Initial cache implementation

Source/SwiftLintFramework/Models/LinterCache.swift

@@ -0,0 +1,86 @@
+//
+//  LinterCache.swift
+//  SwiftLint
+//
+//  Created by Marcelo Fabri on 12/27/16.
+//  Copyright © 2016 Realm. All rights reserved.
+//
+
+import Foundation
+import SourceKittenFramework
+
+public struct LinterCache {
+    private var cache = [String: [String: Any]]()
+
+    public init() { }
+
+    public init(contentsOf url: URL) throws {
+        let data = try Data(contentsOf: url)
+        let json = try JSONSerialization.jsonObject(with: data, options: [])
+        if let json = json as? [String: [String: Any]] {
+            cache = json
+        }
+    }
+
+    public mutating func cacheFile(_ file: String, violations: [StyleViolation], hash: Int) {
+
+        var entry = [String: Any]()
+        var fileViolations = entry["violations"] as? [[String: Any]] ?? []
+
+        for violation in violations {
+            fileViolations.append(dictionaryForViolation(violation))
+        }
+
+        entry["violations"] = fileViolations
+        entry["hash"] = hash
+        cache[file] = entry
+    }
+
+    public func violations(for file: String, hash: Int) -> [StyleViolation]? {
+        guard let entry = cache[file],
+            let cacheHash = entry["hash"] as? Int,
+            cacheHash == hash,
+            let violations = entry["violations"] as? [[String: Any]] else {
+            return nil
+        }
+
+        return violations.flatMap { StyleViolation.fromCache($0, file: file) }
+    }
+
+    public func save(to url: URL) throws {
+        let json = toJSON(cache)
+        try json.write(to: url, atomically: true, encoding: .utf8)
+    }
+
+    private func dictionaryForViolation(_ violation: StyleViolation) -> [String: Any] {
+        return [
+            "line": violation.location.line ?? NSNull() as Any,
+            "character": violation.location.character ?? NSNull() as Any,
+            "severity": violation.severity.rawValue,
+            "type": violation.ruleDescription.name,
+            "rule_id": violation.ruleDescription.identifier,
+            "reason": violation.reason
+        ]
+    }
+}
+
+extension StyleViolation {
+    fileprivate static func fromCache(_ cache: [String: Any], file: String) -> StyleViolation? {
+        guard let severity = (cache["severity"] as? String).flatMap(ViolationSeverity.init),
+            let name = cache["type"] as? String,
+            let ruleId = cache["rule_id"] as? String,
+            let reason = cache["reason"] as? String else {
+                return nil
+        }
+
+        let line = cache["line"] as? Int
+        let character = cache["character"] as? Int
+
+        let ruleDescription = RuleDescription(identifier: ruleId, name: name, description: reason)
+        let location = Location(file: file, line: line, character: character)
+        let violation = StyleViolation(ruleDescription: ruleDescription, severity: severity,
+                                       location: location, reason: reason)
+
+        return violation
+    }
+}

Source/SwiftLintFramework/Models/ViolationSeverity.swift

@@ -9,6 +9,10 @@
 public enum ViolationSeverity: String, Comparable {
     case warning
     case error
+
+    public init?(identifier: String) {
+        self.init(rawValue: identifier)
+    }
 }
 
 // MARK: Comparable

Source/swiftlint/Commands/LintCommand.swift

@@ -40,12 +40,23 @@ struct LintCommand: CommandProtocol {
         let reporter = reporterFromString(
             options.reporter.isEmpty ? configuration.reporter : options.reporter
         )
+
+        let cacheUrl = URL(fileURLWithPath: "swiftlint.json")
+        var cache = (try? LinterCache(contentsOf: cacheUrl)) ?? LinterCache()
         return configuration.visitLintableFiles(options.path, action: "Linting",
             useSTDIN: options.useSTDIN, quiet: options.quiet,
             useScriptInputFiles: options.useScriptInputFiles) { linter in
             var currentViolations: [StyleViolation] = []
+            var readFromCache = false
+            var fileHash: Int?
             autoreleasepool {
-                if options.benchmark {
+                if let file = linter.file.path,
+                    case let hash = linter.file.contents.hash,
+                    let cachedViolations = cache.violations(for: file, hash: hash) {
+                    currentViolations = cachedViolations
+                    readFromCache = true
+                    fileHash = hash
+                } else if options.benchmark {
                     let start = Date()
                     let (_currentViolations, currentRuleTimes) = linter.styleViolationsAndRuleTimes
                     currentViolations = _currentViolations
@@ -58,6 +69,10 @@ struct LintCommand: CommandProtocol {
             }
             violations += currentViolations
             reporter.reportViolations(currentViolations, realtimeCondition: true)
+            if !readFromCache, let file = linter.file.path {
+                let hash = fileHash ?? linter.file.contents.hash
+                cache.cacheFile(file, violations: currentViolations, hash: hash)
+            }
         }.flatMap { files in
             if isWarningThresholdBroken(configuration, violations: violations) {
                 violations.append(createThresholdViolation(configuration.warningThreshold!))
@@ -73,6 +88,9 @@ struct LintCommand: CommandProtocol {
                 fileBenchmark.save()
                 ruleBenchmark.save()
             }
+
+            try? cache.save(to: cacheUrl)
+
             if numberOfSeriousViolations > 0 {
                 exit(2)
             } else if options.strict && !violations.isEmpty {

SwiftLint.xcodeproj/project.pbxproj

@@ -125,6 +125,7 @@
 		D4C4A3521DEFBBB700E0E04C /* FileHeaderConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4C4A3511DEFBBB700E0E04C /* FileHeaderConfiguration.swift */; };
 		D4DAE8BC1DE14E8F00B0AE7A /* NimbleOperatorRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4DAE8BB1DE14E8F00B0AE7A /* NimbleOperatorRule.swift */; };
 		D4FBADD01E00DA0400669C73 /* OperatorUsageWhitespaceRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4FBADCF1E00DA0400669C73 /* OperatorUsageWhitespaceRule.swift */; };
+		D4FD58B21E12A0200019503C /* LinterCache.swift in Sources */ = {isa = PBXBuildFile; fileRef = D4FD58B11E12A0200019503C /* LinterCache.swift */; };
 		DAD3BE4A1D6ECD9500660239 /* PrivateOutletRuleConfiguration.swift in Sources */ = {isa = PBXBuildFile; fileRef = DAD3BE491D6ECD9500660239 /* PrivateOutletRuleConfiguration.swift */; };
 		E315B83C1DFA4BC500621B44 /* DynamicInlineRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = E315B83B1DFA4BC500621B44 /* DynamicInlineRule.swift */; };
 		E57B23C11B1D8BF000DEA512 /* ReturnArrowWhitespaceRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = E57B23C01B1D8BF000DEA512 /* ReturnArrowWhitespaceRule.swift */; };
@@ -375,6 +376,7 @@
 		D4C4A3511DEFBBB700E0E04C /* FileHeaderConfiguration.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = FileHeaderConfiguration.swift; sourceTree = "<group>"; };
 		D4DAE8BB1DE14E8F00B0AE7A /* NimbleOperatorRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = NimbleOperatorRule.swift; sourceTree = "<group>"; };
 		D4FBADCF1E00DA0400669C73 /* OperatorUsageWhitespaceRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OperatorUsageWhitespaceRule.swift; sourceTree = "<group>"; };
+		D4FD58B11E12A0200019503C /* LinterCache.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LinterCache.swift; sourceTree = "<group>"; };
 		DAD3BE491D6ECD9500660239 /* PrivateOutletRuleConfiguration.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PrivateOutletRuleConfiguration.swift; sourceTree = "<group>"; };
 		E315B83B1DFA4BC500621B44 /* DynamicInlineRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DynamicInlineRule.swift; sourceTree = "<group>"; };
 		E57B23C01B1D8BF000DEA512 /* ReturnArrowWhitespaceRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ReturnArrowWhitespaceRule.swift; sourceTree = "<group>"; };
@@ -834,6 +836,7 @@
 				E8B67C3D1C095E6300FDED8E /* Correction.swift */,
 				E809EDA01B8A71DF00399043 /* Configuration.swift */,
 				E812249B1B04FADC001783D2 /* Linter.swift */,
+				D4FD58B11E12A0200019503C /* LinterCache.swift */,
 				E88DEA6E1B09843F00A66CB0 /* Location.swift */,
 				E80E018E1B92C1350078EB70 /* Region.swift */,
 				83D71E261B131EB5000395DE /* RuleDescription.swift */,
@@ -1186,6 +1189,7 @@
 				E88DEA711B09847500A66CB0 /* ViolationSeverity.swift in Sources */,
 				B2902A0C1D66815600BFCCF7 /* PrivateUnitTestRule.swift in Sources */,
 				D47A51101DB2DD4800A4CC21 /* AttributesRule.swift in Sources */,
+				D4FD58B21E12A0200019503C /* LinterCache.swift in Sources */,
 				3BD9CD3D1C37175B009A5D25 /* YamlParser.swift in Sources */,
 				F22314B01D4FA4D7009AD165 /* LegacyNSGeometryFunctionsRule.swift in Sources */,
 				E88DEA8C1B0999A000A66CB0 /* ASTRule.swift in Sources */,