建立标准编码规则（三）-CodeFixProvider 给代码分析器增加修复建议

public abstract ImmutableArray<string> FixableDiagnosticIds { get; } //这里是对应的诊断代码ID

public virtual FixAllProvider GetFixAllProvider() //获取修复的方式 这里没搞明白

public abstract Task RegisterCodeFixesAsync(CodeFixContext context)//注册到方法中

        /// <summary>
        /// 修复代码
        /// 1 获取语义模型
        /// 2 找到正值表达式
        /// 3 给出正确的表达式
        /// 4 返回语法树新节点document
        /// </summary>
        /// <param name="document"></param>
        /// <param name="invocationExpr"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        private async Task<Document> FixRegexAsync(Document document,InvocationExpressionSyntax invocationExpr,CancellationToken cancellationToken)
        {
            var sementicModel = await document.GetSemanticModelAsync(cancellationToken);
            var memberAccessExpr = invocationExpr.Expression as MemberAccessExpressionSyntax;
            var memberSymbol = sementicModel.GetSymbolInfo(memberAccessExpr).Symbol as IMethodSymbol;
            var argumentList = invocationExpr.ArgumentList as ArgumentListSyntax;
            var regexLiteral =
                argumentList.Arguments[1].Expression as LiteralExpressionSyntax;
            var regexOpt = sementicModel.GetConstantValue(regexLiteral);
            var regx = regexOpt.Value as string;
            var newLiteral = SyntaxFactory.ParseExpression("\"valid regex\"")
                .WithLeadingTrivia(regexLiteral.GetLeadingTrivia())
                .WithTrailingTrivia(regexLiteral.GetTrailingTrivia())
                .WithAdditionalAnnotations(Formatter.Annotation);
            var root = await document.GetSyntaxRootAsync();
            var newroot = root.ReplaceNode(regexLiteral, newLiteral);
            var newDocument = document.WithSyntaxRoot(newroot);
            return newDocument;
        }