91 lines
4.5 KiB
Swift
91 lines
4.5 KiB
Swift
import Foundation
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import SourceKittenFramework
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public struct DiscardedNotificationCenterObserverRule: ASTRule, ConfigurationProviderRule, AutomaticTestableRule {
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public var configuration = SeverityConfiguration(.warning)
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public init() {}
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public static let description = RuleDescription(
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identifier: "discarded_notification_center_observer",
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name: "Discarded Notification Center Observer",
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description: "When registering for a notification using a block, the opaque observer that is " +
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"returned should be stored so it can be removed later.",
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kind: .lint,
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nonTriggeringExamples: [
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"let foo = nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil) { }\n",
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"let foo = nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n",
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"func foo() -> Any {\n" +
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" return nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n" +
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"}\n",
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"var obs: [Any?] = []\n" +
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"obs.append(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))\n",
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"var obs: [String: Any?] = []\n" +
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"obs[\"foo\"] = nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n",
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"var obs: [Any?] = []\n" +
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"obs.append(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))\n",
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"func foo(_ notif: Any) {\n" +
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" obs.append(notif)\n" +
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"}\n" +
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"foo(nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { }))\n"
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],
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triggeringExamples: [
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"↓nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil) { }\n",
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"↓nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n",
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"@discardableResult func foo() -> Any {\n" +
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" return ↓nc.addObserver(forName: .NSSystemTimeZoneDidChange, object: nil, queue: nil, using: { })\n" +
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"}\n"
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]
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)
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public func validate(file: SwiftLintFile, kind: SwiftExpressionKind,
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dictionary: SourceKittenDictionary) -> [StyleViolation] {
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return violationOffsets(in: file, dictionary: dictionary, kind: kind).map { location in
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StyleViolation(ruleDescription: type(of: self).description,
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severity: configuration.severity,
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location: Location(file: file, byteOffset: location))
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}
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}
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private func violationOffsets(in file: SwiftLintFile, dictionary: SourceKittenDictionary,
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kind: SwiftExpressionKind) -> [ByteCount] {
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guard kind == .call,
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let name = dictionary.name,
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name.hasSuffix(".addObserver"),
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case let arguments = dictionary.enclosedArguments,
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case let argumentsNames = arguments.compactMap({ $0.name }),
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argumentsNames == ["forName", "object", "queue"] ||
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argumentsNames == ["forName", "object", "queue", "using"],
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let offset = dictionary.offset,
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let range = file.stringView.byteRangeToNSRange(ByteRange(location: 0, length: offset)) else {
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return []
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}
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if let lastMatch = regex("\\b[^\\(]+").matches(in: file.contents, options: [], range: range).last?.range,
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lastMatch.location == range.length - lastMatch.length - 1 {
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return []
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}
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if let lastMatch = regex("\\s?=\\s*").matches(in: file.contents, options: [], range: range).last?.range,
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lastMatch.location == range.length - lastMatch.length {
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return []
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}
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if let lastMatch = file.match(pattern: "\\breturn\\s+", with: [.keyword], range: range).last,
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lastMatch.location == range.length - lastMatch.length,
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let lastFunction = file.structureDictionary.functions(forByteOffset: offset).last,
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!lastFunction.enclosedSwiftAttributes.contains(.discardableResult) {
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return []
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}
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return [offset]
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}
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}
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private extension SourceKittenDictionary {
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func functions(forByteOffset byteOffset: ByteCount) -> [SourceKittenDictionary] {
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return structures(forByteOffset: byteOffset)
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.filter { $0.declarationKind.map(SwiftDeclarationKind.functionKinds.contains) == true }
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}
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}
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