variable_name rule should extend to all identifiers

CHANGELOG.md

@@ -939,7 +939,10 @@ This release has seen a phenomenal uptake in community contributions!
 
 ##### Enhancements
 
-* None.
+* `variable_name` rule is now `identifier_name` as it validates other
+  identifiers as well.  
+  [Marcelo Fabri](https://github.com/marcelofabri)
+  [#663](https://github.com/realm/SwiftLint/issues/663)
 
 ##### Bug Fixes
 

Source/SwiftLintFramework/Extensions/File+SwiftLint.swift

@@ -169,16 +169,6 @@ extension File {
         return matches.filter { !$0.intersects(exclusionRanges) }
     }
 
-    internal func validateVariableName(_ dictionary: [String: SourceKitRepresentable],
-                                       kind: SwiftDeclarationKind) -> (name: String, offset: Int)? {
-        guard let name = dictionary.name,
-            let offset = dictionary.offset,
-            SwiftDeclarationKind.variableKinds().contains(kind) && !name.hasPrefix("$") else {
-                return nil
-        }
-        return (name.nameStrippingLeadingUnderscoreIfPrivate(dictionary), offset)
-    }
-
     internal func append(_ string: String) {
         guard let stringData = string.data(using: .utf8) else {
             fatalError("can't encode '\(string)' with UTF8")

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -98,6 +98,7 @@ public let masterRuleList = RuleList(rules:
     FunctionBodyLengthRule.self,
     FunctionParameterCountRule.self,
     GenericTypeNameRule.self,
+    IdentifierNameRule.self,
     ImplicitGetterRule.self,
     LargeTupleRule.self,
     LeadingWhitespaceRule.self,
@@ -142,7 +143,6 @@ public let masterRuleList = RuleList(rules:
     UnusedOptionalBindingRule.self,
     ValidDocsRule.self,
     ValidIBInspectableRule.self,
-    VariableNameRule.self,
     VerticalParameterAlignmentRule.self,
     VerticalWhitespaceRule.self,
     VoidReturnRule.self,

Source/SwiftLintFramework/Rules/CyclomaticComplexityRule.swift

@@ -40,7 +40,7 @@ public struct CyclomaticComplexityRule: ASTRule, ConfigurationProviderRule {
 
     public func validate(file: File, kind: SwiftDeclarationKind,
                          dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] {
-        if !SwiftDeclarationKind.functionKinds().contains(kind) {
+        guard SwiftDeclarationKind.functionKinds().contains(kind) else {
             return []
         }
 

Source/SwiftLintFramework/Rules/IdentifierNameRule.swift

@@ -0,0 +1,139 @@
+//
+//  IdentifierNameRule.swift
+//  SwiftLint
+//
+//  Created by JP Simard on 5/16/15.
+//  Copyright © 2015 Realm. All rights reserved.
+//
+
+import Foundation
+import SourceKittenFramework
+
+public struct IdentifierNameRule: ASTRule, ConfigurationProviderRule {
+
+    public var configuration = NameConfiguration(minLengthWarning: 3,
+                                                 minLengthError: 2,
+                                                 maxLengthWarning: 40,
+                                                 maxLengthError: 60)
+
+    public init() {}
+
+    public static let description = RuleDescription(
+        identifier: "identifier_name",
+        name: "Identifier Name",
+        description: "Identifier names should only contain alphanumeric characters and " +
+            "start with a lowercase character or should only contain capital letters. " +
+            "In an exception to the above, variable names may start with a capital letter " +
+            "when they are declared static and immutable. Variable names should not be too " +
+            "long or too short.",
+        nonTriggeringExamples: IdentifierNameRuleExamples.swift3NonTriggeringExamples,
+        triggeringExamples: IdentifierNameRuleExamples.swift3TriggeringExamples,
+        deprecatedAliases: ["variable_name"]
+    )
+
+    public func validate(file: File, kind: SwiftDeclarationKind,
+                         dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] {
+        guard !dictionary.enclosedSwiftAttributes.contains("source.decl.attribute.override") else {
+            return []
+        }
+
+        return validateName(dictionary: dictionary, kind: kind).map { name, offset in
+            guard !configuration.excluded.contains(name) else {
+                return []
+            }
+
+            let isFunction = SwiftDeclarationKind.functionKinds().contains(kind)
+            let description = type(of: self).description
+
+            let type = self.type(for: kind)
+            if !isFunction {
+                if !CharacterSet.alphanumerics.isSuperset(ofCharactersIn: name) {
+                    return [
+                        StyleViolation(ruleDescription: description,
+                                       severity: .error,
+                                       location: Location(file: file, byteOffset: offset),
+                                       reason: "\(type) name should only contain alphanumeric " +
+                            "characters: '\(name)'")
+                    ]
+                }
+
+                if let severity = severity(forLength: name.characters.count) {
+                    let reason = "\(type) name should be between " +
+                        "\(configuration.minLengthThreshold) and " +
+                        "\(configuration.maxLengthThreshold) characters long: '\(name)'"
+                    return [
+                        StyleViolation(ruleDescription: type(of: self).description,
+                                       severity: severity,
+                                       location: Location(file: file, byteOffset: offset),
+                                       reason: reason)
+                    ]
+                }
+            }
+
+            if kind != .varStatic && name.isViolatingCase && !name.isOperator {
+                let reason = "\(type) name should start with a lowercase character: '\(name)'"
+                return [
+                    StyleViolation(ruleDescription: description,
+                                   severity: .error,
+                                   location: Location(file: file, byteOffset: offset),
+                                   reason: reason)
+                ]
+            }
+
+            return []
+        } ?? []
+    }
+
+    private func validateName(dictionary: [String: SourceKitRepresentable],
+                              kind: SwiftDeclarationKind) -> (name: String, offset: Int)? {
+        guard let name = dictionary.name,
+            let offset = dictionary.offset,
+            kinds(for: .current).contains(kind),
+            !name.hasPrefix("$") else {
+                return nil
+        }
+
+        return (name.nameStrippingLeadingUnderscoreIfPrivate(dictionary), offset)
+    }
+
+    private func kinds(for version: SwiftVersion) -> [SwiftDeclarationKind] {
+        let common = SwiftDeclarationKind.variableKinds() + SwiftDeclarationKind.functionKinds()
+        switch version {
+        case .two:
+            return common
+        case .three:
+            return common + [.enumelement]
+        }
+    }
+
+    private func type(for kind: SwiftDeclarationKind) -> String {
+        if SwiftDeclarationKind.functionKinds().contains(kind) {
+            return "Function"
+        } else if kind == .enumelement {
+            return "Enum element"
+        } else {
+            return "Variable"
+        }
+    }
+}
+
+fileprivate extension String {
+    var isViolatingCase: Bool {
+        let secondIndex = characters.index(after: startIndex)
+        let firstCharacter = substring(to: secondIndex)
+        guard firstCharacter.isUppercase() else {
+            return false
+        }
+        guard characters.count > 1 else {
+            return true
+        }
+        let range = secondIndex..<characters.index(after: secondIndex)
+        let secondCharacter = substring(with: range)
+        return secondCharacter.isLowercase()
+    }
+
+    var isOperator: Bool {
+        let operators = ["/", "=", "-", "+", "!", "*", "|", "^", "~", "?", ".", "%", "<", ">", "&"]
+        return !operators.filter(hasPrefix).isEmpty
+    }
+}

Source/SwiftLintFramework/Rules/IdentifierNameRuleExamples.swift

@@ -0,0 +1,51 @@
+//
+//  IdentifierNameRuleExamples.swift
+//  SwiftLint
+//
+//  Created by Marcelo Fabri on 12/30/16.
+//  Copyright © 2016 Realm. All rights reserved.
+//
+
+import Foundation
+
+internal struct IdentifierNameRuleExamples {
+    private static let commonNonTriggeringExamples = [
+        "let myLet = 0",
+        "var myVar = 0",
+        "private let _myLet = 0",
+        "class Abc { static let MyLet = 0 }",
+        "let URL: NSURL? = nil",
+        "let XMLString: String? = nil",
+        "override var i = 0",
+        "enum Foo { case myEnum }",
+        "func isOperator(name: String) -> Bool",
+        "func typeForKind(_ kind: SwiftDeclarationKind) -> String",
+        "func == (lhs: SyntaxToken, rhs: SyntaxToken) -> Bool",
+        "override func IsOperator(name: String) -> Bool"
+    ]
+
+    static let swift2NonTriggeringExamples = commonNonTriggeringExamples + [
+        "enum Foo { case MyEnum }"
+    ]
+
+    static let swift3NonTriggeringExamples = commonNonTriggeringExamples
+
+    private static let commonTriggeringExamples = [
+        "↓let MyLet = 0",
+        "↓let _myLet = 0",
+        "private ↓let myLet_ = 0",
+        "↓let myExtremelyVeryVeryVeryVeryVeryVeryLongLet = 0",
+        "↓var myExtremelyVeryVeryVeryVeryVeryVeryLongVar = 0",
+        "private ↓let _myExtremelyVeryVeryVeryVeryVeryVeryLongLet = 0",
+        "↓let i = 0",
+        "↓var id = 0",
+        "private ↓let _i = 0",
+        "↓func IsOperator(name: String) -> Bool"
+    ]
+
+    static let swift2TriggeringExamples = commonTriggeringExamples
+
+    static let swift3TriggeringExamples = commonTriggeringExamples + [
+        "enum Foo { case ↓MyEnum }"
+    ]
+}

Source/SwiftLintFramework/Rules/MissingDocsRule.swift

@@ -52,19 +52,19 @@ extension File {
 }
 
 public enum AccessControlLevel: String, CustomStringConvertible {
-    case Private = "source.lang.swift.accessibility.private"
-    case FilePrivate = "source.lang.swift.accessibility.fileprivate"
-    case Internal = "source.lang.swift.accessibility.internal"
-    case Public = "source.lang.swift.accessibility.public"
-    case Open = "source.lang.swift.accessibility.open"
+    case `private` = "source.lang.swift.accessibility.private"
+    case `fileprivate` = "source.lang.swift.accessibility.fileprivate"
+    case `internal` = "source.lang.swift.accessibility.internal"
+    case `public` = "source.lang.swift.accessibility.public"
+    case `open` = "source.lang.swift.accessibility.open"
 
     internal init?(description value: String) {
         switch value {
-        case "private": self = .Private
-        case "fileprivate": self = .FilePrivate
-        case "internal": self = .Internal
-        case "public": self = .Public
-        case "open": self = .Open
+        case "private": self = .private
+        case "fileprivate": self = .fileprivate
+        case "internal": self = .internal
+        case "public": self = .public
+        case "open": self = .open
         default: return nil
         }
     }
@@ -75,17 +75,17 @@ public enum AccessControlLevel: String, CustomStringConvertible {
 
     public var description: String {
         switch self {
-        case .Private: return "private"
-        case .FilePrivate: return "fileprivate"
-        case .Internal: return "internal"
-        case .Public: return "public"
-        case .Open: return "open"
+        case .private: return "private"
+        case .fileprivate: return "fileprivate"
+        case .internal: return "internal"
+        case .public: return "public"
+        case .open: return "open"
         }
     }
 
     // Returns true if is `private` or `fileprivate`
     var isPrivate: Bool {
-        return self == .Private || self == .FilePrivate
+        return self == .private || self == .fileprivate
     }
 
 }
@@ -106,8 +106,8 @@ public struct MissingDocsRule: OptInRule {
     }
 
     public init() {
-        parameters = [RuleParameter(severity: .warning, value: .Public),
-                      RuleParameter(severity: .warning, value: .Open)]
+        parameters = [RuleParameter(severity: .warning, value: .public),
+                      RuleParameter(severity: .warning, value: .open)]
     }
 
     public let parameters: [RuleParameter<AccessControlLevel>]