RhoMicro.CodeAnalysis.Lyra 1.2.0

Lyra

This is a source generator generating library classes for writing beautiful C# source code; e.g. in source generators.

Licensing

This project is licensed under the MPL-2.0 license.

Features

• indentation and newline aware string building
• reusable component system
• advanced interpolated strings for efficient source building

Installation

.NET CLI:

dotnet add package RhoMicro.CodeAnalysis.Lyra --version 1.1.0

PackageReference:

<PackageReference Include="RhoMicro.CodeAnalysis.Lyra" Version="1.1.0">
    <PrivateAssets>all</PrivateAssets>
    <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
</PackageReference>

How To Use

Simple Example

Instantiate a new CSharpSourceBuilder:

using var sb = new CSharpSourceBuilder();

Append text:

sb.Append("namespace ").AppendLine("Foo").AppendLine('{');

Indent text:

sb.Indent();

Use builtin components:

sb.Append(
        ComponentFactory.Type(
                "enum",
                "Bar",
                ComponentFactory.Create((b, _) => b.AppendLine("Baz = 0"))));

Detent text:

sb.Detent();

Generate output:

sb.AppendLine('}');
Console.WriteLine(sb);

The generated output will look like this:

// <auto-generated>
// This file was generated using the global::RhoMicro.CodeAnalysis.Lyra.CSharpSourceBuilder.
// </auto-generated>
namespace Foo
{
    enum Bar
    {
        Baz = 0
    }
}

The CSharpSourceBuilder can be configured using the CSharpSourceBuilderOptions passed to its constructor:

using var sb1 = new CSharpSourceBuilder(
        new CSharpSourceBuilderOptions()
        {
                Prelude = (b,_)=>b.AppendLine("// <auto-generated/>"),
                DefaultIndentation = "  ".AsMemory()
        });

The output changes to:

// <auto-generated/>
namespace Foo
{
  enum Bar
  {
    Baz = 0
  }
}

Interpolated Strings

Interpolated strings are compiled to Append invocations, with indentation being automatically detected:

var placeholder = "\nbar\nbaz";
sb.Clear().AppendLine(
         $"""
             foo{placeholder}
         """);
Console.WriteLine(sb);

The output changes as follows:

// <auto-generated/>
    foo
    bar
    baz

Note how the initial indentation in front of foo is carried along.

The detection of these indentations can be configured using the CSharpSourceBuilderOptions.InitialInterpolationIndentationDetector property.

Components

Some useful components are provided out of the box:

var body = ComponentFactory.Create(
        myModel,
        static (myModel, b, ct) =>
        {
            ct.ThrowIfCancellationRequested();
        
            b.Append(myModel.Value);
        });

var type = ComponentFactory.Type(
        "partial struct",
        myModel.Name,
        body,
        baseTypeList:
        [
            TypeName<IComparable>()
        ]);

var @namespace = ComponentFactory.Namespace(
        myModel.Namespace,
        type);

builder.AppendLine(@namespace);

The output will look similar to this:

namespace Namespace
{
    partial struct Name : global::System.IComparable
    {
        // myModel.Value
    }
}