Migrate VerticalWhitespaceClosingBracesRule to SwiftSyntax

CHANGELOG.md

@@ -42,6 +42,7 @@
   * `line_length`
   * `trailing_whitespace`
   * `vertical_whitespace`
+  * `vertical_whitespace_closing_braces`
   <!-- Keep empty line to have the contributors on a separate line. -->
   [JP Simard](https://github.com/jpsim)
   [Matt Pennig](https://github.com/pennig)

Source/SwiftLintBuiltInRules/Rules/Style/VerticalWhitespaceClosingBracesRule.swift

@@ -1,7 +1,8 @@
-import Foundation
-import SourceKittenFramework
+import SwiftLintCore
+import SwiftSyntax
 
-struct VerticalWhitespaceClosingBracesRule: CorrectableRule, OptInRule {
+@SwiftSyntaxRule(correctable: true, optIn: true)
+struct VerticalWhitespaceClosingBracesRule: Rule {
     var configuration = VerticalWhitespaceClosingBracesConfiguration()
 
     static let description = RuleDescription(
@@ -14,52 +15,304 @@ struct VerticalWhitespaceClosingBracesRule: CorrectableRule, OptInRule {
         triggeringExamples: Array(VerticalWhitespaceClosingBracesRuleExamples.violatingToValidExamples.keys.sorted()),
         corrections: VerticalWhitespaceClosingBracesRuleExamples.violatingToValidExamples.removingViolationMarkers()
     )
+}
+
+private struct TriviaAnalysis {
+    var consecutiveNewlines = 0
+    var violationStartPosition: AbsolutePosition?
+    var violationEndPosition: AbsolutePosition?
+}
 
-    private let pattern = "((?:\\n[ \\t]*)+)(\\n[ \\t]*[)}\\]])"
-    private let trivialLinePattern = "((?:\\n[ \\t]*)+)(\\n[ \\t)}\\]]*$)"
+private struct CorrectionState {
+    var result = [TriviaPiece]()
+    var consecutiveNewlines = 0
+    var pendingWhitespace = [TriviaPiece]()
+    var correctionCount = 0
+    var hasViolation = false
+}
 
-    func validate(file: SwiftLintFile) -> [StyleViolation] {
-        let pattern = configuration.onlyEnforceBeforeTrivialLines ? self.trivialLinePattern : self.pattern
+private struct NewlineProcessingContext {
+    let currentPosition: AbsolutePosition
+    let consecutiveNewlines: Int
+    var violationStartPosition: AbsolutePosition?
+    var violationEndPosition: AbsolutePosition?
+}
 
-        let patternRegex: NSRegularExpression = regex(pattern)
+private func isTokenLineTrivialHelper(
+    for token: TokenSyntax,
+    file: SwiftLintFile,
+    locationConverter: SourceLocationConverter
+) -> Bool {
+    let lineColumn = locationConverter.location(for: token.positionAfterSkippingLeadingTrivia)
+    let line = lineColumn.line
 
-        return file.violatingRanges(for: pattern).map { violationRange in
-            let substring = file.contents.substring(from: violationRange.location, length: violationRange.length)
-            let matchResult = patternRegex.firstMatch(in: substring, options: [], range: substring.fullNSRange)!
-            let violatingSubrange = matchResult.range(at: 1)
-            let characterOffset = violationRange.location + violatingSubrange.location + 1
+    guard let lineContent = file.lines.first(where: { $0.index == line })?.content else {
+        return false
+    }
 
-            return StyleViolation(
-                ruleDescription: Self.description,
-                severity: configuration.severityConfiguration.severity,
-                location: Location(file: file, characterOffset: characterOffset)
+    let trimmedLine = lineContent.trimmingCharacters(in: .whitespaces)
+    let closingBraces: Set<Character> = ["]", "}", ")"]
+    return !trimmedLine.isEmpty && trimmedLine.allSatisfy { closingBraces.contains($0) }
+}
+
+private extension VerticalWhitespaceClosingBracesRule {
+    final class Visitor: ViolationsSyntaxVisitor<VerticalWhitespaceClosingBracesConfiguration> {
+        override func visitPost(_ node: TokenSyntax) {
+            guard node.isClosingBrace else {
+                return
+            }
+
+            let triviaAnalysis = analyzeTriviaForViolations(
+                trivia: node.leadingTrivia,
+                token: node,
+                position: node.position
             )
+
+            if let violation = triviaAnalysis {
+                violations.append(
+                    ReasonedRuleViolation(
+                        position: violation.position,
+                        correction: .init(
+                            start: violation.position,
+                            end: violation.endPosition,
+                            replacement: ""
+                        )
+                    )
+                )
+            }
+        }
+
+        private func analyzeTriviaForViolations(
+            trivia: Trivia,
+            token: TokenSyntax,
+            position: AbsolutePosition
+        ) -> (position: AbsolutePosition, endPosition: AbsolutePosition)? {
+            let analysis = analyzeTrivia(trivia: trivia, startPosition: position)
+
+            guard let startPos = analysis.violationStartPosition,
+                  let endPos = analysis.violationEndPosition,
+                  analysis.consecutiveNewlines >= 2 else {
+                return nil
+            }
+
+            if configuration.onlyEnforceBeforeTrivialLines &&
+                !isTokenLineTrivialHelper(for: token, file: file, locationConverter: locationConverter) {
+                return nil
+            }
+
+            return (position: startPos, endPosition: endPos)
+        }
+
+        private func analyzeTrivia(
+            trivia: Trivia,
+            startPosition: AbsolutePosition
+        ) -> TriviaAnalysis {
+            var result = TriviaAnalysis()
+            var currentPosition = startPosition
+
+            for piece in trivia {
+                let (newlines, positionAdvance) = processTriviaPiece(
+                    piece: piece,
+                    currentPosition: currentPosition,
+                    consecutiveNewlines: result.consecutiveNewlines,
+                    violationStartPosition: &result.violationStartPosition,
+                    violationEndPosition: &result.violationEndPosition
+                )
+                result.consecutiveNewlines = newlines
+                currentPosition = currentPosition.advanced(by: positionAdvance)
+            }
+
+            return result
+        }
+
+        private func processTriviaPiece(
+            piece: TriviaPiece,
+            currentPosition: AbsolutePosition,
+            consecutiveNewlines: Int,
+            violationStartPosition: inout AbsolutePosition?,
+            violationEndPosition: inout AbsolutePosition?
+        ) -> (newlines: Int, positionAdvance: Int) {
+            switch piece {
+            case .newlines(let count), .carriageReturns(let count):
+                var context = NewlineProcessingContext(
+                    currentPosition: currentPosition,
+                    consecutiveNewlines: consecutiveNewlines,
+                    violationStartPosition: violationStartPosition,
+                    violationEndPosition: violationEndPosition
+                )
+                let result = processNewlines(
+                    count: count,
+                    bytesPerNewline: 1,
+                    context: &context
+                )
+                violationStartPosition = context.violationStartPosition
+                violationEndPosition = context.violationEndPosition
+                return result
+            case .carriageReturnLineFeeds(let count):
+                var context = NewlineProcessingContext(
+                    currentPosition: currentPosition,
+                    consecutiveNewlines: consecutiveNewlines,
+                    violationStartPosition: violationStartPosition,
+                    violationEndPosition: violationEndPosition
+                )
+                let result = processNewlines(
+                    count: count,
+                    bytesPerNewline: 2,
+                    context: &context
+                )
+                violationStartPosition = context.violationStartPosition
+                violationEndPosition = context.violationEndPosition
+                return result
+            case .spaces, .tabs:
+                return (consecutiveNewlines, piece.sourceLength.utf8Length)
+            default:
+                // Any other trivia breaks the sequence
+                violationStartPosition = nil
+                violationEndPosition = nil
+                return (0, piece.sourceLength.utf8Length)
+            }
         }
-    }
 
-    func correct(file: SwiftLintFile) -> Int {
-        let pattern = configuration.onlyEnforceBeforeTrivialLines ? self.trivialLinePattern : self.pattern
-        let violatingRanges = file.ruleEnabled(violatingRanges: file.violatingRanges(for: pattern), for: self)
-        guard violatingRanges.isNotEmpty else {
-            return 0
+        private func processNewlines(
+            count: Int,
+            bytesPerNewline: Int,
+            context: inout NewlineProcessingContext
+        ) -> (newlines: Int, positionAdvance: Int) {
+            var newConsecutiveNewlines = context.consecutiveNewlines
+            var totalAdvance = 0
+
+            for _ in 0..<count {
+                newConsecutiveNewlines += 1
+                // violationStartPosition marks the beginning of the first newline
+                // that constitutes an empty line (i.e., the second in a sequence of \n\n).
+                if newConsecutiveNewlines == 2 && context.violationStartPosition == nil {
+                    context.violationStartPosition = context.currentPosition.advanced(by: totalAdvance)
+                }
+                // violationEndPosition tracks the end of the last newline in any sequence of >= 2 newlines.
+                if newConsecutiveNewlines >= 2 {
+                    context.violationEndPosition = context.currentPosition.advanced(by: totalAdvance + bytesPerNewline)
+                }
+                totalAdvance += bytesPerNewline
+            }
+
+            return (newConsecutiveNewlines, totalAdvance)
         }
-        let patternRegex = regex(pattern)
-        var fileContents = file.contents
-        for violationRange in violatingRanges.reversed() {
-            fileContents = patternRegex.stringByReplacingMatches(
-                in: fileContents,
-                options: [],
-                range: violationRange,
-                withTemplate: "$2"
+    }
+
+    final class Rewriter: ViolationsSyntaxRewriter<VerticalWhitespaceClosingBracesConfiguration> {
+        override func visit(_ token: TokenSyntax) -> TokenSyntax {
+            guard token.isClosingBrace else {
+                return super.visit(token)
+            }
+
+            let correctedTrivia = correctTrivia(
+                trivia: token.leadingTrivia,
+                token: token
             )
+
+            if correctedTrivia.hasCorrections {
+                numberOfCorrections += correctedTrivia.correctionCount
+                return super.visit(token.with(\.leadingTrivia, correctedTrivia.trivia))
+            }
+
+            return super.visit(token)
+        }
+
+        private func correctTrivia(
+            trivia: Trivia,
+            token: TokenSyntax
+        ) -> (trivia: Trivia, hasCorrections: Bool, correctionCount: Int) {
+            // First check if we should apply corrections
+            if configuration.onlyEnforceBeforeTrivialLines &&
+                !isTokenLineTrivialHelper(for: token, file: file, locationConverter: locationConverter) {
+                return (trivia: trivia, hasCorrections: false, correctionCount: 0)
+            }
+
+            var state = CorrectionState()
+
+            for piece in trivia {
+                processPieceForCorrection(piece: piece, state: &state)
+            }
+
+            // Add any remaining whitespace
+            state.result.append(contentsOf: state.pendingWhitespace)
+
+            return (trivia: Trivia(pieces: state.result),
+                    hasCorrections: state.correctionCount > 0,
+                    correctionCount: state.correctionCount)
+        }
+
+        private func processPieceForCorrection(piece: TriviaPiece, state: inout CorrectionState) {
+            switch piece {
+            case .newlines(let count), .carriageReturns(let count):
+                let newlineCreator = piece.isNewline ? TriviaPiece.newlines : TriviaPiece.carriageReturns
+                processNewlinesForCorrection(
+                    count: count,
+                    newlineCreator: { newlineCreator($0) },
+                    state: &state
+                )
+            case .carriageReturnLineFeeds(let count):
+                processNewlinesForCorrection(
+                    count: count,
+                    newlineCreator: { TriviaPiece.carriageReturnLineFeeds($0) },
+                    state: &state
+                )
+            case .spaces, .tabs:
+                // Only keep whitespace if we haven't seen a violation yet
+                if !state.hasViolation {
+                    state.pendingWhitespace.append(piece)
+                }
+            default:
+                // Other trivia breaks the sequence
+                state.consecutiveNewlines = 0
+                state.hasViolation = false
+                state.result.append(contentsOf: state.pendingWhitespace)
+                state.result.append(piece)
+                state.pendingWhitespace.removeAll()
+            }
+        }
+
+        private func processNewlinesForCorrection(
+            count: Int,
+            newlineCreator: (Int) -> TriviaPiece,
+            state: inout CorrectionState
+        ) {
+            for _ in 0..<count {
+                state.consecutiveNewlines += 1
+                if state.consecutiveNewlines == 1 {
+                    // First newline - always keep it with any preceding whitespace
+                    state.result.append(contentsOf: state.pendingWhitespace)
+                    state.result.append(newlineCreator(1))
+                    state.pendingWhitespace.removeAll()
+                } else {
+                    // Additional newlines - these form empty lines and should be removed
+                    state.hasViolation = true
+                    state.correctionCount += 1
+                    state.pendingWhitespace.removeAll()
+                }
+            }
         }
-        file.write(fileContents)
-        return violatingRanges.count
     }
 }
 
-private extension SwiftLintFile {
-    func violatingRanges(for pattern: String) -> [NSRange] {
-        match(pattern: pattern, excludingSyntaxKinds: SyntaxKind.commentAndStringKinds)
+private extension TokenSyntax {
+    var isClosingBrace: Bool {
+        switch tokenKind {
+        case .rightBrace, .rightParen, .rightSquare:
+            return true
+        default:
+            return false
+        }
+    }
+}
+
+private extension TriviaPiece {
+    var isNewline: Bool {
+        switch self {
+        case .newlines, .carriageReturns, .carriageReturnLineFeeds:
+            return true
+        default:
+            return false
+        }
     }
 }