feat: Give Generators Access to MSBuild Properties (#210)

* Add abiilty to pass msbuild properties to the generator * update readme * revert to item approach * escape semicolons when creating _CodeGenToolResponseFileLines * add sample using TargetFrameworks property to show escaping works * update doc comments in transformation context * add link to sample projects in readme, update changelog Co-authored-by: talenfisher <[email protected]>
AArnott · Apr 15, 2020 · f3a03fc · f3a03fc
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -6,6 +6,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+* Support for accessing arbitrary MSBuild properties, see [Readme section](README.md#access-msbuild-properties) ([#210])
+
 
 ## [0.7.63] - 2020-04-08
 
@@ -43,6 +46,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 [#178]: https://github.com/AArnott/CodeGeneration.Roslyn/pull/178
 [#198]: https://github.com/AArnott/CodeGeneration.Roslyn/pull/198
 [#205]: https://github.com/AArnott/CodeGeneration.Roslyn/pull/205
+[#210]: https://github.com/AArnott/CodeGeneration.Roslyn/pull/210
 [v0.7 migration guide]: https://github.com/AArnott/CodeGeneration.Roslyn/wiki/Migrations#v07
 
 

diff --git a/README.md b/README.md
@@ -52,6 +52,7 @@ Instructions on development and using this project's source code are in [CONTRIB
       - [Separate out the attribute](#separate-out-the-attribute)
       - [Create the metapackage](#create-the-metapackage)
       - [Add extra `build/` content in Plugin package](#add-extra-build-content-in-plugin-package)
+    - [Access MSBuild Properties](#access-msbuild-properties)
 
 ## How to write your own code generator
 
@@ -543,6 +544,30 @@ to add custom MSBuild props/targets into NuGet package's `build` folder (and hav
 imported when package is referenced), you'll need to use `PackageBuildFolderProjectImport`
 ItemGroup, as shown in `PackagedGenerator` sample.
 
+### Accesss MSBuild Properties
+
+You may access MSBuild property values of the project being generated for, by first adding the property
+name to the `PluginRequestedProperty` item list.  For example, if you want to access the TargetFramework build 
+property, you would do the following in your generator's .csproj file:
+
+```xml
+<ItemGroup>
+  <PluginRequestedProperty Include="ExampleBuildProperty" />
+</ItemGroup>
+```
+
+Then, you can access its value like this:
+
+```cs
+public Task<SyntaxList<MemberDeclarationSyntax>> GenerateAsync(TransformationContext context, IProgress<Diagnostic> progress, CancellationToken cancellationToken)
+{
+    var targetFramework = context.BuildProperties["TargetFramework"];
+    // ...
+}
+```
+
+> ℹ For a sample generator that accesses MSBuild properties, see [BuildPropsGenerator](samples/BuildPropsGenerator) and its consuming project, [BuildPropsConsumer](samples/BuildPropsConsumer)
+
 [NuPkg]: https://nuget.org/packages/CodeGeneration.Roslyn
 [AttrNuPkg]: https://nuget.org/packages/CodeGeneration.Roslyn.Attributes
 [ToolNuPkg]: https://nuget.org/packages/CodeGeneration.Roslyn.Tool

diff --git a/samples/BuildPropsConsumer/BuildPropsConsumer.csproj b/samples/BuildPropsConsumer/BuildPropsConsumer.csproj
@@ -0,0 +1,16 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFrameworks>netcoreapp2.2;netcoreapp3.1</TargetFrameworks>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="CodeGeneration.Roslyn.Attributes" Version="$(LocalNuGetVersion)" PrivateAssets="all" />
+    <PackageReference Include="CodeGeneration.Roslyn.Tool" Version="$(LocalNuGetVersion)" PrivateAssets="all" />
+    <PackageReference Include="BuildPropsGenerator" Version="1.0.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+</Project>
diff --git a/samples/BuildPropsConsumer/Program.cs b/samples/BuildPropsConsumer/Program.cs
@@ -0,0 +1,27 @@
+using System;
+using CodeGeneration.Roslyn;
+
+namespace BuildPropsConsumer
+{
+
+    [CodeGenerationAttribute("BuildPropsGenerator.FrameworkInfoProviderGenerator, BuildPropsGenerator")]
+    class FrameworkInfoProviderAttribute : Attribute { }
+
+    [FrameworkInfoProvider]
+    partial class Program
+    {
+        static void Main(string[] args)
+        {
+            var program = new Program();
+            var frameworks = program.TargetFrameworks;
+            var currentFramework = program.CurrentTargetFramework;
+
+            Console.WriteLine("This project is build for the following frameworks: ");
+
+            foreach(var framework in frameworks) {
+                var message = framework == currentFramework ? $"{framework} (current)" : framework;
+                Console.WriteLine(message);
+            }
+        }
+    }
+}
diff --git a/samples/BuildPropsGenerator/BuildPropsGenerator.csproj b/samples/BuildPropsGenerator/BuildPropsGenerator.csproj
@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <Import Project="$(CodeGenerationRoslynPluginSdkPath)Sdk.props" />
+
+  <PropertyGroup>
+    <TargetFramework>netcoreapp2.1</TargetFramework>
+    <GeneratePackageOnBuild>true</GeneratePackageOnBuild>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PluginRequestedProperty Include="TargetFrameworks" />
+    <PluginRequestedProperty Include="TargetFramework" />
+  </ItemGroup>
+
+  <Import Project="$(CodeGenerationRoslynPluginSdkPath)Sdk.targets" />
+
+</Project>
diff --git a/samples/BuildPropsGenerator/FrameworkInfoProviderGenerator.cs b/samples/BuildPropsGenerator/FrameworkInfoProviderGenerator.cs
@@ -0,0 +1,54 @@
+using System;
+using System.Linq;
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using CodeGeneration.Roslyn;
+using Microsoft.CodeAnalysis;
+using Microsoft.CodeAnalysis.CSharp;
+using Microsoft.CodeAnalysis.CSharp.Syntax;
+
+namespace BuildPropsGenerator
+{
+    public class FrameworkInfoProviderGenerator : ICodeGenerator
+    {
+        public FrameworkInfoProviderGenerator(AttributeData attributeData)
+        {
+        }
+
+        public Task<SyntaxList<MemberDeclarationSyntax>> GenerateAsync(TransformationContext context, IProgress<Diagnostic> progress, CancellationToken cancellationToken)
+        {
+            var partialType = CreatePartialType();
+            return Task.FromResult(SyntaxFactory.List(partialType));
+
+            IEnumerable<MemberDeclarationSyntax> CreatePartialType()
+            {
+                var newPartialType = 
+                    context.ProcessingNode is ClassDeclarationSyntax classDeclaration
+                        ? SyntaxFactory.ClassDeclaration(classDeclaration.Identifier.ValueText)
+                        : context.ProcessingNode is StructDeclarationSyntax structDeclaration
+                            ? SyntaxFactory.StructDeclaration(structDeclaration.Identifier.ValueText)
+                            : default(TypeDeclarationSyntax);
+                if (newPartialType is null)
+                    yield break;
+                yield return newPartialType
+                    ?.AddModifiers(SyntaxFactory.Token(SyntaxKind.PartialKeyword))
+                    .AddMembers(CreateTargetFrameworkListProperty(), CreateCurrentTargetFrameworkProperty());
+            }
+            MemberDeclarationSyntax CreateTargetFrameworkListProperty()
+            {
+                var collectionType = "System.Collections.Generic.List<string>";
+                var frameworks = context.BuildProperties["TargetFrameworks"];
+                var quotedFrameworks = frameworks.Split(";").Select(framework => $"\"{framework}\"");
+                var commaDelimitedFrameworks = string.Join(',', quotedFrameworks.ToArray());
+
+                return SyntaxFactory.ParseMemberDeclaration($"public {collectionType} TargetFrameworks {{ get; }} = new {collectionType} {{ {commaDelimitedFrameworks} }};");
+            }
+            MemberDeclarationSyntax CreateCurrentTargetFrameworkProperty()
+            {
+                var framework = context.BuildProperties["TargetFramework"];
+                return SyntaxFactory.ParseMemberDeclaration($"public string CurrentTargetFramework {{ get; }} = \"{framework}\";");
+            }
+        }
+    }
+}
diff --git a/samples/BuildPropsGenerator/build.ps1 b/samples/BuildPropsGenerator/build.ps1
@@ -0,0 +1,11 @@
+#!/usr/bin/env pwsh
+
+Write-Host "Running in $PSScriptRoot" -ForegroundColor Cyan
+Push-Location $PSScriptRoot
+try {
+    Write-Host "dotnet build" -ForegroundColor Green
+    dotnet build
+}
+finally {
+    Pop-Location
+}
diff --git a/src/CodeGeneration.Roslyn.Engine/CompilationGenerator.cs b/src/CodeGeneration.Roslyn.Engine/CompilationGenerator.cs
@@ -53,6 +53,11 @@ public class CompilationGenerator
         /// </summary>
         public IReadOnlyList<string> PluginPaths { get; set; } = new List<string>();
 
+        /// <summary>
+        /// Gets or sets the build properties to expose to generators.
+        /// </summary>
+        public IReadOnlyDictionary<string, string> BuildProperties { get; set; }
+
         /// <summary>
         /// Gets or sets the path to the directory that contains generated source files.
         /// </summary>
@@ -122,6 +127,7 @@ public async Task GenerateAsync(IProgress<Diagnostic> progress = null, Cancellat
                                     compilation,
                                     inputSyntaxTree,
                                     this.ProjectDirectory,
+                                    this.BuildProperties,
                                     this.LoadPlugin,
                                     progress,
                                     cancellationToken);

diff --git a/src/CodeGeneration.Roslyn.Engine/DocumentTransform.cs b/src/CodeGeneration.Roslyn.Engine/DocumentTransform.cs
@@ -40,6 +40,7 @@ public static class DocumentTransform
         /// <param name="compilation">The compilation to which the document belongs.</param>
         /// <param name="inputDocument">The document to scan for generator attributes.</param>
         /// <param name="projectDirectory">The path of the <c>.csproj</c> project file.</param>
+        /// <param name="buildProperties">MSBuild properties to expose to the generator.</param>
         /// <param name="assemblyLoader">A function that can load an assembly with the given name.</param>
         /// <param name="progress">Reports warnings and errors in code generation.</param>
         /// <param name="cancellationToken">The token to monitor for cancellation requests.</param>
@@ -48,6 +49,7 @@ public static async Task<SyntaxTree> TransformAsync(
             CSharpCompilation compilation,
             SyntaxTree inputDocument,
             string projectDirectory,
+            IReadOnlyDictionary<string, string> buildProperties,
             Func<AssemblyName, Assembly> assemblyLoader,
             IProgress<Diagnostic> progress,
             CancellationToken cancellationToken)
@@ -91,7 +93,8 @@ public static async Task<SyntaxTree> TransformAsync(
                         compilation,
                         projectDirectory,
                         emittedUsings,
-                        emittedExterns);
+                        emittedExterns,
+                        buildProperties);
 
                     var richGenerator = generator as IRichCodeGenerator ?? new EnrichingCodeGeneratorProxy(generator);
 

diff --git a/src/CodeGeneration.Roslyn.Plugin.Sdk/build/BuildPluginPackage.targets b/src/CodeGeneration.Roslyn.Plugin.Sdk/build/BuildPluginPackage.targets
@@ -64,6 +64,7 @@
 @(_PackageBuildFolderProjectImport_props->'  <Import Project="%(Identity)" />', '%0D%0A')
   <ItemGroup>
     <CodeGenerationRoslynPlugin Include="%24(MSBuildThisFileDirectory)../$(PluginPackagePath)/$(TargetFileName)" />
+@(PluginRequestedProperty->'    <CodeGenerationRoslynRequestedProperty Include="%(Identity)" />', '%0D%0A')
   </ItemGroup>
 </Project>
 ]]>

diff --git a/src/CodeGeneration.Roslyn.Tests.Generators/AddExampleBuildPropertyAttribute.cs b/src/CodeGeneration.Roslyn.Tests.Generators/AddExampleBuildPropertyAttribute.cs
@@ -0,0 +1,16 @@
+// Copyright (c) Andrew Arnott. All rights reserved.
+// Licensed under the MS-PL license. See LICENSE.txt file in the project root for full license information.
+
+namespace CodeGeneration.Roslyn.Tests.Generators
+{
+    using System;
+    using System.Diagnostics;
+    using Validation;
+
+    [AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = true)]
+    [CodeGenerationAttribute(typeof(AddExampleBuildPropertyGenerator))]
+    [Conditional("CodeGeneration")]
+    public class AddExampleBuildPropertyAttribute : Attribute
+    {
+    }
+}
diff --git a/src/CodeGeneration.Roslyn.Tests.Generators/AddExampleBuildPropertyGenerator.cs b/src/CodeGeneration.Roslyn.Tests.Generators/AddExampleBuildPropertyGenerator.cs
@@ -0,0 +1,45 @@
+// Copyright (c) Andrew Arnott. All rights reserved.
+// Licensed under the MS-PL license. See LICENSE.txt file in the project root for full license information.
+
+namespace CodeGeneration.Roslyn.Tests.Generators
+{
+    using System;
+    using System.Collections.Generic;
+    using System.Collections.Immutable;
+    using System.Linq;
+    using System.Text;
+    using System.Threading;
+    using System.Threading.Tasks;
+    using Microsoft.CodeAnalysis;
+    using Microsoft.CodeAnalysis.CSharp;
+    using Microsoft.CodeAnalysis.CSharp.Syntax;
+    using Validation;
+    using static Microsoft.CodeAnalysis.CSharp.SyntaxFactory;
+
+    public class AddExampleBuildPropertyGenerator : ICodeGenerator
+    {
+        public AddExampleBuildPropertyGenerator(AttributeData attributeData)
+        {
+            Requires.NotNull(attributeData, nameof(attributeData));
+        }
+
+        public Task<SyntaxList<MemberDeclarationSyntax>> GenerateAsync(TransformationContext context, IProgress<Diagnostic> progress, CancellationToken cancellationToken)
+        {
+            var partialClass = GeneratePartialClass();
+            return Task.FromResult(SyntaxFactory.List(partialClass));
+
+            IEnumerable<MemberDeclarationSyntax> GeneratePartialClass()
+            {
+                var classDeclaration = context.ProcessingNode as ClassDeclarationSyntax;
+                yield return classDeclaration
+                    .AddMembers(CreateExampleBuildProperty());
+            }
+
+            MemberDeclarationSyntax CreateExampleBuildProperty()
+            {
+                var value = context.BuildProperties["ExampleBuildProperty"];
+                return SyntaxFactory.ParseMemberDeclaration($"public string ExampleBuildProperty {{ get; }} = \"{value}\";");
+            }
+        }
+    }
+}
diff --git a/src/CodeGeneration.Roslyn.Tests/CodeGeneration.Roslyn.Tests.csproj b/src/CodeGeneration.Roslyn.Tests/CodeGeneration.Roslyn.Tests.csproj
@@ -7,8 +7,13 @@
     <!-- Ignore CGR1002 because it's expected to be raised by legacy Amadevus.RecordGenerator -->
     <MSBuildWarningsAsMessages>$(MSBuildWarningsAsMessages);CGR1002</MSBuildWarningsAsMessages>
     <GenerateCodeFromAttributesDependsOn>OverrideCodeGenToolPath;$(GenerateCodeFromAttributesDependsOn)</GenerateCodeFromAttributesDependsOn>
+    <ExampleBuildProperty>c7189d5e-495c-4cab-8e18-ab8d7ab71a2e</ExampleBuildProperty>
   </PropertyGroup>
 
+  <ItemGroup>
+    <CodeGenerationRoslynRequestedProperty Include="ExampleBuildProperty" />
+  </ItemGroup>
+
   <ItemGroup>
     <PackageReference Include="Amadevus.RecordGenerator.Attributes" Version="0.4.1" PrivateAssets="all" />
     <PackageReference Include="Amadevus.RecordGenerator.Generators" Version="0.4.1" PrivateAssets="all" />

diff --git a/src/CodeGeneration.Roslyn.Tests/CodeGenerationTests.cs b/src/CodeGeneration.Roslyn.Tests/CodeGenerationTests.cs
@@ -38,6 +38,13 @@ public void NuGetRecordGeneratorWorks()
         record.ToBuilder();
     }
 
+    [Fact]
+    public void AccessingBuildPropertiesWorks()
+    {
+        var objWithBuildProp = new ClassWithExampleBuildProperty();
+        Assert.Equal("c7189d5e-495c-4cab-8e18-ab8d7ab71a2e", objWithBuildProp.ExampleBuildProperty);
+    }
+
     public partial class Wrapper
     {
         [ExternalDuplicateWithSuffixByName("Suffix")]
@@ -66,4 +73,9 @@ public partial class MultipliedBar
         [Test(X = 10, Y = 20)]
         public string Value { get; set; }
     }
+
+    [AddExampleBuildProperty]
+    public partial class ClassWithExampleBuildProperty
+    {
+    }
 }
diff --git a/src/CodeGeneration.Roslyn.Tests/Helpers/CompilationTestsBase.cs b/src/CodeGeneration.Roslyn.Tests/Helpers/CompilationTestsBase.cs
@@ -79,7 +79,7 @@ protected static async Task<SyntaxTree> GenerateAsync(string source)
         var diagnostics = compilation.GetDiagnostics();
         Assert.Empty(diagnostics.Where(x => x.Severity >= DiagnosticSeverity.Warning));
         var progress = new Progress<Diagnostic>();
-        var result = await DocumentTransform.TransformAsync(compilation, tree, null, Assembly.Load, progress, CancellationToken.None);
+        var result = await DocumentTransform.TransformAsync(compilation, tree, null, null, Assembly.Load, progress, CancellationToken.None);
         return result;
     }
 

diff --git a/src/CodeGeneration.Roslyn.Tool/CommandLine/Enumerable.cs b/src/CodeGeneration.Roslyn.Tool/CommandLine/Enumerable.cs
@@ -64,6 +64,11 @@ public static T[] ToArray<T>(this IEnumerable<T> source)
             return System.Linq.Enumerable.ToArray(source);
         }
 
+        public static Dictionary<TKey, TElement> ToDictionary<T, TKey, TElement>(this IEnumerable<T> source, Func<T, TKey> keySelector, Func<T, TElement> elementSelector)
+        {
+            return System.Linq.Enumerable.ToDictionary(source, keySelector, elementSelector);
+        }
+
         public static T Last<T>(this IEnumerable<T> source)
         {
             return System.Linq.Enumerable.Last(source);