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| 1 | +//===----------------------------------------------------------------------===// |
| 2 | +// |
| 3 | +// This source file is part of the Swift.org open source project |
| 4 | +// |
| 5 | +// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors |
| 6 | +// Licensed under Apache License v2.0 with Runtime Library Exception |
| 7 | +// |
| 8 | +// See https://swift.org/LICENSE.txt for license information |
| 9 | +// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors |
| 10 | +// |
| 11 | +//===----------------------------------------------------------------------===// |
| 12 | + |
| 13 | +import SwiftSyntax |
| 14 | + |
| 15 | +/// Empty lines are forbidden after opening braces and before closing braces. |
| 16 | +/// |
| 17 | +/// Lint: Empty lines after opening braces and before closing braces yield a lint error. |
| 18 | +/// |
| 19 | +/// Format: Empty lines after opening braces and before closing braces will be removed. |
| 20 | +@_spi(Rules) |
| 21 | +public final class NoEmptyLinesOpeningClosingBraces: SyntaxFormatRule { |
| 22 | + public override class var isOptIn: Bool { return true } |
| 23 | + |
| 24 | + public override func visit(_ node: AccessorBlockSyntax) -> AccessorBlockSyntax { |
| 25 | + var result = node |
| 26 | + switch node.accessors { |
| 27 | + case .accessors(let accessors): |
| 28 | + result.accessors = .init(rewritten(accessors)) |
| 29 | + case .getter(let getter): |
| 30 | + result.accessors = .init(rewritten(getter)) |
| 31 | + } |
| 32 | + result.rightBrace = rewritten(node.rightBrace) |
| 33 | + return result |
| 34 | + } |
| 35 | + |
| 36 | + public override func visit(_ node: CodeBlockSyntax) -> CodeBlockSyntax { |
| 37 | + var result = node |
| 38 | + result.statements = rewritten(node.statements) |
| 39 | + result.rightBrace = rewritten(node.rightBrace) |
| 40 | + return result |
| 41 | + } |
| 42 | + |
| 43 | + public override func visit(_ node: MemberBlockSyntax) -> MemberBlockSyntax { |
| 44 | + var result = node |
| 45 | + result.members = rewritten(node.members) |
| 46 | + result.rightBrace = rewritten(node.rightBrace) |
| 47 | + return result |
| 48 | + } |
| 49 | + |
| 50 | + public override func visit(_ node: ClosureExprSyntax) -> ExprSyntax { |
| 51 | + var result = node |
| 52 | + result.statements = rewritten(node.statements) |
| 53 | + result.rightBrace = rewritten(node.rightBrace) |
| 54 | + return ExprSyntax(result) |
| 55 | + } |
| 56 | + |
| 57 | + public override func visit(_ node: SwitchExprSyntax) -> ExprSyntax { |
| 58 | + var result = node |
| 59 | + result.cases = rewritten(node.cases) |
| 60 | + result.rightBrace = rewritten(node.rightBrace) |
| 61 | + return ExprSyntax(result) |
| 62 | + } |
| 63 | + |
| 64 | + public override func visit(_ node: PrecedenceGroupDeclSyntax) -> DeclSyntax { |
| 65 | + var result = node |
| 66 | + result.attributes = rewritten(node.attributes) |
| 67 | + result.rightBrace = rewritten(node.rightBrace) |
| 68 | + return DeclSyntax(result) |
| 69 | + } |
| 70 | + |
| 71 | + func rewritten(_ token: TokenSyntax) -> TokenSyntax { |
| 72 | + let (trimmedLeadingTrivia, count) = token.leadingTrivia.trimmingSuperfluousNewlines() |
| 73 | + if trimmedLeadingTrivia.sourceLength != token.leadingTriviaLength { |
| 74 | + diagnose(.removeEmptyLinesBefore(count), on: token, anchor: .start) |
| 75 | + return token.with(\.leadingTrivia, trimmedLeadingTrivia) |
| 76 | + } else { |
| 77 | + return token |
| 78 | + } |
| 79 | + } |
| 80 | + |
| 81 | + func rewritten<C: SyntaxCollection>(_ collection: C) -> C { |
| 82 | + var result = collection |
| 83 | + if let first = collection.first, first.leadingTrivia.containsNewlines, |
| 84 | + let index = collection.index(of: first) |
| 85 | + { |
| 86 | + let (trimmedLeadingTrivia, count) = first.leadingTrivia.trimmingSuperfluousNewlines() |
| 87 | + if trimmedLeadingTrivia.sourceLength != first.leadingTriviaLength { |
| 88 | + diagnose(.removeEmptyLinesAfter(count), on: first, anchor: .leadingTrivia(0)) |
| 89 | + result[index] = first.with(\.leadingTrivia, trimmedLeadingTrivia) |
| 90 | + } |
| 91 | + } |
| 92 | + return rewrite(result).as(C.self)! |
| 93 | + } |
| 94 | +} |
| 95 | + |
| 96 | +extension Trivia { |
| 97 | + func trimmingSuperfluousNewlines() -> (Trivia, Int) { |
| 98 | + var trimmmed = 0 |
| 99 | + let pieces = self.indices.reduce([TriviaPiece]()) { (partialResult, index) in |
| 100 | + let piece = self[index] |
| 101 | + // Collapse consecutive newlines into a single one |
| 102 | + if case .newlines(let count) = piece { |
| 103 | + if let last = partialResult.last, last.isNewline { |
| 104 | + trimmmed += count |
| 105 | + return partialResult |
| 106 | + } else { |
| 107 | + trimmmed += count - 1 |
| 108 | + return partialResult + [.newlines(1)] |
| 109 | + } |
| 110 | + } |
| 111 | + // Remove spaces/tabs surrounded by newlines |
| 112 | + if piece.isSpaceOrTab, index > 0, index < self.count - 1, self[index - 1].isNewline, self[index + 1].isNewline { |
| 113 | + return partialResult |
| 114 | + } |
| 115 | + // Retain other trivia pieces |
| 116 | + return partialResult + [piece] |
| 117 | + } |
| 118 | + |
| 119 | + return (Trivia(pieces: pieces), trimmmed) |
| 120 | + } |
| 121 | +} |
| 122 | + |
| 123 | +extension Finding.Message { |
| 124 | + fileprivate static func removeEmptyLinesAfter(_ count: Int) -> Finding.Message { |
| 125 | + "remove empty \(count > 1 ? "lines" : "line") after '{'" |
| 126 | + } |
| 127 | + |
| 128 | + fileprivate static func removeEmptyLinesBefore(_ count: Int) -> Finding.Message { |
| 129 | + "remove empty \(count > 1 ? "lines" : "line") before '}'" |
| 130 | + } |
| 131 | +} |
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