Class: UniswapV2Pair

Inherits:
UniswapV2ERC20 show all
Defined in:
lib/uniswap/UniswapV2Pair.rb

Overview

contract :IUniswapV2Factory, abstract: true do

function :feeTo, {}, :external, :view, returns: :address do
end

end

Constant Summary collapse

MINIMUM_LIQUIDITY =

> 1000

10 ** 3

Instance Method Summary collapse

Methods inherited from ERC20

#_burn, #_mint, #approve, #transfer, #transferFrom

Instance Method Details

#_mintFee(reserve0:, reserve1:) ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 112

def _mintFee( reserve0:, reserve1: )
  feeTo = UniswapV2Factory.at( @factory ).feeTo
  feeOn = feeTo != address(0)
  kLast = @kLast
  
  if feeOn
    if kLast != 0
      ## note: sqrt NOT built-in - double check
      rootK = Integer.sqrt( reserve0 * reserve1 )
      rootKLast = Integer.sqrt( kLast )
      if rootK > rootKLast
        numerator = @totalSupply * (rootK - rootKLast)
        denominator = rootK * 5 + rootKLast
        liquidity = numerator.div(denominator)
        _mint( feeTo, liquidity )   if liquidity > 0
      end
    end
  elsif kLast != 0
    @kLast = 0
  end
  feeOn
end

#_safeTransfer(token:, to:, value:) ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 74

def _safeTransfer( token:, to:, value:)
  result = ERC20.at( token ).transfer(to: to, amount: value)
  
  assert result, "ScribeSwap: TRANSFER_FAILED"
end

#_update(balance0:, balance1:, reserve0:, reserve1:) ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 82

def _update(
  balance0:,
  balance1:,
  reserve0:,
  reserve1: )
  assert balance0 <= (2 ** 112 - 1) && balance1 <= (2 ** 112 - 1), 'ScribeSwap: OVERFLOW'
  
  # blockTimestamp = uint32(block.timestamp % 2 ** 32)
  # overflow is desired  - why??
  timeElapsed = block.timestamp - @_blockTimestampLast   
  
  if timeElapsed > 0 && reserve0 != 0 && reserve1 != 0
    # * never overflows, and + overflow is desired
    #   up reserve1 from 112 to 224 bit (shift by 112bit)
    #   up reserve2 from 112 to 224 bit (shift by 112bit)
    @price0CumulativeLast +=  (reserve1*(2 ** 112)) / reserve0  * timeElapsed
    @price1CumulativeLast +=  (reserve0*(2 ** 112)) / reserve1  * timeElapsed
  end
  
  log PreSwapReserves, reserve0: @_reserve0, reserve1: @_reserve1
  
  @_reserve0 = balance0   ## was uint112()
  @_reserve1 = balance1
  
  @_blockTimestampLast = block.timestamp
  log Sync, reserve0: @_reserve0, reserve1: @_reserve1
end

#constructor ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 51

def constructor
  super
  @factory   = msg.sender
  @_unlocked = uint( 1 )
end

#getReserves ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 67

def getReserves
  return [@_reserve0,
          @_reserve1,
          @_blockTimestampLast]
end

#init(token0:, token1:) ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 59

def init( token0:, token1: )
  assert msg.sender == @factory, 'ScribeSwap: FORBIDDEN'

  @token0 = token0
  @token1 = token1    
end

#mint(to:) ⇒ Object 



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# File 'lib/uniswap/UniswapV2Pair.rb', line 136

def mint( to: )
  assert @_unlocked == 1, 'ScribeSwap: LOCKED'
  
  reserve0, reserve1, _ = getReserves
  
  balance0 = ERC20.at( @token0 ).balanceOf( __address__ ) ## address(this)
  balance1 = ERC20.at( @token1 ).balanceOf( __address__ ) ## address(this)
 
  amount0 = balance0 - reserve0
  amount1 = balance1 - reserve1
  
  feeOn = _mintFee( reserve0, reserve1)
  totalSupply = @totalSupply

 
  if totalSupply == 0
    ## note: sqrt NOT built-in - double check
    ##  move "upstream" into contract base (for all) - why? why not?
    liquidity = uint( Integer.sqrt(amount0 * amount1)) - MINIMUM_LIQUIDITY
    _mint( address(0), MINIMUM_LIQUIDITY )
  else
    liquidity = [
      (amount0 * totalSupply).div(reserve0),
      (amount1 * totalSupply).div(reserve1)
    ].min
  end

  assert liquidity > 0, 'ScribeSwap: INSUFFICIENT_LIQUIDITY_MINTED'
  _mint( to, liquidity )
 

  _update( balance0, balance1, reserve0, reserve1 )
  @kLast = @_reserve0 * @_reserve1    if feeOn
  
  log Mint, sender: msg.sender, amount0: amount0, amount1: amount1
  
  liquidity
end