Merge pull request #985 from realm/jp-correctable-void-return

make VoidReturnRule correctable

CHANGELOG.md

@@ -82,8 +82,10 @@
   [Aaron McTavish](https://github.com/aamctustwo)
   [#970](https://github.com/realm/SwiftLint/issues/970)
 
-* Add `void_return` rule to validate usage of `-> Void` over `-> ()`.  
+* Add correctable `void_return` rule to validate usage of `-> Void`
+  over `-> ()`.  
   [Marcelo Fabri](https://github.com/marcelofabri)
+  [JP Simard](https://github.com/jpsim)
   [#964](https://github.com/realm/SwiftLint/issues/964)
 
 * Add `empty_parameters` rule to validate usage of `() -> ` over `Void -> `.  

Source/SwiftLintFramework/Rules/VoidReturnRule.swift

@@ -9,7 +9,7 @@
 import Foundation
 import SourceKittenFramework
 
-public struct VoidReturnRule: Rule, ConfigurationProviderRule {
+public struct VoidReturnRule: ConfigurationProviderRule, CorrectableRule {
     public var configuration = SeverityConfiguration(.warning)
 
     public init() {}
@@ -31,26 +31,60 @@ public struct VoidReturnRule: Rule, ConfigurationProviderRule {
             "func foo(completion: () -> ↓())\n",
             "func foo(completion: () -> ↓(   ))\n",
             "let foo: (ConfigurationTests) -> () throws -> ↓())\n"
+        ],
+        corrections: [
+            "let abc: () -> () = {}\n": "let abc: () -> Void = {}\n",
+            "func foo(completion: () -> ())\n": "func foo(completion: () -> Void)\n",
+            "func foo(completion: () -> (   ))\n": "func foo(completion: () -> Void)\n",
+            "let foo: (ConfigurationTests) -> () throws -> ())\n":
+                "let foo: (ConfigurationTests) -> () throws -> Void)\n"
         ]
     )
 
     public func validateFile(_ file: File) -> [StyleViolation] {
+        return violationRanges(file: file).map {
+            StyleViolation(ruleDescription: type(of: self).description,
+                           severity: configuration.severity,
+                           location: Location(file: file, characterOffset: $0.location))
+        }
+    }
+
+    private func violationRanges(file: File) -> [NSRange] {
         let kinds = SyntaxKind.commentAndStringKinds()
-        let pattern = "->\\s*\\(\\s*\\)\\s*(?!->)"
+        let parensPattern = "\\(\\s*\\)"
+        let pattern = "->\\s*\(parensPattern)\\s*(?!->)"
         let excludingPattern = "(\(pattern))\\s*(throws\\s+)?->"
 
         return file.matchPattern(pattern, excludingSyntaxKinds: kinds,
                                  excludingPattern: excludingPattern) { $0.rangeAt(1) }.flatMap {
+            let parensRegex = NSRegularExpression.forcePattern(parensPattern)
+            return parensRegex.firstMatch(in: file.contents, options: [], range: $0)?.range
+        }
+    }
 
-            let range = file.contents.bridge().substring(with: $0).bridge().range(of: "(")
-            guard range.location != NSNotFound else {
-                return nil
+    public func correctFile(_ file: File) -> [Correction] {
+        let violatingRanges = file.ruleEnabledViolatingRanges(violationRanges(file: file),
+                                                              forRule: self)
+        return writeToFile(file, violatingRanges: violatingRanges)
+    }
+
+    private func writeToFile(_ file: File, violatingRanges: [NSRange]) -> [Correction] {
+        var correctedContents = file.contents
+        var adjustedLocations = [Int]()
+
+        for violatingRange in violatingRanges.reversed() {
+            if let indexRange = correctedContents.nsrangeToIndexRange(violatingRange) {
+                correctedContents = correctedContents
+                    .replacingCharacters(in: indexRange, with: "Void")
+                adjustedLocations.insert(violatingRange.location, at: 0)
             }
+        }
 
-            let offset = range.location + $0.location
-            return StyleViolation(ruleDescription: type(of: self).description,
-                                  severity: configuration.severity,
-                                  location: Location(file: file, characterOffset: offset))
+        file.write(correctedContents)
+
+        return adjustedLocations.map {
+            Correction(ruleDescription: type(of: self).description,
+                       location: Location(file: file, characterOffset: $0))
         }
     }
 }