Indentation style

CHANGELOG.md

@@ -283,6 +283,13 @@
 * Rewrite `control_statement` rule using SwiftSyntax. 
  [SimplyDanny](https://github.com/SimplyDanny)
 
+* Add rule `indentation_style`. Warns when tabs and spaces are mixed within the
+ same file and allows for setting your entire project to either tabs OR 
+ spaces. Also allows for spaces to finesse placement at the end of a tabbed 
+ indentation. 
+ [Michael Redig](https://github.com/mredig)
+ [PR 5144](https://github.com/realm/SwiftLint/pull/5144)
+
 * Add new `non_overridable_class_declaration` rule that triggers on `class`
  function and variable declarations in final classes that are not final
  themselves or private. 

Source/SwiftLintBuiltInRules/Models/BuiltInRules.swift

@@ -89,6 +89,7 @@ public let builtInRules: [any Rule.Type] = [
  ImplicitReturnRule.self,
  ImplicitlyUnwrappedOptionalRule.self,
  InclusiveLanguageRule.self,
+ IndentationStyleRule.self,
  IndentationWidthRule.self,
  InertDeferRule.self,
  InvalidSwiftLintCommandRule.self,

Source/SwiftLintBuiltInRules/Rules/RuleConfigurations/IndentationStyleConfiguration.swift

@@ -0,0 +1,60 @@
+import SwiftLintCore
+
+struct IndentationStyleConfiguration: SeverityBasedRuleConfiguration, Equatable {
+ typealias Parent = IndentationStyleRule
+
+ @ConfigurationElement(key: "severity")
+ private(set) var severityConfiguration = SeverityConfiguration<Parent>.warning
+ @ConfigurationElement(key: "include_multiline_strings")
+ private(set) var includeMultilineStrings = false
+ @ConfigurationElement(key: "include_multiline_comments")
+ private(set) var includeMultilineComments = true
+ @ConfigurationElement(key: "per_file")
+ private(set) var perFile = true
+ @ConfigurationElement(key: "preferred_style")
+ private(set) var preferredStyle = PreferredStyle.spaces
+ /// Checks to make sure that in tab mode indentation, any spaces are only at the end and are, at most, tabWidth-1
+ /// in quantity, if tabWidth is set.
+ @ConfigurationElement(key: "tab_width")
+ private(set) var tabWidth: Int?
+
+ static let testTabWidth: [String: any Sendable] = ["tab_width": 4]
+ static let testMultilineString: [String: any Sendable] = ["include_multiline_strings": true]
+ static let testMultilineComment: [String: any Sendable] = ["include_multiline_comments": false]
+
+ @MakeAcceptableByConfigurationElement
+ enum PreferredStyle: String {
+ case tabs
+ case spaces
+ }
+
+ mutating func apply(configuration: Any) throws {
+ guard let configurationDict = configuration as? [String: Any] else {
+ throw Issue.unknownConfiguration(ruleID: Parent.identifier)
+ }
+
+ if let config = configurationDict[$severityConfiguration.key] {
+ try severityConfiguration.apply(configuration: config)
+ }
+
+ if let perFile = configurationDict[$perFile.key] as? Bool {
+ self.perFile = perFile
+ }
+
+ if perFile == false {
+ if let preferredStyle = configurationDict[$preferredStyle.key] as? String {
+ self.preferredStyle = PreferredStyle(rawValue: preferredStyle) ?? .spaces
+ }
+ }
+
+ if let includeMultilineStrings = configurationDict[$includeMultilineStrings.key] as? Bool {
+ self.includeMultilineStrings = includeMultilineStrings
+ }
+
+ if let includeMultilineComments = configurationDict[$includeMultilineComments.key] as? Bool {
+ self.includeMultilineComments = includeMultilineComments
+ }
+
+ self.tabWidth = configurationDict[$tabWidth.key] as? Int
+ }
+}