Merge pull request #580 from allevato/separable-config

Move the default `Configuration.init()` into a separate file.

Author: allevato

Sources/SwiftFormatConfiguration/Configuration+Default.swift

@@ -0,0 +1,41 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+extension Configuration {
+  /// Creates a new `Configuration` with default values.
+  ///
+  /// This initializer is isolated to its own file to make it easier for users who are forking or
+  /// building swift-format themselves to hardcode a different default configuration. To do this,
+  /// simply replace this file with your own default initializer that sets the values to whatever
+  /// you want.
+  ///
+  /// When swift-format reads a configuration file from disk, any values that are not specified in
+  /// the JSON will be populated from this default configuration.
+  public init() {
+    self.rules = Self.defaultRuleEnablements
+    self.maximumBlankLines = 1
+    self.lineLength = 100
+    self.tabWidth = 8
+    self.indentation = .spaces(2)
+    self.respectsExistingLineBreaks = true
+    self.lineBreakBeforeControlFlowKeywords = false
+    self.lineBreakBeforeEachArgument = false
+    self.lineBreakBeforeEachGenericRequirement = false
+    self.prioritizeKeepingFunctionOutputTogether = false
+    self.indentConditionalCompilationBlocks = true
+    self.lineBreakAroundMultilineExpressionChainComponents = false
+    self.fileScopedDeclarationPrivacy = FileScopedDeclarationPrivacyConfiguration()
+    self.indentSwitchCaseLabels = false
+    self.spacesAroundRangeFormationOperators = false
+    self.noAssignmentInExpressions = NoAssignmentInExpressionsConfiguration()
+  }
+}

Sources/SwiftFormatConfiguration/Configuration.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
@@ -14,7 +14,12 @@ import Foundation
 
 /// A version number that can be specified in the configuration file, which allows us to change the
 /// format in the future if desired and still support older files.
-fileprivate let highestSupportedConfigurationVersion = 1
+///
+/// Note that *adding* new configuration values is not a version-breaking change; swift-format will
+/// use default values when loading older configurations that don't contain the new settings. This
+/// value only needs to be updated if the configuration changes in a way that would be incompatible
+/// with the previous format.
+internal let highestSupportedConfigurationVersion = 1
 
 /// Holds the complete set of configured values and defaults.
 public struct Configuration: Codable, Equatable {
@@ -39,30 +44,36 @@ public struct Configuration: Codable, Equatable {
     case noAssignmentInExpressions
   }
 
+  /// A dictionary containing the default enabled/disabled states of rules, keyed by the rules'
+  /// names.
+  ///
+  /// This value is generated by `generate-pipeline` based on the `isOptIn` value of each rule.
+  public static let defaultRuleEnablements: [String: Bool] = RuleRegistry.rules
+
   /// The version of this configuration.
-  private let version: Int
+  private var version: Int = highestSupportedConfigurationVersion
 
   /// MARK: Common configuration
 
   /// The dictionary containing the rule names that we wish to run on. A rule is not used if it is
   /// marked as `false`, or if it is missing from the dictionary.
-  public var rules: [String: Bool] = RuleRegistry.rules
+  public var rules: [String: Bool]
 
   /// The maximum number of consecutive blank lines that may appear in a file.
-  public var maximumBlankLines = 1
+  public var maximumBlankLines: Int
 
   /// The maximum length of a line of source code, after which the formatter will break lines.
-  public var lineLength = 100
+  public var lineLength: Int
 
   /// The width of the horizontal tab in spaces.
   ///
   /// This value is used when converting indentation types (for example, from tabs into spaces).
-  public var tabWidth = 8
+  public var tabWidth: Int
 
   /// A value representing a single level of indentation.
   ///
   /// All indentation will be conducted in multiples of this configuration.
-  public var indentation: Indent = .spaces(2)
+  public var indentation: Indent
 
   /// Indicates that the formatter should try to respect users' discretionary line breaks when
   /// possible.
@@ -71,7 +82,7 @@ public struct Configuration: Codable, Equatable {
   /// line, but for readability the user might break it inside the curly braces. If this setting is
   /// true, those line breaks will be kept. If this setting is false, the formatter will act more
   /// "opinionated" and collapse the statement onto a single line.
-  public var respectsExistingLineBreaks = true
+  public var respectsExistingLineBreaks: Bool
 
   /// MARK: Rule-specific configuration
 
@@ -81,23 +92,23 @@ public struct Configuration: Codable, Equatable {
   /// If true, a line break will be added before the keyword, forcing it onto its own line. If
   /// false (the default), the keyword will be placed after the closing brace (separated by a
   /// space).
-  public var lineBreakBeforeControlFlowKeywords = false
+  public var lineBreakBeforeControlFlowKeywords: Bool
 
   /// Determines the line-breaking behavior for generic arguments and function arguments when a
   /// declaration is wrapped onto multiple lines.
   ///
   /// If false (the default), arguments will be laid out horizontally first, with line breaks only
   /// being fired when the line length would be exceeded. If true, a line break will be added before
   /// each argument, forcing the entire argument list to be laid out vertically.
-  public var lineBreakBeforeEachArgument = false
+  public var lineBreakBeforeEachArgument: Bool
 
   /// Determines the line-breaking behavior for generic requirements when the requirements list
   /// is wrapped onto multiple lines.
   ///
   /// If true, a line break will be added before each requirement, forcing the entire requirements
   /// list to be laid out vertically. If false (the default), requirements will be laid out
   /// horizontally first, with line breaks only being fired when the line length would be exceeded.
-  public var lineBreakBeforeEachGenericRequirement = false
+  public var lineBreakBeforeEachGenericRequirement: Bool
 
   /// Determines if function-like declaration outputs should be prioritized to be together with the
   /// function signature right (closing) parenthesis.
@@ -107,21 +118,21 @@ public struct Configuration: Codable, Equatable {
   /// a line break will be fired after the function signature first, indenting the declaration output
   /// one additional level. If true, A line break will be fired further up in the function's
   /// declaration (e.g. generic parameters, parameters) before breaking on the function's output.
-  public var prioritizeKeepingFunctionOutputTogether = false
+  public var prioritizeKeepingFunctionOutputTogether: Bool
 
   /// Determines the indentation behavior for `#if`, `#elseif`, and `#else`.
-  public var indentConditionalCompilationBlocks = true
+  public var indentConditionalCompilationBlocks: Bool
 
   /// Determines whether line breaks should be forced before and after multiline components of
   /// dot-chained expressions, such as function calls and subscripts chained together through member
   /// access (i.e. "." expressions). When any component is multiline and this option is true, a line
   /// break is forced before the "." of the component and after the component's closing delimiter
   /// (i.e. right paren, right bracket, right brace, etc.).
-  public var lineBreakAroundMultilineExpressionChainComponents = false
+  public var lineBreakAroundMultilineExpressionChainComponents: Bool
 
   /// Determines the formal access level (i.e., the level specified in source code) for file-scoped
   /// declarations whose effective access level is private to the containing file.
-  public var fileScopedDeclarationPrivacy = FileScopedDeclarationPrivacyConfiguration()
+  public var fileScopedDeclarationPrivacy: FileScopedDeclarationPrivacyConfiguration
 
   /// Determines if `case` statements should be indented compared to the containing `switch` block.
   ///
@@ -142,19 +153,14 @@ public struct Configuration: Codable, Equatable {
   ///   ...
   /// }
   ///```
-  public var indentSwitchCaseLabels = false
+  public var indentSwitchCaseLabels: Bool
 
   /// Determines whether whitespace should be forced before and after the range formation operators
   /// `...` and `..<`.
-  public var spacesAroundRangeFormationOperators = false
+  public var spacesAroundRangeFormationOperators: Bool
 
   /// Contains exceptions for the `NoAssignmentInExpressions` rule.
-  public var noAssignmentInExpressions = NoAssignmentInExpressionsConfiguration()
-
-  /// Constructs a Configuration with all default values.
-  public init() {
-    self.version = highestSupportedConfigurationVersion
-  }
+  public var noAssignmentInExpressions: NoAssignmentInExpressionsConfiguration
 
   /// Constructs a Configuration by loading it from a configuration file.
   public init(contentsOf url: URL) throws {
@@ -165,11 +171,6 @@ public struct Configuration: Codable, Equatable {
   public init(from decoder: Decoder) throws {
     let container = try decoder.container(keyedBy: CodingKeys.self)
 
-    // Unfortunately, to allow the user to leave out configuration options in the JSON, we would
-    // have to make them optional properties, but that makes using the type in the rest of the code
-    // more annoying because we'd have to unwrap everything. So, we override this initializer and
-    // provide the defaults ourselves if needed.
-
     // If the version number is not present, assume it is 1.
     self.version = try container.decodeIfPresent(Int.self, forKey: .version) ?? 1
     guard version <= highestSupportedConfigurationVersion else {
@@ -182,47 +183,70 @@ public struct Configuration: Codable, Equatable {
     // If we ever introduce a new version, this is where we should switch on the decoded version
     // number and dispatch to different decoding methods.
 
-    self.maximumBlankLines
-      = try container.decodeIfPresent(Int.self, forKey: .maximumBlankLines) ?? 1
-    self.lineLength = try container.decodeIfPresent(Int.self, forKey: .lineLength) ?? 100
-    self.tabWidth = try container.decodeIfPresent(Int.self, forKey: .tabWidth) ?? 8
-    self.indentation
-      = try container.decodeIfPresent(Indent.self, forKey: .indentation) ?? .spaces(2)
-    self.respectsExistingLineBreaks
-      = try container.decodeIfPresent(Bool.self, forKey: .respectsExistingLineBreaks) ?? true
-    self.lineBreakBeforeControlFlowKeywords
-      = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeControlFlowKeywords) ?? false
-    self.lineBreakBeforeEachArgument
-      = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachArgument) ?? false
-    self.lineBreakBeforeEachGenericRequirement
-      = try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachGenericRequirement) ?? false
-    self.prioritizeKeepingFunctionOutputTogether
-      = try container.decodeIfPresent(Bool.self, forKey: .prioritizeKeepingFunctionOutputTogether) ?? false
-    self.indentConditionalCompilationBlocks
-      = try container.decodeIfPresent(Bool.self, forKey: .indentConditionalCompilationBlocks) ?? true
+    // Unfortunately, to allow the user to leave out configuration options in the JSON, we would
+    // have to make them optional properties, but that makes using the type in the rest of the code
+    // more annoying because we'd have to unwrap everything. So, we override this initializer and
+    // provide the defaults ourselves if needed. We get those defaults by pulling them from a
+    // default-initialized instance.
+    let defaults = Configuration()
+
+    self.maximumBlankLines =
+      try container.decodeIfPresent(Int.self, forKey: .maximumBlankLines)
+      ?? defaults.maximumBlankLines
+    self.lineLength =
+      try container.decodeIfPresent(Int.self, forKey: .lineLength)
+      ?? defaults.lineLength
+    self.tabWidth =
+      try container.decodeIfPresent(Int.self, forKey: .tabWidth)
+      ?? defaults.tabWidth
+    self.indentation =
+      try container.decodeIfPresent(Indent.self, forKey: .indentation)
+      ?? defaults.indentation
+    self.respectsExistingLineBreaks =
+      try container.decodeIfPresent(Bool.self, forKey: .respectsExistingLineBreaks)
+      ?? defaults.respectsExistingLineBreaks
+    self.lineBreakBeforeControlFlowKeywords =
+      try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeControlFlowKeywords)
+      ?? defaults.lineBreakBeforeControlFlowKeywords
+    self.lineBreakBeforeEachArgument =
+      try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachArgument)
+      ?? defaults.lineBreakBeforeEachArgument
+    self.lineBreakBeforeEachGenericRequirement =
+      try container.decodeIfPresent(Bool.self, forKey: .lineBreakBeforeEachGenericRequirement)
+      ?? defaults.lineBreakBeforeEachGenericRequirement
+    self.prioritizeKeepingFunctionOutputTogether =
+      try container.decodeIfPresent(Bool.self, forKey: .prioritizeKeepingFunctionOutputTogether)
+      ?? defaults.prioritizeKeepingFunctionOutputTogether
+    self.indentConditionalCompilationBlocks =
+      try container.decodeIfPresent(Bool.self, forKey: .indentConditionalCompilationBlocks)
+    ?? defaults.indentConditionalCompilationBlocks
     self.lineBreakAroundMultilineExpressionChainComponents =
       try container.decodeIfPresent(
-        Bool.self, forKey: .lineBreakAroundMultilineExpressionChainComponents) ?? false
+        Bool.self, forKey: .lineBreakAroundMultilineExpressionChainComponents)
+      ?? defaults.lineBreakAroundMultilineExpressionChainComponents
     self.spacesAroundRangeFormationOperators =
       try container.decodeIfPresent(
-        Bool.self, forKey: .spacesAroundRangeFormationOperators) ?? false
+        Bool.self, forKey: .spacesAroundRangeFormationOperators)
+      ?? defaults.spacesAroundRangeFormationOperators
     self.fileScopedDeclarationPrivacy =
       try container.decodeIfPresent(
         FileScopedDeclarationPrivacyConfiguration.self, forKey: .fileScopedDeclarationPrivacy)
-      ?? FileScopedDeclarationPrivacyConfiguration()
-    self.indentSwitchCaseLabels
-      = try container.decodeIfPresent(Bool.self, forKey: .indentSwitchCaseLabels) ?? false
+      ?? defaults.fileScopedDeclarationPrivacy
+    self.indentSwitchCaseLabels =
+      try container.decodeIfPresent(Bool.self, forKey: .indentSwitchCaseLabels)
+    ?? defaults.indentSwitchCaseLabels
     self.noAssignmentInExpressions =
       try container.decodeIfPresent(
         NoAssignmentInExpressionsConfiguration.self, forKey: .noAssignmentInExpressions)
-      ?? NoAssignmentInExpressionsConfiguration()
+      ?? defaults.noAssignmentInExpressions
 
     // 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
     // default-initialized. To get an empty rules dictionary, one can explicitly
     // set the `rules` key to `{}`.
-    self.rules
-      = try container.decodeIfPresent([String: Bool].self, forKey: .rules) ?? RuleRegistry.rules
+    self.rules =
+      try container.decodeIfPresent([String: Bool].self, forKey: .rules)
+      ?? defaults.rules
   }
 
   public func encode(to encoder: Encoder) throws {
@@ -295,6 +319,8 @@ public struct FileScopedDeclarationPrivacyConfiguration: Codable, Equatable {
   /// The formal access level to use when encountering a file-scoped declaration with effective
   /// private access.
   public var accessLevel: AccessLevel = .private
+
+  public init() {}
 }
 
 /// Configuration for the `NoAssignmentInExpressions` rule.
@@ -307,4 +333,6 @@ public struct NoAssignmentInExpressionsConfiguration: Codable, Equatable {
     // in the test.
     "XCTAssertNoThrow"
   ]
+
+  public init() {}
 }

Sources/SwiftFormatTestSupport/Configuration+Testing.swift

@@ -0,0 +1,45 @@
+//===----------------------------------------------------------------------===//
+//
+// This source file is part of the Swift.org open source project
+//
+// Copyright (c) 2014 - 2023 Apple Inc. and the Swift project authors
+// Licensed under Apache License v2.0 with Runtime Library Exception
+//
+// See https://swift.org/LICENSE.txt for license information
+// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
+//
+//===----------------------------------------------------------------------===//
+
+import SwiftFormatConfiguration
+
+extension Configuration {
+  /// The default configuration to be used during unit tests.
+  ///
+  /// This configuration is separate from `Configuration.init()` so that that configuration can be
+  /// replaced without breaking tests that implicitly rely on it. Unfortunately, since this is in a
+  /// different module than where `Configuration` is defined, we can't make this an initializer that
+  /// would enforce that every field of `Configuration` is initialized here (we're forced to
+  /// delegate to another initializer first, which defeats the purpose). So, users adding new
+  /// configuration settings shouls be sure to supply a default here for testing, otherwise they
+  /// will be implicitly relying on the real default.
+  public static var forTesting: Configuration {
+    var config = Configuration()
+    config.rules = Configuration.defaultRuleEnablements
+    config.maximumBlankLines = 1
+    config.lineLength = 100
+    config.tabWidth = 8
+    config.indentation = .spaces(2)
+    config.respectsExistingLineBreaks = true
+    config.lineBreakBeforeControlFlowKeywords = false
+    config.lineBreakBeforeEachArgument = false
+    config.lineBreakBeforeEachGenericRequirement = false
+    config.prioritizeKeepingFunctionOutputTogether = false
+    config.indentConditionalCompilationBlocks = true
+    config.lineBreakAroundMultilineExpressionChainComponents = false
+    config.fileScopedDeclarationPrivacy = FileScopedDeclarationPrivacyConfiguration()
+    config.indentSwitchCaseLabels = false
+    config.spacesAroundRangeFormationOperators = false
+    config.noAssignmentInExpressions = NoAssignmentInExpressionsConfiguration()
+    return config
+  }
+}

Tests/SwiftFormatPrettyPrintTests/AssignmentExprTests.swift

@@ -84,7 +84,7 @@ final class AssignmentExprTests: PrettyPrintTestCase {
 
         """
 
-      var config = Configuration()
+      var config = Configuration.forTesting
       config.lineBreakBeforeEachArgument = false
       assertPrettyPrintEqual(
         input: input, expected: expectedWithArgBinPacking, linelength: 35, configuration: config)
@@ -166,7 +166,7 @@ final class AssignmentExprTests: PrettyPrintTestCase {
 
       """
 
-    var config = Configuration()
+    var config = Configuration.forTesting
     config.lineBreakBeforeEachArgument = false
     assertPrettyPrintEqual(
       input: input, expected: expectedWithArgBinPacking, linelength: 35, configuration: config)