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60 lines
2.0 KiB
60 lines
2.0 KiB
2 months ago
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// SPDX-License-Identifier: UNLICENSED
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pragma solidity ^0.8.0;
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contract TokenAuthorization {
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mapping(address => uint256) private _balances;
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mapping(address => mapping(address => uint256)) private _allowances;
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event Transfer(address indexed from, address indexed to, uint256 amount);
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event Approval(address indexed owner, address indexed spender, uint256 amount);
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uint256 private _totalSupply;
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constructor(uint256 initialSupply) {
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_totalSupply = initialSupply;
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_balances[msg.sender] = initialSupply;
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}
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function totalSupply() external view returns (uint256) {
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return _totalSupply;
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}
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function balanceOf(address account) external view returns (uint256) {
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return _balances[account];
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}
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function transfer(address to, uint256 amount) external returns (bool) {
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require(to != address(0), "Invalid recipient");
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require(amount <= _balances[msg.sender], "Insufficient balance");
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_balances[msg.sender] -= amount;
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_balances[to] += amount;
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emit Transfer(msg.sender, to, amount);
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return true;
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}
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function approve(address spender, uint256 amount) external returns (bool) {
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_allowances[msg.sender][spender] = amount;
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emit Approval(msg.sender, spender, amount);
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return true;
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}
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function allowance(address owner, address spender) external view returns (uint256) {
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return _allowances[owner][spender];
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}
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function transferFrom(address from, address to, uint256 amount) external returns (bool) {
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require(to != address(0), "Invalid recipient");
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require(amount <= _balances[from], "Insufficient balance");
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require(amount <= _allowances[from][msg.sender], "Insufficient allowance");
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_balances[from] -= amount;
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_balances[to] += amount;
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_allowances[from][msg.sender] -= amount;
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emit Transfer(from, to, amount);
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return true;
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}
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}
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