Re-write ExplicitInitRule to ASTRule

Source/SwiftLintFramework/Rules/ExplicitInitRule.swift

@@ -9,9 +9,7 @@
 import Foundation
 import SourceKittenFramework
 
-public struct ExplicitInitRule: ConfigurationProviderRule, CorrectableRule, OptInRule {
-
-    private let pattern = "\\b([A-Z][A-Za-z]*)\\.init\\("
+public struct ExplicitInitRule: ASTRule, ConfigurationProviderRule, CorrectableRule, OptInRule {
 
     public var configuration = SeverityConfiguration(.Warning)
 
@@ -22,49 +20,99 @@ public struct ExplicitInitRule: ConfigurationProviderRule, CorrectableRule, OptI
         name: "Explicit Init",
         description: "Explicitly calling .init() should be avoided.",
         nonTriggeringExamples: [
-            "self.init(",
-            "self.init",
-            "Abc.init",
-            "abc.init(",
-            "$0.init("
+            "import Foundation; class C: NSObject { override init() { super.init() }}", // super
+            "struct S { let n: Int }; extension S { init() { self.init(n: 1) } }",      // self
+            "[1].flatMap(String.init)",                   // pass init as closure
+            "[String.self].map { $0.init(1) }",           // initialize from a metatype value
+            "[String.self].map { type in type.init(1) }", // initialize from a metatype value
         ],
         triggeringExamples: [
-            "Abc.init(",
-            "Abc(NSURL.init(someString"
+            "[1].flatMap{String↓.init($0)}",
+            "[String.self].map { Type in Type↓.init(1) }", // starting with capital assumes as type
         ],
         corrections: [
-            "Abc.init(": "Abc(",
-            "Abc(NSURL.init(someString": "Abc(NSURL(someString"
+            "[1].flatMap{String.init($0)}" : "[1].flatMap{String($0)}",
         ]
     )
 
-    public func validateFile(file: File) -> [StyleViolation] {
-        return violationRangesInFile(file).flatMap { range in
-            return StyleViolation(ruleDescription: self.dynamicType.description,
+    public enum Kind: String {
+        case expr_call = "source.lang.swift.expr.call"
+        case other
+        public init?(rawValue: String) {
+            switch rawValue {
+            case expr_call.rawValue: self = .expr_call
+            default: self = .other
+            }
+        }
+    }
+
+    public func validateFile(
+        file: File,
+        kind: ExplicitInitRule.Kind,
+        dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] {
+        return violationRangesInFile(file, kind: kind, dictionary: dictionary).map {
+            StyleViolation(ruleDescription: self.dynamicType.description,
                 severity: configuration.severity,
-                location: Location(file: file, characterOffset: range.location))
+                location: Location(file: file, characterOffset: $0.location))
         }
     }
 
-    private func violationRangesInFile(file: File) -> [NSRange] {
-        let excludingKinds = SyntaxKind.commentAndStringKinds()
+    private let initializerWithType = regex("^[A-Z].*\\.init$")
+
+    private func violationRangesInFile(
+        file: File,
+        kind: ExplicitInitRule.Kind,
+        dictionary: [String: SourceKitRepresentable]) -> [NSRange] {
+
+        func isExpected(name: String) -> Bool {
+            let range = NSRange(location: 0, length: name.utf16.count)
+            return !["super.init", "self.init"].contains(name)
+                && initializerWithType.numberOfMatchesInString(name, options: [], range: range) != 0
+        }
 
-        return file.matchPattern(pattern, excludingSyntaxKinds: excludingKinds)
+        let length = ".init".utf16.count
+
+        guard kind == .expr_call,
+            let name = dictionary["key.name"] as? String where isExpected(name),
+            let nameOffset = dictionary["key.nameoffset"] as? Int64,
+            let nameLength = dictionary["key.namelength"] as? Int64,
+            let range = (file.contents as NSString)
+                .byteRangeToNSRange(start: Int(nameOffset + nameLength) - length, length: length)
+            else { return [] }
+        return [range]
+    }
+
+    private func violationRangesInFile(
+        file: File,
+        dictionary: [String: SourceKitRepresentable]) -> [NSRange] {
+        let substructure = dictionary["key.substructure"] as? [SourceKitRepresentable] ?? []
+        return substructure.flatMap { subItem -> [NSRange] in
+            guard let subDict = subItem as? [String: SourceKitRepresentable],
+                kindString = subDict["key.kind"] as? String,
+                kind = ExplicitInitRule.Kind(rawValue: kindString) else {
+                    return []
+            }
+            return violationRangesInFile(file, dictionary: subDict) +
+                violationRangesInFile(file, kind: kind, dictionary: subDict)
+        }
+    }
+
+    private func violationRangesInFile(file: File) -> [NSRange] {
+        return violationRangesInFile(file, dictionary: file.structure.dictionary).sort { lh, rh in
+            lh.location > rh.location
+        }
     }
 
     public func correctFile(file: File) -> [Correction] {
         let matches = violationRangesInFile(file)
         guard !matches.isEmpty else { return [] }
 
-        let regularExpression = regex(pattern)
         let description = self.dynamicType.description
         var corrections = [Correction]()
         var contents = file.contents
-        for range in matches.reverse() {
-            contents = regularExpression.stringByReplacingMatchesInString(contents,
-                                                                          options: [],
-                                                                          range: range,
-                                                                          withTemplate: "$1(")
+        for range in matches {
+            contents = (contents as NSString)
+                .stringByReplacingCharactersInRange(range, withString: "")
             let location = Location(file: file, characterOffset: range.location)
             corrections.append(Correction(ruleDescription: description, location: location))
         }