[vecdb_derive]

Procedural macros for the VecDB storage engine, providing automatic trait implementations for compressed vector types.

Overview

This crate provides derive macros that automatically implement the necessary traits for storing and compressing custom data types in VecDB. The main macro StoredCompressed enables transparent compression for wrapper types.

Derive Macros

#[derive(StoredCompressed)]

Automatically implements compression traits for single-field tuple structs, enabling them to be stored efficiently in compressed vectors.

Requirements:

• Must be used on a single-field tuple struct
• The inner type must already implement StoredCompressed

Example:

use vecdb_derive::StoredCompressed;
use vecdb::CompressedVec;

// Define a wrapper type
#[derive(StoredCompressed)]
struct UserId(u32);

// Now UserId can be used in compressed vectors
type UserVec = CompressedVec<usize, UserId>;

With Generics:

#[derive(StoredCompressed)]
struct Wrapper<T>(T);

// The derive macro handles generic parameters automatically
// T must implement StoredCompressed for this to work

Implementation Details

The macro generates implementations for:

• StoredCompressed trait with the appropriate NumberType
• TransparentStoredCompressed trait for zero-cost wrapper semantics

The generated code ensures that wrapper types have the same compression characteristics as their inner types, making them truly transparent for storage purposes.

Usage Notes

• Only works with tuple structs containing exactly one field
• The inner type must implement the StoredCompressed trait
• Supports generic parameters with appropriate where clauses
• Designed for zero-overhead abstractions over compressed numeric types