Command Line Options for Interacting with the Configuration Merging Process

CHANGELOG.md

@@ -8,6 +8,11 @@
   [JP Simard](https://github.com/jpsim)
   [#676](https://github.com/realm/SwiftLint/issues/676)
 
+  * Several command line options allow interaction with the merging process.
+    (See `swiftlint help lint`.)  
+    [Jeremy David Giesbrecht](https://github.com/SDGGiesbrecht)
+    [##1693](https://github.com/realm/SwiftLint/issues/1693)
+
 ##### Enhancements
 
 * Add `xctfail_message` rule to enforce XCTFail

Source/SwiftLintFramework/Extensions/Configuration+Merging.swift

@@ -18,29 +18,57 @@ extension Configuration {
     }
 
     private func configuration(forPath path: String) -> Configuration {
-        if path == rootPath {
+        if ignoreNested {
+            if let commandLineDefaults = defaults?.value {
+                // --config-defaults is lowest in the tree
+                return commandLineDefaults
+            } else {
+                // when no --config-defaults, the root directory is lowest in the tree
+                return self
+            }
+        }
+
+        var merged = mergeConfigurationFiles(upTo: path)
+        if let commandLineDefaults = defaults?.value {
+            // add --config-defaults underneath
+            merged = commandLineDefaults.merge(with: merged)
+        }
+        if let commandLineOverrides = overrides?.value {
+            // add --config-overrides on top
+            merged = merged.merge(with: commandLineOverrides)
+        }
+        return merged
+    }
+
+    private func mergeConfigurationFiles(upTo path: String) -> Configuration {
+        if path == rootPath || path == "/" {
             return self
         }
 
         let pathNSString = path.bridge()
         let configurationSearchPath = pathNSString.appendingPathComponent(Configuration.fileName)
+        if configurationSearchPath == configurationPath {
+            // We are the configuration, no need to read from the disk again, just return self
+            return self
+        }
+
+        // We are not at the root path, so get the parent configuration
+        let parent = mergeConfigurationFiles(upTo: path.bridge().deletingLastPathComponent)
 
-        // If a configuration exists and it isn't us, load and merge the configurations
+        // If a configuration exists, load it
         if configurationSearchPath != configurationPath &&
             FileManager.default.fileExists(atPath: configurationSearchPath) {
             let fullPath = pathNSString.absolutePathRepresentation()
             let config = Configuration.getCached(atPath: fullPath) ??
                 Configuration(path: configurationSearchPath, rootPath: fullPath, optional: false, quiet: true)
-            return merge(with: config)
-        }
 
-        // If we are not at the root path, continue down the tree
-        if path != rootPath && path != "/" {
-            return configuration(forPath: pathNSString.deletingLastPathComponent)
-        }
+            // merge the changes specified in this directory on top of the parent
+            return parent.merge(with: config)
 
-        // If nothing else, return self
-        return self
+        } else {
+            // no changes specified in this directory, so just return the parent
+            return parent
+        }
     }
 
     private struct HashableRule: Hashable {

Source/SwiftLintFramework/Models/Configuration.swift

@@ -27,6 +27,9 @@ public struct Configuration: Equatable {
     public var warningThreshold: Int?     // warning threshold
     public var rootPath: String?          // the root path to search for nested configurations
     public var configurationPath: String? // if successfully loaded from a path
+    public var defaults: Ref<Configuration>?  // --config-defaults
+    public var overrides: Ref<Configuration>? // --config-overrides
+    public var ignoreNested: Bool = false     // --ignore-nested-configs
     public let cachePath: String?
 
     // MARK: Rules Properties
@@ -136,8 +139,28 @@ public struct Configuration: Equatable {
         rootPath = configuration.rootPath
     }
 
-    public init(path: String = Configuration.fileName, rootPath: String? = nil,
-                optional: Bool = true, quiet: Bool = false, enableAllRules: Bool = false, cachePath: String? = nil) {
+    // swiftlint:disable:next function_body_length
+    public init(path: String = Configuration.fileName, rootPath: String? = nil, optional: Bool = true,
+                defaults: String? = nil, overrides: String? = nil, ignoreNested: Bool = false,
+                quiet: Bool = false, enableAllRules: Bool = false, cachePath: String? = nil) {
+
+        defer {
+            if let defaultsPath = defaults {
+                // The defaults must inherit all but the path
+                // (i.e. quiet, enableAllRules & cachePath)
+                // because the root will not be merged into the defaults
+                // if merging is prevented by --ignore-nested-configs.
+                self.defaults = Ref(Configuration(path: defaultsPath, optional: false,
+                                                  overrides: overrides, ignoreNested: ignoreNested,
+                                                  quiet: quiet, enableAllRules: enableAllRules,
+                                                  cachePath: cachePath))
+            }
+            if let overridesPath = overrides {
+                self.overrides = Ref(Configuration(path: overridesPath, optional: false))
+            }
+            self.ignoreNested = ignoreNested
+        }
+
         let fullPath: String
         if let rootPath = rootPath, rootPath.isDirectory() {
             fullPath = path.bridge().absolutePathRepresentation(rootDirectory: rootPath)
@@ -190,7 +213,8 @@ public struct Configuration: Equatable {
             (lhs.reporter == rhs.reporter) &&
             (lhs.configurationPath == rhs.configurationPath) &&
             (lhs.rootPath == lhs.rootPath) &&
-            (lhs.rules == rhs.rules)
+            (lhs.rules.sorted(by: { String(describing: $0) < String(describing: $1) })
+                == rhs.rules.sorted(by: { String(describing: $0) < String(describing: $1) }))
     }
 }
 
@@ -242,3 +266,13 @@ private extension String {
         return false
     }
 }
+
+public class Ref<T> {
+    // Indirection to allow one configuration to store another as a property
+
+    public let value: T
+
+    public init(_ value: T) {
+        self.value = value
+    }
+}

Source/swiftlint/Commands/AutoCorrectCommand.swift

@@ -45,6 +45,9 @@ struct AutoCorrectCommand: CommandProtocol {
 struct AutoCorrectOptions: OptionsProtocol {
     let path: String
     let configurationFile: String
+    let configurationDefaults: String?
+    let configurationOverrides: String?
+    let ignoreNestedConfigurations: Bool
     let useScriptInputFiles: Bool
     let quiet: Bool
     let format: Bool
@@ -53,17 +56,20 @@ struct AutoCorrectOptions: OptionsProtocol {
     let useTabs: Bool
 
     // swiftlint:disable line_length
-    static func create(_ path: String) -> (_ configurationFile: String) -> (_ useScriptInputFiles: Bool) -> (_ quiet: Bool) -> (_ format: Bool) -> (_ cachePath: String) -> (_ ignoreCache: Bool) -> (_ useTabs: Bool) -> AutoCorrectOptions {
-        return { configurationFile in { useScriptInputFiles in { quiet in { format in { cachePath in { ignoreCache in { useTabs in
-            self.init(path: path, configurationFile: configurationFile, useScriptInputFiles: useScriptInputFiles, quiet: quiet, format: format, cachePath: cachePath, ignoreCache: ignoreCache, useTabs: useTabs)
-        }}}}}}}
+    static func create(_ path: String) -> (_ configurationFile: String) -> (_ configurationDefaults: String?) -> (_ configurationOverrides: String?) -> (_ ignoreNestedConfigurations: Bool) -> (_ useScriptInputFiles: Bool) -> (_ quiet: Bool) -> (_ format: Bool) -> (_ cachePath: String) -> (_ ignoreCache: Bool) -> (_ useTabs: Bool) -> AutoCorrectOptions {
+        return { configurationFile in { configurationDefaults in { configurationOverrides in { ignoreNestedConfigurations in { useScriptInputFiles in { quiet in { format in { cachePath in { ignoreCache in { useTabs in
+            self.init(path: path, configurationFile: configurationFile, configurationDefaults: configurationDefaults, configurationOverrides: configurationOverrides, ignoreNestedConfigurations: ignoreNestedConfigurations, useScriptInputFiles: useScriptInputFiles, quiet: quiet, format: format, cachePath: cachePath, ignoreCache: ignoreCache, useTabs: useTabs)
+        }}}}}}}}}}
     }
 
     static func evaluate(_ mode: CommandMode) -> Result<AutoCorrectOptions, CommandantError<CommandantError<()>>> {
         // swiftlint:enable line_length
         return create
             <*> mode <| pathOption(action: "correct")
             <*> mode <| configOption
+            <*> mode <| configDefaultsOption
+            <*> mode <| configOverridesOption
+            <*> mode <| ignoreNestedConfigsOption
             <*> mode <| useScriptInputFilesOption
             <*> mode <| quietOption(action: "correcting")
             <*> mode <| Option(key: "format",

Source/swiftlint/Commands/LintCommand.swift

@@ -128,6 +128,9 @@ struct LintOptions: OptionsProtocol {
     let path: String
     let useSTDIN: Bool
     let configurationFile: String
+    let configurationDefaults: String?
+    let configurationOverrides: String?
+    let ignoreNestedConfigurations: Bool
     let strict: Bool
     let lenient: Bool
     let useScriptInputFiles: Bool
@@ -139,10 +142,10 @@ struct LintOptions: OptionsProtocol {
     let enableAllRules: Bool
 
     // swiftlint:disable line_length
-    static func create(_ path: String) -> (_ useSTDIN: Bool) -> (_ configurationFile: String) -> (_ strict: Bool) -> (_ lenient: Bool) -> (_ useScriptInputFiles: Bool) -> (_ benchmark: Bool) -> (_ reporter: String) -> (_ quiet: Bool) -> (_ cachePath: String) -> (_ ignoreCache: Bool) -> (_ enableAllRules: Bool) -> LintOptions {
-        return { useSTDIN in { configurationFile in { strict in { lenient in { useScriptInputFiles in { benchmark in { reporter in { quiet in { cachePath in { ignoreCache in { enableAllRules in
-            self.init(path: path, useSTDIN: useSTDIN, configurationFile: configurationFile, strict: strict, lenient: lenient, useScriptInputFiles: useScriptInputFiles, benchmark: benchmark, reporter: reporter, quiet: quiet, cachePath: cachePath, ignoreCache: ignoreCache, enableAllRules: enableAllRules)
-        }}}}}}}}}}}
+    static func create(_ path: String) -> (_ useSTDIN: Bool) -> (_ configurationFile: String) -> (_ configurationDefaults: String?) -> (_ configurationOverrides: String?) -> (_ ignoreNestedConfigurations: Bool) -> (_ strict: Bool) -> (_ lenient: Bool) -> (_ useScriptInputFiles: Bool) -> (_ benchmark: Bool) -> (_ reporter: String) -> (_ quiet: Bool) -> (_ cachePath: String) -> (_ ignoreCache: Bool) -> (_ enableAllRules: Bool) -> LintOptions {
+        return { useSTDIN in { configurationFile in { configurationDefaults in { configurationOverrides in { ignoreNestedConfigurations in { strict in { lenient in { useScriptInputFiles in { benchmark in { reporter in { quiet in { cachePath in { ignoreCache in { enableAllRules in
+            self.init(path: path, useSTDIN: useSTDIN, configurationFile: configurationFile, configurationDefaults: configurationDefaults, configurationOverrides: configurationOverrides, ignoreNestedConfigurations: ignoreNestedConfigurations, strict: strict, lenient: lenient, useScriptInputFiles: useScriptInputFiles, benchmark: benchmark, reporter: reporter, quiet: quiet, cachePath: cachePath, ignoreCache: ignoreCache, enableAllRules: enableAllRules)
+        }}}}}}}}}}}}}}
     }
 
     static func evaluate(_ mode: CommandMode) -> Result<LintOptions, CommandantError<CommandantError<()>>> {
@@ -152,6 +155,9 @@ struct LintOptions: OptionsProtocol {
             <*> mode <| Option(key: "use-stdin", defaultValue: false,
                                usage: "lint standard input")
             <*> mode <| configOption
+            <*> mode <| configDefaultsOption
+            <*> mode <| configOverridesOption
+            <*> mode <| ignoreNestedConfigsOption
             <*> mode <| Option(key: "strict", defaultValue: false,
                                usage: "fail on warnings")
             <*> mode <| Option(key: "lenient", defaultValue: false,

Source/swiftlint/Commands/RulesCommand.swift

@@ -78,22 +78,28 @@ struct RulesCommand: CommandProtocol {
 struct RulesOptions: OptionsProtocol {
     fileprivate let ruleID: String?
     let configurationFile: String
+    let configurationDefaults: String?
+    let configurationOverrides: String?
     fileprivate let onlyEnabledRules: Bool
     fileprivate let onlyDisabledRules: Bool
 
     // swiftlint:disable line_length
-    static func create(_ configurationFile: String) -> (_ ruleID: String) -> (_ onlyEnabledRules: Bool) -> (_ onlyDisabledRules: Bool) -> RulesOptions {
-        return { ruleID in { onlyEnabledRules in { onlyDisabledRules in
+    static func create(_ configurationFile: String) -> (_ configurationDefaults: String?) -> (_ configurationOverrides: String?) -> (_ ruleID: String) -> (_ onlyEnabledRules: Bool) -> (_ onlyDisabledRules: Bool) -> RulesOptions {
+        return { configurationDefaults in { configurationOverrides in { ruleID in { onlyEnabledRules in { onlyDisabledRules in
             self.init(ruleID: (ruleID.isEmpty ? nil : ruleID),
                       configurationFile: configurationFile,
+                      configurationDefaults: configurationDefaults,
+                      configurationOverrides: configurationOverrides,
                       onlyEnabledRules: onlyEnabledRules,
                       onlyDisabledRules: onlyDisabledRules)
-        }}}
+        }}}}}
     }
 
     static func evaluate(_ mode: CommandMode) -> Result<RulesOptions, CommandantError<CommandantError<()>>> {
         return create
             <*> mode <| configOption
+            <*> mode <| configDefaultsOption
+            <*> mode <| configOverridesOption
             <*> mode <| Argument(defaultValue: "",
                                  usage: "the rule identifier to display description for")
             <*> mode <| Switch(flag: "e",

Source/swiftlint/Extensions/Configuration+CommandLine.swift

@@ -124,7 +124,9 @@ extension Configuration {
         let cachePath = options.cachePath.isEmpty ? nil : options.cachePath
         let optional = !CommandLine.arguments.contains("--config")
         self.init(path: options.configurationFile, rootPath: options.path.absolutePathStandardized(),
-                  optional: optional, quiet: options.quiet,
+                  optional: optional,
+                  defaults: options.configurationDefaults, overrides: options.configurationOverrides,
+                  ignoreNested: options.ignoreNestedConfigurations, quiet: options.quiet,
                   enableAllRules: options.enableAllRules, cachePath: cachePath)
     }
 
@@ -141,13 +143,17 @@ extension Configuration {
         let cachePath = options.cachePath.isEmpty ? nil : options.cachePath
         let optional = !CommandLine.arguments.contains("--config")
         self.init(path: options.configurationFile, rootPath: options.path.absolutePathStandardized(),
-                  optional: optional, quiet: options.quiet, cachePath: cachePath)
+                  optional: optional,
+                  defaults: options.configurationDefaults, overrides: options.configurationOverrides,
+                  ignoreNested: options.ignoreNestedConfigurations,
+                  quiet: options.quiet, cachePath: cachePath)
     }
 
     // MARK: Rules command
 
     init(options: RulesOptions) {
         let optional = !CommandLine.arguments.contains("--config")
-        self.init(path: options.configurationFile, optional: optional)
+        self.init(path: options.configurationFile, optional: optional,
+                  defaults: options.configurationDefaults, overrides: options.configurationOverrides)
     }
 }

Source/swiftlint/Helpers/CommonOptions.swift

@@ -19,6 +19,20 @@ let configOption = Option(key: "config",
                           defaultValue: Configuration.fileName,
                           usage: "the path to SwiftLint's configuration file")
 
+let configDefaultsOption = Option<String?>(key: "config-defaults",
+                                           defaultValue: nil,
+                                           usage: "the path of an external configuration file " +
+                                                  "to use as the root of the merge tree")
+
+let configOverridesOption = Option<String?>(key: "config-overrides",
+                                            defaultValue: nil,
+                                            usage: "the path of an external configuration file " +
+                                                   "to append to the end of each branch of the merge tree")
+
+let ignoreNestedConfigsOption = Option(key: "ignore-nested-configs",
+                                       defaultValue: false,
+                                       usage: "ignores nested configuration files")
+
 let useScriptInputFilesOption = Option(key: "use-script-input-files",
                                        defaultValue: false,
                                        usage: "read SCRIPT_INPUT_FILE* environment variables " +