feat: made initialized mutable variables initialization optional in member-wise initializers (#15)

* feat: made initialized mutable variables initialization optional in member-wise initializers
- added multiple member-wise initializers based on mulatable initialized variables present

* wip: use code-factor suggestions

Author: soumyamahunt

README.md

@@ -21,7 +21,7 @@ Supercharge `Swift`'s `Codable` implementations with macros.
 - Allows to create flattened model for nested `CodingKey` values with ``CodedAt(_:)`` and ``CodedIn(_:)``.
 - Allows to create composition of multiple `Codable` types with ``CodedAt(_:)`` passing no arguments.
 - Allows to provide default value in case of decoding failures with ``Default(_:)``.
-- Generates member-wise initializer considering the above default value syntax as well.
+- Generates member-wise initializer(s) considering the above default value syntax as well.
 - Allows to create custom decoding/encoding strategies with ``HelperCoder`` and using them with ``CodedBy(_:)``. i.e. ``LossySequenceCoder`` etc.
 
 ## Requirements
@@ -181,7 +181,7 @@ struct Coordinate {
 </details>
 
 <details>
-  <summary>Provide default value in case of decoding failures and member-wise initializer generated considers these default values.</summary>
+  <summary>Provide default value in case of decoding failures and member-wise initializer(s) generated considers these default values.</summary>
 
 Instead of throwing error in case of missing data or type mismatch, you can provide a default value that will be assigned in this case. The memberwise initializer generated also uses this default value for the field. The following definition with `MetaCodable`:
 

Sources/CodableMacroPlugin/Attributes/Codable.swift

@@ -15,7 +15,7 @@ import SwiftSyntaxMacros
 ///     for the attached struct declaration named `CodingKeys` and use
 ///     this type for `Codable` implementation of both `init(from:)`
 ///     and `encode(to:)` methods by using `CodedPropertyMacro`
-///     declarations. Additionally member-wise initializer is also generated.
+///     declarations. Additionally member-wise initializer(s) also generated.
 struct Codable: Attribute {
     /// The node syntax provided
     /// during initialization.
@@ -110,7 +110,7 @@ extension Codable: ConformanceMacro, MemberMacro {
     ///
     /// - Returns: `CodingKeys` type and `init(from:)`, `encode(to:)`,
     ///             method declarations for `Codable` implementation along with
-    ///             member-wise initializer declaration.
+    ///             member-wise initializer declaration(s).
     static func expansion(
         of node: AttributeSyntax,
         providingMembersOf declaration: some DeclGroupSyntax,
@@ -147,12 +147,7 @@ extension Codable: ConformanceMacro, MemberMacro {
         }
 
         // generate
-        return [
-            DeclSyntax(registrar.memberInit(in: context)),
-            DeclSyntax(registrar.decoding(in: context)),
-            DeclSyntax(registrar.encoding(in: context)),
-            DeclSyntax(registrar.codingKeys(in: context)),
-        ]
+        return registrar.memberDeclarations(in: context)
     }
 }
 

Sources/CodableMacroPlugin/Builders/Default+RegistrationBuilder.swift

@@ -1,24 +1,26 @@
 import SwiftSyntax
 
 extension Default: RegistrationBuilder {
+    /// The any variable data with required initialization that input registration can have.
+    typealias Input = AnyVariable<RequiredInitialization>
     /// The variable data with default expression that output registration will have.
-    typealias Output = DefaultValueVariable<AnyVariable>
+    typealias Output = DefaultValueVariable<Input>
 
     /// Build new registration with provided input registration.
     ///
     /// New registration is updated with default expression data that will be used
-    /// for decoding failure and member-wise initializer, if provided.
+    /// for decoding failure and member-wise initializer(s), if provided.
     ///
     /// - Parameter input: The registration built so far.
     /// - Returns: Newly built registration with default expression data.
-    func build(with input: Registration<AnyVariable>) -> Registration<Output> {
+    func build(with input: Registration<Input>) -> Registration<Output> {
         let expr = node.argument!
             .as(TupleExprElementListSyntax.self)!.first!.expression
         return input.updating(with: input.variable.with(default: expr))
     }
 }
 
-fileprivate extension Variable {
+fileprivate extension Variable where Initialization == RequiredInitialization {
     /// Update variable data with the default value expression provided.
     ///
     /// `DefaultValueVariable` is created with this variable as base

Sources/CodableMacroPlugin/Builders/InitializationRegistrationBuilder.swift

@@ -4,7 +4,8 @@ import SwiftSyntax
 ///
 /// Checks whether variable can be initialized and whether variable has been already initialized
 /// from the current syntax and updates the registrations variable data accordingly.
-struct InitializationRegistrationBuilder<Input: Variable>: RegistrationBuilder {
+struct InitializationRegistrationBuilder<Input: Variable>: RegistrationBuilder
+where Input.Initialization == RequiredInitialization {
     /// The output registration variable type that handles initialization data.
     typealias Output = InitializationVariable<Input>
 
@@ -33,7 +34,7 @@ struct InitializationRegistrationBuilder<Input: Variable>: RegistrationBuilder {
             || input.context.binding.initializer == nil
         }
 
-        let initialized = input.context.binding.initializer == nil
+        let initialized = input.context.binding.initializer != nil
         let options = Output.Options(init: canInit, initialized: initialized)
         let newVariable = Output(base: input.variable, options: options)
         return input.updating(with: newVariable)

Sources/CodableMacroPlugin/Builders/OptionalRegistrationBuilder.swift

@@ -4,8 +4,14 @@
 /// The optional registration is used to update registration data with current syntax.
 /// If optional registration not provided, input registration is passed with variable type erased.
 struct OptionalRegistrationBuilder<Builder>: RegistrationBuilder
-where Builder: RegistrationBuilder {
+where Builder: RegistrationBuilder,
+      Builder.Input.Initialization == Builder.Output.Initialization {
+    /// The variable data of underlying builder's input registration.
     typealias Input = Builder.Input
+    /// The variable data generated by passed builder or the input
+    /// variable data if no builder passed.
+    typealias Output = AnyVariable<Input.Initialization>
+
     /// The optional builder to use.
     ///
     /// This will be used as underlying
@@ -31,9 +37,9 @@ where Builder: RegistrationBuilder {
     ///
     /// - Parameter input: The registration built so far.
     /// - Returns: Newly built registration with additional data.
-    func build(with input: Registration<Input>) -> Registration<AnyVariable> {
+    func build(with input: Registration<Input>) -> Registration<Output> {
         let keyPath: [String]
-        let variable: Variable
+        let variable: any Variable<Input.Initialization>
         if let reg = base?.build(with: input) {
             keyPath = reg.keyPath
             variable = reg.variable

Sources/CodableMacroPlugin/Registration/Node.swift

@@ -53,15 +53,15 @@ extension Registrar {
             }
         }
         /// All the variables registered at this node.
-        private(set) var variables: [Variable]
+        private(set) var variables: [any Variable]
         /// Nested registration node associated with keys.
         private(set) var children: OrderedDictionary<Key, Self>
 
         /// List of all the linked variables registered.
         ///
         /// Gets all variables at current node
         /// and children nodes.
-        var linkedVariables: [Variable] {
+        var linkedVariables: [any Variable] {
             return variables + children.flatMap { $1.linkedVariables }
         }
 
@@ -73,7 +73,7 @@ extension Registrar {
         ///
         /// - Returns: The newly created node instance.
         init(
-            variables: [Variable] = [],
+            variables: [any Variable] = [],
             children: OrderedDictionary<Key, Self> = [:]
         ) {
             self.variables = variables
@@ -90,7 +90,7 @@ extension Registrar {
         ///               additional macro metadata.
         ///   - keyPath: The `CodingKey` path where the value
         ///              will be decode/encoded.
-        mutating func register(variable: Variable, keyPath: [Key]) {
+        mutating func register(variable: any Variable, keyPath: [Key]) {
             guard !keyPath.isEmpty else { variables.append(variable); return }
 
             let key = keyPath.first!

Sources/CodableMacroPlugin/Registration/Registrar.swift

@@ -19,6 +19,14 @@ struct Registrar {
         /// conformance implementation declarations.
         fileprivate let modifiers: ModifierListSyntax?
 
+        /// Member-wise initialization generator with provided options.
+        ///
+        /// Creates member-wise initialization generator by passing
+        /// the provided access modifiers.
+        var initGenerator: MemberwiseInitGenerator {
+            return .init(options: .init(modifiers: modifiers))
+        }
+
         /// Creates a new options instance with provided parameters.
         ///
         /// - Parameters:
@@ -82,6 +90,26 @@ struct Registrar {
         )
     }
 
+    /// Generates member declarations for `Codable` macro.
+    ///
+    /// From the variables registered by `Codable` macro,
+    /// member-wise initialization, `Codable` protocol conformance
+    /// and `CodingKey` declarations are generated.
+    ///
+    /// - Parameter context: The context in which to perform
+    ///                      the macro expansion.
+    ///
+    /// - Returns: The generated member declarations.
+    func memberDeclarations(
+        in context: some MacroExpansionContext
+    ) -> [DeclSyntax] {
+        var decls = memberInit(in: context).map { DeclSyntax($0) }
+        decls.append(DeclSyntax(decoding(in: context)))
+        decls.append(DeclSyntax(encoding(in: context)))
+        decls.append(DeclSyntax(codingKeys(in: context)))
+        return decls
+    }
+
     /// Provides the declaration of `CodingKey` type that is used
     /// for `Codable` implementation generation.
     ///
@@ -92,7 +120,7 @@ struct Registrar {
     ///                      the macro expansion.
     ///
     /// - Returns: The generated enum declaration.
-    func codingKeys(
+    private func codingKeys(
         in context: some MacroExpansionContext
     ) -> EnumDeclSyntax {
         return caseMap.decl(in: context)
@@ -105,7 +133,7 @@ struct Registrar {
     ///                      the macro expansion.
     ///
     /// - Returns: The generated initializer declaration.
-    func decoding(
+    private func decoding(
         in context: some MacroExpansionContext
     ) -> InitializerDeclSyntax {
         return InitializerDeclSyntax.decode(
@@ -125,7 +153,7 @@ struct Registrar {
     ///                      the macro expansion.
     ///
     /// - Returns: The generated function declaration.
-    func encoding(
+    private func encoding(
         in context: some MacroExpansionContext
     ) -> FunctionDeclSyntax {
         return FunctionDeclSyntax.encode(
@@ -138,43 +166,20 @@ struct Registrar {
         }
     }
 
-    /// Provides the member-wise initializer declaration.
+    /// Provides the member-wise initializer declaration(s).
     ///
     /// - Parameter context: The context in which to perform
     ///                      the macro expansion.
     ///
-    /// - Returns: The generated initializer declaration.
-    func memberInit(
+    /// - Returns: The generated initializer declarations.
+    private func memberInit(
         in context: some MacroExpansionContext
-    ) -> InitializerDeclSyntax {
-        let allVariables = root.linkedVariables
-        var params: [FunctionParameterSyntax] = []
-        var exprs: [CodeBlockItemSyntax] = []
-        params.reserveCapacity(allVariables.count)
-        exprs.reserveCapacity(allVariables.count)
-
-        allVariables.forEach { variable in
-            switch variable.initializing(in: context) {
-            case .ignored:
-                break
-            case .optional(let param, let expr),
-                .required(let param, let expr):
-                params.append(param)
-                exprs.append(expr)
-            }
-        }
-        return InitializerDeclSyntax(
-            modifiers: options.modifiers,
-            signature: .init(
-                input: .init(
-                    parameterList: .init {
-                        for param in params { param }
-                    }
-                )
-            )
-        ) {
-            for expr in exprs { expr }
+    ) -> [InitializerDeclSyntax] {
+        var generator = options.initGenerator
+        for variable in root.linkedVariables {
+            generator = variable.initializing(in: context).add(to: generator)
         }
+        return generator.declarations(in: context)
     }
 }
 

Sources/CodableMacroPlugin/Variables/AnyVariable.swift

@@ -1,18 +1,17 @@
 import SwiftSyntax
 import SwiftSyntaxMacros
 
-/// A type-erased variable value.
+/// A type-erased variable value only containing initialization type data.
 ///
-/// The `AnyVariable` type forwards `Variable`
-/// implementations to an underlying variable value,
-/// hiding the type of the wrapped value.
-struct AnyVariable: Variable {
+/// The `AnyVariable` type forwards `Variable` implementations to an underlying
+/// variable value, hiding the type of the wrapped value.
+struct AnyVariable<Initialization: VariableInitialization>: Variable {
     /// The value wrapped by this instance.
     ///
     /// The base property can be cast back
     /// to its original type using type casting
     /// operators (`as?`, `as!`, or `as`).
-    let base: Variable
+    let base: any Variable<Initialization>
 
     /// The name of the variable.
     ///
@@ -22,6 +21,11 @@ struct AnyVariable: Variable {
     ///
     /// Provides type of the underlying variable value.
     var type: TypeSyntax { base.type }
+    /// Whether the variable is needed for final code generation.
+    ///
+    /// Provides whether underlying variable value is needed
+    /// for final code generation.
+    var canBeRegistered: Bool { base.canBeRegistered }
 
     /// Indicates the initialization type for this variable.
     ///
@@ -32,7 +36,7 @@ struct AnyVariable: Variable {
     /// - Returns: The type of initialization for variable.
     func initializing(
         in context: some MacroExpansionContext
-    ) -> VariableInitialization {
+    ) -> Initialization {
         return base.initializing(in: context)
     }