rootchain-std

The standard library for developing RootChain smart contracts.

rootchain-std is the developer-facing toolkit for authoring on-chain programs that run inside the RootChain WASM virtual machine. It provides safe, ergonomic access to host functions (state storage, events, caller context), token standards (RRC-20, RRC-721), and the #[rootchain_contract] macro.

What's Inside

Module	Description
`traits`	RRC-20 and RRC-721 token standard trait definitions
`rrc721`	Base implementation for Non-Fungible Token collections
`types`	Contract-local types (e.g., `TokenId`)
`error`	`ContractError` type for safe error handling
`lib`	Host function bindings: `state_get`, `state_set`, `get_caller`, `log_event`, `set_metadata`

Installation

[dependencies]
rootchain-std = { version = "1.0.2", default-features = false }

Note: Always use default-features = false for production contracts. The std feature enables the full standard library, which is not available in WASM.

Enable the test-utils feature to use in-memory mock host functions during unit testing:

[dev-dependencies]
rootchain-std = { version = "1.0.2", features = ["test-utils"] }

Writing a Contract

1. Define Your Contract

#![no_std]
extern crate alloc;

use rootchain_std::{rootchain_contract, traits::RRC20, Address};

pub struct MyToken {
    name: alloc::string::String,
}

#[rootchain_contract]
impl MyToken {
    pub fn init(&mut self, _input: &[u8]) { /* ... */ }
    pub fn transfer(&mut self, input: &[u8]) { /* ... */ }
    pub fn balance_of(&self, input: &[u8]) { /* ... */ }
}

2. Access Host Functions

use rootchain_std::{read_input, write_output, log, get_caller, log_event};

// Read ABI-encoded input from the VM
let input = read_input();

// Write output back to the VM
write_output(&encoded_response);

// Emit a structured event (indexed by topic hashes)
let topic = Hash([0u8; 32]);
log_event(&[topic], &payload);

3. State Management

// State is accessed via raw host function calls
// The rootchain_std::storage module provides typed helpers
unsafe {
    state_set(key.as_ptr(), key.len(), value.as_ptr(), value.len());
}

Token Standards

RRC-20 (Fungible Tokens)

Implement the RRC20 trait to create a fungible token compatible with the RootChain explorer and wallet.

RRC-721 (Non-Fungible Tokens)

Implement the RRC721 trait or extend BaseRRC721 from rootchain_std::rrc721 for an NFT collection.

License

MIT — See LICENSE for details.

rootchain-std 1.0.2