Files
swift-composable-architectu…/Sources/ComposableArchitecture/SwiftUI/Binding.swift
Brandon Williams 2ddf47f87b Disfavor new subscript (#2875)
* Disfavor case key path for binding actions.

* wip

* fix

---------

Co-authored-by: Stephen Celis <stephen@stephencelis.com>
2024-02-29 14:25:40 -08:00

803 lines
26 KiB
Swift

import CustomDump
import SwiftUI
/// A property wrapper type that can designate properties of app state that can be directly bindable
/// in SwiftUI views.
///
/// Along with an action type that conforms to the ``BindableAction`` protocol, this type can be
/// used to safely eliminate the boilerplate that is typically incurred when working with multiple
/// mutable fields on state.
///
/// > Note: It is not necessary to annotate _every_ field with `@BindingState`, and in fact it is
/// > not recommended. Marking a field with the property wrapper makes it instantly mutable from the
/// > outside, which may hurt the encapsulation of your feature. It is best to limit the usage of
/// > the property wrapper to only those fields that need to have bindings derived for handing to
/// > SwiftUI components.
///
/// Read <doc:Bindings> for more information.
@available(
iOS,
deprecated: 9999,
message:
"Deriving bindings directly from stores using '@ObservableState'. See the following migration guide for more information: https://pointfreeco.github.io/swift-composable-architecture/main/documentation/composablearchitecture/migratingto1.7#BindingState"
)
@available(
macOS,
deprecated: 9999,
message:
"Deriving bindings directly from stores using '@ObservableState'. See the following migration guide for more information: https://pointfreeco.github.io/swift-composable-architecture/main/documentation/composablearchitecture/migratingto1.7#BindingState"
)
@available(
tvOS,
deprecated: 9999,
message:
"Deriving bindings directly from stores using '@ObservableState'. See the following migration guide for more information: https://pointfreeco.github.io/swift-composable-architecture/main/documentation/composablearchitecture/migratingto1.7#BindingState"
)
@available(
watchOS,
deprecated: 9999,
message:
"Deriving bindings directly from stores using '@ObservableState'. See the following migration guide for more information: https://pointfreeco.github.io/swift-composable-architecture/main/documentation/composablearchitecture/migratingto1.7#BindingState"
)
@propertyWrapper
public struct BindingState<Value> {
/// The underlying value wrapped by the binding state.
public var wrappedValue: Value
#if DEBUG
let fileID: StaticString
let line: UInt
#endif
/// Creates bindable state from the value of another bindable state.
public init(
wrappedValue: Value,
fileID: StaticString = #fileID,
line: UInt = #line
) {
self.wrappedValue = wrappedValue
#if DEBUG
self.fileID = fileID
self.line = line
#endif
}
/// A projection that can be used to derive bindings from a view store.
///
/// Use the projected value to derive bindings from a view store with properties annotated with
/// `@BindingState`. To get the `projectedValue`, prefix the property with `$`:
///
/// ```swift
/// TextField("Display name", text: viewStore.$displayName)
/// ```
///
/// See ``BindingState`` for more details.
public var projectedValue: Self {
get { self }
set { self = newValue }
}
}
extension BindingState: Equatable where Value: Equatable {
public static func == (lhs: Self, rhs: Self) -> Bool {
lhs.wrappedValue == rhs.wrappedValue
}
}
extension BindingState: Hashable where Value: Hashable {
public func hash(into hasher: inout Hasher) {
self.wrappedValue.hash(into: &hasher)
}
}
extension BindingState: Decodable where Value: Decodable {
public init(from decoder: Decoder) throws {
do {
let container = try decoder.singleValueContainer()
self.init(wrappedValue: try container.decode(Value.self))
} catch {
self.init(wrappedValue: try Value(from: decoder))
}
}
}
extension BindingState: Encodable where Value: Encodable {
public func encode(to encoder: Encoder) throws {
do {
var container = encoder.singleValueContainer()
try container.encode(self.wrappedValue)
} catch {
try self.wrappedValue.encode(to: encoder)
}
}
}
extension BindingState: CustomReflectable {
public var customMirror: Mirror {
Mirror(reflecting: self.wrappedValue)
}
}
extension BindingState: CustomDumpRepresentable {
public var customDumpValue: Any {
self.wrappedValue
}
}
extension BindingState: CustomDebugStringConvertible where Value: CustomDebugStringConvertible {
public var debugDescription: String {
self.wrappedValue.debugDescription
}
}
extension BindingState: Sendable where Value: Sendable {}
/// An action that describes simple mutations to some root state at a writable key path.
///
/// Used in conjunction with ``BindingState`` and ``BindableAction`` to safely eliminate the
/// boilerplate typically associated with mutating multiple fields in state.
///
/// Read <doc:Bindings> for more information.
public struct BindingAction<Root>: CasePathable, Equatable, @unchecked Sendable {
public let keyPath: PartialKeyPath<Root>
@usableFromInline
let set: @Sendable (inout Root) -> Void
// NB: swift(<5.8) has an enum existential layout bug that can cause crashes when extracting
// payloads. We can box the existential to work around the bug.
#if swift(<5.8)
private let _value: [AnySendable]
var value: AnySendable { self._value[0] }
#else
let value: AnySendable
#endif
let valueIsEqualTo: @Sendable (Any) -> Bool
init(
keyPath: PartialKeyPath<Root>,
set: @escaping @Sendable (inout Root) -> Void,
value: AnySendable,
valueIsEqualTo: @escaping @Sendable (Any) -> Bool
) {
self.keyPath = keyPath
self.set = set
#if swift(<5.8)
self._value = [value]
#else
self.value = value
#endif
self.valueIsEqualTo = valueIsEqualTo
}
public static func == (lhs: Self, rhs: Self) -> Bool {
lhs.keyPath == rhs.keyPath && lhs.valueIsEqualTo(rhs.value)
}
public static var allCasePaths: AllCasePaths {
AllCasePaths()
}
@dynamicMemberLookup
public struct AllCasePaths {
#if canImport(Perception)
public subscript<Value: Equatable>(
dynamicMember keyPath: WritableKeyPath<Root, Value>
) -> AnyCasePath<BindingAction, Value> where Root: ObservableState {
AnyCasePath(
embed: { .set(keyPath, $0) },
extract: { $0.keyPath == keyPath ? $0.value.base as? Value : nil }
)
}
#endif
public subscript<Value: Equatable>(
dynamicMember keyPath: WritableKeyPath<Root, BindingState<Value>>
) -> AnyCasePath<BindingAction, Value> {
AnyCasePath(
embed: { .set(keyPath, $0) },
extract: { $0.keyPath == keyPath ? $0.value.base as? Value : nil }
)
}
}
}
struct AnySendable: @unchecked Sendable {
let base: Any
@inlinable
init<Base: Sendable>(_ base: Base) {
self.base = base
}
}
extension BindingAction {
/// Returns an action that describes simple mutations to some root state at a writable key path
/// to binding state.
///
/// - Parameters:
/// - keyPath: A key path to the property that should be mutated. This property must be
/// annotated with the ``BindingState`` property wrapper.
/// - value: A value to assign at the given key path.
/// - Returns: An action that describes simple mutations to some root state at a writable key
/// path.
public static func set<Value: Equatable & Sendable>(
_ keyPath: WritableKeyPath<Root, BindingState<Value>>,
_ value: Value
) -> Self {
return .init(
keyPath: keyPath,
set: { $0[keyPath: keyPath].wrappedValue = value },
value: value
)
}
/// Matches a binding action by its key path.
///
/// Implicitly invoked when switching on a reducer's action and pattern matching on a binding
/// action directly to do further work:
///
/// ```swift
/// case .binding(\.$displayName): // Invokes the `~=` operator.
/// // Validate display name
///
/// case .binding(\.$enableNotifications):
/// // Return an authorization request effect
/// ```
public static func ~= <Value>(
keyPath: WritableKeyPath<Root, BindingState<Value>>,
bindingAction: Self
) -> Bool {
keyPath == bindingAction.keyPath
}
init<Value: Equatable & Sendable>(
keyPath: WritableKeyPath<Root, BindingState<Value>>,
set: @escaping @Sendable (_ state: inout Root) -> Void,
value: Value
) {
self.init(
keyPath: keyPath,
set: set,
value: AnySendable(value),
valueIsEqualTo: { ($0 as? AnySendable)?.base as? Value == value }
)
}
}
extension BindingAction: CustomDumpStringConvertible {
public var customDumpDescription: String {
var description = ".set("
customDump(self.keyPath, to: &description, maxDepth: 0)
description.append(", ")
customDump(self.value.base, to: &description, maxDepth: 0)
description.append(")")
return description
}
}
/// An action type that exposes a `binding` case that holds a ``BindingAction``.
///
/// Used in conjunction with ``BindingState`` to safely eliminate the boilerplate typically
/// associated with mutating multiple fields in state.
///
/// Read <doc:Bindings> for more information.
public protocol BindableAction {
/// The root state type that contains bindable fields.
associatedtype State
/// Embeds a binding action in this action type.
///
/// - Returns: A binding action.
static func binding(_ action: BindingAction<State>) -> Self
/// Extracts a binding action from this action type.
var binding: BindingAction<State>? { get }
}
extension BindableAction {
public var binding: BindingAction<State>? {
AnyCasePath(unsafe: Self.binding).extract(from: self)
}
}
extension BindableAction {
/// Constructs a binding action for the given key path and bindable value.
///
/// Shorthand for `.binding(.set(\.$keyPath, value))`.
///
/// - Returns: A binding action.
public static func set<Value: Equatable>(
_ keyPath: WritableKeyPath<State, BindingState<Value>>,
_ value: Value
) -> Self {
self.binding(.set(keyPath, value))
}
}
extension ViewStore where ViewAction: BindableAction, ViewAction.State == ViewState {
@MainActor
public subscript<Value: Equatable>(
dynamicMember keyPath: WritableKeyPath<ViewState, BindingState<Value>>
) -> Binding<Value> {
self.binding(
get: { $0[keyPath: keyPath].wrappedValue },
send: { value in
#if DEBUG
let bindingState = self.state[keyPath: keyPath]
let debugger = BindableActionViewStoreDebugger(
value: value,
bindableActionType: ViewAction.self,
context: .bindingState,
isInvalidated: self.store._isInvalidated,
fileID: bindingState.fileID,
line: bindingState.line
)
let set: @Sendable (inout ViewState) -> Void = {
$0[keyPath: keyPath].wrappedValue = value
debugger.wasCalled = true
}
#else
let set: @Sendable (inout ViewState) -> Void = {
$0[keyPath: keyPath].wrappedValue = value
}
#endif
return .binding(.init(keyPath: keyPath, set: set, value: value))
}
)
}
}
/// A property wrapper type that can designate properties of view state that can be directly
/// bindable in SwiftUI views.
///
/// Read <doc:Bindings> for more information.
@dynamicMemberLookup
@propertyWrapper
public struct BindingViewState<Value> {
let binding: Binding<Value>
let initialValue: Value
init(binding: Binding<Value>) {
self.binding = binding
self.initialValue = binding.wrappedValue
}
public var wrappedValue: Value {
get { self.binding.wrappedValue }
set { self.binding.wrappedValue = newValue }
}
public var projectedValue: Binding<Value> {
self.binding
}
public subscript<Subject>(
dynamicMember keyPath: WritableKeyPath<Value, Subject>
) -> BindingViewState<Subject> {
BindingViewState<Subject>(binding: self.binding[dynamicMember: keyPath])
}
}
extension BindingViewState: Equatable where Value: Equatable {
public static func == (lhs: Self, rhs: Self) -> Bool {
lhs.initialValue == rhs.initialValue && lhs.wrappedValue == rhs.wrappedValue
}
}
extension BindingViewState: Hashable where Value: Hashable {
public func hash(into hasher: inout Hasher) {
hasher.combine(self.initialValue)
hasher.combine(self.wrappedValue)
}
}
extension BindingViewState: CustomReflectable {
public var customMirror: Mirror {
Mirror(reflecting: self.wrappedValue)
}
}
extension BindingViewState: CustomDumpRepresentable {
public var customDumpValue: Any {
self.wrappedValue
}
}
extension BindingViewState: CustomDebugStringConvertible
where Value: CustomDebugStringConvertible {
public var debugDescription: String {
self.wrappedValue.debugDescription
}
}
/// A property wrapper type that can derive ``BindingViewState`` values for a ``ViewStore``.
///
/// Read <doc:Bindings> for more information.
@dynamicMemberLookup
@propertyWrapper
public struct BindingViewStore<State> {
let store: Store<State, BindingAction<State>>
#if DEBUG
let bindableActionType: Any.Type
let fileID: StaticString
let line: UInt
#endif
init<Action: BindableAction>(
store: Store<State, Action>,
fileID: StaticString = #fileID,
line: UInt = #line
) where Action.State == State {
self.store = store.scope(
id: nil,
state: ToState(\.self),
action: Action.binding,
isInvalid: nil
)
#if DEBUG
self.bindableActionType = type(of: Action.self)
self.fileID = fileID
self.line = line
#endif
}
public init(projectedValue: Self) {
self = projectedValue
}
public var wrappedValue: State {
self.store.withState { $0 }
}
public var projectedValue: Self {
get { self }
set { self = newValue }
}
public subscript<Value>(dynamicMember keyPath: KeyPath<State, Value>) -> Value {
self.wrappedValue[keyPath: keyPath]
}
public subscript<Value: Equatable>(
dynamicMember keyPath: WritableKeyPath<State, BindingState<Value>>
) -> BindingViewState<Value> {
BindingViewState(
binding: ViewStore(self.store, observe: { $0[keyPath: keyPath].wrappedValue })
.binding(
send: { value in
#if DEBUG
let debugger = BindableActionViewStoreDebugger(
value: value,
bindableActionType: self.bindableActionType,
context: .bindingStore,
isInvalidated: self.store._isInvalidated,
fileID: self.fileID,
line: self.line
)
let set: @Sendable (inout State) -> Void = {
$0[keyPath: keyPath].wrappedValue = value
debugger.wasCalled = true
}
#else
let set: @Sendable (inout State) -> Void = {
$0[keyPath: keyPath].wrappedValue = value
}
#endif
return .init(keyPath: keyPath, set: set, value: value)
}
)
)
}
}
extension ViewStore {
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - fromViewAction: A function that transforms view actions into store action.
/// - isDuplicate: A function to determine when two `ViewState` values are equal. When values
/// are equal, repeat view computations are removed.
public convenience init<State, Action>(
_ store: Store<State, Action>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
send fromViewAction: @escaping (_ viewAction: ViewAction) -> Action,
removeDuplicates isDuplicate: @escaping (_ lhs: ViewState, _ rhs: ViewState) -> Bool
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: { (_: State) in
toViewState(
BindingViewStore(
store: store.scope(
id: nil,
state: ToState(\.self),
action: fromViewAction,
isInvalid: nil
)
)
)
},
send: fromViewAction,
removeDuplicates: isDuplicate
)
}
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - isDuplicate: A function to determine when two `ViewState` values are equal. When values
/// are equal, repeat view computations are removed.
@_disfavoredOverload
public convenience init<State>(
_ store: Store<State, ViewAction>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
removeDuplicates isDuplicate: @escaping (_ lhs: ViewState, _ rhs: ViewState) -> Bool
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: toViewState,
send: { $0 },
removeDuplicates: isDuplicate
)
}
}
extension ViewStore where ViewState: Equatable {
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - fromViewAction: A function that transforms view actions into store action.
@_disfavoredOverload
public convenience init<State, Action>(
_ store: Store<State, Action>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
send fromViewAction: @escaping (_ viewAction: ViewAction) -> Action
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: toViewState,
send: fromViewAction,
removeDuplicates: ==
)
}
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - content: A function that can generate content from a view store.
@_disfavoredOverload
public convenience init<State>(
_ store: Store<State, ViewAction>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: toViewState,
removeDuplicates: ==
)
}
}
extension WithViewStore where Content: View {
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings and views from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - fromViewAction: A function that transforms view actions into store action.
/// - isDuplicate: A function to determine when two `ViewState` values are equal. When values
/// are equal, repeat view computations are removed.
/// - content: A function that can generate content from a view store.
@_disfavoredOverload
public init<State, Action>(
_ store: Store<State, Action>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
send fromViewAction: @escaping (_ viewAction: ViewAction) -> Action,
removeDuplicates isDuplicate: @escaping (_ lhs: ViewState, _ rhs: ViewState) -> Bool,
@ViewBuilder content: @escaping (_ viewStore: ViewStore<ViewState, ViewAction>) -> Content,
file: StaticString = #fileID,
line: UInt = #line
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: { (_: State) in
toViewState(
BindingViewStore(
store: store.scope(
id: nil,
state: ToState(\.self),
action: fromViewAction,
isInvalid: nil
)
)
)
},
send: fromViewAction,
removeDuplicates: isDuplicate,
content: content,
file: file,
line: line
)
}
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings and views from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - isDuplicate: A function to determine when two `ViewState` values are equal. When values
/// are equal, repeat view computations are removed.
/// - content: A function that can generate content from a view store.
@_disfavoredOverload
public init<State>(
_ store: Store<State, ViewAction>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
removeDuplicates isDuplicate: @escaping (_ lhs: ViewState, _ rhs: ViewState) -> Bool,
@ViewBuilder content: @escaping (_ viewStore: ViewStore<ViewState, ViewAction>) -> Content,
file: StaticString = #fileID,
line: UInt = #line
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: toViewState,
send: { $0 },
removeDuplicates: isDuplicate,
content: content,
file: file,
line: line
)
}
}
extension WithViewStore where ViewState: Equatable, Content: View {
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings and views from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - fromViewAction: A function that transforms view actions into store action.
/// - content: A function that can generate content from a view store.
@_disfavoredOverload
public init<State, Action>(
_ store: Store<State, Action>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
send fromViewAction: @escaping (_ viewAction: ViewAction) -> Action,
@ViewBuilder content: @escaping (_ viewStore: ViewStore<ViewState, ViewAction>) -> Content,
file: StaticString = #fileID,
line: UInt = #line
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: toViewState,
send: fromViewAction,
removeDuplicates: ==,
content: content,
file: file,
line: line
)
}
/// Initializes a structure that transforms a ``Store`` into an observable ``ViewStore`` in order
/// to compute bindings and views from state.
///
/// Read <doc:Bindings> for more information.
///
/// - Parameters:
/// - store: A store.
/// - toViewState: A function that transforms binding store state into observable view state.
/// All changes to the view state will cause the `WithViewStore` to re-compute its view.
/// - content: A function that can generate content from a view store.
@_disfavoredOverload
public init<State>(
_ store: Store<State, ViewAction>,
observe toViewState: @escaping (_ state: BindingViewStore<State>) -> ViewState,
@ViewBuilder content: @escaping (_ viewStore: ViewStore<ViewState, ViewAction>) -> Content,
file: StaticString = #fileID,
line: UInt = #line
) where ViewAction: BindableAction, ViewAction.State == State {
self.init(
store,
observe: toViewState,
removeDuplicates: ==,
content: content,
file: file,
line: line
)
}
}
#if DEBUG
private final class BindableActionViewStoreDebugger<Value> {
enum Context {
case bindingState
case bindingStore
case viewStore
}
let value: Value
let bindableActionType: Any.Type
let context: Context
let isInvalidated: () -> Bool
let fileID: StaticString
let line: UInt
var wasCalled = false
init(
value: Value,
bindableActionType: Any.Type,
context: Context,
isInvalidated: @escaping () -> Bool,
fileID: StaticString,
line: UInt
) {
self.value = value
self.bindableActionType = bindableActionType
self.context = context
self.isInvalidated = isInvalidated
self.fileID = fileID
self.line = line
}
deinit {
// NB: `isInvalidated()` can access store state, which must happen on the main thread.
let isInvalidated =
Thread.isMainThread
? self.isInvalidated()
: DispatchQueue.main.sync(execute: self.isInvalidated)
guard !isInvalidated else { return }
guard self.wasCalled else {
var value = ""
customDump(self.value, to: &value, maxDepth: 0)
runtimeWarn(
"""
A binding action sent from a view store \
\(self.context == .bindingState ? "for binding state defined " : "")at \
"\(self.fileID):\(self.line)" was not handled. …
Action:
\(typeName(self.bindableActionType)).binding(.set(_, \(value)))
To fix this, invoke "BindingReducer()" from your feature reducer's "body".
"""
)
return
}
}
}
#endif