Add lineBreakBeforeControlFlowBodies configuration option

Author: natestedman

Sources/SwiftFormatConfiguration/Configuration.swift

@@ -26,6 +26,7 @@ public struct Configuration: Codable, Equatable {
     case tabWidth
     case indentation
     case respectsExistingLineBreaks
+    case lineBreakBeforeControlFlowBodies
     case lineBreakBeforeControlFlowKeywords
     case lineBreakBeforeEachArgument
     case lineBreakBeforeFuncBodies
@@ -75,6 +76,14 @@ public struct Configuration: Codable, Equatable {
 
   /// MARK: Rule-specific configuration
 
+  /// Determines the line-breaking behavior for bodies of control flow keywords, like `if` and
+  /// `for`.
+  ///
+  /// If true, a line break will be added after the opening brace of these bodies, forcing them
+  /// onto their own lines. If false (the default), these bodies will be laid out on the same line
+  /// as the keyword, with line breaks only being added when the line length would be exceeded.
+  public var lineBreakBeforeControlFlowBodies = false
+
   /// Determines the line-breaking behavior for control flow keywords that follow a closing brace,
   /// like `else` and `catch`.
   ///
@@ -201,6 +210,8 @@ public struct Configuration: Codable, Equatable {
       = try container.decodeIfPresent(Indent.self, forKey: .indentation) ?? .spaces(2)
     self.respectsExistingLineBreaks
       = try container.decodeIfPresent(Bool.self, forKey: .respectsExistingLineBreaks) ?? true
+    self.lineBreakBeforeControlFlowBodies
+      = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeControlFlowBodies) ?? false
     self.lineBreakBeforeControlFlowKeywords
       = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeControlFlowKeywords) ?? false
     self.lineBreakBeforeEachArgument
@@ -242,6 +253,7 @@ public struct Configuration: Codable, Equatable {
     try container.encode(tabWidth, forKey: .tabWidth)
     try container.encode(indentation, forKey: .indentation)
     try container.encode(respectsExistingLineBreaks, forKey: .respectsExistingLineBreaks)
+    try container.encode(lineBreakBeforeControlFlowBodies, forKey: .lineBreakBeforeControlFlowBodies)
     try container.encode(lineBreakBeforeControlFlowKeywords, forKey: .lineBreakBeforeControlFlowKeywords)
     try container.encode(lineBreakBeforeEachArgument, forKey: .lineBreakBeforeEachArgument)
     try container.encode(lineBreakBeforeEachGenericRequirement, forKey: .lineBreakBeforeEachGenericRequirement)

Sources/SwiftFormatPrettyPrint/TokenStreamCreator.swift

@@ -476,7 +476,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       after(condition.lastToken, tokens: .break(.close(mustBreak: false), size: 0))
     }
 
-    arrangeBracesAndContents(of: node.body, contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.body,
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
 
     if let elseKeyword = node.elseKeyword {
       // Add a token before the else keyword. Breaking before `else` is explicitly allowed when
@@ -498,7 +502,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       }
     }
 
-    arrangeBracesAndContents(of: node.elseBody?.as(CodeBlockSyntax.self), contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.elseBody?.as(CodeBlockSyntax.self),
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
 
     return .visitChildren
   }
@@ -537,7 +545,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       after(typeAnnotation.lastToken, tokens: .break(.close(mustBreak: false), size: 0))
     }
 
-    arrangeBracesAndContents(of: node.body, contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.body,
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
 
     return .visitChildren
   }
@@ -559,14 +571,22 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       after(condition.lastToken, tokens: .break(.close(mustBreak: false), size: 0))
     }
 
-    arrangeBracesAndContents(of: node.body, contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.body,
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
 
     return .visitChildren
   }
 
   override func visit(_ node: RepeatWhileStmtSyntax) -> SyntaxVisitorContinueKind {
     after(node.labelColon, tokens: .space)
-    arrangeBracesAndContents(of: node.body, contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.body,
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
 
     if config.lineBreakBeforeControlFlowKeywords {
       before(node.whileKeyword, tokens: .break(.same), .open)
@@ -586,7 +606,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
 
   override func visit(_ node: DoStmtSyntax) -> SyntaxVisitorContinueKind {
     after(node.labelColon, tokens: .space)
-    arrangeBracesAndContents(of: node.body, contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.body,
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
     return .visitChildren
   }
 
@@ -609,7 +633,11 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
       }
     }
 
-    arrangeBracesAndContents(of: node.body, contentsKeyPath: \.statements)
+    arrangeBracesAndContents(
+      of: node.body,
+      contentsKeyPath: \.statements,
+      openBraceNewlineBehavior: config.lineBreakBeforeControlFlowBodies ? .hard : .elective
+    )
 
     return .visitChildren
   }