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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
public struct DictionaryStorageMacro {}
extension DictionaryStorageMacro: MemberMacro {
public static func expansion(
of node: AttributeSyntax,
providingMembersOf declaration: some DeclGroupSyntax,
in context: some MacroExpansionContext
) throws -> [DeclSyntax] {
return ["\n var _storage: [String: Any] = [:]"]
}
}
extension DictionaryStorageMacro: MemberAttributeMacro {
public static func expansion(
of node: AttributeSyntax,
attachedTo declaration: some DeclGroupSyntax,
providingAttributesFor member: some DeclSyntaxProtocol,
in context: some MacroExpansionContext
) throws -> [AttributeSyntax] {
guard let property = member.as(VariableDeclSyntax.self),
property.isStoredProperty
else {
return []
}
return [
AttributeSyntax(
leadingTrivia: [.newlines(1), .spaces(2)],
attributeName: IdentifierTypeSyntax(
name: .identifier("DictionaryStorageProperty")
)
)
]
}
}
public struct DictionaryStoragePropertyMacro: AccessorMacro {
public static func expansion<
Context: MacroExpansionContext,
Declaration: DeclSyntaxProtocol
>(
of node: AttributeSyntax,
providingAccessorsOf declaration: Declaration,
in context: Context
) throws -> [AccessorDeclSyntax] {
guard let varDecl = declaration.as(VariableDeclSyntax.self),
let binding = varDecl.bindings.first,
let identifier = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier,
binding.accessorBlock == nil,
let type = binding.typeAnnotation?.type
else {
return []
}
// Ignore the "_storage" variable.
if identifier.text == "_storage" {
return []
}
guard let defaultValue = binding.initializer?.value else {
throw CustomError.message("stored property must have an initializer")
}
return [
"""
get {
_storage[\(literal: identifier.text), default: \(defaultValue)] as! \(type)
}
""",
"""
set {
_storage[\(literal: identifier.text)] = newValue
}
""",
]
}
}
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