Add ReduceBooleanRule

CHANGELOG.md

@@ -10,6 +10,10 @@
 
 #### Enhancements
 
+* Add `reduce_boolean` rule to prefer simpler constructs over `reduce(Boolean)`.
+  [Xavier Lowmiller](https://github.com/xavierLowmiller)
+  [#2675](https://github.com/realm/SwiftLint/issues/2675)
+
 * Add `nsobject_prefer_isequal` rule to warn against implementing `==` on an
   `NSObject` subclass as calling `isEqual` (i.e. when using the class from
   Objective-C) will will not use the defined `==` method.  

Rules.md

@@ -114,6 +114,7 @@
 * [Quick Discouraged Call](#quick-discouraged-call)
 * [Quick Discouraged Focused Test](#quick-discouraged-focused-test)
 * [Quick Discouraged Pending Test](#quick-discouraged-pending-test)
+* [Reduce Boolean](#reduce-boolean)
 * [Redundant Discardable Let](#redundant-discardable-let)
 * [Redundant Nil Coalescing](#redundant-nil-coalescing)
 * [Redundant @objc Attribute](#redundant-@objc-attribute)
@@ -15783,6 +15784,67 @@ class TotoTests: QuickSpec {
 
 
 
+## Reduce Boolean
+
+Identifier | Enabled by default | Supports autocorrection | Kind | Analyzer | Minimum Swift Compiler Version
+--- | --- | --- | --- | --- | ---
+`reduce_boolean` | Enabled | No | performance | No | 4.2.0 
+
+Prefer using `.allSatisfy()` or `.contains()` over `reduce(true)` or `reduce(false)`
+
+### Examples
+
+<details>
+<summary>Non Triggering Examples</summary>
+
+```swift
+nums.reduce(0) { $0.0 + $0.1 }
+```
+
+```swift
+nums.reduce(0.0) { $0.0 + $0.1 }
+```
+
+</details>
+<details>
+<summary>Triggering Examples</summary>
+
+```swift
+let allNines = nums.↓reduce(true) { $0.0 && $0.1 == 9 }
+```
+
+```swift
+let anyNines = nums.↓reduce(false) { $0.0 || $0.1 == 9 }
+```
+
+```swift
+let allValid = validators.↓reduce(true) { $0 && $1(input) }
+```
+
+```swift
+let anyValid = validators.↓reduce(false) { $0 || $1(input) }
+```
+
+```swift
+let allNines = nums.↓reduce(true, { $0.0 && $0.1 == 9 })
+```
+
+```swift
+let anyNines = nums.↓reduce(false, { $0.0 || $0.1 == 9 })
+```
+
+```swift
+let allValid = validators.↓reduce(true, { $0 && $1(input) })
+```
+
+```swift
+let anyValid = validators.↓reduce(false, { $0 || $1(input) })
+```
+
+</details>
+
+
+
 ## Redundant Discardable Let
 
 Identifier | Enabled by default | Supports autocorrection | Kind | Analyzer | Minimum Swift Compiler Version

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -115,6 +115,7 @@ public let masterRuleList = RuleList(rules: [
     QuickDiscouragedCallRule.self,
     QuickDiscouragedFocusedTestRule.self,
     QuickDiscouragedPendingTestRule.self,
+    ReduceBooleanRule.self,
     RedundantDiscardableLetRule.self,
     RedundantNilCoalescingRule.self,
     RedundantObjcAttributeRule.self,

Source/SwiftLintFramework/Rules/Lint/NSObjectPreferIsEqualRule.swift

@@ -60,8 +60,8 @@ public struct NSObjectPreferIsEqualRule: Rule, ConfigurationProviderRule, Automa
 
     private func areAllArguments(toMethod method: [String: SourceKitRepresentable],
                                  ofType typeName: String) -> Bool {
-        return method.enclosedVarParameters.reduce(true) { soFar, param -> Bool in
-            soFar && (param.typeName == typeName)
+        return method.enclosedVarParameters.allSatisfy { param in
+            param.typeName == typeName
         }
     }
 }

Source/SwiftLintFramework/Rules/Performance/ReduceBooleanRule.swift

@@ -0,0 +1,50 @@
+import SourceKittenFramework
+
+public struct ReduceBooleanRule: Rule, ConfigurationProviderRule, AutomaticTestableRule {
+    public var configuration = SeverityConfiguration(.warning)
+
+    public init() {}
+
+    public static let description = RuleDescription(
+        identifier: "reduce_boolean",
+        name: "Reduce Boolean",
+        description: "Prefer using `.allSatisfy()` or `.contains()` over `reduce(true)` or `reduce(false)`",
+        kind: .performance,
+        minSwiftVersion: .fourDotTwo,
+        nonTriggeringExamples: [
+            "nums.reduce(0) { $0.0 + $0.1 }",
+            "nums.reduce(0.0) { $0.0 + $0.1 }"
+        ],
+        triggeringExamples: [
+            "let allNines = nums.↓reduce(true) { $0.0 && $0.1 == 9 }",
+            "let anyNines = nums.↓reduce(false) { $0.0 || $0.1 == 9 }",
+            "let allValid = validators.↓reduce(true) { $0 && $1(input) }",
+            "let anyValid = validators.↓reduce(false) { $0 || $1(input) }",
+            "let allNines = nums.↓reduce(true, { $0.0 && $0.1 == 9 })",
+            "let anyNines = nums.↓reduce(false, { $0.0 || $0.1 == 9 })",
+            "let allValid = validators.↓reduce(true, { $0 && $1(input) })",
+            "let anyValid = validators.↓reduce(false, { $0 || $1(input) })"
+        ]
+    )
+
+    public func validate(file: File) -> [StyleViolation] {
+        let pattern = "\\breduce\\((true|false)"
+        return file
+            .match(pattern: pattern, with: [.identifier, .keyword])
+            .map { range in
+                let reason: String
+                if file.contents[Range(range, in: file.contents)!].contains("true") {
+                    reason = "Use `allSatisfy` instead"
+                } else {
+                    reason = "Use `contains` instead"
+                }
+
+                return StyleViolation(
+                    ruleDescription: type(of: self).description,
+                    severity: configuration.severity,
+                    location: Location(file: file, characterOffset: range.location),
+                    reason: reason
+                )
+            }
+    }
+}

Source/SwiftLintFramework/Rules/Style/UnneededParenthesesInClosureArgumentRule.swift

@@ -83,11 +83,7 @@ public struct UnneededParenthesesInClosureArgumentRule: ConfigurationProviderRul
             }
 
             let parametersTokens = file.syntaxMap.tokens(inByteRange: parametersByteRange)
-            let parametersAreValid = parametersTokens.reduce(true) { isValid, token in
-                guard isValid else {
-                    return false
-                }
-
+            let parametersAreValid = parametersTokens.allSatisfy { token in
                 let kind = SyntaxKind(rawValue: token.type)
                 if kind == .identifier {
                     return true

SwiftLint.xcodeproj/project.pbxproj

@@ -85,6 +85,7 @@
 		4A9A3A3A1DC1D75F00DF5183 /* HTMLReporter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4A9A3A391DC1D75F00DF5183 /* HTMLReporter.swift */; };
 		4DB7815E1CAD72BA00BC4723 /* LegacyCGGeometryFunctionsRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DB7815C1CAD690100BC4723 /* LegacyCGGeometryFunctionsRule.swift */; };
 		4DCB8E7F1CBE494E0070FCF0 /* RegexHelpers.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4DCB8E7D1CBE43640070FCF0 /* RegexHelpers.swift */; };
+		4E342B4C2215C793008E4EF8 /* ReduceBooleanRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 4E342B4A2215C6DF008E4EF8 /* ReduceBooleanRule.swift */; };
 		57ED827B1CF656E3002B3513 /* JUnitReporter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 57ED82791CF65183002B3513 /* JUnitReporter.swift */; };
 		584B0D3A2112BA78002F7E25 /* SonarQubeReporter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 584B0D392112BA78002F7E25 /* SonarQubeReporter.swift */; };
 		584B0D3C2112E8FB002F7E25 /* CannedSonarQubeReporterOutput.json in Resources */ = {isa = PBXBuildFile; fileRef = 584B0D3B2112E8FB002F7E25 /* CannedSonarQubeReporterOutput.json */; };
@@ -539,6 +540,7 @@
 		4A9A3A391DC1D75F00DF5183 /* HTMLReporter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = HTMLReporter.swift; sourceTree = "<group>"; };
 		4DB7815C1CAD690100BC4723 /* LegacyCGGeometryFunctionsRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LegacyCGGeometryFunctionsRule.swift; sourceTree = "<group>"; };
 		4DCB8E7D1CBE43640070FCF0 /* RegexHelpers.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RegexHelpers.swift; sourceTree = "<group>"; };
+		4E342B4A2215C6DF008E4EF8 /* ReduceBooleanRule.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ReduceBooleanRule.swift; sourceTree = "<group>"; };
 		5499CA961A2394B700783309 /* Components.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Components.plist; sourceTree = "<group>"; };
 		5499CA971A2394B700783309 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		57ED82791CF65183002B3513 /* JUnitReporter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = JUnitReporter.swift; sourceTree = "<group>"; };
@@ -1033,6 +1035,7 @@
 				D42D2B371E09CC0D00CD7A2E /* FirstWhereRule.swift */,
 				D414D6AD21D22FF500960935 /* LastWhereRule.swift */,
 				429644B41FB0A99E00D75128 /* SortedFirstLastRule.swift */,
+				4E342B4A2215C6DF008E4EF8 /* ReduceBooleanRule.swift */,
 			);
 			path = Performance;
 			sourceTree = "<group>";
@@ -1762,7 +1765,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "if which sourcery >/dev/null; then\n  make Source/SwiftLintFramework/Models/MasterRuleList.swift\nelse\n  echo \"Sourcery not found, install with 'brew install sourcery'\"\nfi";
+			shellScript = "if which sourcery >/dev/null; then\n  make Source/SwiftLintFramework/Models/MasterRuleList.swift\nelse\n  echo \"Sourcery not found, install with 'brew install sourcery'\"\nfi\n";
 			showEnvVarsInLog = 0;
 		};
 		6CF24C421FC99616008CB0B1 /* Update Tests/LinuxMain.swift */ = {
@@ -1779,7 +1782,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "if which sourcery >/dev/null; then\n  make Tests/LinuxMain.swift\nelse\n  echo \"Sourcery not found, install with 'brew install sourcery'\"\nfi";
+			shellScript = "if which sourcery >/dev/null; then\n  make Tests/LinuxMain.swift\nelse\n  echo \"Sourcery not found, install with 'brew install sourcery'\"\nfi\n";
 			showEnvVarsInLog = 0;
 		};
 		C2265FAB1A4B86AC00158358 /* Check Xcode Version */ = {
@@ -1871,6 +1874,7 @@
 				E88198571BEA953300333A11 /* ForceCastRule.swift in Sources */,
 				D44AD2761C0AA5350048F7B0 /* LegacyConstructorRule.swift in Sources */,
 				D41985E721F85014003BE2B7 /* NSLocalizedStringKeyRule.swift in Sources */,
+				4E342B4C2215C793008E4EF8 /* ReduceBooleanRule.swift in Sources */,
 				D286EC021E02DF6F0003CF72 /* SortedImportsRule.swift in Sources */,
 				D40E041C1F46E3B30043BC4E /* SuperfluousDisableCommandRule.swift in Sources */,
 				82F614F42106015100D23904 /* MultilineArgumentsBracketsRule.swift in Sources */,

Tests/LinuxMain.swift

@@ -984,6 +984,12 @@ extension QuickDiscouragedPendingTestRuleTests {
     ]
 }
 
+extension ReduceBooleanRuleTests {
+    static var allTests: [(String, (ReduceBooleanRuleTests) -> () throws -> Void)] = [
+        ("testWithDefaultConfiguration", testWithDefaultConfiguration)
+    ]
+}
+
 extension RedundantDiscardableLetRuleTests {
     static var allTests: [(String, (RedundantDiscardableLetRuleTests) -> () throws -> Void)] = [
         ("testWithDefaultConfiguration", testWithDefaultConfiguration)
@@ -1593,6 +1599,7 @@ XCTMain([
     testCase(QuickDiscouragedCallRuleTests.allTests),
     testCase(QuickDiscouragedFocusedTestRuleTests.allTests),
     testCase(QuickDiscouragedPendingTestRuleTests.allTests),
+    testCase(ReduceBooleanRuleTests.allTests),
     testCase(RedundantDiscardableLetRuleTests.allTests),
     testCase(RedundantNilCoalescingRuleTests.allTests),
     testCase(RedundantObjcAttributeRuleTests.allTests),

Tests/SwiftLintFrameworkTests/AutomaticRuleTests.generated.swift

@@ -510,6 +510,12 @@ class QuickDiscouragedPendingTestRuleTests: XCTestCase {
     }
 }
 
+class ReduceBooleanRuleTests: XCTestCase {
+    func testWithDefaultConfiguration() {
+        verifyRule(ReduceBooleanRule.description)
+    }
+}
+
 class RedundantDiscardableLetRuleTests: XCTestCase {
     func testWithDefaultConfiguration() {
         verifyRule(RedundantDiscardableLetRule.description)