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Add
@_UncheckedMemberwiseInit macro (#36)
Introduce a new experimental macro for generating memberwise
initializers with reduced safety checks compared to `@MemberwiseInit`.
Features of `@_UncheckedMemberwiseInit`:
- Include all properties in the initializer, regardless of access level
- Include attributed properties by default (differs from
`@MemberwiseInit`)
- Allow exposure of lower access level members without per-member
annotation
- Has the same usage as `@MemberwiseInit`
`@_UncheckedMemberwiseInit` provides a trade-off between ease of use and
compile-time safety, suitable for scenarios where brevity is preferred
over strict access control enforcement. Note that the underscore prefix
indicates this is an experimental feature.
Example:
```swift
@_UnsafeMemberwiseInit(.public)
public struct ViewModel {
private let title: String
}
```
Yields:
```swift
public init(title: String) {
self.title = title
}
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105 changes: 105 additions & 0 deletions
105
Sources/MemberwiseInitMacros/Macros/Support/MemberwiseInitFormatter.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,105 @@ | ||
| import SwiftSyntax | ||
| import SwiftSyntaxBuilder | ||
|
|
||
| struct MemberwiseInitFormatter { | ||
| static func formatInitializer( | ||
| properties: [MemberProperty], | ||
| accessLevel: AccessLevelModifier, | ||
| deunderscoreParameters: Bool, | ||
| optionalsDefaultNil: Bool? | ||
| ) -> InitializerDeclSyntax { | ||
| let formattedParameters = formatParameters( | ||
| properties: properties, | ||
| deunderscoreParameters: deunderscoreParameters, | ||
| optionalsDefaultNil: optionalsDefaultNil, | ||
| accessLevel: accessLevel | ||
| ) | ||
|
|
||
| let formattedInitSignature = "\n\(accessLevel) init(\(formattedParameters))" | ||
|
|
||
| return try! InitializerDeclSyntax(SyntaxNodeString(stringLiteral: formattedInitSignature)) { | ||
| CodeBlockItemListSyntax( | ||
| properties.map { property in | ||
| CodeBlockItemSyntax( | ||
| stringLiteral: formatInitializerAssignmentStatement( | ||
| for: property, | ||
| considering: properties, | ||
| deunderscoreParameters: deunderscoreParameters | ||
| ) | ||
| ) | ||
| } | ||
| ) | ||
| } | ||
| } | ||
|
|
||
| private static func formatParameters( | ||
| properties: [MemberProperty], | ||
| deunderscoreParameters: Bool, | ||
| optionalsDefaultNil: Bool?, | ||
| accessLevel: AccessLevelModifier | ||
| ) -> String { | ||
| guard !properties.isEmpty else { return "" } | ||
|
|
||
| return "\n" | ||
| + properties | ||
| .map { property in | ||
| formatParameter( | ||
| for: property, | ||
| considering: properties, | ||
| deunderscoreParameters: deunderscoreParameters, | ||
| optionalsDefaultNil: optionalsDefaultNil | ||
| ?? MemberwiseInitMacro.defaultOptionalsDefaultNil( | ||
| for: property.keywordToken, | ||
| initAccessLevel: accessLevel | ||
| ) | ||
| ) | ||
| } | ||
| .joined(separator: ",\n") + "\n" | ||
| } | ||
|
|
||
| private static func formatParameter( | ||
| for property: MemberProperty, | ||
| considering allProperties: [MemberProperty], | ||
| deunderscoreParameters: Bool, | ||
| optionalsDefaultNil: Bool | ||
| ) -> String { | ||
| let defaultValue = | ||
| property.initializerValue.map { " = \($0.description)" } | ||
| ?? property.customSettings?.defaultValue.map { " = \($0)" } | ||
| ?? (optionalsDefaultNil && property.type.isOptionalType ? " = nil" : "") | ||
|
|
||
| let escaping = | ||
| (property.customSettings?.forceEscaping ?? false || property.type.isFunctionType) | ||
| ? "@escaping " : "" | ||
|
|
||
| let label = property.initParameterLabel( | ||
| considering: allProperties, deunderscoreParameters: deunderscoreParameters) | ||
|
|
||
| let parameterName = property.initParameterName( | ||
| considering: allProperties, deunderscoreParameters: deunderscoreParameters) | ||
|
|
||
| return "\(label)\(parameterName): \(escaping)\(property.type.description)\(defaultValue)" | ||
| } | ||
|
|
||
| private static func formatInitializerAssignmentStatement( | ||
| for property: MemberProperty, | ||
| considering allProperties: [MemberProperty], | ||
| deunderscoreParameters: Bool | ||
| ) -> String { | ||
| let assignee = | ||
| switch property.customSettings?.assignee { | ||
| case .none: | ||
| "self.\(property.name)" | ||
| case .wrapper: | ||
| "self._\(property.name)" | ||
| case let .raw(assignee): | ||
| assignee | ||
| } | ||
|
|
||
| let parameterName = property.initParameterName( | ||
| considering: allProperties, | ||
| deunderscoreParameters: deunderscoreParameters | ||
| ) | ||
| return "\(assignee) = \(parameterName)" | ||
| } | ||
| } |
74 changes: 74 additions & 0 deletions
74
Sources/MemberwiseInitMacros/Macros/UncheckedMemberwiseInitMacro.swift
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,74 @@ | ||
| import SwiftCompilerPlugin | ||
| import SwiftDiagnostics | ||
| import SwiftSyntax | ||
| import SwiftSyntaxBuilder | ||
| import SwiftSyntaxMacroExpansion | ||
| import SwiftSyntaxMacros | ||
|
|
||
| public struct UncheckedMemberwiseInitMacro: MemberMacro { | ||
| public static func expansion<D, C>( | ||
| of node: AttributeSyntax, | ||
| providingMembersOf decl: D, | ||
| in context: C | ||
| ) throws -> [SwiftSyntax.DeclSyntax] | ||
| where D: DeclGroupSyntax, C: MacroExpansionContext { | ||
| guard [SwiftSyntax.SyntaxKind.classDecl, .structDecl, .actorDecl].contains(decl.kind) else { | ||
| throw MacroExpansionErrorMessage( | ||
| """ | ||
| @_UncheckedMemberwiseInit can only be attached to a struct, class, or actor; \ | ||
| not to \(decl.descriptiveDeclKind(withArticle: true)). | ||
| """ | ||
| ) | ||
| } | ||
|
|
||
| let accessLevel = | ||
| MemberwiseInitMacro.extractConfiguredAccessLevel(from: node) ?? .internal | ||
| let optionalsDefaultNil: Bool? = | ||
| MemberwiseInitMacro.extractLabeledBoolArgument("_optionalsDefaultNil", from: node) | ||
| let deunderscoreParameters: Bool = | ||
| MemberwiseInitMacro.extractLabeledBoolArgument("_deunderscoreParameters", from: node) ?? false | ||
|
|
||
| let properties = try collectUncheckedMemberProperties( | ||
| from: decl.memberBlock.members | ||
| ) | ||
|
|
||
| return [ | ||
| DeclSyntax( | ||
| MemberwiseInitFormatter.formatInitializer( | ||
| properties: properties, | ||
| accessLevel: accessLevel, | ||
| deunderscoreParameters: deunderscoreParameters, | ||
| optionalsDefaultNil: optionalsDefaultNil | ||
| ) | ||
| ) | ||
| ] | ||
| } | ||
|
|
||
| private static func collectUncheckedMemberProperties( | ||
| from memberBlockItemList: MemberBlockItemListSyntax | ||
| ) throws -> [MemberProperty] { | ||
| memberBlockItemList.compactMap { member -> MemberProperty? in | ||
| guard let variable = member.decl.as(VariableDeclSyntax.self), | ||
| !variable.isComputedProperty, | ||
| variable.modifiersExclude([.static, .lazy]), | ||
| let binding = variable.bindings.first, | ||
| let name = binding.pattern.as(IdentifierPatternSyntax.self)?.identifier.text, | ||
| let type = binding.typeAnnotation?.type ?? binding.initializer?.value.inferredTypeSyntax | ||
| else { return nil } | ||
|
|
||
| let customSettings = MemberwiseInitMacro.extractVariableCustomSettings(from: variable) | ||
| if customSettings?.ignore == true { | ||
| return nil | ||
| } | ||
|
|
||
| return MemberProperty( | ||
| accessLevel: variable.accessLevel, | ||
| customSettings: customSettings, | ||
| initializerValue: binding.initializer?.value, | ||
| keywordToken: variable.bindingSpecifier.tokenKind, | ||
| name: name, | ||
| type: type.trimmed | ||
| ) | ||
| } | ||
| } | ||
| } |
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