Stop removing underscores from CodingKey names in InputKey

Sources/ArgumentParser/Completions/BashCompletionsGenerator.swift

@@ -132,7 +132,7 @@ struct BashCompletionsGenerator {
   ///
   /// These consist of completions that are defined as `.list` or `.custom`.
   fileprivate static func generateArgumentCompletions(_ commands: [ParsableCommand.Type]) -> [String] {
-    ArgumentSet(commands.last!, visibility: .default, parent: .root)
+    ArgumentSet(commands.last!, visibility: .default, parent: nil)
       .compactMap { arg -> String? in
         guard arg.isPositional else { return nil }
 
@@ -159,7 +159,7 @@ struct BashCompletionsGenerator {
 
   /// Returns the case-matching statements for supplying completions after an option or flag.
   fileprivate static func generateOptionHandlers(_ commands: [ParsableCommand.Type]) -> String {
-    ArgumentSet(commands.last!, visibility: .default, parent: .root)
+    ArgumentSet(commands.last!, visibility: .default, parent: nil)
       .compactMap { arg -> String? in
         let words = arg.bashCompletionWords()
         if words.isEmpty { return nil }

Sources/ArgumentParser/Parsable Properties/Flag.swift

@@ -396,7 +396,7 @@ extension Flag where Value: EnumerableFlag {
       // flag, the default value to show to the user is the `--value-name`
       // flag that a user would provide on the command line, not a Swift value.
       let defaultValueFlag = initial.flatMap { value -> String? in
-        let defaultKey = InputKey(name: String(describing: value), parent: .key(key))
+        let defaultKey = InputKey(name: String(describing: value), parent: key)
         let defaultNames = Value.name(for: value).makeNames(defaultKey)
         return defaultNames.first?.synopsisString
       }
@@ -405,7 +405,7 @@ extension Flag where Value: EnumerableFlag {
       let hasCustomCaseHelp = caseHelps.contains(where: { $0 != nil })
 
       let args = Value.allCases.enumerated().map { (i, value) -> ArgumentDefinition in
-        let caseKey = InputKey(name: String(describing: value), parent: .key(key))
+        let caseKey = InputKey(name: String(describing: value), parent: key)
         let name = Value.name(for: value)
 
         let helpForCase = caseHelps[i] ?? help
@@ -519,7 +519,7 @@ extension Flag {
       let hasCustomCaseHelp = caseHelps.contains(where: { $0 != nil })
 
       let args = Element.allCases.enumerated().map { (i, value) -> ArgumentDefinition in
-        let caseKey = InputKey(name: String(describing: value), parent: .key(parentKey))
+        let caseKey = InputKey(name: String(describing: value), parent: parentKey)
         let name = Element.name(for: value)
         let helpForCase = hasCustomCaseHelp ? (caseHelps[i] ?? help) : help
 
@@ -552,7 +552,7 @@ extension Flag {
       let hasCustomCaseHelp = caseHelps.contains(where: { $0 != nil })
 
       let args = Element.allCases.enumerated().map { (i, value) -> ArgumentDefinition in
-        let caseKey = InputKey(name: String(describing: value), parent: .key(parentKey))
+        let caseKey = InputKey(name: String(describing: value), parent: parentKey)
         let name = Element.name(for: value)
         let helpForCase = hasCustomCaseHelp ? (caseHelps[i] ?? help) : help
         let help = ArgumentDefinition.Help(

Sources/ArgumentParser/Parsable Properties/NameSpecification.swift

@@ -167,7 +167,7 @@ extension FlagInversion {
         case .short, .customShort:
           return includingShort ? element.name(for: key) : nil
         case .long:
-          let modifiedKey = key.with(newName: key.name.addingIntercappedPrefix(prefix))
+          let modifiedKey = InputKey(name: key.name.addingIntercappedPrefix(prefix), parent: key)
           return element.name(for: modifiedKey)
         case .customLong(let name, let withSingleDash):
           let modifiedName = name.addingPrefixWithAutodetectedStyle(prefix)

Sources/ArgumentParser/Parsable Properties/OptionGroup.swift

@@ -78,7 +78,7 @@ public struct OptionGroup<Value: ParsableArguments>: Decodable, ParsedWrapper {
     visibility: ArgumentVisibility = .default
   ) {
     self.init(_parsedValue: .init { parentKey in
-      var args = ArgumentSet(Value.self, visibility: .private, parent: .key(parentKey))
+      var args = ArgumentSet(Value.self, visibility: .private, parent: parentKey)
       args.content.withEach {
         $0.help.parentTitle = title
       }

Sources/ArgumentParser/Parsable Types/ParsableArguments.swift

@@ -248,7 +248,7 @@ extension ArgumentSetProvider {
 }
 
 extension ArgumentSet {
-  init(_ type: ParsableArguments.Type, visibility: ArgumentVisibility, parent: InputKey.Parent) {
+  init(_ type: ParsableArguments.Type, visibility: ArgumentVisibility, parent: InputKey?) {
     #if DEBUG
     do {
       try type._validate(parent: parent)

Sources/ArgumentParser/Parsable Types/ParsableArgumentsValidation.swift

@@ -10,7 +10,7 @@
 //===----------------------------------------------------------------------===//
 
 fileprivate protocol ParsableArgumentsValidator {
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError?
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError?
 }
 
 enum ValidatorErrorKind {
@@ -37,7 +37,7 @@ struct ParsableArgumentsValidationError: Error, CustomStringConvertible {
 }
 
 extension ParsableArguments {
-  static func _validate(parent: InputKey.Parent) throws {
+  static func _validate(parent: InputKey?) throws {
     let validators: [ParsableArgumentsValidator.Type] = [
       PositionalArgumentsValidator.self,
       ParsableArgumentsCodingKeyValidator.self,
@@ -80,7 +80,7 @@ struct PositionalArgumentsValidator: ParsableArgumentsValidator {
     var kind: ValidatorErrorKind { .failure }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let sets: [ArgumentSet] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in
@@ -190,7 +190,7 @@ struct ParsableArgumentsCodingKeyValidator: ParsableArgumentsValidator {
     }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let argumentKeys: [InputKey] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in
@@ -235,7 +235,7 @@ struct ParsableArgumentsUniqueNamesValidator: ParsableArgumentsValidator {
     var kind: ValidatorErrorKind { .failure }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let argSets: [ArgumentSet] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in
@@ -283,7 +283,7 @@ struct NonsenseFlagsValidator: ParsableArgumentsValidator {
     var kind: ValidatorErrorKind { .warning }
   }
 
-  static func validate(_ type: ParsableArguments.Type, parent: InputKey.Parent) -> ParsableArgumentsValidatorError? {
+  static func validate(_ type: ParsableArguments.Type, parent: InputKey?) -> ParsableArgumentsValidatorError? {
     let argSets: [ArgumentSet] = Mirror(reflecting: type.init())
       .children
       .compactMap { child in

Sources/ArgumentParser/Parsable Types/ParsableCommand.swift

@@ -166,7 +166,7 @@ extension ParsableCommand {
   /// `true` if this command contains any array arguments that are declared
   /// with `.unconditionalRemaining`.
   internal static var includesUnconditionalArguments: Bool {
-    ArgumentSet(self, visibility: .private, parent: .root).contains(where: {
+    ArgumentSet(self, visibility: .private, parent: nil).contains(where: {
       $0.isRepeatingPositional && $0.parsingStrategy == .allRemainingInput
     })
   }

Sources/ArgumentParser/Parsing/ArgumentDefinition.swift

@@ -217,7 +217,7 @@ extension ArgumentDefinition {
   ///
   /// This initializer is used for any property defined on a `ParsableArguments`
   /// type that isn't decorated with one of ArgumentParser's property wrappers.
-  init(unparsedKey: String, default defaultValue: Any?, parent: InputKey.Parent) {
+  init(unparsedKey: String, default defaultValue: Any?, parent: InputKey?) {
     self.init(
       container: Bare<Any>.self,
       key: InputKey(name: unparsedKey, parent: parent),

Sources/ArgumentParser/Parsing/ArgumentSet.swift

@@ -438,7 +438,7 @@ extension ArgumentSet {
   func firstPositional(
     named name: String
   ) -> ArgumentDefinition? {
-    let key = InputKey(name: name, parent: .root)
+    let key = InputKey(name: name, parent: nil)
     return first(where: { $0.help.keys.contains(key) })
   }
 

Sources/ArgumentParser/Parsing/CommandParser.swift

@@ -140,7 +140,7 @@ extension CommandParser {
   /// possible.
   fileprivate mutating func parseCurrent(_ split: inout SplitArguments) throws -> ParsableCommand {
     // Build the argument set (i.e. information on how to parse):
-    let commandArguments = ArgumentSet(currentNode.element, visibility: .private, parent: .root)
+    let commandArguments = ArgumentSet(currentNode.element, visibility: .private, parent: nil)
 
     // Parse the arguments, ignoring anything unexpected
     let values = try commandArguments.lenientParse(
@@ -325,7 +325,7 @@ extension CommandParser {
     let completionValues = Array(args)
 
     // Generate the argument set and parse the argument to find in the set
-    let argset = ArgumentSet(current.element, visibility: .private, parent: .root)
+    let argset = ArgumentSet(current.element, visibility: .private, parent: nil)
     let parsedArgument = try! parseIndividualArg(argToMatch, at: 0).first!
 
     // Look up the specified argument and retrieve its custom completion function

Sources/ArgumentParser/Parsing/InputKey.swift

@@ -9,122 +9,48 @@
 //
 //===----------------------------------------------------------------------===//
 
-/// Represents the path to a parsed field, annotated with ``Flag``, ``Option`` or
-/// ``Argument``. It has a parent, which will either be ``InputKey/Parent/root``
-/// if the field is on the root ``ParsableComand`` or ``AsyncParsableCommand``,
-/// or it will have a ``InputKey/Parent/key(InputKey)`` if it is defined in
-/// a ``ParsableArguments`` instance.
+/// Represents the path to a parsed field, annotated with ``Flag``, ``Option``
+/// or ``Argument``. Fields that are directly declared on a ``ParsableComand``
+/// have a path of length 1, while fields that are declared indirectly (and
+/// included via an option group) have longer paths.
 struct InputKey: Hashable {
-  /// Describes the parent of an ``InputKey``.
-  indirect enum Parent: Hashable {
-    /// There is no parent key.
-    case root
-    /// There is a parent key.
-    case key(InputKey)
-
-    /// Initialises a parent depending on whether the key is provided.
-    init(_ key: InputKey?) {
-      if let key = key {
-        self = .key(key)
-      } else {
-        self = .root
-      }
-    }
-  }
-
   /// The name of the input key.
-  let name: String
-  
-  /// The parent of this key.
-  let parent: Parent
+  var name: String
+
+  /// The path through the field's parents, if any.
+  var path: [String]
 
+  /// The full path of the field.
+  var fullPath: [String] { path + [name] }
 
-  /// Constructs a new ``InputKey``, cleaing the `name`, with the specified ``InputKey/Parent``.
+  /// Constructs a new input key, cleaning the name, with the specified parent.
   ///
   /// - Parameter name: The name of the key.
-  /// - Parameter parent: The ``InputKey/Parent`` of the key.
-  init(name: String, parent: Parent) {
-    self.name = Self.clean(codingKey: name)
-    self.parent = parent
-  }
-
-  @inlinable
-  init?(path: [CodingKey]) {
-    var parentPath = path
-    guard let key = parentPath.popLast() else {
-      return nil
-    }
-    self.name = Self.clean(codingKey: key)
-    self.parent = Parent(InputKey(path: parentPath))
-  }
-
-  /// Constructs a new ``InputKey``, "cleaning the `value` and `path` if necessary.
-  ///
-  /// - Parameter value: The base value of the key.
-  /// - Parameter path: The list of ``CodingKey`` values that lead to this one. May be empty.
-  @inlinable
-  init(name: String, path: [CodingKey]) {
-    self.init(name: name, parent: Parent(InputKey(path: path)))
+  /// - Parameter parent: The input key of the parent.
+  init(name: String, parent: InputKey?) {
+    // Property wrappers have underscore-prefixed names, so we remove the
+    // leading `_`, if present.
+    self.name = name.first == "_"
+      ? String(name.dropFirst(1))
+      : name
+    self.path = parent?.fullPath ?? []
   }
 
-  /// Constructs a new ``InputKey``, "cleaning the `value` and `path` if necessary.
+  /// Constructs a new input key from the given coding key and parent path.
   ///
-  /// - Parameter codingKey: The base ``CodingKey``
-  /// - Parameter path: The list of ``CodingKey`` values that lead to this one. May be empty.
+  /// - Parameter codingKey: The base ``CodingKey``. Leading underscores in
+  ///   `codingKey` is preserved.
+  /// - Parameter path: The list of ``CodingKey`` values that lead to this one.
+  ///   `path` may be empty.
   @inlinable
   init(codingKey: CodingKey, path: [CodingKey]) {
-    self.init(name: codingKey.stringValue, parent: Parent(InputKey(path: path)))
-  }
-
-  /// The full path, including the ``parent`` and the ``name``.
-  var fullPath: [String] {
-    switch parent {
-    case .root:
-      return [name]
-    case .key(let key):
-      var parentPath = key.fullPath
-      parentPath.append(name)
-      return parentPath
-    }
-  }
-
-  /// Returns a new ``InputKey`` with the same ``path`` and a new ``name``.
-  /// The new value will be cleaned.
-  ///
-  /// - Parameter newName: The new ``String`` value.
-  /// - Returns: A new ``InputKey`` with the cleaned value and the same ``path``.
-  func with(newName: String) -> InputKey {
-    return .init(name: Self.clean(codingKey: newName), parent: self.parent)
-  }
-}
-
-extension InputKey {
-  /// Property wrappers have underscore-prefixed names, so this returns a "clean"
-  /// version of the `codingKey`, which has the leading `'_'` removed, if present.
-  ///
-  /// - Parameter codingKey: The key to clean.
-  /// - Returns: The cleaned key.
-  static func clean(codingKey: String) -> String {
-    String(codingKey.first == "_" ? codingKey.dropFirst(1) : codingKey.dropFirst(0))
-  }
-
-  /// Property wrappers have underscore-prefixed names, so this returns a "clean"
-  /// version of the `codingKey`, which has the leading `'_'` removed, if present.
-  ///
-  /// - Parameter codingKey: The key to clean.
-  /// - Returns: The cleaned key.
-  static func clean(codingKey: CodingKey) -> String {
-    clean(codingKey: codingKey.stringValue)
+    self.name = codingKey.stringValue
+    self.path = path.map { $0.stringValue }
   }
 }
 
 extension InputKey: CustomStringConvertible {
   var description: String {
-    switch parent {
-    case .key(let parent):
-      return "\(parent).\(name)"
-    case .root:
-      return name
-    }
+    fullPath.joined(separator: ".")
   }
 }

Sources/ArgumentParser/Usage/DumpHelpGenerator.swift

@@ -38,7 +38,7 @@ fileprivate extension BidirectionalCollection where Element == ParsableCommand.T
   /// Returns the ArgumentSet for the last command in this stack, including
   /// help and version flags, when appropriate.
   func allArguments() -> ArgumentSet {
-    guard var arguments = self.last.map({ ArgumentSet($0, visibility: .private, parent: .root) })
+    guard var arguments = self.last.map({ ArgumentSet($0, visibility: .private, parent: nil) })
     else { return ArgumentSet() }
     self.versionArgumentDefinition().map { arguments.append($0) }
     self.helpArgumentDefinition().map { arguments.append($0) }

Sources/ArgumentParser/Usage/HelpGenerator.swift

@@ -97,7 +97,7 @@ internal struct HelpGenerator {
       fatalError()
     }
 
-    let currentArgSet = ArgumentSet(currentCommand, visibility: visibility, parent: .root)
+    let currentArgSet = ArgumentSet(currentCommand, visibility: visibility, parent: nil)
     self.commandStack = commandStack
 
     // Build the tool name and subcommand name from the command configuration
@@ -292,7 +292,7 @@ fileprivate extension NameSpecification {
   /// step, the name are returned in descending order.
   func generateHelpNames(visibility: ArgumentVisibility) -> [Name] {
     self
-      .makeNames(InputKey(name: "help", parent: .root))
+      .makeNames(InputKey(name: "help", parent: nil))
       .compactMap { name in
         guard visibility.base != .default else { return name }
         switch name {
@@ -333,7 +333,7 @@ internal extension BidirectionalCollection where Element == ParsableCommand.Type
         options: [.isOptional],
         help: "Show the version.",
         defaultValue: nil,
-        key: InputKey(name: "", parent: .root),
+        key: InputKey(name: "", parent: nil),
         isComposite: false),
       completion: .default,
       update: .nullary({ _, _, _ in })
@@ -350,7 +350,7 @@ internal extension BidirectionalCollection where Element == ParsableCommand.Type
         options: [.isOptional],
         help: "Show help information.",
         defaultValue: nil,
-        key: InputKey(name: "", parent: .root),
+        key: InputKey(name: "", parent: nil),
         isComposite: false),
       completion: .default,
       update: .nullary({ _, _, _ in })
@@ -365,7 +365,7 @@ internal extension BidirectionalCollection where Element == ParsableCommand.Type
         options: [.isOptional],
         help: ArgumentHelp("Dump help information as JSON."),
         defaultValue: nil,
-        key: InputKey(name: "", parent: .root),
+        key: InputKey(name: "", parent: nil),
         isComposite: false),
       completion: .default,
       update: .nullary({ _, _, _ in })
@@ -375,7 +375,7 @@ internal extension BidirectionalCollection where Element == ParsableCommand.Type
   /// Returns the ArgumentSet for the last command in this stack, including
   /// help and version flags, when appropriate.
   func argumentsForHelp(visibility: ArgumentVisibility) -> ArgumentSet {
-    guard var arguments = self.last.map({ ArgumentSet($0, visibility: visibility, parent: .root) })
+    guard var arguments = self.last.map({ ArgumentSet($0, visibility: visibility, parent: nil) })
       else { return ArgumentSet() }
     self.versionArgumentDefinition().map { arguments.append($0) }
     self.helpArgumentDefinition().map { arguments.append($0) }