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2.2-finished-code.rs
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2.2-finished-code.rs
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#![cfg_attr(not(feature = "std"), no_std)]
use ink_lang as ink;
#[ink::contract]
mod erc20 {
#[cfg(not(feature = "ink-as-dependency"))]
#[ink(storage)]
pub struct Erc20 {
/// The total supply.
total_supply: Balance,
/// The balance of each user.
balances: ink_storage::collections::HashMap<AccountId, Balance>,
}
impl Erc20 {
#[ink(constructor)]
pub fn new(initial_supply: Balance) -> Self {
let mut balances = ink_storage::collections::HashMap::new();
balances.insert(Self::env().caller(), initial_supply);
Self {
total_supply: initial_supply,
balances
}
}
#[ink(message)]
pub fn total_supply(&self) -> Balance {
self.total_supply
}
#[ink(message)]
pub fn balance_of(&self, owner: AccountId) -> Balance {
self.balance_of_or_zero(&owner)
}
#[ink(message)]
pub fn transfer(&mut self, to: AccountId, value: Balance) -> bool {
self.transfer_from_to(self.env().caller(), to, value)
}
fn transfer_from_to(&mut self, from: AccountId, to: AccountId, value: Balance) -> bool {
let from_balance = self.balance_of_or_zero(&from);
if from_balance < value {
return false
}
// Update the sender's balance.
self.balances.insert(from, from_balance - value);
// Update the receiver's balance.
let to_balance = self.balance_of_or_zero(&to);
self.balances.insert(to, to_balance + value);
true
}
fn balance_of_or_zero(&self, owner: &AccountId) -> Balance {
*self.balances.get(owner).unwrap_or(&0)
}
}
#[cfg(test)]
mod tests {
use super::*;
use ink_lang as ink;
#[ink::test]
fn new_works() {
let contract = Erc20::new(777);
assert_eq!(contract.total_supply(), 777);
}
#[ink::test]
fn balance_works() {
let contract = Erc20::new(100);
assert_eq!(contract.total_supply(), 100);
assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 0);
}
#[ink::test]
fn transfer_works() {
let mut contract = Erc20::new(100);
assert_eq!(contract.balance_of(AccountId::from([0x1; 32])), 100);
assert!(contract.transfer(AccountId::from([0x0; 32]), 10));
assert_eq!(contract.balance_of(AccountId::from([0x0; 32])), 10);
assert!(!contract.transfer(AccountId::from([0x0; 32]), 100));
}
}
}