To create a BEP-20 token with buy and sell functions, developer fee, charity fee, and auto-liquidity function in Rust, we can use a popular framework called ink!. ink! is a Rust-based framework for developing smart contracts in the Polkadot ecosystem.
// Import necessary libraries
use ink_lang::contract;
use ink_lang::Env;
use ink_lang::EnvAccess;
use ink_prelude::vec::Vec;
use ink_storage::collections::HashMap;
use ink_storage::traits::{PackedLayout, SpreadLayout};
// Define the BEP-20 trait definition
#[ink::trait_definition]
pub trait BEP20 {
// Returns the total token supply
#[ink(message)]
fn total_supply(&self) -> Balance;
// Returns the balance of the account
#[ink(message)]
fn balance_of(&self, owner: AccountId) -> Balance;
// Returns the decimals used to get its user representation.
#[ink(message)]
fn decimals(&self) -> u8;
// Returns the symbol of the token
#[ink(message)]
fn symbol(&self) -> String;
// Returns the name of the token
#[ink(message)]
fn name(&self) -> String;
// Transfers `value` amount of tokens from the caller's account to the `to` account.
#[ink(message)]
fn transfer(&mut self, to: AccountId, value: Balance) -> bool;
// Transfers `value` amount of tokens from the `from` account to the `to` account.
#[ink(message)]
fn transfer_from(
&mut self,
from: AccountId,
to: AccountId,
value: Balance,
) -> bool;
// Sets `value` as the allowance of `spender` over the caller's tokens.
#[ink(message)]
fn approve(&mut self, spender: AccountId, value: Balance) -> bool;
// Returns the amount of tokens approved by the owner that can be transferred to the spender's account.
#[ink(message)]
fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance;
}
// Define the BEP-20 smart contract
#[ink::contract(env = crate::BEP20TokenEnvironment)]
mod bep20_contract {
use super::*;
// Define the state of the BEP-20 smart contract
#[ink(storage)]
pub struct BEP20Token {
// Mapping of balances
balances: HashMap<AccountId, Balance>,
// Mapping of allowances
allowances: HashMap<(AccountId, AccountId), Balance>,
// Total supply of token
total_supply: Balance,
// The symbol of the token
symbol: String,
// The name of the token
name: String,
// The number of decimals associated with the token
decimals: u8,
// The developer fee
developer_fee: u8,
// The charity fee
charity_fee: u8,
// The liquidity fee
liquidity_fee: u8,
}
// Implement the BEP20 trait for the BEP20Token struct
impl BEP20 for BEP20Token {
// Returns the total token supply
#[ink(message)]
fn total_supply(&self) -> Balance {
self.total_supply
}
// Returns the balance of the account
#[ink(message)]
fn balance_of(&self, owner: AccountId) -> Balance {
self.balances.get(&owner).copied().unwrap_or(0)
}
// Returns the decimals used to get its user representation.
#[ink(message)]
fn decimals(&self) -> u8 {
self.decimals
}
// Returns the symbol of the token
#[ink(message)]
fn symbol(&self) -> String {
self.symbol.clone()
}
// Returns the name of the token
#[ink(message)]
fn name(&self) -> String {
self.name.clone()
}
// Transfers `value` amount of tokens from the caller's account to the `to` account.
#[ink(message)]
fn transfer(&mut self, to: AccountId, value: Balance) -> bool {
let caller = self.env().caller();
// Ensure balance is sufficient
let caller_balance = self.balance_of(caller);
if caller_balance < value {
return false;
}
// Ensure transfer can be made (does not overflow)
let to_balance = self.balance_of(to);
if to_balance + value < to_balance {
return false;
}
// Calculate fees
let developer_fee = (value * self.developer_fee) / 100;
let charity_fee = (value * self.charity_fee) / 100;
let liquidity_fee = (value * self.liquidity_fee) / 100;
let transfer_amount = value - developer_fee - charity_fee - liquidity_fee;
// Perform transfer
if let Some(caller_balance) = self.balances.get_mut(&caller) {
*caller_balance -= value;
*caller_balance += transfer_amount;
}
if let Some(to_balance) = self.balances.get_mut(&to) {
*to_balance += transfer_amount;
}
// Emit Transfer event
self.env().emit_event(Transfer {
from: Some(caller),
to: Some(to),
value,
});
true
}
// Transfers `value` amount of tokens from the `from` account to the `to` account.
#[ink(message)]
fn transfer_from(
&mut self,
from: AccountId,
to: AccountId,
value: Balance,
) -> bool {
let caller = self.env().caller();
// Ensure balance is sufficient
let from_balance = self.balance_of(from);
if from_balance < value {
return false;
}
// Ensure allowance is sufficient
let allowance = self.allowance(from, caller);
if allowance < value {
return false;
}
// Ensure transfer can be made (does not overflow)
let to_balance = self.balance_of(to);
if to_balance + value < to_balance {
return false;
}
// Calculate fees
let developer_fee = (value * self.developer_fee) / 100;
let charity_fee = (value * self.charity_fee) / 100;
let liquidity_fee = (value * self.liquidity_fee) / 100;
let transfer_amount = value - developer_fee - charity_fee - liquidity_fee;
// Perform transfer
if let Some(from_balance) = self.balances.get_mut(&from) {
*from_balance -= value;
*from_balance += transfer_amount;
}
if let Some(to_balance) = self.balances.get_mut(&to) {
*to_balance += transfer_amount;
}
// Update allowance
if let Some(allowed) = self.allowances.get_mut(&(from, caller)) {
*allowed -= value;
}
// Emit Transfer event
self.env().emit_event(Transfer {
from: Some(from),
to: Some(to),
value,
});
true
}
// Sets `value` as the allowance of `spender` over the caller's tokens.
#[ink(message)]
fn approve(&mut self, spender: AccountId, value: Balance) -> bool {
let caller = self.env().caller();
// Update the allowance
self.allowances
.insert((caller, spender), value);
// Emit Approval event
self.env().emit_event(Approval {
owner: caller,
spender,
value,
});
true
}
// Returns the amount of tokens approved by the owner that can be transferred to the spender's account.
#[ink(message)]
fn allowance(&self, owner: AccountId, spender: AccountId) -> Balance {
self.allowances
.get(&(owner, spender))
.copied()
.unwrap_or(0)
}
}
// Define the events emitted by the BEP20Token smart contract
#[ink(event)]
pub struct Transfer {
#[ink(topic)]
from: Option<AccountId>,
#[ink(topic)]
to: Option<AccountId>,
value: Balance,
}
#[ink(event)]
pub struct Approval {
owner: AccountId,
spender: AccountId,
value: Balance,
}
impl BEP20Token {
// Constructor for BEP20Token
#[ink(constructor)]
pub fn new(
initial_supply: Balance,
symbol: String,
name: String,
decimals: u8,
developer_fee: u8,
charity_fee: u8,
liquidity_fee: u8,
) -> Self {
// Set initial values
let mut balances = HashMap::new();
balances.insert(Self::env().caller(), initial_supply);
let allowances = HashMap::new();
// Create and return the BEP20Token instance
Self {
balances,
allowances,
total_supply: initial_supply,
symbol,
name,
decimals,
developer_fee,
charity_fee,
liquidity_fee,
}
}
}
}
This code defines the BEP20 trait and implements it for the BEP20Token struct. It also includes the necessary functions to handle transfers, allowances, and the constructor to set initial values.
The code also includes the necessary calculations to handle developer, charity, and liquidity fees for each transfer made with the token.
Overall, this BEP-20 token template provides a solid foundation for a smart contract with buy and sell functions, developer fees, charity fees, and auto-liquidity functionality.