Question

我可以检测（使用roslyn）lambda体中的x引用是对外部变量x的闭包，而不是lambda本身的一些变量吗？

var x = "foo";
var a = string[0];
a.Any(i => i == x);

Answer 1

烨。您可以使用DataFlowAnalysis API。

var tree = CSharpSyntaxTree.ParseText(
    @"
class C{
void M(){
    var x = ""foo"";
    var a = new string[0];
    var testing = a.Any(i => i == x);
}
} 
");
var Mscorlib = PortableExecutableReference.CreateFromAssembly(typeof(object).Assembly);
var compilation = CSharpCompilation.Create("MyCompilation",
    syntaxTrees: new[] { tree }, references: new[] { Mscorlib });
var model = compilation.GetSemanticModel(tree);

var lambda = tree.GetRoot().DescendantNodes().OfType<LocalDeclarationStatementSyntax>().Last();

var dataFlowAnalysis = model.AnalyzeDataFlow(lambda);
var capturedVariables = dataFlowAnalysis.Captured;

foreach(var variable in capturedVariables)
{
    //Do something
}

Answer 2

https://github.com/mjsabby/RoslynClrHeapAllocationAnalyzer/blob/master/ClrHeapAllocationsAnalyzer/DisplayClassAllocationAnalyzer.cs#L58

（1）获取语义模型

（2）检查 AnonymousMethodExpressionSyntax / SimpleLambdaExpressionSyntax / ParenthesizedLambdaExpressionSyntax

（3）将该节点传递给SemanticModel上的AnalyzeDataFlow扩展方法

（4）迭代.Captured属性

如何使用Roslyn检测代码中的闭包？

2 个答案: