mROA/mROA.Codegen/SampleIncrementalSourceGenerator.cs

using System;
using System.Collections.Generic;
using System.Collections.Immutable;
using System.ComponentModel;
using System.Linq;
using System.Text;
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Microsoft.CodeAnalysis.Text;


namespace mROA.Codegen;

/// <summary>
/// A sample source generator that creates a custom report based on class properties. The target class should be annotated with the 'Generators.ReportAttribute' attribute.
/// When using the source code as a baseline, an incremental source generator is preferable because it reduces the performance overhead.
/// </summary>
[Generator]
public class SampleIncrementalSourceGenerator : IIncrementalGenerator
{
    private const string Namespace = "mROA.Implementation";
    private const string AttributeName = "SharedObjectInterafceAttribute";

    private const string AttributeSourceCode = $@"// <auto-generated/>

namespace {Namespace}
{{
    [System.AttributeUsage(System.AttributeTargets.Class)]
    public class {AttributeName} : System.Attribute
    {{
    }}
}}";

    public void Initialize(IncrementalGeneratorInitializationContext context)
    {
        // Filter classes annotated with the [Report] attribute. Only filtered Syntax Nodes can trigger code generation.
        var provider = context.SyntaxProvider
            .CreateSyntaxProvider(
                (s, _) => s is InterfaceDeclarationSyntax,
                (ctx, _) => GetClassDeclarationForSourceGen(ctx))
            .Where(t => t.reportAttributeFound)
            .Select((t, _) => t.Item1);

        // Generate the source code.
        context.RegisterSourceOutput(context.CompilationProvider.Combine(provider.Collect()),
            ((ctx, t) => GenerateCode(ctx, t.Left, t.Right)));
    }

    /// <summary>
    /// Checks whether the Node is annotated with the [Report] attribute and maps syntax context to the specific node type (ClassDeclarationSyntax).
    /// </summary>
    /// <param name="context">Syntax context, based on CreateSyntaxProvider predicate</param>
    /// <returns>The specific cast and whether the attribute was found.</returns>
    private static (InterfaceDeclarationSyntax, bool reportAttributeFound) GetClassDeclarationForSourceGen(
        GeneratorSyntaxContext context)
    {
        var classDeclarationSyntax = (InterfaceDeclarationSyntax)context.Node;

        // Go through all attributes of the class.
        foreach (AttributeListSyntax attributeListSyntax in classDeclarationSyntax.AttributeLists)
        foreach (AttributeSyntax attributeSyntax in attributeListSyntax.Attributes)
        {
            if (context.SemanticModel.GetSymbolInfo(attributeSyntax).Symbol is not IMethodSymbol attributeSymbol)
                continue; // if we can't get the symbol, ignore it

            string attributeName = attributeSymbol.ContainingType.ToDisplayString();

            // Check the full name of the [Report] attribute.
            if (attributeName == "mROA.Implementation.SharedObjectInterfaceAttribute")
                return (classDeclarationSyntax, true);
        }

        return (classDeclarationSyntax, false);
    }

    /// <summary>
    /// Generate code action.
    /// It will be executed on specific nodes (ClassDeclarationSyntax annotated with the [Report] attribute) changed by the user.
    /// </summary>
    /// <param name="context">Source generation context used to add source files.</param>
    /// <param name="compilation">Compilation used to provide access to the Semantic Model.</param>
    /// <param name="classDeclarations">Nodes annotated with the [Report] attribute that trigger the generate action.</param>
    private void GenerateCode(SourceProductionContext context, Compilation compilation,
        ImmutableArray<InterfaceDeclarationSyntax> classDeclarations)
    {
        var methods = new List<(string, IMethodSymbol)>();
        var frontendContextRepo = new List<string>();
        // Go through all filtered class declarations.
        foreach (var classDeclarationSyntax in classDeclarations)
        {
            // We need to get semantic model of the class to retrieve metadata.
            var semanticModel = compilation.GetSemanticModel(classDeclarationSyntax.SyntaxTree);


            // Symbols allow us to get the compile-time information.
            if (semanticModel.GetDeclaredSymbol(classDeclarationSyntax) is not INamedTypeSymbol classSymbol)
                continue;

            
            var namespaceName = classSymbol.ContainingNamespace.ToDisplayString();

            // 'Identifier' means the token of the node. Get class name from the syntax node.
            var className = classDeclarationSyntax.Identifier.Text;

            // Go through all class members with a particular type (property) to generate method lines.
            var methodBody = classSymbol.GetMembers()
                .OfType<IMethodSymbol>();

            var originalName = className;
            // Build up the source code
            className = className.TrimStart('I') + "RemoteEndpoint";


            var methodsText = new List<string>();

            foreach (var method in methodBody)
            {
                var index = methods.Count;
                methods.Add((namespaceName + "." + originalName, method));
                var sb = new StringBuilder();

                //Creating signature
                // if (method.Parameters.Length == 0)
                //     sb.AppendLine($"public {method.ReturnType.ToDisplayString()} {method.Name}(){{");
                // else

                bool isAsync = method.ReturnType.Name == "Task";
                sb.AppendLine("public" + (isAsync
                                  ? " async "
                                  : " ") +
                              $"{method.ReturnType.ToDisplayString()} {method.Name}({string.Join(", ", method.Parameters.Select(p => p.ToDisplayString()))}){{");

                //Creating request
                if (method.Parameters.Length == 1 && !isAsync ||
                    method.Parameters.Length == 2 && isAsync)
                {
                    sb.AppendLine(
                        $"\t\tvar request = new DefaultCallRequest {{ CommandId = {index}, ObjectId = id, Parameter = {method.Parameters.First().Name} }};");
                }
                else
                {
                    sb.AppendLine(
                        $"\t\tvar request = new DefaultCallRequest {{ CommandId = {index}, ObjectId = id }};");
                }

                //Post created request
                sb.AppendLine("\t\tserialisationModule.PostCallRequest(request);");


                if (method.ReturnType.ToString() == "System.Threading.Tasks.Task")
                {
                    sb.AppendLine(
                        "\t\tawait serialisationModule.GetNextCommandExecution<FinalCommandExecution>(request.CallRequestId);");
                }
                else if (method.ReturnType.OriginalDefinition.ToString() == "System.Threading.Tasks.Task<TResult>")
                {
                    var type = method.ReturnType.ToString().Split(['<', '>'], StringSplitOptions.RemoveEmptyEntries)
                        .Last();
                    sb.AppendLine(
                        $"\t\tvar response = await serialisationModule.GetFinalCommandExecution<{type}>(request.CallRequestId);");
                    sb.AppendLine($"\t\treturn ({type})response.Result;");
                }
                else if (!isAsync && method.ReturnType.ToDisplayString() != "void")
                {
                    var type = method.ReturnType.ToDisplayString();
                    sb.AppendLine(
                        $"\t\tvar response = serialisationModule.GetFinalCommandExecution<{type}>(request.CallRequestId).GetAwaiter().GetResult();");
                    sb.AppendLine($"\t\treturn ({type})response.Result;");
                }

                sb.AppendLine("\t}");

                methodsText.Add(sb.ToString());
            }

            var code = $@"// <auto-generated/>

using System;
using mROA.Implementation;
using System.Collections.Generic;

namespace {namespaceName};

partial class {className} (int id, ISerialisationModule.IFrontendSerialisationModule serialisationModule) : {originalName}, IRemoteObject
{{
    public int Id => id;

    {string.Join("\r\n\t", methodsText)}
}}
";


            // Add the source code to the compilation.
            context.AddSource($"{className}.g.cs", SourceText.From(code, Encoding.UTF8));
            
            frontendContextRepo.Add($"{{ typeof({classSymbol.ToDisplayString()}), typeof({namespaceName}.{className}) }}");
        }


        var methodsStringed = methods.Select(i =>
                $"typeof({i.Item1}).GetMethod(\"{i.Item2.Name}\", [{string.Join(", ", i.Item2.Parameters.Select(p => $"typeof({p.Type.ToDisplayString()})"))}])")
            .ToList();

        var coCodegenRepoCode = @$"// <auto-generated/>
using System.Collections.Generic;
using System.Reflection;

namespace mROA.Codegen;

public class CoCodegenMethodRepository :IMethodRepository
{{
    private readonly List<MethodInfo> _methods = [
        {string.Join(", \r\n\t\t", methodsStringed)}
    ];
    public MethodInfo GetMethod(int id)
    {{
        if (_methods.Count <= id)
            return null;
        
        return _methods[id];
    }}

    public int RegisterMethod(MethodInfo method)
    {{
        _methods.Add(method);
        return _methods.Count - 1;
    }}

    public IEnumerable<MethodInfo> GetMethods()
    {{
        return _methods;
    }}

    public void Inject<T>(T dependency)
    {{
    }}

    public void Bake()
    {{
    }}
}}
";
        context.AddSource($"CoCodegenMethodRepository.g.cs", SourceText.From(coCodegenRepoCode, Encoding.UTF8));

        var fronendRepoCode = @$"// <auto-generated/>
using System.Collections.Frozen;

namespace mROA.Codegen;

public class FrontendContextRepository : IContextRepository
{{
    private ISerialisationModule.IFrontendSerialisationModule _serialisationModule;
    private static readonly FrozenDictionary<Type, Type> _remoteTypes = new Dictionary<Type, Type> {{
        {string.Join(", \r\n\t\t", frontendContextRepo)}}}.ToFrozenDictionary();
    
    public int ResisterObject(object o)
    {{
        throw new NotSupportedException();
    }}

    public void ClearObject(int id)
    {{
        throw new NotSupportedException();
    }}

    public object GetObject(int id)
    {{
        throw new NotSupportedException();
    }}

    public T GetObject<T>(int id)
    {{
        if (_remoteTypes.TryGetValue(typeof(T), out var remoteType))
        {{
            var remote = (T)Activator.CreateInstance(remoteType, id, _serialisationModule)!;
            return remote;
        }}
        throw new NotSupportedException();
    }}

    public object GetSingleObject(Type type)
    {{
        return Activator.CreateInstance(_remoteTypes[type], -1, _serialisationModule)!;
    }}

    public int GetObjectIndex(object o)
    {{
        if (o is IRemoteObject remote)
        {{
            return remote.Id;
        }}
        throw new NotSupportedException();
    }}

    public void Inject<T>(T dependency)
    {{
        if (dependency is ISerialisationModule.IFrontendSerialisationModule serialisationModule)
            _serialisationModule = serialisationModule;
    }}

    public void Bake()
    {{
    }}
}}
";
        context.AddSource("FrontendContextRepository.g.cs", SourceText.From(fronendRepoCode, Encoding.UTF8));
    }
}