStringConvertible {
    func hash(into hasher: inout Hasher)
    var protobufExtension: any AnyMessageExtension { get }
    func isEqual(other: any AnyExtensionField) -> Bool

    /// Merging field decoding
    mutating func decodeExtensionField<T: Decoder>(decoder: inout T) throws

    /// Fields know their own type, so can dispatch to a visitor
    func traverse<V: Visitor>(visitor: inout V) throws

    /// Check if the field is initialized.
    var isInitialized: Bool { get }
}

extension AnyExtensionField {
    // Default implementation for extensions fields.  The message types below provide
    // custom versions.
    public var isInitialized: Bool { true }
}

///
/// The regular ExtensionField type exposes the value directly.
///
@preconcurrency
public protocol ExtensionField: AnyExtensionField, Hashable {
    associatedtype ValueType
    var value: ValueType { get set }
    init(protobufExtension: any AnyMessageExtension, value: ValueType)
    init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws
}

///
/// Singular field
///
public struct OptionalExtensionField<T: FieldType>: ExtensionField {
    public typealias BaseType = T.BaseType
    public typealias ValueType = BaseType
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: OptionalExtensionField,
        rhs: OptionalExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return String(reflecting: value)
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! OptionalExtensionField<T>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        var v: ValueType?
        try T.decodeSingular(value: &v, from: &decoder)
        if let v = v {
            value = v
        }
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType?
        try T.decodeSingular(value: &v, from: &decoder)
        if let v = v {
            self.init(protobufExtension: protobufExtension, value: v)
        } else {
            return nil
        }
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        try T.visitSingular(value: value, fieldNumber: protobufExtension.fieldNumber, with: &visitor)
    }
}

///
/// Repeated fields
///
public struct RepeatedExtensionField<T: FieldType>: ExtensionField {
    public typealias BaseType = T.BaseType
    public typealias ValueType = [BaseType]
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: RepeatedExtensionField,
        rhs: RepeatedExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return "[" + value.map { String(reflecting: $0) }.joined(separator: ",") + "]"
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! RepeatedExtensionField<T>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        try T.decodeRepeated(value: &value, from: &decoder)
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType = []
        try T.decodeRepeated(value: &v, from: &decoder)
        self.init(protobufExtension: protobufExtension, value: v)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if value.count > 0 {
            try T.visitRepeated(value: value, fieldNumber: protobufExtension.fieldNumber, with: &visitor)
        }
    }
}

///
/// Packed Repeated fields
///
/// TODO: This is almost (but not quite) identical to RepeatedFields;
/// find a way to collapse the implementations.
///
public struct PackedExtensionField<T: FieldType>: ExtensionField {
    public typealias BaseType = T.BaseType
    public typealias ValueType = [BaseType]
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: PackedExtensionField,
        rhs: PackedExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return "[" + value.map { String(reflecting: $0) }.joined(separator: ",") + "]"
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! PackedExtensionField<T>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        try T.decodeRepeated(value: &value, from: &decoder)
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType = []
        try T.decodeRepeated(value: &v, from: &decoder)
        self.init(protobufExtension: protobufExtension, value: v)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if value.count > 0 {
            try T.visitPacked(value: value, fieldNumber: protobufExtension.fieldNumber, with: &visitor)
        }
    }
}

///
/// Enum extensions
///
public struct OptionalEnumExtensionField<E: Enum>: ExtensionField where E.RawValue == Int {
    public typealias BaseType = E
    public typealias ValueType = E
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: OptionalEnumExtensionField,
        rhs: OptionalEnumExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return String(reflecting: value)
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! OptionalEnumExtensionField<E>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        var v: ValueType?
        try decoder.decodeSingularEnumField(value: &v)
        if let v = v {
            value = v
        }
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType?
        try decoder.decodeSingularEnumField(value: &v)
        if let v = v {
            self.init(protobufExtension: protobufExtension, value: v)
        } else {
            return nil
        }
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        try visitor.visitSingularEnumField(
            value: value,
            fieldNumber: protobufExtension.fieldNumber
        )
    }
}

///
/// Repeated Enum fields
///
public struct RepeatedEnumExtensionField<E: Enum>: ExtensionField where E.RawValue == Int {
    public typealias BaseType = E
    public typealias ValueType = [E]
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: RepeatedEnumExtensionField,
        rhs: RepeatedEnumExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return "[" + value.map { String(reflecting: $0) }.joined(separator: ",") + "]"
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! RepeatedEnumExtensionField<E>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        try decoder.decodeRepeatedEnumField(value: &value)
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType = []
        try decoder.decodeRepeatedEnumField(value: &v)
        self.init(protobufExtension: protobufExtension, value: v)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if value.count > 0 {
            try visitor.visitRepeatedEnumField(
                value: value,
                fieldNumber: protobufExtension.fieldNumber
            )
        }
    }
}

///
/// Packed Repeated Enum fields
///
/// TODO: This is almost (but not quite) identical to RepeatedEnumFields;
/// find a way to collapse the implementations.
///
public struct PackedEnumExtensionField<E: Enum>: ExtensionField where E.RawValue == Int {
    public typealias BaseType = E
    public typealias ValueType = [E]
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: PackedEnumExtensionField,
        rhs: PackedEnumExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return "[" + value.map { String(reflecting: $0) }.joined(separator: ",") + "]"
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! PackedEnumExtensionField<E>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        try decoder.decodeRepeatedEnumField(value: &value)
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType = []
        try decoder.decodeRepeatedEnumField(value: &v)
        self.init(protobufExtension: protobufExtension, value: v)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if value.count > 0 {
            try visitor.visitPackedEnumField(
                value: value,
                fieldNumber: protobufExtension.fieldNumber
            )
        }
    }
}

//
// ========== Message ==========
//
public struct OptionalMessageExtensionField<M: Message & Equatable>:
    ExtensionField
{
    public typealias BaseType = M
    public typealias ValueType = BaseType
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: OptionalMessageExtensionField,
        rhs: OptionalMessageExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return String(reflecting: value)
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        value.hash(into: &hasher)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! OptionalMessageExtensionField<M>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        var v: ValueType? = value
        try decoder.decodeSingularMessageField(value: &v)
        if let v = v {
            self.value = v
        }
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType?
        try decoder.decodeSingularMessageField(value: &v)
        if let v = v {
            self.init(protobufExtension: protobufExtension, value: v)
        } else {
            return nil
        }
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        try visitor.visitSingularMessageField(
            value: value,
            fieldNumber: protobufExtension.fieldNumber
        )
    }

    public var isInitialized: Bool {
        value.isInitialized
    }
}

public struct RepeatedMessageExtensionField<M: Message & Equatable>:
    ExtensionField
{
    public typealias BaseType = M
    public typealias ValueType = [BaseType]
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: RepeatedMessageExtensionField,
        rhs: RepeatedMessageExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return "[" + value.map { String(reflecting: $0) }.joined(separator: ",") + "]"
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        for e in value {
            e.hash(into: &hasher)
        }
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! RepeatedMessageExtensionField<M>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        try decoder.decodeRepeatedMessageField(value: &value)
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType = []
        try decoder.decodeRepeatedMessageField(value: &v)
        self.init(protobufExtension: protobufExtension, value: v)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if value.count > 0 {
            try visitor.visitRepeatedMessageField(
                value: value,
                fieldNumber: protobufExtension.fieldNumber
            )
        }
    }

    public var isInitialized: Bool {
        Internal.areAllInitialized(value)
    }
}

//
// ======== Groups within Messages ========
//
// Protoc internally treats groups the same as messages, but
// they serialize very differently, so we have separate serialization
// handling here...
public struct OptionalGroupExtensionField<G: Message & Hashable>:
    ExtensionField
{
    public typealias BaseType = G
    public typealias ValueType = BaseType
    public var value: G
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: OptionalGroupExtensionField,
        rhs: OptionalGroupExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return value.debugDescription
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! OptionalGroupExtensionField<G>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        var v: ValueType? = value
        try decoder.decodeSingularGroupField(value: &v)
        if let v = v {
            value = v
        }
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType?
        try decoder.decodeSingularGroupField(value: &v)
        if let v = v {
            self.init(protobufExtension: protobufExtension, value: v)
        } else {
            return nil
        }
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        try visitor.visitSingularGroupField(
            value: value,
            fieldNumber: protobufExtension.fieldNumber
        )
    }

    public var isInitialized: Bool {
        value.isInitialized
    }
}

public struct RepeatedGroupExtensionField<G: Message & Hashable>:
    ExtensionField
{
    public typealias BaseType = G
    public typealias ValueType = [BaseType]
    public var value: ValueType
    public var protobufExtension: any AnyMessageExtension

    public static func == (
        lhs: RepeatedGroupExtensionField,
        rhs: RepeatedGroupExtensionField
    ) -> Bool {
        lhs.value == rhs.value
    }

    public init(protobufExtension: any AnyMessageExtension, value: ValueType) {
        self.protobufExtension = protobufExtension
        self.value = value
    }

    public var debugDescription: String {
        #if DEBUG
        return "[" + value.map { $0.debugDescription }.joined(separator: ",") + "]"
        #else
        return String(reflecting: type(of: self))
        #endif
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(value)
    }

    public func isEqual(other: any AnyExtensionField) -> Bool {
        let o = other as! RepeatedGroupExtensionField<G>
        return self == o
    }

    public mutating func decodeExtensionField<D: Decoder>(decoder: inout D) throws {
        try decoder.decodeRepeatedGroupField(value: &value)
    }

    public init?<D: Decoder>(protobufExtension: any AnyMessageExtension, decoder: inout D) throws {
        var v: ValueType = []
        try decoder.decodeRepeatedGroupField(value: &v)
        self.init(protobufExtension: protobufExtension, value: v)
    }

    public func traverse<V: Visitor>(visitor: inout V) throws {
        if value.count > 0 {
            try visitor.visitRepeatedGroupField(
                value: value,
                fieldNumber: protobufExtension.fieldNumber
            )
        }
    }

    public var isInitialized: Bool {
        Internal.areAllInitialized(value)
    }
}