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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2019 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
/// Function calls with no arguments and a trailing closure should not have empty parentheses.
///
/// Lint: If a function call with a trailing closure has an empty argument list with parentheses,
/// a lint error is raised.
///
/// Format: Empty parentheses in function calls with trailing closures will be removed.
@_spi(Rules)
public final class NoEmptyTrailingClosureParentheses: SyntaxFormatRule {
public override func visit(_ node: FunctionCallExprSyntax) -> ExprSyntax {
guard node.arguments.count == 0 else { return super.visit(node) }
guard
let trailingClosure = node.trailingClosure,
let leftParen = node.leftParen,
let rightParen = node.rightParen,
node.arguments.isEmpty,
!leftParen.trailingTrivia.hasAnyComments,
!rightParen.leadingTrivia.hasAnyComments
else {
return super.visit(node)
}
guard let name = node.calledExpression.lastToken(viewMode: .sourceAccurate) else {
return super.visit(node)
}
diagnose(.removeEmptyTrailingParentheses(name: "\(name.trimmedDescription)"), on: leftParen)
// Need to visit `calledExpression` before creating a new node so that the location data (column
// and line numbers) is available.
guard var rewrittenCalledExpr = ExprSyntax(rewrite(Syntax(node.calledExpression))) else {
return super.visit(node)
}
rewrittenCalledExpr.trailingTrivia = [.spaces(1)]
var result = node
result.leftParen = nil
result.rightParen = nil
result.calledExpression = rewrittenCalledExpr
result.trailingClosure = rewrite(trailingClosure).as(ClosureExprSyntax.self)
return ExprSyntax(result)
}
}
extension Finding.Message {
fileprivate static func removeEmptyTrailingParentheses(name: String) -> Finding.Message {
"remove the empty parentheses following '\(name)'"
}
}
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