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@yoninachmany
Last active April 3, 2017 04:02
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pragma solidity ^0.4.8;
contract Token {
/// @return total amount of tokens
function totalSupply() constant returns (uint256 supply) {}
/// @param _owner The address from which the balance will be retrieved
/// @return The balance
function balanceOf(address _owner) constant returns (uint256 balance) {}
/// @notice send `_value` token to `_to` from `msg.sender`
/// @param _to The address of the recipient
/// @param _value The amount of token to be transferred
/// @return Whether the transfer was successful or not
function transfer(address _to, uint256 _value) returns (bool success) {}
/// @notice send `_value` token to `_to` from `_from` on the condition it is approved by `_from`
/// @param _from The address of the sender
/// @param _to The address of the recipient
/// @param _value The amount of token to be transferred
/// @return Whether the transfer was successful or not
function transferFrom(address _from, address _to, uint256 _value) returns (bool success) {}
/// @notice `msg.sender` approves `_addr` to spend `_value` tokens
/// @param _spender The address of the account able to transfer the tokens
/// @param _value The amount of wei to be approved for transfer
/// @return Whether the approval was successful or not
function approve(address _spender, uint256 _value) returns (bool success) {}
/// @param _owner The address of the account owning tokens
/// @param _spender The address of the account able to transfer the tokens
/// @return Amount of remaining tokens allowed to spent
function allowance(address _owner, address _spender) constant returns (uint256 remaining) {}
event Transfer(address indexed _from, address indexed _to, uint256 _value);
event Approval(address indexed _owner, address indexed _spender, uint256 _value);
uint public decimals;
string public name;
}
contract TokenExchange {
mapping (address => mapping (address => uint256)) amounts;
mapping (address => mapping (address => uint256)) prices;
mapping (address => uint256) etherOf;
// Allows user to deposit some number of tokens that you are willing to sell for some price.
// Should also check that the user has has given the exchange an allowance of this token
// (and transfer the tokens into the contracts control).
function depositToken(address _token, uint _amount) {
Token t = Token(_token);
if (_amount < 0) throw;
amounts[_token][msg.sender] += _amount;
if (!t.transferFrom(msg.sender, this, _amount)) throw;
}
// Allows users who have previously deposited tokens to reclaim possession of them.
// Also allows users who have bought tokens to claim possession of them.
// The decentralized exchange should use the tokens transfer functon
function withdrawToken(address _token, uint _amount) {
Token t = Token(_token);
if (_amount < 0) throw;
if (amounts[_token][msg.sender] < _amount) throw;
amounts[_token][msg.sender] -= _amount;
if (!t.transfer(msg.sender, _amount)) throw;
}
// Returns the number of tokens that a user has deposited of that specific _token.
function getTokenBalance(address _owner, address _token) constant returns (uint256 balance) {
Token t = Token(_token);
return amounts[_token][_owner];
}
// Set the price you are willing to sell your tokens for (in Ether)
function setPrice(address _token, uint _price) {
Token t = Token(_token);
if (_price < 0) throw;
prices[_token][msg.sender] = _price;
}
// Send this function with at least _amount * _price of token for that
// specific seller, and have the tokens transferred into your ownership
// (within this contract only, not in the token contract yet - that's
// what the withdrawTokens function is for).
function buyToken(address _token, address _seller, uint _amount) payable {
Token t = Token(_token);
if (_amount < 0) throw;
if (_amount < amounts[_token][_seller]) throw;
if (_amount < msg.value) throw;
amounts[_token][_seller] -= _amount;
amounts[_token][this] += _amount;
etherOf[_token] -= _amount * prices[_token][_seller];
etherOf[this] += _amount * prices[_token][_seller];
}
// withdraw _amount of Ether that you have in the exchange (from selling tokens).
function withdrawEther(uint _amount) {
// sender.send for transfering ether
if (_amount < 0) throw;
if (etherOf[msg.sender] < _amount) throw;
if (!msg.sender.send(etherOf[msg.sender])) throw;
}
}
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