Add lineBreakBeforeEachSwitchCaseOrDefaultBody configuration option

Sources/SwiftFormatConfiguration/Configuration.swift

@@ -29,6 +29,7 @@ public struct Configuration: Codable, Equatable {
     case lineBreakBeforeControlFlowKeywords
     case lineBreakBeforeEachArgument
     case lineBreakBeforeEachGenericRequirement
+    case lineBreakBeforeEachSwitchCaseOrDefaultBody
     case prioritizeKeepingFunctionOutputTogether
     case indentConditionalCompilationBlocks
     case lineBreakAroundMultilineExpressionChainComponents
@@ -97,6 +98,15 @@ public struct Configuration: Codable, Equatable {
   /// horizontally first, with line breaks only being fired when the line length would be exceeded.
   public var lineBreakBeforeEachGenericRequirement = false
 
+  /// Determines the line-breaking behavior for the bodies of `case` and `default` items within
+  /// a `switch` statement.
+  ///
+  /// If true, a line break will be added after the colon following `case` or `default`, forcing the
+  /// body to be on a separate line from the `case` or `default`. If false (the default), these bodies
+  /// will be laid out on the same line as the `case` or `default`, with line breaks only being added
+  /// when the line length would be exceeded.
+  public var lineBreakBeforeEachSwitchCaseOrDefaultBody = false
+
   /// Determines if function-like declaration outputs should be prioritized to be together with the
   /// function signature right (closing) parenthesis.
   ///
@@ -187,6 +197,8 @@ public struct Configuration: Codable, Equatable {
       = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachArgument) ?? false
     self.lineBreakBeforeEachGenericRequirement
       = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachGenericRequirement) ?? false
+    self.lineBreakBeforeEachSwitchCaseOrDefaultBody
+      = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachSwitchCaseOrDefaultBody) ?? false
     self.prioritizeKeepingFunctionOutputTogether
       = try container.decodeIfPresent(Bool.self, forKey: .prioritizeKeepingFunctionOutputTogether) ?? false
     self.indentConditionalCompilationBlocks
@@ -221,6 +233,7 @@ public struct Configuration: Codable, Equatable {
     try container.encode(lineBreakBeforeControlFlowKeywords, forKey: .lineBreakBeforeControlFlowKeywords)
     try container.encode(lineBreakBeforeEachArgument, forKey: .lineBreakBeforeEachArgument)
     try container.encode(lineBreakBeforeEachGenericRequirement, forKey: .lineBreakBeforeEachGenericRequirement)
+    try container.encode(lineBreakBeforeEachSwitchCaseOrDefaultBody, forKey: .lineBreakBeforeEachSwitchCaseOrDefaultBody)
     try container.encode(prioritizeKeepingFunctionOutputTogether, forKey: .prioritizeKeepingFunctionOutputTogether)
     try container.encode(indentConditionalCompilationBlocks, forKey: .indentConditionalCompilationBlocks)
     try container.encode(

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -659,7 +659,12 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
     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.label.lastToken,
+      tokens: .break(.reset, size: 0),
+      .break(.open, newlines: config.lineBreakBeforeEachSwitchCaseOrDefaultBody ? .hard : .elective),
+      .open
+    )
 
     // If switch/case labels were configured to be indented, insert an extra `close` break after the
     // case body to match the `open` break above