🏊‍♀️Constant Product Pool

The famous xy=k pool implementation

1. Overview

The constant product pool uses the widely known xy=k formula. More details around how the pool functions can be found here.

2. Variables & Functions

Constants

Name	Description
CONTRACT_NAME	The constant product contract name
CONTRACT_VERSION	The contract version
INSTANTIATE_TOKEN_REPLY_ID	A reply call code ID used for sub-messages
DEFAULT_SLIPPAGE	Default slippage tolerance enforced on swaps
MAX_ALLOWED_SLIPPAGE	The maximum possible slippage tolerance
TWAP_PRECISION	Decimal precision for TWAP results

Structs

Name	Description	Contains
Config	This struct holds general contract parameters	pair_info - General pair information (e.g pair type) factory_addr - The Astroport factory contract address block_time_last - The last timestamp when the pair contract update the asset cumulative prices price0_cumulative_last - The last cumulative price for asset 0 price1_cumulative_last - The last cumulative price for asset 1
InstantiateMsg	This struct holds parameters used to instantiate the pair contract	asset_infos - Information about the two assets in the pool token_code_id - The token contract code ID used for the tokens in the pool factory_addr - The factory contract address init_params - Optional binary serialised parameters for custom pool types
PoolResponse	This struct is used to return a query result with the total amount of LP tokens and the two assets in a specific pool	assets - The assets in the pool together with asset amounts total_share - The total amount of LP tokens currently issued
ConfigResponse	This struct is used to return a query result with the general contract configuration	block_time_last - Last timestamp when the cumulative prices in the pool were updated params - The pool's parameters
SimulationResponse	This structure holds the parameters that are returned from a swap simulation response	return_amount - The amount of ask assets returned by the swap spread_amount - The spread used in the swap operation commission_amount - The amount of fees charged by the transaction
ReverseSimulationResponse	This structure holds the parameters that are returned from a reverse swap simulation response	offer_amount - The amount of offer assets returned by the reverse swap spread_amount - The spread used in the swap operation commission_amount - The amount of fees charged by the transaction
CumulativePricesResponse	This structure is used to return a cumulative prices query response	assets - The two assets in the pool to query total_share - The total amount of LP tokens currently issued price0_cumulative_last - The last value for the token0 cumulative price price1_cumulative_last - The last value for the token1 cumulative price

Functions

Name	Params	Description
instantiate	(deps: DepsMut, _env: Env, _info: MessageInfo, msg: InstantiateMsg) -> Result<Response, ContractError>	Instantiate the pair contract
reply	(deps: DepsMut, _env: Env, msg: Reply) -> Result<Response, ContractError>	The entry point to the contract for processing replies from submessages
execute	(deps: DepsMut, env: Env, info: MessageInfo, msg: ExecuteMsg) -> Result<Response, ContractError>	Execute a function from the contract
receive_cw20	(deps: DepsMut, env: Env, info: MessageInfo, cw20_msg: Cw20ReceiveMsg) -> Result<Response, ContractError>	Receives a message of type [Cw20ReceiveMsg] and processes it depending on the received template
provide_liquidity	(deps: DepsMut, env: Env, info: MessageInfo, assets: [Asset; 2], slippage_tolerance: Option<Decimal>, auto_stake: Option<bool>, receiver: Option<String>) -> Result<Response, ContractError>	Provide liquidity in the pair. Asset is imported from the asset file
mint_liquidity_token_message	(deps: Deps, config: &Config, env: Env, recipient: Addr, amount: Uint128, auto_stake: bool) -> Result<Vec, ContractError>	Internal function used to mint LP tokens for a beneficiary and auto stake the tokens in the Generator contract (if auto staking is specified)
withdraw_liquidity	(deps: DepsMut, env: Env, info: MessageInfo, sender: Addr, amount: Uint128) -> Result<Response, ContractError>	Withdraw liquidity from the pool
get_share_in_assets	(pools: &[Asset; 2], amount: Uint128, total_share: Uint128) -> Vec<Asset>	Returns the amount of pool assets that correspond to an amount of LP tokens. Asset is imported from the asset file
swap	(deps: DepsMut, env: Env, info: MessageInfo, sender: Addr, offer_asset: Asset, belief_price: Option<Decimal>, max_spread: Option<Decimal>, to: Option<Addr>) -> Result<Response, ContractError>	Performs an swap operation with the specified parameters. Asset is imported from the asset file
accumulate_prices	(env: Env, config: &Config, x: Uint128, y: Uint128) -> StdResult<Option<(Uint128, Uint128, u64)>>	Internal function used to accumulate token prices for the assets in the pool. Note that this function shifts block_time when any of the token prices is zero in order to not fill an accumulator with a null price for that period
calculate_maker_fee	(pool_info: AssetInfo, commission_amount: Uint128, maker_commission_rate: Decimal) -> Option<Asset>	Internal function used to calculate the amount of fees the Maker contract gets according to specified pair parameters. AssetInfo is imported from the asset file
migrate	(_deps: DepsMut, _env: Env, _msg: MigrateMsg) -> StdResult<Response>	Used for the contract migration
query	(deps: Deps, env: Env, msg: QueryMsg) -> StdResult<Binary>	Query the contract
query_pair_info	(deps: Deps) -> StdResult<PairInfo>	Returns information about the pair contract. PairInfo is imported from the asset file
query_pool	(deps: Deps) -> StdResult<PoolResponse>	Returns the amounts of assets in the pair contract as well as the amount of LP tokens currently issued
query_share	(deps: Deps, amount: Uint128) -> StdResult<Vec<Asset>>	Returns the amount of assets that could be withdrawn from the pool using a specific amount of LP tokens. Asset is imported from the asset file
query_simulation	(deps: Deps, offer_asset: Asset) -> StdResult<SimulationResponse>	Returns information about a swap simulation. Asset is imported from the asset file
query_reverse_simulation	(deps: Deps, ask_asset: Asset) -> StdResult<ReverseSimulationResponse>	Returns information about a reverse swap simulation. Asset is imported from the asset file
query_cumulative_prices	(deps: Deps, env: Env) -> StdResult<CumulativePricesResponse>	Returns information about cumulative prices for the assets in the pool
query_config	(deps: Deps) -> StdResult<ConfigResponse>	Returns the pair contract configuration
amount_of	(coins: &[Coin], denom: String) -> Uint128	Returns an amount of coins
compute_swap	(offer_pool: Uint128, ask_pool: Uint128, offer_amount: Uint128, commission_rate: Decimal) -> StdResult<(Uint128, Uint128, Uint128)>	Returns the result of a swap
compute_offer_amount	(offer_pool: Uint128, ask_pool: Uint128, ask_amount: Uint128, commission_rate: Decimal) -> StdResult<(Uint128, Uint128, Uint128)>	Returns an amount of offer assets for a specified amount of ask assets
assert_max_spread	(belief_price: Option<Decimal>, max_spread: Option<Decimal>, offer_amount: Uint128, return_amount: Uint128, spread_amount: Uint128) -> Result<(), ContractError>	This is an internal function; if belief_price and max_spread are both specified, we compute a new spread, otherwise we just use the swap spread to check max_spread
assert_slippage_tolerance	(slippage_tolerance: Option<Decimal>, deposits: &[Uint128; 2], pools: &[Asset; 2]) -> Result<(), ContractError>	This is an internal function that enforces slippage tolerance for swaps. Asset is imported from the asset file
pool_info	(deps: Deps, config: Config) -> StdResult<([Asset; 2], Uint128)>	Returns the total amount of assets in the pool as well as