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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import SwiftSyntax
import SwiftSyntaxMacros
private extension DeclSyntaxProtocol {
var isObservableStoredProperty: Bool {
if let property = self.as(VariableDeclSyntax.self),
let binding = property.bindings.first,
let identifier = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier,
identifier.text != "_registrar", identifier.text != "_storage",
binding.accessorBlock == nil
{
return true
}
return false
}
}
public struct ObservableMacro: MemberMacro, MemberAttributeMacro {
// MARK: - MemberMacro
public static func expansion(
of node: AttributeSyntax,
providingMembersOf declaration: some DeclGroupSyntax,
in context: some MacroExpansionContext
) throws -> [DeclSyntax] {
guard let identified = declaration.asProtocol(NamedDeclSyntax.self) else {
return []
}
let parentName = identified.name
let registrar: DeclSyntax =
"""
let _registrar = ObservationRegistrar<\(parentName)>()
"""
let addObserver: DeclSyntax =
"""
public nonisolated func addObserver(_ observer: some Observer<\(parentName)>) {
_registrar.addObserver(observer)
}
"""
let removeObserver: DeclSyntax =
"""
public nonisolated func removeObserver(_ observer: some Observer<\(parentName)>) {
_registrar.removeObserver(observer)
}
"""
let withTransaction: DeclSyntax =
"""
private func withTransaction<T>(_ apply: () throws -> T) rethrows -> T {
_registrar.beginAccess()
defer { _registrar.endAccess() }
return try apply()
}
"""
let memberList = declaration.memberBlock.members.filter {
$0.decl.isObservableStoredProperty
}
let storageStruct: DeclSyntax =
"""
private struct Storage {
\(memberList)
}
"""
let storage: DeclSyntax =
"""
private var _storage = Storage()
"""
return [
registrar,
addObserver,
removeObserver,
withTransaction,
storageStruct,
storage,
]
}
// MARK: - MemberAttributeMacro
public static func expansion(
of node: AttributeSyntax,
attachedTo declaration: some DeclGroupSyntax,
providingAttributesFor member: some DeclSyntaxProtocol,
in context: some MacroExpansionContext
) throws -> [SwiftSyntax.AttributeSyntax] {
guard member.isObservableStoredProperty else {
return []
}
return [
AttributeSyntax(
attributeName: IdentifierTypeSyntax(
name: .identifier("ObservableProperty")
)
)
]
}
}
extension ObservableMacro: ExtensionMacro {
public static func expansion(
of node: AttributeSyntax,
attachedTo declaration: some DeclGroupSyntax,
providingExtensionsOf type: some TypeSyntaxProtocol,
conformingTo protocols: [TypeSyntax],
in context: some MacroExpansionContext
) throws -> [ExtensionDeclSyntax] {
[try ExtensionDeclSyntax("extension \(type): Observable {}")]
}
}
public struct ObservablePropertyMacro: AccessorMacro {
public static func expansion(
of node: AttributeSyntax,
providingAccessorsOf declaration: some DeclSyntaxProtocol,
in context: some MacroExpansionContext
) throws -> [AccessorDeclSyntax] {
guard let property = declaration.as(VariableDeclSyntax.self),
let binding = property.bindings.first,
let identifier = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier,
binding.accessorBlock == nil
else {
return []
}
let getAccessor: AccessorDeclSyntax =
"""
get {
_registrar.beginAccess(\\.\(identifier))
defer { _registrar.endAccess() }
return _storage.\(identifier)
}
"""
let setAccessor: AccessorDeclSyntax =
"""
set {
_registrar.beginAccess(\\.\(identifier))
_registrar.register(observable: self, willSet: \\.\(identifier), to: newValue)
defer {
_registrar.register(observable: self, didSet: \\.\(identifier))
_registrar.endAccess()
}
_storage.\(identifier) = newValue
}
"""
return [getAccessor, setAccessor]
}
}
|
