temple for a bep20 token smart contract with buy&sell function, developer fee, charity fee, and autoliquidity function in rust in rust

To write a BEP20 token smart contract with buy&sell function, developer fee, charity fee, and autoliquidity function in Rust, you can use a framework like ink!. Here's an example implementation:


main.rs
use ink_lang::contract;
use ink_core::storage;
use ink_core::env::DefaultSrmlTypes;

contract!{
    #![env = DefaultSrmlTypes]

    struct MyToken {
        // Storage fields
        total_supply: storage::Value<u64>,
        balances: storage::HashMap<AccountId, u64>,
        dev_fee_percent: storage::Value<u8>,
        charity_fee_percent: storage::Value<u8>,
        liquidity_pool: storage::Value<u64>,
        // Events
        Transfer: ink::Event<{from: AccountId, to: AccountId, value: u64}>,
    }

    impl MyToken {
        // Constructor
        #[ink(constructor)]
        fn new(&mut self, total_supply: u64) {
            self.total_supply.set(total_supply);
            self.balances.insert(Self::env().caller(), total_supply);
        }

        // Buy function
        #[ink(message)]
        fn buy(&mut self) -> u64 {
            let value = self.env().transferred_balance();
            let liquidity_fee = value * self.liquidity_pool.get() / self.total_supply.get();
            let charity_fee = value * self.charity_fee_percent.get() / 100;
            let dev_fee = value * self.dev_fee_percent.get() / 100;
            let tokens = value - liquidity_fee - charity_fee - dev_fee;
            self.balances.insert(Self::env().caller(), self.balances.get(&Self::env().caller()).unwrap_or(0) + tokens);
            self.total_supply.set(self.total_supply.get() + tokens);
            self.env().transfer(Self::env().account_id(), liquidity_fee).expect("Transfer failed");
            self.env().transfer(charity_address, charity_fee).expect("Transfer failed");
            self.env().transfer(dev_address, dev_fee).expect("Transfer failed");
            self.env().emit_event(Transfer {
                from: Self::env().account_id(),
                to: Self::env().caller(),
                value: tokens,
            });
            tokens
        }

        // Sell function
        #[ink(message)]
        fn sell(&mut self, tokens: u64) -> u64 {
            assert!(self.balances.get(&Self::env().caller()).unwrap_or(0) >= tokens, "Insufficient balance");
            let value = tokens * self.total_supply.get() / self.balances.get(&Self::env().caller()).unwrap_or(1);
            let liquidity_fee = value * self.liquidity_pool.get() / self.total_supply.get();
            let charity_fee = value * self.charity_fee_percent.get() / 100;
            let dev_fee = value * self.dev_fee_percent.get() / 100;
            let actual_value = value - liquidity_fee - charity_fee - dev_fee;
            self.balances.insert(Self::env().caller(), self.balances.get(&Self::env().caller()).unwrap() - tokens);
            self.total_supply.set(self.total_supply.get() - tokens);
            self.env().transfer(Self::env().account_id(), liquidity_fee).expect("Transfer failed");
            self.env().transfer(charity_address, charity_fee).expect("Transfer failed");
            self.env().transfer(dev_address, dev_fee).expect("Transfer failed");
            self.env().emit_event(Transfer {
                from: Self::env().caller(),
                to: Self::env().account_id(),
                value: tokens,
            });
            self.env().transfer(Self::env().caller(), actual_value).expect("Transfer failed");
            actual_value
        }

        // Add liquidity to the pool
        #[ink(anonymous)]
        fn add_liquidity(&mut self) {
            let value = self.env().transferred_balance();
            self.liquidity_pool.set(self.liquidity_pool.get() + value);
        }
    }
}
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Explanation:

The MyToken struct defines the storage fields and events.
The new constructor initializes the total_supply and sets the balance of the contract creator.
The buy function is used to purchase tokens. It calculates the developer fee, charity fee, liquidity fee and the actual number of tokens to be minted. It transfers the required amounts of ETH and tokens to the different addresses and updates the storage balances.
The sell function is used to sell tokens. It calculates the developer fee, charity fee, liquidity fee and the actual ETH value to be returned. It transfers the required amounts of ETH and tokens to the different addresses and updates the storage balances.
The add_liquidity function is used to add liquidity to the pool.
Note that the implementation of this smart contract is just an example and it is not meant to be used in a production environment without further testing, auditing and optimization.