我們一樣還是透過 CursorInfo 查詢

並取得 key.annotated_decl

範例

let a = 1
weak var wa = a
print(wa)

key.annotated_decl

是一個 xml 的格式，但是我們只需要裡面的值

<Declaration>
    let a: <Type usr=\"s:Si\">Int</Type>
</Declaration>

<decl.var.local>
    <syntaxtype.keyword>weak</syntaxtype.keyword>
    <syntaxtype.keyword>var</syntaxtype.keyword>
    ` `
    <decl.name>wa</decl.name>
    `: `
    <decl.var.type>
        <ref.struct usr=\"s:Si\">Int</ref.struct>
        ?
    </decl.var.type>
</decl.var.local>

取得 value

let a: Int

weak var wa: Int?

detect weak

最終我們可以取得類似於這三種範例

• weak var c: Int?
• unowned var c: Int
• var c: Int

WeakDetector

為了避免判斷錯誤，於是用一個 visitor 去訪問他

public enum WeakDetector {
  public static func detect(code: String) -> Bool {
    let target: String = code
    let source: SourceFileSyntax = Parser.parse(source: target)
    let visitor = WeakVisitor(viewMode: .sourceAccurate)
    visitor.walk(source)
    return visitor.isHaveWeak || visitor.isHaveUnowned
  }
}

private final class WeakVisitor: SyntaxVisitor {
  var isHaveWeak: Bool = false
  var isHaveUnowned: Bool = false
  override func visit(_ node: VariableDeclSyntax) -> SyntaxVisitorContinueKind {
    let modifiers = node.modifiers?.map { $0.withoutTrivia().description } ?? []
    isHaveWeak = modifiers.contains("weak")
    isHaveUnowned = modifiers.contains("unowned")

    return .skipChildren
  }
}