Roslyn `IIncrementalGenerator` Pipeline Architecture

1Concept

`IIncrementalGenerator` hooks into the Roslyn compiler compilation pipeline. It inspects syntax trees, filters symbols incrementally, and outputs C# source files that are compiled directly into the target assembly.

2Architecture Diagram

[ User Code with Attributes ]
             │
             ▼
[ Roslyn SyntaxProvider / Incremental Generator ]
             │ (Caches intermediate model: only re-runs when annotated code edits occur)
             ▼
[ Emits Generated .g.cs Files ] ──> Merged into final compilation with ZERO runtime reflection!

3Code Example

using System;

// Conceptual demonstration of Source Generated output
public partial class UserDto
{
    public int Id { get; set; }
    public string Name { get; set; } = string.Empty;
}

// In real applications, the Source Generator emits this partial class automatically:
public partial class UserDto
{
    public string ToCustomJsonString() => $"{{\"id\":{Id},\"name\":\"{Name}\"}}";
}

public class SourceGeneratorConceptDemo
{
    public static void Main()
    {
        var user = new UserDto { Id = 101, Name = "Alice" };
        Console.WriteLine($"Generated Output: {user.ToCustomJsonString()}");
    }
}

4Expected Output

Generated Output: {"id":101,"name":"Alice"}

5Key Takeaways

• ✓Incremental generators cache steps to maintain sub-second IDE typing performance.
• ✓Replaces slow runtime reflection with compile-time generated strongly-typed code.
• ✓Guarantees 100% Native AOT compatibility.