Crate allfeat_midds_v2_codegen 

MIDDS V2 Codegen - Procedural Macro for Dual-Mode Type Generation

This crate provides the runtime_midds procedural macro that enables automatic transformation of Rust data structures between std and Substrate runtime modes.

Overview

The core functionality revolves around the #[runtime_midds] attribute macro that:

• Generates two versions of each annotated type (std and runtime)
• Automatically transforms String and Vec<T> fields to BoundedVec in runtime mode
• Adds appropriate trait derivations for each compilation mode
• Supports complex nested structures and enums

Key Features

Type Transformations

• String → BoundedVec<u8, ConstU32<N>>
• Vec<T> → BoundedVec<T, ConstU32<N>>
• Option<String> → Option<BoundedVec<u8, ConstU32<N>>>
• Option<Vec<T>> → Option<BoundedVec<T, ConstU32<N>>>
• Recursive transformation for nested Option types

Bound Specification

Use #[runtime_bound(N)] attributes to specify maximum sizes:

• On struct fields for field-level bounds
• On enum variants for variant-level bounds (applies to all fields in that variant)

Trait Derivations

• Runtime mode: Encode, Decode, DecodeWithMemTracking, TypeInfo, MaxEncodedLen, Debug, Clone, PartialEq, Eq
• Std mode: Debug, Clone, PartialEq, Eq

Usage Examples

Basic Struct

use allfeat_midds_v2_codegen::runtime_midds;

#[runtime_midds]
pub struct MyStruct {
    #[runtime_bound(256)]
    pub title: String,

    #[runtime_bound(64)]
    pub tags: Vec<String>,

    pub id: u64, // No transformation
}

Newtype Struct

use allfeat_midds_v2_codegen::runtime_midds;

#[runtime_midds]
pub struct Identifier(#[runtime_bound(32)] String);

Enum with Bounds

use allfeat_midds_v2_codegen::runtime_midds;

#[runtime_midds]
pub enum WorkType {
    Original,
    #[runtime_bound(512)]
    Medley(Vec<u64>),
    #[runtime_bound(256)]
    Adaptation(String, u32),
}

Optional Fields

use allfeat_midds_v2_codegen::runtime_midds;

#[runtime_midds]
pub struct OptionalData {
    #[runtime_bound(128)]
    pub optional_title: Option<String>,

    #[runtime_bound(32)]
    pub optional_list: Option<Vec<u32>>,
}

Architecture

The crate is organized into several modules:

• [attribute] - Parsing and validation of #[runtime_bound(N)] attributes
• [transform] - Type transformation logic between std and runtime modes
• [generate] - Code generation utilities for structs and enums
• [error] - Comprehensive error handling with detailed diagnostics

Attribute Macros

runtime_midds

Attribute macro that transforms String and Vec fields to BoundedVec when runtime feature is enabled.