Pair (ERC-20)

This documentation covers ERC-20 functionality for denominating pool tokens. For Uniswap-specific functionality, see Pair.

Code

UniswapV2ERC20.sol

Events

Approval

event Approval(address indexed owner, address indexed spender, uint value);Copy

Emitted each time an approval occurs via approve or permit.

Transfer

event Transfer(address indexed from, address indexed to, uint value);Copy

Emitted each time a transfer occurs via transfer, transferFrom, mint, or burn.

Read-Only Functions

name

function name() external pure returns (string memory);Copy

Returns Uniswap V2 for all pairs.

symbol

function symbol() external pure returns (string memory);Copy

Returns UNI-V2 for all pairs.

decimals

function decimals() external pure returns (uint8);Copy

Returns 18 for all pairs.

totalSupply

function totalSupply() external view returns (uint);Copy

Returns the total amount of pool tokens for a pair.

balanceOf

function balanceOf(address owner) external view returns (uint);Copy

Returns the amount of pool tokens owned by an address.

allowance

function allowance(address owner, address spender) external view returns (uint);Copy

Returns the amount of liquidity tokens owned by an address that a spender is allowed to transfer via transferFrom.

DOMAIN_SEPARATOR

function DOMAIN_SEPARATOR() external view returns (bytes32);Copy

Returns a domain separator for use in permit.

PERMIT_TYPEHASH

function PERMIT_TYPEHASH() external view returns (bytes32);Copy

Returns a typehash for use in permit.

nonces

function nonces(address owner) external view returns (uint);Copy

Returns the current nonce for an address for use in permit.

State-Changing Functions

approve

function approve(address spender, uint value) external returns (bool);Copy

Lets msg.sender set their allowance for a spender.

• Emits Approval.

transfer

function transfer(address to, uint value) external returns (bool);Copy

Lets msg.sender send pool tokens to an address.

• Emits Transfer.

transferFrom

function transferFrom(address from, address to, uint value) external returns (bool);Copy

Sends pool tokens from one address to another.

• Requires approval.

• Emits Transfer.

permit

function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;Copy

Sets the allowance for a spender where approval is granted via a signature.

• See Using Permit.
• Emits Approval.

Interface

import '@uniswap/v2-core/contracts/interfaces/IUniswapV2ERC20.sol';Copy

pragma solidity >=0.5.0;interface IUniswapV2ERC20 {  event Approval(address indexed owner, address indexed spender, uint value);  event Transfer(address indexed from, address indexed to, uint value);  function name() external pure returns (string memory);  function symbol() external pure returns (string memory);  function decimals() external pure returns (uint8);  function totalSupply() external view returns (uint);  function balanceOf(address owner) external view returns (uint);  function allowance(address owner, address spender) external view returns (uint);  function approve(address spender, uint value) external returns (bool);  function transfer(address to, uint value) external returns (bool);  function transferFrom(address from, address to, uint value) external returns (bool);  function DOMAIN_SEPARATOR() external view returns (bytes32);  function PERMIT_TYPEHASH() external pure returns (bytes32);  function nonces(address owner) external view returns (uint);  function permit(address owner, address spender, uint value, uint deadline, uint8 v, bytes32 r, bytes32 s) external;}Copy

ABI

import IUniswapV2ERC20 from '@uniswap/v2-core/build/IUniswapV2ERC20.json'