r-koubou/VisitorGenerator

Create C# Visitor pattern interface code with C# 9.0 Source Generator

Visitor generator

A C# Visitor pattern interface generator with C# 9.0 Source Generator

Installation

from Nuget

Usage

Use an VisitTo attribute to generate "Visit" method.

public interface INode {}
public interface IChildNodeA : INode {}
public interface IChildNodeB : INode {}
public interface IChildNodeC : INode {}

[VisitTo(typeof(IChildNodeA))]
[VisitTo(typeof(IChildNodeB))]
[VisitTo(typeof(IChildNodeC))]
public partial interface IChildNodeVisitor<T>{} // note:Template must be <T>

will generate following

public partial interface IChildNodeVisitor<T>
{
    public T Visit( IChildNodeA obj );
    public T Visit( IChildNodeB obj );
    public T Visit( IChildNodeC obj );
}

If use an VisitDynamicFrom, generate a type dynamic synatax code.

public interface INode {}
public interface IChildNodeA : INode {}
public interface IChildNodeB : INode {}
public interface IChildNodeC : INode {}

[VisitTo(typeof(IChildNodeA))]
[VisitTo(typeof(IChildNodeB))]
[VisitTo(typeof(IChildNodeC))]
[VisitDynamicFrom(typeof(INode))]
public partial interface IChildNodeVisitor<T>{} // note:Template must be <T>

will generate following

public partial interface IChildNodeVisitor<T>
{
    public T Visit( IChildNodeA obj );
    public T Visit( IChildNodeB obj );
    public T Visit( IChildNodeC obj );

    public T Visit( INode obj )
    {
        return Visit( (dynamic)obj );
    }
}