Add LibraryContentProvider to file_types_order rule (realm#4209)

CHANGELOG.md

@@ -60,6 +60,10 @@
 * Include the configured `bind_identifier` in `self_binding` violation
   messages.  
   [JP Simard](https://github.com/jpims)
+
+* Add `library_content_provider` file type to `file_types_order` rule 
+  to allow `LibraryContentProvider` to be ordered independent from `main_type`.  
+  [dahlborn](https://github.com/dahlborn)
 
 #### Bug Fixes
 

Source/SwiftLintFramework/Rules/RuleConfigurations/FileTypesOrderConfiguration.swift

@@ -3,6 +3,7 @@ enum FileType: String {
     case mainType = "main_type"
     case `extension` = "extension"
     case previewProvider = "preview_provider"
+    case libraryContentProvider = "library_content_provider"
 }
 
 public struct FileTypesOrderConfiguration: RuleConfiguration, Equatable {
@@ -11,7 +12,8 @@ public struct FileTypesOrderConfiguration: RuleConfiguration, Equatable {
         [.supportingType],
         [.mainType],
         [.extension],
-        [.previewProvider]
+        [.previewProvider],
+        [.libraryContentProvider]
     ]
 
     public var consoleDescription: String {

Source/SwiftLintFramework/Rules/Style/FileTypesOrderRule.swift

@@ -20,7 +20,7 @@ public struct FileTypesOrderRule: ConfigurationProviderRule, OptInRule {
     // swiftlint:disable:next function_body_length
     public func validate(file: SwiftLintFile) -> [StyleViolation] {
         guard let mainTypeSubstructure = mainTypeSubstructure(in: file),
-            let mainTypeSubstuctureOffset = mainTypeSubstructure.offset else { return [] }
+              let mainTypeSubstuctureOffset = mainTypeSubstructure.offset else { return [] }
 
         let extensionsSubstructures = self.extensionsSubstructures(
             in: file,
@@ -32,25 +32,28 @@ public struct FileTypesOrderRule: ConfigurationProviderRule, OptInRule {
             mainTypeSubstructure: mainTypeSubstructure
         )
 
-        let previewProviderSubstructures = self.previewProviderSubstructures(in: file)
+        let previewProviderSubstructures = self.substructures(
+            in: file,
+            withInheritedType: "PreviewProvider"
+        )
 
-        let mainTypeOffset: [FileTypeOffset] = [(.mainType, mainTypeSubstuctureOffset)]
-        let extensionOffsets: [FileTypeOffset] = extensionsSubstructures.compactMap { substructure in
-            guard let offset = substructure.offset else { return nil }
-            return (.extension, offset)
-        }
+        let libraryContentSubstructures = self.substructures(
+            in: file,
+            withInheritedType: "LibraryContentProvider"
+        )
 
-        let supportingTypeOffsets: [FileTypeOffset] = supportingTypesSubstructures.compactMap { substructure in
-            guard let offset = substructure.offset else { return nil }
-            return (.supportingType, offset)
-        }
+        let mainTypeOffset: [FileTypeOffset] = [(.mainType, mainTypeSubstuctureOffset)]
+        let extensionOffsets: [FileTypeOffset] = extensionsSubstructures.offsets(for: .extension)
+        let supportingTypeOffsets: [FileTypeOffset] = supportingTypesSubstructures.offsets(for: .supportingType)
+        let previewProviderOffsets: [FileTypeOffset] = previewProviderSubstructures.offsets(for: .previewProvider)
+        let libraryContentOffsets: [FileTypeOffset] = libraryContentSubstructures.offsets(for: .libraryContentProvider)
 
-        let previewProviderOffsets: [FileTypeOffset] = previewProviderSubstructures.compactMap { substructure in
-            guard let offset = substructure.offset else { return nil }
-            return (.previewProvider, offset)
-        }
+        let allOffsets = mainTypeOffset
+            + extensionOffsets
+            + supportingTypeOffsets
+            + previewProviderOffsets
+            + libraryContentOffsets
 
-        let allOffsets = mainTypeOffset + extensionOffsets + supportingTypeOffsets + previewProviderOffsets
         let orderedFileTypeOffsets = allOffsets.sorted { lhs, rhs in lhs.offset < rhs.offset }
 
         var violations = [StyleViolation]()
@@ -97,8 +100,8 @@ public struct FileTypesOrderRule: ConfigurationProviderRule, OptInRule {
         let dict = file.structureDictionary
         return dict.substructure.filter { substructure in
             guard let kind = substructure.kind else { return false }
-            return substructure.offset != mainTypeSubstructure.offset &&
-                kind.contains(SwiftDeclarationKind.extension.rawValue)
+            return substructure.offset != mainTypeSubstructure.offset
+                && kind.contains(SwiftDeclarationKind.extension.rawValue)
         }
     }
 
@@ -112,16 +115,19 @@ public struct FileTypesOrderRule: ConfigurationProviderRule, OptInRule {
         let dict = file.structureDictionary
         return dict.substructure.filter { substructure in
             guard let declarationKind = substructure.declarationKind else { return false }
-            guard !substructure.inheritedTypes.contains("PreviewProvider") else { return false }
+            guard !substructure.hasExcludedInheritedType else { return false }
 
-            return substructure.offset != mainTypeSubstructure.offset &&
-                supportingTypeKinds.contains(declarationKind)
+            return substructure.offset != mainTypeSubstructure.offset
+                && supportingTypeKinds.contains(declarationKind)
         }
     }
 
-    private func previewProviderSubstructures(in file: SwiftLintFile) -> [SourceKittenDictionary] {
-        return file.structureDictionary.substructure.filter { substructure in
-            return substructure.inheritedTypes.contains("PreviewProvider")
+    private func substructures(
+        in file: SwiftLintFile,
+        withInheritedType inheritedType: String
+    ) -> [SourceKittenDictionary] {
+        file.structureDictionary.substructure.filter { substructure in
+            substructure.inheritedTypes.contains(inheritedType)
         }
     }
 
@@ -147,16 +153,33 @@ public struct FileTypesOrderRule: ConfigurationProviderRule, OptInRule {
 
         let priorityKindSubstructures = dict.substructure.filter { substructure in
             guard let kind = substructure.declarationKind else { return false }
-            guard !substructure.inheritedTypes.contains("PreviewProvider") else { return false }
+            guard !substructure.hasExcludedInheritedType else { return false }
 
             return priorityKinds.contains(kind)
         }
 
         let substructuresSortedByBodyLength = priorityKindSubstructures.sorted { lhs, rhs in
-            return (lhs.bodyLength ?? 0) > (rhs.bodyLength ?? 0)
+            (lhs.bodyLength ?? 0) > (rhs.bodyLength ?? 0)
         }
 
         // specify class, enum or struct with longest body as main type
         return substructuresSortedByBodyLength.first
     }
 }
+
+private extension SourceKittenDictionary {
+    var hasExcludedInheritedType: Bool {
+        self.inheritedTypes.contains { inheritedType in
+            inheritedType == "PreviewProvider" || inheritedType == "LibraryContentProvider"
+        }
+    }
+}
+
+private extension Array where Element == SourceKittenDictionary {
+    func offsets(for fileType: FileType) -> [(fileType: FileType, offset: ByteCount)] {
+        self.compactMap { substructure in
+            guard let offset = substructure.offset else { return nil }
+            return (fileType, offset)
+        }
+    }
+}

Source/SwiftLintFramework/Rules/Style/FileTypesOrderRuleExamples.swift

@@ -1,3 +1,4 @@
+// swiftlint:disable:next type_body_length
 internal struct FileTypesOrderRuleExamples {
     static let defaultOrderParts = [
         """
@@ -120,15 +121,24 @@ internal struct FileTypesOrderRuleExamples {
         }
         """),
         Example("""
+        // Main Type
         struct ContentView: View {
             var body: some View {
                 Text("Hello, World!")
             }
         }
 
+        // Preview Provider
         struct ContentView_Previews: PreviewProvider {
             static var previews: some View { ContentView() }
         }
+
+        // Library Content Provider
+        struct ContentView_LibraryContent: LibraryContentProvider {
+            var views: [LibraryItem] {
+                LibraryItem(ContentView())
+            }
+        }
         """)
     ]
 
@@ -188,10 +198,31 @@ internal struct FileTypesOrderRuleExamples {
         """),
         Example("""
         // Preview Provider
-        ↓struct ContentView_Previews: PreviewProvider {}
+        ↓struct ContentView_Previews: PreviewProvider {
+            static var previews: some View { ContentView() }
+        }
 
         // Main Type
-        struct ContentView: View {}
+        struct ContentView: View {
+            var body: some View {
+                Text("Hello, World!")
+            }
+        }
+        """),
+        Example("""
+        // Library Content Provider
+        ↓struct ContentView_LibraryContent: LibraryContentProvider {
+            var views: [LibraryItem] {
+                LibraryItem(ContentView())
+            }
+        }
+
+        // Main Type
+        struct ContentView: View {
+            var body: some View {
+                Text("Hello, World!")
+            }
+        }
         """)
     ]
 }

Tests/SwiftLintFrameworkTests/FileTypesOrderRuleTests.swift

@@ -55,6 +55,19 @@ class FileTypesOrderRuleTests: XCTestCase {
             struct ContentView_Previews: PreviewProvider {
                static var previews: some View { ContentView() }
             }
+            """),
+            Example("""
+            ↓struct ContentView: View {
+               var body: some View {
+                   Text("Hello, World!")
+               }
+            }
+
+            struct ContentView_LibraryContent: LibraryContentProvider {
+                var views: [LibraryItem] {
+                    LibraryItem(ContentView())
+                }
+            }
             """)
         ]
 
@@ -65,7 +78,7 @@ class FileTypesOrderRuleTests: XCTestCase {
         verifyRule(
             reversedOrderDescription,
             ruleConfiguration: [
-                "order": ["preview_provider", "extension", "main_type", "supporting_type"]
+                "order": ["library_content_provider", "preview_provider", "extension", "main_type", "supporting_type"]
             ]
         )
     }