TedToolkit.RoslynHelper 2026.7.6

TedToolkit.RoslynHelper

A fluent API for generating C# source code, designed for Roslyn source generators, analyzers, and other code generation workflows.

Good Fit

This library is useful when you want to compose:

• files, namespaces, and type declarations
• methods, properties, fields, events, indexers, and constructors
• expressions and statements
• XML documentation comments
• conditional compilation blocks
• code-generation syntax derived from Roslyn symbols

It targets netstandard2.0 and can be distributed as part of analyzer-oriented packages.

Installation

<ItemGroup>
  <PackageReference Include="TedToolkit.RoslynHelper" Version="1.0.0" />
</ItemGroup>

Quick Start

using TedToolkit.RoslynHelper;
using TedToolkit.RoslynHelper.Syntaxes;

using static TedToolkit.RoslynHelper.SourceComposer;

var code = File()
    .AddUsing(Using("System"))
    .AddNameSpace(NameSpace("Demo.Space")
        .AddMember(Class("Sample").Public
            .AddMember(
                new Method("Run")
                    .Public
                    .Static
                    .AddStatement(1.ToLiteral().Return))))
    .ToCode();

The generated output includes the auto-generated file header, #pragma warning disable, plus the using directives, namespaces, and members you add.

Common Capabilities

1. Generate types and members

using TedToolkit.RoslynHelper.Syntaxes;

var typeDeclaration = new TypeDeclaration("Sample", TypeDeclarationType.CLASS)
    .Public
    .Partial
    .AddBaseType<IDisposable>()
    .AddMember(new Field(DataType.Int, "count"))
    .AddMember(
        new Property(DataType.String, "Name")
            .AddAccessor(new Accessor(AccessorType.GET)))
    .AddMember(
        new Method("Run")
            .AddStatement("count".ToSimpleName().Return));

Primary declaration types include:

• TypeDeclaration
• Method
• Property
• Field
• Event
• Indexer
• Constructor
• Operator
• Conversion
• Enum
• Delegate

2. Generate expressions and statements

using TedToolkit.RoslynHelper.Syntaxes;

var statement = new IfStatement("ready".ToSimpleName())
    .AddStatement("work".ToSimpleName())
    .Else()
    .AddStatement("fallback".ToSimpleName());

var expression = "items".ToSimpleName()
    .Sub("Count")
    .Add(1.ToLiteral());

Common statement types covered by the current library include:

• Statement
• ReturnStatement
• IfStatement
• ForEachStatement
• UsingStatement
• TryStatement
• SwitchStatement

3. Generate conditional compilation

using TedToolkit.RoslynHelper.Syntaxes;
using TedToolkit.RoslynHelper.Syntaxes.Preprocessors;

var field = new Field(DataType.Int, "count")
    .AddCondition(PreprocessorExpression.Debug);

var block = new ConditionalCompilationStatement(PreprocessorExpression.Debug)
    .AddStatement("work".ToSimpleName())
    .Else()
    .AddStatement("fallback".ToSimpleName());

This is useful when the generated output needs #if DEBUG-style structure.

4. Convert Roslyn symbols into generation syntax

using Microsoft.CodeAnalysis;
using TedToolkit.RoslynHelper;

Parameter parameter = SourceComposer.Parameter(parameterSymbol, compilation);
var dataType = DataType.FromSymbol(typeSymbol, compilation);
var attribute = SourceComposer.Attribute(attributeData, compilation);
var typeParameter = SourceComposer.TypeParameter(typeParameterSymbol, compilation);

This is the main bridge between Roslyn analysis data and generated code composition.

5. Stamp generated members with generator metadata

using static TedToolkit.RoslynHelper.SourceComposer<MyGenerator>;

var method = Method("Run")
    .Public
    .AddStatement("value".ToSimpleName().Return);

When you create members through SourceComposer<TGenerator>, the library automatically adds GeneratedCodeAttribute.

Notes

• This is a code generation helper library, not a full semantic rewriter
• The main public namespaces used by examples are TedToolkit.RoslynHelper and TedToolkit.RoslynHelper.Syntaxes
• It is best suited to composing code first, then emitting it through ToCode() or SourceFile.Generate(...)

License

LGPL-3.0-or-later.