I'm trying to use Roslyn to generate and compile a runtime library of simple objects containing get/set properties.
However, for some reason, compiling the assembly fails with error of adding the Linq namespace (error CS0246: The type or namespace name 'System.Linq' could not be found (are you missing a using directive or an assembly reference?)}).
I've tried manipulating the generated tree in a number of ways and compiling each, but still compilation fails.
The only way in which compilation succeeds is if the tree is parsed to a string, then parsed back to a syntax tree and then compiled.
The code below does the following:
The code:
private static readonly CSharpCompilationOptions DefaultCompilationOptions =
new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
.WithOverflowChecks(true)
.WithPlatform(Platform.X86)
.WithOptimizationLevel(OptimizationLevel.Release)
.WithUsings(DefaultNamespaces);
private static readonly IEnumerable<string> DefaultNamespaces =
new[]
{
"System",
"System.IO",
"System.Net",
"System.Linq",
"System.Text",
"System.Text.RegularExpressions"
};
private static readonly IEnumerable<MetadataReference> DefaultReferences =
new[]
{
MetadataReference.CreateFromFile(typeof (object).Assembly.Location),
MetadataReference.CreateFromFile(typeof (System.Linq.Enumerable).Assembly.Location),
MetadataReference.CreateFromFile(typeof (System.GenericUriParser).Assembly.Location),
MetadataReference.CreateFromFile(typeof (Microsoft.CSharp.RuntimeBinder.RuntimeBinderException).Assembly.Location)
};
static void Main(string[] args)
{
MakeAssembly();
Console.ReadLine();
}
private static void MakeAssembly()
{
//Compilation Unit and Usings
CompilationUnitSyntax cu = SyntaxFactory.CompilationUnit()
.AddUsings(SyntaxFactory.UsingDirective(SyntaxFactory.IdentifierName("System")),
SyntaxFactory.UsingDirective(SyntaxFactory.IdentifierName(typeof(System.Linq.Enumerable).Namespace)))
;
// NameSpace
NamespaceDeclarationSyntax ns = SyntaxFactory.NamespaceDeclaration(SyntaxFactory.IdentifierName("Roslyn"));
// Class
ClassDeclarationSyntax classNode = SyntaxFactory.ClassDeclaration("MyClass")
.AddModifiers(SyntaxFactory.Token(SyntaxKind.PublicKeyword))
;
// Property
classNode= classNode.AddMembers(
SyntaxFactory.PropertyDeclaration(SyntaxFactory.ParseTypeName("Int32"), "MyProperty")
.AddAccessorListAccessors(
SyntaxFactory.AccessorDeclaration(SyntaxKind.GetAccessorDeclaration).WithSemicolonToken(SyntaxFactory.Token(SyntaxKind.SemicolonToken)),
SyntaxFactory.AccessorDeclaration(SyntaxKind.SetAccessorDeclaration).WithSemicolonToken(SyntaxFactory.Token(SyntaxKind.SemicolonToken))).
AddModifiers(SyntaxFactory.Token(SyntaxKind.PublicKeyword)));
ns = ns.AddMembers(classNode);
cu = cu.AddMembers(ns);
// Try To Compile Syntax Tree root
var root = cu.SyntaxTree.GetRoot();
var st = root.SyntaxTree;
var assembly = CompileAndLoad(st);
if (assembly != null)
{
Console.WriteLine("Success compile syntax tree root");
return;
}
else
Console.WriteLine("failed to compile syntax tree root");
// Try to compile new syntax tree
var stNew = SyntaxFactory.SyntaxTree(cu, CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp6));
assembly = CompileAndLoad(stNew);
if (assembly != null)
{
Console.WriteLine("Success compile new syntax tree");
return;
}
else
Console.WriteLine("failed to compile new syntax tree");
// Try to format node
AdhocWorkspace cw = new AdhocWorkspace();
OptionSet options = cw.Options;
options = options.WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInMethods, false);
options = options.WithChangedOption(CSharpFormattingOptions.NewLinesForBracesInTypes, false);
SyntaxNode formattedNode = Formatter.Format(cu, cw, options);
var stFormat = SyntaxFactory.SyntaxTree(cu, CSharpParseOptions.Default.WithLanguageVersion(LanguageVersion.CSharp6));
assembly = CompileAndLoad(stFormat);
if (assembly != null)
{
Console.WriteLine("Success compile formatted syntax tree");
return;
}
else
Console.WriteLine("failed to compile formatted syntax tree");
// Try to serialize and parse
StringBuilder sb = new StringBuilder();
using (StringWriter writer = new StringWriter(sb))
{
formattedNode.WriteTo(writer);
}
var treeAsString = sb.ToString();
var stParsed = SyntaxFactory.ParseSyntaxTree(treeAsString);
assembly = CompileAndLoad(stParsed);
if (assembly != null)
{
Console.WriteLine("Success compile parsed syntax tree");
return;
}
else
Console.WriteLine("failed to compile formatted syntax tree");
}
private static Assembly CompileAndLoad(SyntaxTree st)
{
var compilation
= CSharpCompilation.Create("TestRoslyn.dll", new SyntaxTree[] { st }, null, DefaultCompilationOptions);
compilation = compilation.WithReferences(DefaultReferences);
using (var stream = new MemoryStream())
{
EmitResult result = compilation.Emit(stream);
if (result.Success)
{
var assembly = Assembly.Load(stream.GetBuffer());
return assembly;
}
return null;
}
}
Roslyn, the . NET Compiler Platform, empowers the C# compiler on . NET Core and allows developers to leverage the rich code analysis APIs to perform code generation, analysis and compilation.
NET Compiler Platform, also known by its codename Roslyn, is a set of open-source compilers and code analysis APIs for C# and Visual Basic (VB.NET) languages from Microsoft.
The . NET Compiler Platform ("Roslyn") provides open-source C# and Visual Basic compilers with rich code analysis APIs. You can build code analysis tools with the same APIs that Microsoft is using to implement Visual Studio!
I fell into this trap with Roslyn also. The using directive is not just expressed as a string each part of the qualified name is a syntax node. You need to create your node like this
var qualifiedName= SyntaxFactory.QualifiedName(SyntaxFactory.IdentifierName("System"),
SyntaxFactory.IdentifierName("Linq"));
var usingDirective = SyntaxFactory.UsingDirective(qualifedName);
I wrote a helper method to convert a string to the correct syntax node.
private UsingDirectiveSyntax CreateUsingDirective(string usingName)
{
NameSyntax qualifiedName = null;
foreach (var identifier in usingName.Split('.'))
{
var name = SyntaxFactory.IdentifierName(identifier);
if (qualifiedName != null)
{
qualifiedName = SyntaxFactory.QualifiedName(qualifiedName, name);
}
else
{
qualifiedName = name;
}
}
return SyntaxFactory.UsingDirective(qualifiedName);
}
You can use SyntaxFactory.ParseName
which will handle parsing the string and then building the qualified name syntax node for your using directives:
var qualifiedName = SyntaxFactory.ParseName("System.Linq");
var usingDirective = SyntaxFactory.UsingDirective(qualifiedName);
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