我正在编写一个
Roslyn Code Analyzer,我想识别异步方法是否不采用CancellationToken然后建议添加它的代码修复:
//Before Code Fix:
public async Task Example(){}
//After Code Fix
public async Task Example(CancellationToken token){}
我已经通过检查methodDeclaration.ParameterList.Parameters来连接DiagnosticAnalyzer来正确报告Diagnostic,但是我找不到Roslyn API来将Paramater添加到CodeFixProvider中的ParameterList.
这是我到目前为止所得到的:
private async Task<Document> HaveMethodTakeACancellationTokenParameter(
Document document, SyntaxNode syntaxNode, CancellationToken cancellationToken)
{
var method = syntaxNode as MethodDeclarationSyntax;
// what goes here?
// what I want to do is:
// method.ParameterList.Parameters.Add(
new ParameterSyntax(typeof(CancellationToken));
//somehow return the Document from method
}
如何正确更新方法声明并返回更新的文档?
最佳答案 @Nate Barbettini是正确的,语法节点都是不可变的,所以我需要创建一个新版本的MethodDeclarationSyntax,然后用文档的SyntaxTree中的new方法替换旧方法:
private async Task<Document> HaveMethodTakeACancellationTokenParameter(
Document document, SyntaxNode syntaxNode, CancellationToken cancellationToken)
{
var method = syntaxNode as MethodDeclarationSyntax;
var updatedMethod = method.AddParameterListParameters(
SyntaxFactory.Parameter(
SyntaxFactory.Identifier("cancellationToken"))
.WithType(SyntaxFactory.ParseTypeName(typeof (CancellationToken).FullName)));
var syntaxTree = await document.GetSyntaxTreeAsync(cancellationToken);
var updatedSyntaxTree =
syntaxTree.GetRoot().ReplaceNode(method, updatedMethod);
return document.WithSyntaxRoot(updatedSyntaxTree);
}