feature: logic for handling assembly replacement via config (#404)

* logic for handling assembly replacement via config

* fix issue with assembly arg not being ignored if empty

Author: dpvreony

src/Vetuviem.IntegrationTests/Vetuviem.IntegrationTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
-    <TargetFramework>net7.0-windows</TargetFramework>
+    <TargetFramework>net8.0-windows</TargetFramework>
     <UseWpf>True</UseWpf>
     <IsPackable>False</IsPackable>
   </PropertyGroup>

src/Vetuviem.SourceGenerator/AbstractBaseSourceGenerator.cs

@@ -12,6 +12,7 @@
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
+using Vetuviem.SourceGenerator.Features.Configuration;
 using Vetuviem.SourceGenerator.Features.Core;
 
 namespace Vetuviem.SourceGenerator
@@ -124,8 +125,17 @@ public void Execute(GeneratorExecutionContext context)
 
             globalOptions.TryGetBuildPropertyValue("Vetuviem_Make_Classes_Public", out var makeClassesPublicAsString);
             bool.TryParse(makeClassesPublicAsString, out var makeClassesPublic);
+
             globalOptions.TryGetBuildPropertyValue("Vetuviem_Assemblies", out var assemblies);
-            var assembliesArray = assemblies?.Split(';');
+            var assembliesArray = assemblies?.Split(
+                [';'],
+                StringSplitOptions.RemoveEmptyEntries)
+                .Where(s => !string.IsNullOrWhiteSpace(s))
+                .ToArray();
+
+            globalOptions.TryGetBuildPropertyValue("Vetuviem_Assembly_Mode", out var assemblyModeAsString);
+
+            var assemblyMode = GetAssemblyMode(assemblyModeAsString);
 
             // base type name only used if passing a custom set of assemblies to search for.
             // allows for 3rd parties to use the generator and produce a custom namespace that inherits off the root, or custom namespace.
@@ -150,9 +160,11 @@ public void Execute(GeneratorExecutionContext context)
             //}
 #endif
 
-            // TODO: allow the assemblies to be overriden by config.
-            // TODO: allow the classes to be internal rather than public
-            var assembliesOfInterest = platformResolver.GetAssemblyNames();
+            var assembliesOfInterest = GetAssembliesOfInterest(platformResolver, assembliesArray, assemblyMode);
+            if (assembliesOfInterest.Length == 0)
+            {
+                return null;
+            }
 
             if (cancellationToken.IsCancellationRequested)
             {
@@ -214,6 +226,45 @@ public void Execute(GeneratorExecutionContext context)
             return result;
         }
 
+        private static AssemblyMode GetAssemblyMode(string? assemblyModeAsString)
+        {
+            if (string.IsNullOrWhiteSpace(assemblyModeAsString))
+            {
+                return AssemblyMode.Replace;
+            }
+
+            if ( !Enum.TryParse<AssemblyMode>(assemblyModeAsString, out var assemblyMode))
+            {
+                return assemblyMode;
+            }
+
+            throw new InvalidOperationException("Invalid assembly mode.");
+        }
+
+        private static string[] GetAssembliesOfInterest(
+            IPlatformResolver platformResolver,
+            string[]? assembliesArray,
+            AssemblyMode assemblyMode)
+        {
+            var assembliesOfInterest = platformResolver.GetAssemblyNames();
+            if (assembliesArray?.Length > 0)
+            {
+                switch (assemblyMode)
+                {
+                    case AssemblyMode.Replace:
+                        assembliesOfInterest = assembliesArray;
+                        break;
+                    case AssemblyMode.Extend:
+                        assembliesOfInterest = assembliesOfInterest.Concat(assembliesArray).ToArray();
+                        break;
+                    default:
+                        throw new InvalidOperationException("Invalid assembly mode.");
+                }
+            }
+
+            return assembliesOfInterest;
+        }
+
         private void ValidateRootNamespace(string? rootNamespace)
         {
             if (string.IsNullOrWhiteSpace(rootNamespace))

src/Vetuviem.SourceGenerator/Features/Configuration/AssemblyMode.cs

@@ -0,0 +1,27 @@
+// Copyright (c) 2022 DPVreony and Contributors. All rights reserved.
+// DPVreony and Contributors licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for full license information.
+
+namespace Vetuviem.SourceGenerator.Features.Configuration
+{
+    /// <summary>
+    /// The operation to carry out if assemblies are specified in the config.
+    /// </summary>
+    public enum AssemblyMode
+    {
+        /// <summary>
+        /// None, this is a language default to pickup invalid values.
+        /// </summary>
+        None,
+
+        /// <summary>
+        /// Replace the default platform assemblies with the specified assemblies.
+        /// </summary>
+        Replace,
+
+        /// <summary>
+        /// Extend the default platform assemblies with the specified assemblies.
+        /// </summary>
+        Extend
+    }
+}

src/Vetuviem.SourceGenerator/Vetuviem-SourceGenerator.props

@@ -3,6 +3,7 @@
     <CompilerVisibleProperty Include="Vetuviem_Root_Namespace" />
     <CompilerVisibleProperty Include="Vetuviem_Make_Classes_Public" />
     <CompilerVisibleProperty Include="Vetuviem_Assemblies" />
+    <CompilerVisibleProperty Include="Vetuviem_Assembly_Mode" />
     <CompilerVisibleProperty Include="Vetuviem_Base_Namespace" />
   </ItemGroup>
 </Project>

src/Vetuviem.SourceGenerator/Vetuviem.SourceGenerator.csproj

@@ -2,7 +2,7 @@
 
   <PropertyGroup>
     <TargetFramework>netstandard2.0</TargetFramework>
-    <LangVersion>9</LangVersion>
+    <LangVersion>12</LangVersion>
     <DebugType>full</DebugType>
     <DebugSymbols>True</DebugSymbols>
   </PropertyGroup>