# Pair (ERC 20)

This documentation covers ERC-20 functionality for denominating pool tokens. For JediSwap-specific functionality, see [Pair](https://docs.jediswap.xyz/for-developers/jediswap-v1/smart-contract-reference/pair).

## Code

[Pair.cairo](https://github.com/jediswaplabs/jediswap/blob/main/contracts/pair.cairo)

## Events

### Approval​

```js
@event
func Approval(owner: felt, spender: felt, amount: Uint256):
end
```

Emitted each time allowances is updated in [approve](#approve), [increaseAllowance](#increaseallowance), [decreaseAllowance](#decreaseallowance) or [transferFrom](#transferfrom)

### Transfer​

```js
@event
func Transfer(from_address: felt, to_address: felt, amount: Uint256):
end
```

Emitted each time a transfer occurs via [transfer](#transfer-1), [transferFrom](#transferfrom), [mint](https://docs.jediswap.xyz/for-developers/jediswap-v1/pair#mint-1), or [burn](https://docs.jediswap.xyz/for-developers/jediswap-v1/pair#burn-1).

## View Functions

### name​

```js
func name() -> (name: felt):
```

Returns JediSwap Pair for all pairs.

### symbol​

```js
func symbol() -> (symbol: felt):
```

Returns JEDIP for all pairs.

### decimals​

```js
func decimals() -> (decimals: felt):
```

Returns 18 for all pairs.

### totalSupply​

```js
func totalSupply() -> (totalSupply: Uint256):
```

Returns the total amount of pool tokens for a pair.

### balanceOf​

```js
func balanceOf(account: felt) -> (balance: Uint256):
```

Returns the amount of pool tokens owned by an address.

### allowance​

```js
func allowance(owner: felt, spender: felt) -> (remaining: Uint256):
```

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

## State-Changing Functions

### approve​

```js
func approve(spender: felt, amount: Uint256) -> (success: felt):
```

Lets *caller* set their allowance for a spender.

* Emits [Approval](#approval).

### increaseAllowance​

```js
func increaseAllowance(spender: felt, added_value: Uint256) -> (success: felt):
```

Lets *caller* increase their allowance for a spender by added\_value.

* Emits [Approval](#approval).

### decreaseAllowance​

```js
func decreaseAllowance(spender: felt, subtracted_value: Uint256) -> (success: felt):
```

Lets *caller* decrease their allowance for a spender by subtracted\_value.

* Emits [Approval](#approval).

### transfer​

```js
func transfer(recipient: felt, amount: Uint256) -> (success: felt):
```

Lets *caller* send pool tokens to an address.

* Emits [Transfer](#transfer).

### transferFrom​

```js
func transferFrom(
            sender: felt, 
            recipient: felt, 
            amount: Uint256
        ) -> (success: felt):
```

Sends pool tokens from one address to another.

* Requires approval.
* Emits [Transfer](#transfer)

## Interface

```js
%lang starknet

from starkware.cairo.common.uint256 import Uint256

@contract_interface
namespace IJediSwapPairERC20:
    func name() -> (name: felt):
    end

    func symbol() -> (symbol: felt):
    end

    func decimals() -> (decimals: felt):
    end

    func totalSupply() -> (totalSupply: Uint256):
    end

    func balanceOf(account: felt) -> (balance: Uint256):
    end

    func allowance(owner: felt, spender: felt) -> (remaining: Uint256):
    end

    func transfer(recipient: felt, amount: Uint256) -> (success: felt):
    end

    func transferFrom(
            sender: felt, 
            recipient: felt, 
            amount: Uint256
        ) -> (success: felt):
    end

    func approve(spender: felt, amount: Uint256) -> (success: felt):
    end

    func increaseAllowance(spender: felt, added_value: Uint256) -> (success: felt):
    end

    func decreaseAllowance(spender: felt, subtracted_value: Uint256) -> (success: felt):
    end
end


```

## ABI

See [Pair ABI](https://docs.jediswap.xyz/for-developers/jediswap-v1/pair#abi)