Add —nilinit for redundantNilInit rule (#1680)

Rules.md

@@ -1686,11 +1686,17 @@ Remove redundant `let error` from `catch` clause.
 
 ## redundantNilInit
 
-Remove redundant `nil` default value (Optional vars are nil by default).
+Remove/insert redundant `nil` default value (Optional vars are nil by default).
+
+Option | Description
+--- | ---
+`--nilinit` | "remove" (default) redundant nil or "insert" missing nil
 
 <details>
 <summary>Examples</summary>
 
+`--nilinit remove`
+
 ```diff
 - var foo: Int? = nil
 + var foo: Int?
@@ -1706,6 +1712,13 @@ let foo: Int? = nil
 var foo: Int? = 0
 ```
 
+`--nilinit insert`
+
+```diff
+- var foo: Int?
++ var foo: Int? = nil
+```
+
 </details>
 <br/>
 

Sources/Examples.swift

@@ -552,6 +552,8 @@ private struct Examples {
  """
 
  let redundantNilInit = """
+ `--nilinit remove`
+
  ```diff
  - var foo: Int? = nil
  + var foo: Int?
@@ -566,6 +568,13 @@ private struct Examples {
  // doesn't affect non-nil initialization
  var foo: Int? = 0
  ```
+
+ `--nilinit insert`
+
+ ```diff
+ - var foo: Int?
+ + var foo: Int? = nil
+ ```
  """
 
  let redundantObjc = """

Sources/OptionDescriptor.swift

@@ -1013,6 +1013,12 @@ struct _Descriptors {
  fromArgument: { FormatTimeZone(rawValue: $0) },
  toArgument: { $0.rawValue }
  )
+ let nilInit = OptionDescriptor(
+ argumentName: "nilinit",
+ displayName: "Nil init type",
+ help: "\"remove\" (default) redundant nil or \"insert\" missing nil",
+ keyPath: \.nilInit
+ )
 
  // MARK: - Internal
 

Sources/Options.swift

@@ -542,6 +542,16 @@ public enum FormatTimeZone: Equatable, RawRepresentable, CustomStringConvertible
  }
 }
 
+/// When initializing an optional value type,
+/// is it necessary to explicitly declare a default value
+public enum NilInitType: String, CaseIterable {
+ /// Remove redundant `nil` if it is added as default value
+ case remove
+
+ /// Add `nil` as default if not explicitly declared
+ case insert
+}
+
 /// Configuration options for formatting. These aren't actually used by the
 /// Formatter class itself, but it makes them available to the format rules.
 public struct FormatOptions: CustomStringConvertible {
@@ -640,6 +650,7 @@ public struct FormatOptions: CustomStringConvertible {
  public var initCoderNil: Bool
  public var dateFormat: DateFormat
  public var timeZone: FormatTimeZone
+ public var nilInit: NilInitType
 
  /// Deprecated
  public var indentComments: Bool
@@ -753,6 +764,7 @@ public struct FormatOptions: CustomStringConvertible {
  initCoderNil: Bool = false,
  dateFormat: DateFormat = .system,
  timeZone: FormatTimeZone = .system,
+ nilInit: NilInitType = .remove,
  // Doesn't really belong here, but hard to put elsewhere
  fragment: Bool = false,
  ignoreConflictMarkers: Bool = false,
@@ -856,6 +868,7 @@ public struct FormatOptions: CustomStringConvertible {
  self.initCoderNil = initCoderNil
  self.dateFormat = dateFormat
  self.timeZone = timeZone
+ self.nilInit = nilInit
  // Doesn't really belong here, but hard to put elsewhere
  self.fragment = fragment
  self.ignoreConflictMarkers = ignoreConflictMarkers

Sources/Rules.swift

@@ -2944,23 +2944,33 @@ public struct _FormatRules {
  }
  }
 
- /// Remove redundant `= nil` initialization for Optional properties
+ /// Remove or insert redundant `= nil` initialization for Optional properties
  public let redundantNilInit = FormatRule(
- help: "Remove redundant `nil` default value (Optional vars are nil by default)."
+ help: "Remove/insert redundant `nil` default value (Optional vars are nil by default).",
+ options: ["nilinit"]
  ) { formatter in
  func search(from index: Int) {
  if let optionalIndex = formatter.index(of: .unwrapOperator, after: index) {
  if formatter.index(of: .endOfStatement, in: index + 1 ..< optionalIndex) != nil {
  return
  }
- if !formatter.tokens[optionalIndex - 1].isSpaceOrCommentOrLinebreak,
- let equalsIndex = formatter.index(of: .nonSpaceOrLinebreak, after: optionalIndex, if: {
- $0 == .operator("=", .infix)
- }), let nilIndex = formatter.index(of: .nonSpaceOrLinebreak, after: equalsIndex, if: {
- $0 == .identifier("nil")
- })
- {
- formatter.removeTokens(in: optionalIndex + 1 ... nilIndex)
+ if !formatter.tokens[optionalIndex - 1].isSpaceOrCommentOrLinebreak {
+ let equalsIndex = formatter.index(of: .nonSpaceOrLinebreak, after: optionalIndex, if: {
+ $0 == .operator("=", .infix)
+ })
+ switch formatter.options.nilInit {
+ case .remove:
+ if let equalsIndex = equalsIndex, let nilIndex = formatter.index(of: .nonSpaceOrLinebreak, after: equalsIndex, if: {
+ $0 == .identifier("nil")
+ }) {
+ formatter.removeTokens(in: optionalIndex + 1 ... nilIndex)
+ }
+ case .insert:
+ if equalsIndex == nil {
+ let tokens: [Token] = [.space(" "), .operator("=", .infix), .space(" "), .identifier("nil")]
+ formatter.insert(tokens, at: optionalIndex + 1)
+ }
+ }
  }
  search(from: optionalIndex)
  }