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Add
unowned_variable_capture
opt-in rule
Fixes #2097
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82 changes: 82 additions & 0 deletions
82
Source/SwiftLintFramework/Rules/Lint/UnownedVariableCaptureRule.swift
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,82 @@ | ||
import Foundation | ||
import SourceKittenFramework | ||
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public struct UnownedVariableCaptureRule: ASTRule, OptInRule, ConfigurationProviderRule, AutomaticTestableRule { | ||
public var configuration = SeverityConfiguration(.warning) | ||
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public init() {} | ||
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public static let description = RuleDescription( | ||
identifier: "unowned_variable_capture", | ||
name: "Unowned Variable Capture", | ||
description: "Prefer capturing references as weak to avoid potential crashes.", | ||
kind: .lint, | ||
minSwiftVersion: .five, | ||
nonTriggeringExamples: [ | ||
"foo { [weak self] in _ }", | ||
"foo { [weak self] param in _ }", | ||
"foo { [weak bar] in _ }", | ||
"foo { [weak bar] param in _ }", | ||
"foo { bar in _ }", | ||
"foo { $0 }" | ||
], | ||
triggeringExamples: [ | ||
"foo { [↓unowned self] in _ }", | ||
"foo { [↓unowned bar] in _ }", | ||
"foo { [bar, ↓unowned self] in _ }" | ||
] | ||
) | ||
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public func validate(file: File, kind: SwiftExpressionKind, | ||
dictionary: [String: SourceKitRepresentable]) -> [StyleViolation] { | ||
guard kind == .closure, let bodyOffset = dictionary.bodyOffset, let bodyLength = dictionary.bodyLength, | ||
case let contents = file.contents.bridge(), | ||
let closureRange = contents.byteRangeToNSRange(start: bodyOffset, length: bodyLength), | ||
let inTokenRange = file.match(pattern: "\\bin\\b", with: [.keyword], range: closureRange).first, | ||
let inTokenByteRange = contents.NSRangeToByteRange(start: inTokenRange.location, | ||
length: inTokenRange.length) else { | ||
return [] | ||
} | ||
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let length = inTokenByteRange.location - bodyOffset | ||
let variables = localVariableDeclarations(inByteRange: NSRange(location: bodyOffset, length: length), | ||
structure: file.structure) | ||
let unownedVariableOffsets = variables.compactMap { dictionary in | ||
return dictionary.swiftAttributes.first { attributeDict in | ||
guard attributeDict.attribute.flatMap(SwiftDeclarationAttributeKind.init) == .weak, | ||
let offset = attributeDict.offset, let length = attributeDict.length else { | ||
return false | ||
} | ||
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return contents.substringWithByteRange(start: offset, length: length) == "unowned" | ||
}?.offset | ||
} | ||
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return unownedVariableOffsets.map { offset in | ||
return StyleViolation(ruleDescription: type(of: self).description, | ||
severity: configuration.severity, | ||
location: Location(file: file, byteOffset: offset)) | ||
} | ||
} | ||
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private func localVariableDeclarations(inByteRange byteRange: NSRange, | ||
structure: Structure) -> [[String: SourceKitRepresentable]] { | ||
var results = [[String: SourceKitRepresentable]]() | ||
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func parse(dictionary: [String: SourceKitRepresentable]) { | ||
if let kindString = (dictionary.kind), | ||
SwiftDeclarationKind(rawValue: kindString) == .varLocal, | ||
let offset = dictionary.offset, | ||
let length = dictionary.length { | ||
let variableByteRange = NSRange(location: offset, length: length) | ||
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if byteRange.intersects(variableByteRange) { | ||
results.append(dictionary) | ||
} | ||
} | ||
dictionary.substructure.forEach(parse) | ||
} | ||
parse(dictionary: structure.dictionary) | ||
return results | ||
} | ||
} |
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