MPC-20 Token Contract

A token is a standardized digital asset on the Partisia blockchain, the token standard is inspired from the guidelines outlined in the Ethereum Improvement Proposal (EIP) 20. The token standard provides basic functionality to transfer tokens as well as approve the transfer of the token.

Version 1

A contract is detected as a valid Token V1 Contract if: The following actions exists where names and types match exactly:

#[action(shortname=0x01)] transfer(to: Address, amount: u128)
#[action(shortname=0x03)] transfer_from(from: Address, to: Address, amount: u128)
#[action(shortname=0x05)] approve(spender: Address, amount: u128)

The root state struct has the following state fields in the root state struct or a sub-struct that has a 1-1 composition with the root state struct where names and types match exactly:

balances: Map<Address, u128>
name: String
symbol: String
decimals: u8
allowed: Map<Address, Map<Address, u128>>

You can dive into our token example contract to explore this standard.

Version 2

This version makes use of Avl Trees to store balances. This allows the contract to store many more balances with reduced gas cost.

A contract is detected as a valid Token V2 Contract if: The following actions exists where names and types match exactly:

#[action(shortname=0x01)] transfer(to: Address, amount: u128)
#[action(shortname=0x03)] transfer_from(from: Address, to: Address, amount: u128)
#[action(shortname=0x05)] approve(spender: Address, amount: u128)

The root state struct has the following state fields in the root state struct or a sub-struct that has a 1-1 composition with the root state struct where names and types match exactly:

balances: AvlTreeMap<Address, u128>
name: String
symbol: String
decimals: u8
allowed: AvlTreeMap<AllowedAddress, u128>,

Where AllowedAddress is a sub-struct with fields where names and types match exactly:

owner: Address,
spender: Address,

References:

https://ethereum.org/en/developers/docs/standards/tokens/erc-20/

https://gitlab.com/partisiablockchain/language/contracts/defi/-/tree/main/token