将C＃代码与roslyn合并：注释消失

问题描述

场景：我正在尝试使用Roslyn将一组C＃源代码片段合并为一个代码片段。

问题：使用前导注释解析不同的类时，不会保留第一类（示例中的SomeClass）上方的注释。对于第二类（AnotherClass），注释保留...

下面的代码演示了该问题。在控制台程序中使用此程序（并安装Microsoft.CodeAnalysis.CSharp nuget程序包）

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using System.Collections.Generic;
using System.Diagnostics;
using System;

namespace roslyn01
{
    class Program
    {
        static void Main(string[] args)
        {
            var input = new[]
            {
               "// some comment\r\nclass SomeClass {}","// another comment\r\nclass AnotherClass {}",};

            // parse all input and collect members
            var members = new List<MemberDeclarationSyntax>();
            foreach (var item in input)
            {
                var SyntaxTree = CSharpSyntaxTree.ParseText(item);
                var compilationunit = (compilationunitSyntax)SyntaxTree.GetRoot();
                members.AddRange(compilationunit.Members);
            }

            // assemble all members in a new compilation unit
            var result = SyntaxFactory.compilationunit()
                .AddMembers(members.ToArray())
                .normalizeWhitespace()
                .ToString();

            var expected = @"// some comment
class SomeClass
{
}

// another comment
class AnotherClass
{
}";

            Console.WriteLine(result);
            // the assert fails; the first comment ('// some comment') is missing from the output
            Debug.Assert(expected == result);
        }
    }
}

我想念什么？

解决方法

将ToString()转换为ToFullString()时，您使用的是CompilationUnitSyntax而不是string。 ToString()返回删除前导和尾随琐事（包括注释）的字符串，但是ToFullString()不会删除此琐事。您可以在代码文档中看到它：

//
// Description:
//     Returns the string representation of this node,not including its leading and
//     trailing trivia.
//
// Returns:
//     The string representation of this node,not including its leading and trailing
//     trivia.
//
// Comments:
//     The length of the returned string is always the same as Span.Length
public override string ToString();

//
// Description:
//     Returns full string representation of this node including its leading and trailing
//     trivia.
//
// Returns:
//     The full string representation of this node including its leading and trailing
//     trivia.
//
// Comments:
//     The length of the returned string is always the same as FullSpan.Length
public virtual string ToFullString();