[new rule] VerticalWhitespace rule

CHANGELOG.md

@@ -14,6 +14,10 @@
   `NSRect` constants and constructors to existing rules.  
   [David Rönnqvist](https://github.com/d-ronnqvist)
 
+* Added Vertical Whitespace Rule.  
+  [J. Cheyo Jimenez](https://github.com/masters3d)
+  [#548](https://github.com/realm/SwiftLint/issues/548)
+
 * Removed ConditionalBindingCascadeRule.  
   [J. Cheyo Jimenez](https://github.com/masters3d)
   [#701](https://github.com/realm/SwiftLint/issues/701)

Source/SwiftLintFramework/Models/MasterRuleList.swift

@@ -74,5 +74,6 @@ public let masterRuleList = RuleList(rules:
     TypeBodyLengthRule.self,
     TypeNameRule.self,
     ValidDocsRule.self,
-    VariableNameRule.self
+    VariableNameRule.self,
+    VerticalWhitespaceRule.self
 )

Source/SwiftLintFramework/Rules/ClosingBraceRule.swift

@@ -44,7 +44,6 @@ public struct ClosingBraceRule: CorrectableRule, ConfigurationProviderRule {
         ]
     )
 
-
     public func validateFile(file: File) -> [StyleViolation] {
         return file.violatingClosingBraceRanges().map {
             StyleViolation(ruleDescription: self.dynamicType.description,

Source/SwiftLintFramework/Rules/VerticalWhitespaceRule.swift

@@ -0,0 +1,168 @@
+//
+//  VerticalWhitespaceRule.swift
+//  SwiftLint
+//
+//  Created by J. Cheyo Jimenez on 2015-05-16.
+//  Copyright (c) 2016 Realm. All rights reserved.
+//
+
+import Foundation
+import SourceKittenFramework
+
+private let descriptionReason = "Limit vertical whitespace to a single empty line."
+
+public struct VerticalWhitespaceRule: CorrectableRule,
+                                      ConfigurationProviderRule {
+
+    public var configuration = SeverityConfiguration(.Warning)
+
+    public init() {}
+
+    public static let description = RuleDescription(
+        identifier: "vertical_whitespace",
+        name: "Vertical Whitespace",
+        description: descriptionReason,
+        nonTriggeringExamples: [
+            "let abc = 0\n",
+            "let abc = 0\n\n",
+            "/* bcs \n\n\n\n*/",
+            "// bca \n\n",
+        ],
+        triggeringExamples: [
+            "let aaaa = 0\n\n\n",
+            "struct AAAA {}\n\n\n\n",
+             "class BBBB {}\n\n\n",
+        ],
+        corrections: [
+            "let b = 0\n\n\nclass AAA {}\n": "let b = 0\n\nclass AAA {}\n",
+            "let c = 0\n\n\nlet num = 1\n": "let c = 0\n\nlet num = 1\n",
+            "// bca \n\n\n": "// bca \n\n",
+        ] // End of line autocorrections are handeled by Trailing Newline Rule.
+    )
+
+    public func validateFile(file: File) -> [StyleViolation] {
+
+        let linesSections = validate(file)
+        if linesSections.isEmpty { return [] }
+
+        var violations = [StyleViolation]()
+        for (eachLastLine, eachSectionCount) in linesSections {
+
+            // Skips violation for areas where the rule is disabled
+            let region = file.regions().filter {
+                $0.contains(Location(file: file.path, line: eachLastLine.index, character: 0))
+            }.first
+            if region?.isRuleDisabled(self) == true {
+                continue
+            }
+
+            let violation = StyleViolation(ruleDescription: self.dynamicType.description,
+                                           severity: configuration.severity,
+                                           location: Location(file: file.path,
+                                            line: eachLastLine.index ),
+                                           reason: descriptionReason
+                                            + " Currently \(eachSectionCount + 1)." )
+            violations.append(violation)
+        }
+
+        return violations
+    }
+
+    func validate(file: File) -> [(lastLine: Line, linesToRemove: Int)] {
+
+        let filteredLines = file.lines.filter {
+            $0.content.stringByTrimmingCharactersInSet(.whitespaceCharacterSet()).isEmpty
+        }
+
+        if filteredLines.isEmpty { return [] }
+
+        var blankLinesSections = [[Line]]()
+        var lineSection = [Line]()
+
+        var previousIndex = 0
+        for index in 0..<filteredLines.count {
+            if filteredLines[previousIndex].index + 1 == filteredLines[index].index {
+                lineSection.append(filteredLines[index])
+            } else if !lineSection.isEmpty {
+                blankLinesSections.append(lineSection)
+                lineSection.removeAll()
+            }
+            previousIndex = index
+        }
+        if !lineSection.isEmpty {
+            blankLinesSections.append(lineSection)
+        }
+
+        // matching all accurrences of /* */
+        let matchMultilineComments = "/\\*(.|[\\r\\n])*?\\*/"
+        let comments = file.matchPattern(matchMultilineComments)
+
+        var result = [(lastLine: Line, linesToRemove: Int)]()
+        for eachSection in blankLinesSections {
+            guard let lastLine = eachSection.last else { continue }
+
+            // filtering out violations within a multiple comment block
+            let isSectionInComment = !comments.filter {
+                (eachRange, _ ) in eachRange.intersectsRange(lastLine.range)
+            }.isEmpty
+
+            if isSectionInComment {
+                continue  // skipping the lines found in multiline comment
+            } else {
+                result.append((lastLine, eachSection.count))
+            }
+        }
+
+        return result
+
+    }
+
+    public func correctFile(file: File) -> [Correction] {
+        let linesSections = validate(file)
+        if linesSections.isEmpty { return [] }
+
+        var indexOfLinesToDelete = [Int]()
+
+        for eachLine in linesSections {
+            let start = eachLine.lastLine.index - eachLine.linesToRemove
+            indexOfLinesToDelete.appendContentsOf(start..<eachLine.lastLine.index)
+        }
+
+        var correctedLines = [String]()
+        var corrections = [Correction]()
+        let fileRegions = file.regions()
+
+        forLoopCounter: for currentLine in file.lines {
+
+            // Doesnt correct lines where rule is disabled
+            let region = fileRegions.filter {
+                $0.contains(Location(file: file.path, line: currentLine.index, character: 0))
+            }.first
+            if region?.isRuleDisabled(self) == true {
+                correctedLines.append(currentLine.content)
+                continue forLoopCounter
+            }
+
+            // by not incling lines in correctedLines, it removes them
+            if Set(indexOfLinesToDelete).contains(currentLine.index) {
+                let description = self.dynamicType.description
+                let location = Location(file: file.path, line: currentLine.index)
+
+                //reports every line that is being deleted
+                corrections.append(Correction(ruleDescription: description, location: location))
+                continue forLoopCounter
+            }
+
+            // all lines that pass get added to final output file
+            correctedLines.append(currentLine.content)
+        }
+        // converts lines back to file, add trailing line
+        if !corrections.isEmpty {
+            file.write(correctedLines.joinWithSeparator("\n") + "\n")
+            return corrections
+        }
+        return []
+
+    }
+
+}

SwiftLint.xcodeproj/project.pbxproj

@@ -9,6 +9,7 @@
 /* Begin PBXBuildFile section */
 		006ECFC41C44E99E00EF6364 /* LegacyConstantRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 006ECFC31C44E99E00EF6364 /* LegacyConstantRule.swift */; };
 		02FD8AEF1BFC18D60014BFFB /* ExtendedNSStringTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 02FD8AEE1BFC18D60014BFFB /* ExtendedNSStringTests.swift */; };
+		1EC163521D5992D900DD2928 /* VerticalWhitespaceRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1EC163511D5992D900DD2928 /* VerticalWhitespaceRule.swift */; };
 		094385041D5D4F7C009168CF /* PrivateOutletRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 094385021D5D4F78009168CF /* PrivateOutletRule.swift */; };
 		1F11B3CF1C252F23002E8FA8 /* ClosingBraceRule.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1F11B3CE1C252F23002E8FA8 /* ClosingBraceRule.swift */; };
 		24E17F721B14BB3F008195BE /* File+Cache.swift in Sources */ = {isa = PBXBuildFile; fileRef = 24E17F701B1481FF008195BE /* File+Cache.swift */; };
@@ -174,6 +175,7 @@
 /* Begin PBXFileReference section */
 		006ECFC31C44E99E00EF6364 /* LegacyConstantRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LegacyConstantRule.swift; sourceTree = "<group>"; };
 		02FD8AEE1BFC18D60014BFFB /* ExtendedNSStringTests.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ExtendedNSStringTests.swift; sourceTree = "<group>"; };
+		1EC163511D5992D900DD2928 /* VerticalWhitespaceRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = VerticalWhitespaceRule.swift; sourceTree = "<group>"; };
 		094385021D5D4F78009168CF /* PrivateOutletRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PrivateOutletRule.swift; sourceTree = "<group>"; };
 		1F11B3CE1C252F23002E8FA8 /* ClosingBraceRule.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ClosingBraceRule.swift; sourceTree = "<group>"; };
 		24E17F701B1481FF008195BE /* File+Cache.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "File+Cache.swift"; sourceTree = "<group>"; };
@@ -615,6 +617,7 @@
 				E88DEA911B099B1F00A66CB0 /* TypeNameRule.swift */,
 				E81CDE701C00FEAA00B430F6 /* ValidDocsRule.swift */,
 				E88DEA931B099C0900A66CB0 /* VariableNameRule.swift */,
+				1EC163511D5992D900DD2928 /* VerticalWhitespaceRule.swift */,
 			);
 			path = Rules;
 			sourceTree = "<group>";
@@ -906,6 +909,7 @@
 				006ECFC41C44E99E00EF6364 /* LegacyConstantRule.swift in Sources */,
 				E88DEA731B0984C400A66CB0 /* String+SwiftLint.swift in Sources */,
 				E88198591BEA95F100333A11 /* LeadingWhitespaceRule.swift in Sources */,
+				1EC163521D5992D900DD2928 /* VerticalWhitespaceRule.swift in Sources */,
 				57ED827B1CF656E3002B3513 /* JUnitReporter.swift in Sources */,
 				24E17F721B14BB3F008195BE /* File+Cache.swift in Sources */,
 				E80E018F1B92C1350078EB70 /* Region.swift in Sources */,

Tests/SwiftLintFramework/FunctionBodyLengthRuleTests.swift

@@ -31,6 +31,7 @@ class FunctionBodyLengthRuleTests: XCTestCase {
             "whitespace: currently spans 41 lines")])
 
         let longerFunctionBodyWithEmptyLines = funcWithBody(
+            "// swiftlint:disable vertical_whitespace\n" +
             Repeat(count: 100, repeatedValue: "\n").joinWithSeparator("")
         )
         XCTAssertEqual(violations(longerFunctionBodyWithEmptyLines), [])

Tests/SwiftLintFramework/RulesTests.swift

@@ -162,6 +162,10 @@ class RulesTests: XCTestCase {
         verifyRule(NestingRule.description)
     }
 
+    func testVerticalWhitespace() {
+        verifyRule(VerticalWhitespaceRule.description)
+    }
+
     func testOpeningBrace() {
         verifyRule(OpeningBraceRule.description)
     }