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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import SwiftSyntax
/// Empty lines are forbidden after opening braces and before closing braces.
///
/// Lint: Empty lines after opening braces and before closing braces yield a lint error.
///
/// Format: Empty lines after opening braces and before closing braces will be removed.
@_spi(Rules)
public final class NoEmptyLinesOpeningClosingBraces: SyntaxFormatRule {
public override class var isOptIn: Bool { return true }
public override func visit(_ node: AccessorBlockSyntax) -> AccessorBlockSyntax {
var result = node
switch node.accessors {
case .accessors(let accessors):
result.accessors = .init(rewritten(accessors))
case .getter(let getter):
result.accessors = .init(rewritten(getter))
}
result.rightBrace = rewritten(node.rightBrace)
return result
}
public override func visit(_ node: CodeBlockSyntax) -> CodeBlockSyntax {
var result = node
result.statements = rewritten(node.statements)
result.rightBrace = rewritten(node.rightBrace)
return result
}
public override func visit(_ node: MemberBlockSyntax) -> MemberBlockSyntax {
var result = node
result.members = rewritten(node.members)
result.rightBrace = rewritten(node.rightBrace)
return result
}
public override func visit(_ node: ClosureExprSyntax) -> ExprSyntax {
var result = node
result.statements = rewritten(node.statements)
result.rightBrace = rewritten(node.rightBrace)
return ExprSyntax(result)
}
public override func visit(_ node: SwitchExprSyntax) -> ExprSyntax {
var result = node
result.cases = rewritten(node.cases)
result.rightBrace = rewritten(node.rightBrace)
return ExprSyntax(result)
}
public override func visit(_ node: PrecedenceGroupDeclSyntax) -> DeclSyntax {
var result = node
result.attributes = rewritten(node.attributes)
result.rightBrace = rewritten(node.rightBrace)
return DeclSyntax(result)
}
func rewritten(_ token: TokenSyntax) -> TokenSyntax {
let (trimmedLeadingTrivia, count) = token.leadingTrivia.trimmingSuperfluousNewlines(
fromClosingBrace: token.tokenKind == .rightBrace
)
if trimmedLeadingTrivia.sourceLength != token.leadingTriviaLength {
diagnose(.removeEmptyLinesBefore(count), on: token, anchor: .start)
return token.with(\.leadingTrivia, trimmedLeadingTrivia)
} else {
return token
}
}
func rewritten<C: SyntaxCollection>(_ collection: C) -> C {
var result = collection
if let first = collection.first, first.leadingTrivia.containsNewlines,
let index = collection.index(of: first)
{
let (trimmedLeadingTrivia, count) = first.leadingTrivia.trimmingSuperfluousNewlines(fromClosingBrace: false)
if trimmedLeadingTrivia.sourceLength != first.leadingTriviaLength {
diagnose(.removeEmptyLinesAfter(count), on: first, anchor: .leadingTrivia(0))
var first = first
first.leadingTrivia = trimmedLeadingTrivia
result[index] = first
}
}
return rewrite(result).as(C.self)!
}
}
extension Trivia {
func trimmingSuperfluousNewlines(fromClosingBrace: Bool) -> (Trivia, Int) {
var trimmmed = 0
var pendingNewlineCount = 0
let pieces = self.indices.reduce([TriviaPiece]()) { (partialResult, index) in
let piece = self[index]
// Collapse consecutive newlines into a single one
if case .newlines(let count) = piece {
if fromClosingBrace {
if index == self.count - 1 {
// For the last index(newline right before the closing brace), collapse into a single newline
trimmmed += count - 1
return partialResult + [.newlines(1)]
} else {
pendingNewlineCount += count
return partialResult
}
} else {
if let last = partialResult.last, last.isNewline {
trimmmed += count
return partialResult
} else if index == 0 {
// For leading trivia not associated with a closing brace, collapse the first newline into a single one
trimmmed += count - 1
return partialResult + [.newlines(1)]
} else {
return partialResult + [piece]
}
}
}
// Remove spaces/tabs surrounded by newlines
if piece.isSpaceOrTab, index > 0, index < self.count - 1, self[index - 1].isNewline, self[index + 1].isNewline {
return partialResult
}
// Handle pending newlines if there are any
if pendingNewlineCount > 0 {
if index < self.count - 1 {
let newlines = TriviaPiece.newlines(pendingNewlineCount)
pendingNewlineCount = 0
return partialResult + [newlines] + [piece]
} else {
return partialResult + [.newlines(1)] + [piece]
}
}
// Retain other trivia pieces
return partialResult + [piece]
}
return (Trivia(pieces: pieces), trimmmed)
}
}
extension Finding.Message {
fileprivate static func removeEmptyLinesAfter(_ count: Int) -> Finding.Message {
"remove empty \(count > 1 ? "lines" : "line") after '{'"
}
fileprivate static func removeEmptyLinesBefore(_ count: Int) -> Finding.Message {
"remove empty \(count > 1 ? "lines" : "line") before '}'"
}
}
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