C# ISourceGenerator

通过ISourceGenerator可以实现代码生成，这个例子网上好多，就不再重复说了，但是有几个关键点不注意的话，生成不了代码

项目结构如下

1、dll代码

using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Text;
using System.Text;

namespace SourceGeneratorSamples
{
    [Generator]
    public class HelloWorldGenerator : ISourceGenerator
    {
        public void Execute(GeneratorExecutionContext context)
        {
            // begin creating the source we'll inject into the users compilation
            var sourceBuilder = new StringBuilder(@"
using System;
namespace HelloWorldGenerated
{
    public static class HelloWorld
    {
        public static void SayHello() 
        {
            Console.WriteLine(""Hello from generated code!"");
            Console.WriteLine(""The following syntax trees existed in the compilation that created this program:"");
");

            // using the context, get a list of syntax trees in the users compilation
            var syntaxTrees = context.Compilation.SyntaxTrees;

            // add the filepath of each tree to the class we're building
            foreach (SyntaxTree tree in syntaxTrees)
            {
                sourceBuilder.AppendLine($@"Console.WriteLine(@"" - {tree.FilePath}"");");
            }

            // finish creating the source to inject
            sourceBuilder.Append(@"
        }
    }
}");

            // inject the created source into the users compilation
            context.AddSource("helloWorldGenerator", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));
        }


        public void Initialize(GeneratorInitializationContext context)
        {
            // No initialization required for this one
        }
    }
}

　2、调用代码

using Nest;
using System;

using SourceGeneratorSamples;
namespace ConsoleApp2
{
    class Program
    {
        static void Main(string[] args)
        {
            SomeMethodIHave();


        }
        static void SomeMethodIHave()
        {
            HelloWorldGenerated.HelloWorld.SayHello(); // calls Console.WriteLine("Hello World!") and then prints out 		syntax trees
        }
    }
}

3、需要注意两点

调用者proj文件里要这样写

  <ItemGroup>
    <ProjectReference Include="..ClassLibrary2ClassLibrary2.csproj">
      <Private>true</Private>
    </ProjectReference>
  </ItemGroup>

  <ItemGroup>
      <Analyzer Include="..ClassLibrary2inDebug
etstandard2.0ClassLibrary2.dll"/>
  </ItemGroup>

或者这样写

 <ItemGroup>
    <ProjectReference Include="..ClassLibrary2ClassLibrary2.csproj" OutputItemType="Analyzer" ReferenceOutputAssembly="true"/>
 </ItemGroup>