Add multiple_closures_with_trailing_closure rule

CHANGELOG.md

@@ -72,6 +72,11 @@
   [Marcelo Fabri](https://github.com/marcelofabri)
   [#1803](https://github.com/realm/SwiftLint/issues/1803)
 
+* Add `multiple_closures_with_trailing_closure` rule that disallows trailing
+  closure syntax when passing more than one closure argument to a function.  
+  [Erik Strottmann](https://github.com/erikstrottmann)
+  [#1801](https://github.com/realm/SwiftLint/issues/1801)
+
 ##### Bug Fixes
 
 * Fix false positive on `force_unwrapping` rule when declaring

Rules.md

@@ -54,6 +54,7 @@
 * [Line Length](#line-length)
 * [Mark](#mark)
 * [Multiline Parameters](#multiline-parameters)
+* [Multiple Closures with Trailing Closure](#multiple-closures-with-trailing-closure)
 * [Nesting](#nesting)
 * [Nimble Operator](#nimble-operator)
 * [No Extension Access Modifier](#no-extension-access-modifier)
@@ -6522,6 +6523,67 @@ class Foo {
 
 
 
+## Multiple Closures with Trailing Closure
+
+Identifier | Enabled by default | Supports autocorrection | Kind 
+--- | --- | --- | ---
+`multiple_closures_with_trailing_closure` | Enabled | No | style
+
+Trailing closure syntax should not be used when passing more than one closure argument.
+
+### Examples
+
+<details>
+<summary>Non Triggering Examples</summary>
+
+```swift
+foo.map { $0 + 1 }
+
+```
+
+```swift
+foo.reduce(0) { $0 + $1 }
+
+```
+
+```swift
+if let foo = bar.map({ $0 + 1 }) {
+
+}
+
+```
+
+```swift
+foo.something(param1: { $0 }, param2: { $0 + 1 })
+
+```
+
+```swift
+UIView.animate(withDuration: 1.0) {
+    someView.alpha = 0.0
+}
+```
+
+</details>
+<details>
+<summary>Triggering Examples</summary>
+
+```swift
+foo.something(param1: { $0 }) ↓{ $0 + 1 }
+```
+
+```swift
+UIView.animate(withDuration: 1.0, animations: {
+    someView.alpha = 0.0
+}) ↓{ _ in
+    someView.removeFromSuperview()
+}
+```
+
+</details>
+
+
+
 ## Nesting
 
 Identifier | Enabled by default | Supports autocorrection | Kind 

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -62,6 +62,7 @@ public let masterRuleList = RuleList(rules: [
     LineLengthRule.self,
     MarkRule.self,
     MultilineParametersRule.self,
+    MultipleClosuresWithTrailingClosureRule.self,
     NestingRule.self,
     NimbleOperatorRule.self,
     NoExtensionAccessModifierRule.self,

Source/SwiftLintFramework/Rules/MultipleClosuresWithTrailingClosureRule.swift

@@ -0,0 +1,98 @@
+//
+//  MultipleClosuresWithTrailingClosureRule.swift
+//  SwiftLint
+//
+//  Created by Erik Strottmann on 8/26/17.
+//  Copyright © 2017 Realm. All rights reserved.
+//
+
+import Foundation
+import SourceKittenFramework
+
+public struct MultipleClosuresWithTrailingClosureRule: ASTRule, ConfigurationProviderRule {
+    public var configuration = SeverityConfiguration(.warning)
+
+    public init() {}
+
+    public static let description = RuleDescription(
+        identifier: "multiple_closures_with_trailing_closure",
+        name: "Multiple Closures with Trailing Closure",
+        description: "Trailing closure syntax should not be used when passing more than one closure argument.",
+        kind: .style,
+        nonTriggeringExamples: [
+            "foo.map { $0 + 1 }\n",
+            "foo.reduce(0) { $0 + $1 }\n",
+            "if let foo = bar.map({ $0 + 1 }) {\n\n}\n",
+            "foo.something(param1: { $0 }, param2: { $0 + 1 })\n",
+            "UIView.animate(withDuration: 1.0) {\n" +
+            "    someView.alpha = 0.0\n" +
+            "}"
+        ],
+        triggeringExamples: [
+            "foo.something(param1: { $0 }) ↓{ $0 + 1 }",
+            "UIView.animate(withDuration: 1.0, animations: {\n" +
+            "    someView.alpha = 0.0\n" +
+            "}) ↓{ _ in\n" +
+            "    someView.removeFromSuperview()\n" +
+            "}"
+        ]
+    )
+
+    public func validate(file: File, kind: SwiftExpressionKind,
+                         dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] {
+
+        guard let call = Call(file: file, kind: kind, dictionary: dictionary), call.hasTrailingClosure else {
+            return []
+        }
+
+        let closureArguments = call.closureArguments
+        guard closureArguments.count > 1, let trailingClosureOffset = closureArguments.last?.offset else {
+            return []
+        }
+
+        return [
+            StyleViolation(ruleDescription: type(of: self).description,
+                           severity: configuration.severity,
+                           location: Location(file: file, byteOffset: trailingClosureOffset))
+        ]
+    }
+}
+
+private struct Call {
+    let file: File
+    let dictionary: [String: SourceKitRepresentable]
+    let offset: Int
+
+    init?(file: File, kind: SwiftExpressionKind, dictionary: [String: SourceKitRepresentable]) {
+        guard kind == .call, let offset = dictionary.offset else {
+            return nil
+        }
+        self.file = file
+        self.dictionary = dictionary
+        self.offset = offset
+    }
+
+    var hasTrailingClosure: Bool {
+        guard let length = dictionary.length,
+            let text = file.contents.bridge().substringWithByteRange(start: offset, length: length)
+            else {
+                return false
+        }
+
+        return !text.hasSuffix(")")
+    }
+
+    var closureArguments: [[String: SourceKitRepresentable]] {
+        return dictionary.enclosedArguments.filter { argument in
+            guard let offset = argument.bodyOffset,
+                let length = argument.bodyLength,
+                let range = file.contents.bridge().byteRangeToNSRange(start: offset, length: length),
+                let match = regex("\\s*\\{").firstMatch(in: file.contents, options: [], range: range)?.range,
+                match.location == range.location else {
+                    return false
+            }
+
+            return true
+        }
+    }
+}

SwiftLint.xcodeproj/project.pbxproj

@@ -114,6 +114,7 @@
 		B3935A32BE03C4D11B4364D6 /* CannedCSVReporterOutput.csv in Resources */ = {isa = PBXBuildFile; fileRef = B3935939C8366514D2694722 /* CannedCSVReporterOutput.csv */; };
 		B3935EE74B1E8E14FBD65E7F /* String+XML.swift in Sources */ = {isa = PBXBuildFile; fileRef = B39353F28BCCA39247B316BD /* String+XML.swift */; };
 		B58AEED61C492C7B00E901FD /* ForceUnwrappingRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = B58AEED51C492C7B00E901FD /* ForceUnwrappingRule.swift */; };
+		BB00B4E91F5216090079869F /* MultipleClosuresWithTrailingClosureRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = BB00B4E71F5216070079869F /* MultipleClosuresWithTrailingClosureRule.swift */; };
 		BFF028AE1CBCF8A500B38A9D /* TrailingWhitespaceConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = BF48D2D61CBCCA5F0080BDAE /* TrailingWhitespaceConfiguration.swift */; };
 		C328A2F71E6759AE00A9E4D7 /* ExplicitTypeInterfaceRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = C328A2F51E67595500A9E4D7 /* ExplicitTypeInterfaceRule.swift */; };
 		C3DE5DAC1E7DF9CA00761483 /* FatalErrorMessageRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = C3DE5DAA1E7DF99B00761483 /* FatalErrorMessageRule.swift */; };
@@ -427,6 +428,7 @@
 		B3935939C8366514D2694722 /* CannedCSVReporterOutput.csv */ = {isa = PBXFileReference; lastKnownFileType = file.csv; path = CannedCSVReporterOutput.csv; sourceTree = "<group>"; };
 		B39359A325FE84B7EDD1C455 /* CannedJunitReporterOutput.xml */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xml; path = CannedJunitReporterOutput.xml; sourceTree = "<group>"; };
 		B58AEED51C492C7B00E901FD /* ForceUnwrappingRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ForceUnwrappingRule.swift; sourceTree = "<group>"; };
+		BB00B4E71F5216070079869F /* MultipleClosuresWithTrailingClosureRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MultipleClosuresWithTrailingClosureRule.swift; sourceTree = "<group>"; };
 		BF48D2D61CBCCA5F0080BDAE /* TrailingWhitespaceConfiguration.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TrailingWhitespaceConfiguration.swift; sourceTree = "<group>"; };
 		C328A2F51E67595500A9E4D7 /* ExplicitTypeInterfaceRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ExplicitTypeInterfaceRule.swift; sourceTree = "<group>"; };
 		C3DE5DAA1E7DF99B00761483 /* FatalErrorMessageRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FatalErrorMessageRule.swift; sourceTree = "<group>"; };
@@ -998,6 +1000,7 @@
 				856651A61D6B395F005E6B29 /* MarkRule.swift */,
 				6238AE411ED4D734006C3601 /* MultilineParametersRule.swift */,
 				621061BE1ED57E640082D51E /* MultilineParametersRuleExamples.swift */,
+				BB00B4E71F5216070079869F /* MultipleClosuresWithTrailingClosureRule.swift */,
 				E88DEA951B099CF200A66CB0 /* NestingRule.swift */,
 				D4DAE8BB1DE14E8F00B0AE7A /* NimbleOperatorRule.swift */,
 				1E18574A1EADBA51004F89F7 /* NoExtensionAccessModifierRule.swift */,
@@ -1405,6 +1408,7 @@
 				D47079A91DFDBED000027086 /* ClosureParameterPositionRule.swift in Sources */,
 				E8B67C3E1C095E6300FDED8E /* Correction.swift in Sources */,
 				623E36F21F3DB988002E5B71 /* QuickDiscouragedCallRuleExamples.swift in Sources */,
+				BB00B4E91F5216090079869F /* MultipleClosuresWithTrailingClosureRule.swift in Sources */,
 				E88198531BEA944400333A11 /* LineLengthRule.swift in Sources */,
 				D47F31151EC918B600E3E1CA /* ProtocolPropertyAccessorsOrderRule.swift in Sources */,
 				92CCB2D71E1EEFA300C8E5A3 /* UnusedOptionalBindingRule.swift in Sources */,

Tests/LinuxMain.swift

@@ -385,6 +385,7 @@ extension RulesTests {
         ("testLetVarWhitespace", testLetVarWhitespace),
         ("testMark", testMark),
         ("testMultilineParameters", testMultilineParameters),
+        ("testMultipleClosuresWithTrailingClosure", testMultipleClosuresWithTrailingClosure),
         ("testNesting", testNesting),
         ("testNoExtensionAccessModifierRule", testNoExtensionAccessModifierRule),
         ("testNoGroupingExtension", testNoGroupingExtension),

Tests/SwiftLintFrameworkTests/RulesTests.swift

@@ -9,6 +9,7 @@
 import SwiftLintFramework
 import XCTest
 
+// swiftlint:disable file_length
 // swiftlint:disable type_body_length
 
 class RulesTests: XCTestCase {
@@ -192,6 +193,10 @@ class RulesTests: XCTestCase {
         verifyRule(MultilineParametersRule.description)
     }
 
+    func testMultipleClosuresWithTrailingClosure() {
+        verifyRule(MultipleClosuresWithTrailingClosureRule.description)
+    }
+
     func testNesting() {
         verifyRule(NestingRule.description)
     }