# AyCode.Core.Serializers.SourceGenerator

Roslyn incremental source generator that produces optimized `IGeneratedBinaryWriter` and `IGeneratedBinaryReader` implementations for types marked with `[AcBinarySerializable]`. Eliminates runtime reflection on serialization hot paths.

Targets **netstandard2.0** (required for Roslyn analyzers/generators).

## Key Files

- **`AcBinarySourceGenerator.cs`** — Single-file `IIncrementalGenerator` (~2100 lines). Generates:
  - `{ClassName}_GeneratedWriter` — Per-type writer with `ScanObject()` + `WriteProperties()` methods. Handles primitives, strings (with interning), collections, dictionaries, complex nested types, and polymorphic objects.
  - `{ClassName}_GeneratedReader` — Per-type reader with `ReadProperties()` method.
  - `ModuleInitializer` — Auto-registers all generated writers/readers at startup.
  - Circular reference detection with `ACBIN001` diagnostic warning.

## Slot Allocation

Each generated writer reserves a unique type slot via `AcBinarySerializer.AllocateWrapperSlot()` (static field initializer, `Interlocked.Increment`).

- **Slots 0–63** — reserved for runtime polymorphic types (assigned dynamically on first encounter)
- **Slots 64+** — source-generated types (allocated at `[ModuleInitializer]` registration time)

**Slot indices are NOT stable across compilations.** The order depends on Roslyn's `ForAttributeWithMetadataName()` enumeration order, which may vary between builds. This is fine because slots are only meaningful within a single serialization/deserialization session — they are never persisted to disk or sent over the wire as slot indices (the wire format uses type names or metadata hashes for cross-session/cross-type compatibility).

## Feature Flags

The `[AcBinarySerializable]` attribute supports per-type feature control:
- `enableMetadata` — Property hash metadata for cross-type deserialization
- `enableIdTracking` — IId-based reference tracking
- `enableRefHandling` — General reference tracking
- `enableInternString` — String interning/deduplication

Disabled features eliminate corresponding code blocks from generated output (zero dead code).

## Dependencies

| Dependency | Purpose |
|---|---|
| `Microsoft.CodeAnalysis.CSharp` | Roslyn syntax/semantic APIs |
| `Microsoft.CodeAnalysis.Analyzers` | Analyzer best practices |