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pragma solidity ^0.4.11;
import "../Tokens/Token.sol";
import "../Utils/Math.sol";
/// @title Standard token contract with overflow protection
contract StandardToken is Token {
using Math for *;
/*
* Storage
*/
mapping (address => uint) balances;
mapping (address => mapping (address => uint)) allowances;
uint totalTokens;
/*
* Public functions
*/
/// @dev Transfers sender's tokens to a given address. Returns success
/// @param to Address of token receiver
/// @param value Number of tokens to transfer
/// @return Was transfer successful?
function transfer(address to, uint value)
public
returns (bool)
{
if ( !balances[msg.sender].safeToSub(value)
|| !balances[to].safeToAdd(value))
return false;
balances[msg.sender] -= value;
balances[to] += value;
emit Transfer(msg.sender, to, value);
return true;
}
/// @dev Allows allowed third party to transfer tokens from one address to another. Returns success
/// @param from Address from where tokens are withdrawn
/// @param to Address to where tokens are sent
/// @param value Number of tokens to transfer
/// @return Was transfer successful?
function transferFrom(address from, address to, uint value)
public
returns (bool)
{
if ( !balances[from].safeToSub(value)
|| !allowances[from][msg.sender].safeToSub(value)
|| !balances[to].safeToAdd(value))
return false;
balances[from] -= value;
allowances[from][msg.sender] -= value;
balances[to] += value;
emit Transfer(from, to, value);
return true;
}
/// @dev Sets approved amount of tokens for spender. Returns success
/// @param spender Address of allowed account
/// @param value Number of approved tokens
/// @return Was approval successful?
function approve(address spender, uint value)
public
returns (bool)
{
allowances[msg.sender][spender] = value;
emit Approval(msg.sender, spender, value);
return true;
}
/// @dev Returns number of allowed tokens for given address
/// @param owner Address of token owner
/// @param spender Address of token spender
/// @return Remaining allowance for spender
function allowance(address owner, address spender)
public
view
returns (uint)
{
return allowances[owner][spender];
}
/// @dev Returns number of tokens owned by given address
/// @param owner Address of token owner
/// @return Balance of owner
function balanceOf(address owner)
public
view
returns (uint)
{
return balances[owner];
}
/// @dev Returns total supply of tokens
/// @return Total supply
function totalSupply()
public
view
returns (uint)
{
return totalTokens;
}
}
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