Add lineBreakBeforeTypeBodies configuration option

Sources/SwiftFormatConfiguration/Configuration.swift

@@ -32,6 +32,7 @@ public struct Configuration: Codable, Equatable {
     case lineBreakBeforeFuncBodies
     case lineBreakBeforeEachGenericRequirement
     case lineBreakBeforeSwitchCaseOrDefaultBodies
+    case lineBreakBeforeTypeBodies
     case prioritizeKeepingFunctionOutputTogether
     case indentConditionalCompilationBlocks
     case lineBreakAroundMultilineExpressionChainComponents
@@ -126,6 +127,14 @@ public struct Configuration: Codable, Equatable {
   /// when the line length would be exceeded.
   public var lineBreakBeforeSwitchCaseOrDefaultBodies = false
 
+  /// Determines the line-breaking behavior for the bodies of types: `class`, `enum`, `extension`,
+  /// `protocol`, and `struct`.
+  ///
+  /// If true, a line break will be added after the opening brace for all non-empty types. If false
+  /// (the default), these bodies will be laid out on the same line as the type declaration, with
+  /// line breaks only being added when the line length would be exceeded.
+  public var lineBreakBeforeTypeBodies = false
+
   /// Determines if function-like declaration outputs should be prioritized to be together with the
   /// function signature right (closing) parenthesis.
   ///
@@ -222,6 +231,8 @@ public struct Configuration: Codable, Equatable {
       = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeFuncBodies) ?? false
     self.lineBreakBeforeSwitchCaseOrDefaultBodies
       = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeSwitchCaseOrDefaultBodies) ?? false
+    self.lineBreakBeforeTypeBodies
+      = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeTypeBodies) ?? false
     self.prioritizeKeepingFunctionOutputTogether
       = try container.decodeIfPresent(Bool.self, forKey: .prioritizeKeepingFunctionOutputTogether) ?? false
     self.indentConditionalCompilationBlocks
@@ -259,6 +270,7 @@ public struct Configuration: Codable, Equatable {
     try container.encode(lineBreakBeforeEachGenericRequirement, forKey: .lineBreakBeforeEachGenericRequirement)
     try container.encode(lineBreakBeforeFuncBodies, forKey: .lineBreakBeforeFuncBodies)
     try container.encode(lineBreakBeforeSwitchCaseOrDefaultBodies, forKey: .lineBreakBeforeSwitchCaseOrDefaultBodies)
+    try container.encode(lineBreakBeforeTypeBodies, forKey: .lineBreakBeforeTypeBodies)
     try container.encode(prioritizeKeepingFunctionOutputTogether, forKey: .prioritizeKeepingFunctionOutputTogether)
     try container.encode(indentConditionalCompilationBlocks, forKey: .indentConditionalCompilationBlocks)
     try container.encode(

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -246,7 +246,13 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     before(firstTokenAfterAttributes, tokens: .open)
     after(typeKeyword, tokens: .break)
 
-    arrangeBracesAndContents(of: members, contentsKeyPath: \.members)
+    arrangeBracesAndContents(
+      of: members,
+      contentsKeyPath: \.members,
+      openBraceNewlineBehavior: !areBracesCompletelyEmpty(members, contentsKeyPath: \.members)
+        && config.lineBreakBeforeTypeBodies
+        ? .hard : .elective
+    )
 
     if let genericWhereClause = genericWhereClause {
       before(genericWhereClause.firstToken, tokens: .break(.same), .open)