Merge pull request #204 from MPLew-is/indented-case

Allow indenting case statements relative to the containing switch block

Author: allevato

Sources/SwiftFormatConfiguration/Configuration.swift

@@ -33,6 +33,7 @@ public struct Configuration: Codable, Equatable {
     case indentConditionalCompilationBlocks
     case lineBreakAroundMultilineExpressionChainComponents
     case fileScopedDeclarationPrivacy
+    case indentSwitchCaseLabels
     case rules
   }
 
@@ -120,6 +121,27 @@ public struct Configuration: Codable, Equatable {
   /// declarations whose effective access level is private to the containing file.
   public var fileScopedDeclarationPrivacy = FileScopedDeclarationPrivacyConfiguration()
 
+  /// Determines if `case` statements should be indented compared to the containing `switch` block.
+  ///
+  /// When `false`, the correct form is:
+  /// ```swift
+  /// switch someValue {
+  /// case someCase:
+  ///   someStatement
+  /// ...
+  /// }
+  /// ```
+  ///
+  /// When `true`, the correct form is:
+  /// ```swift
+  /// switch someValue {
+  ///   case someCase:
+  ///     someStatement
+  ///   ...
+  /// }
+  ///```
+  public var indentSwitchCaseLabels = false
+
   /// Constructs a Configuration with all default values.
   public init() {
     self.version = highestSupportedConfigurationVersion
@@ -176,6 +198,8 @@ public struct Configuration: Codable, Equatable {
       try container.decodeIfPresent(
         FileScopedDeclarationPrivacyConfiguration.self, forKey: .fileScopedDeclarationPrivacy)
       ?? FileScopedDeclarationPrivacyConfiguration()
+    self.indentSwitchCaseLabels
+      = try container.decodeIfPresent(Bool.self, forKey: .indentSwitchCaseLabels) ?? false
 
     // If the `rules` key is not present at all, default it to the built-in set
     // so that the behavior is the same as if the configuration had been
@@ -203,6 +227,7 @@ public struct Configuration: Codable, Equatable {
       lineBreakAroundMultilineExpressionChainComponents,
       forKey: .lineBreakAroundMultilineExpressionChainComponents)
     try container.encode(fileScopedDeclarationPrivacy, forKey: .fileScopedDeclarationPrivacy)
+    try container.encode(indentSwitchCaseLabels, forKey: .indentSwitchCaseLabels)
     try container.encode(rules, forKey: .rules)
   }
 

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -644,10 +644,27 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
   }
 
   override func visit(_ node: SwitchCaseSyntax) -> SyntaxVisitorContinueKind {
-    before(node.firstToken, tokens: .break(.same, newlines: .soft))
+    // If switch/case labels were configured to be indented, use an `open` break; otherwise, use
+    // the default `same` break.
+    let openBreak: Token
+    if config.indentSwitchCaseLabels {
+      openBreak = .break(.open, newlines: .elective)
+    } else {
+      openBreak = .break(.same, newlines: .soft)
+    }
+    before(node.firstToken, tokens: openBreak)
+
     after(node.unknownAttr?.lastToken, tokens: .space)
     after(node.label.lastToken, tokens: .break(.reset, size: 0), .break(.open), .open)
-    after(node.lastToken, tokens: .break(.close, size: 0), .close)
+
+    // If switch/case labels were configured to be indented, insert an extra `close` break after the
+    // case body to match the `open` break above
+    var afterLastTokenTokens: [Token] = [.break(.close, size: 0), .close]
+    if config.indentSwitchCaseLabels {
+      afterLastTokenTokens.append(.break(.close, size: 0))
+    }
+    after(node.lastToken, tokens: afterLastTokenTokens)
+
     return .visitChildren
   }
 
@@ -2028,7 +2045,7 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     }
     return .visitChildren
   }
-  
+
   override func visit(_ node: SameTypeRequirementSyntax) -> SyntaxVisitorContinueKind {
     before(node.equalityToken, tokens: .break)
     after(node.equalityToken, tokens: .space)