Entrypoints

This section outlines the core entrypoints for the Invariant program, providing developers with essential methods to interact with the protocol. These entrypoints cover various aspects of the contract, including protocol fee management, fee tier administration, pool creation and management, position handling, and swap functionality. Program has 3 main entrypoints(Init, Handle, State). Invariant specific entrypoints are reached by sending a message with a proper enum variant to either Handle or State entrypoint. It should be noted that the message types for those entrypoints differ and can't be used interchangeably.

Init Entrypoint

Corresponding method

#[async_init]
async fn init() 

Input

pub struct InitInvariant {
    pub config: InvariantConfig,
}

This entrypoint initializes the program with the specified protocol fee and administrator ActorId.

Input parameters

Name	Type	Description
config	InvariantConfig	Config for the program

State Entrypoint

Corresponding method

#[no_mangle]
extern "C" fn state()

This entrypoint is used for methods that don't alter the state.

Invariant entrypoints can be accessed with variants of the InvariantStateQuery enum.

pub enum InvariantStateQuery {
    FeeTierExist(FeeTier),
    GetFeeTiers,
    GetProtocolFee,
    GetPool(ActorId, ActorId, FeeTier),
    GetPools(u8, u16),
    GetPosition(ActorId, u32),
    GetTick(PoolKey, i32),
    IsTickInitialized(PoolKey, i32),
    GetAllPositions(ActorId),
}

Entrypoint return messages are variants of InvariantStateReply enum.

pub enum InvariantStateReply {
    ProtocolFee(Percentage),
    QueriedFeeTiers(Vec<FeeTier>),
    FeeTierExist(bool),
    Pool(Pool),
    Pools(Vec<PoolKey>),
    Position(Position),
    Positions(Vec<Position>),
    Tick(Tick),
    IsTickInitialized(bool),
    QueryFailed(InvariantError),
}

Errors

Errors are returned through the QueryFailed variant.

Handle Entrypoint

Corresponding method

#[async_main]
async fn main()

This entrypoint is used for methods that don't alter the state.

Invariant entrypoints can be accessed with variants of the InvariantAction enum.

Input

pub enum InvariantAction {
    ChangeProtocolFee(Percentage),
    AddFeeTier(FeeTier),
    RemoveFeeTier(FeeTier),
    CreatePool {
        token_0: ActorId,
        token_1: ActorId,
        fee_tier: FeeTier,
        init_sqrt_price: SqrtPrice,
        init_tick: i32,
    },
    ChangeFeeReceiver(PoolKey, ActorId),
    CreatePosition {
        pool_key: PoolKey,
        lower_tick: i32,
        upper_tick: i32,
        liquidity_delta: Liquidity,
        slippage_limit_lower: SqrtPrice,
        slippage_limit_upper: SqrtPrice,
    },
    RemovePosition {
        position_id: u32,
    },
    TransferPosition {
        index: u32,
        receiver: ActorId,
    },
    Swap {
        pool_key: PoolKey,
        x_to_y: bool,
        amount: TokenAmount,
        by_amount_in: bool,
        sqrt_price_limit: SqrtPrice,
    },
    Quote {
        pool_key: PoolKey,
        x_to_y: bool,
        amount: TokenAmount,
        by_amount_in: bool,
        sqrt_price_limit: SqrtPrice,
    },
    QuoteRoute {
        amount_in: TokenAmount,
        swaps: Vec<SwapHop>,
    },
    ClaimFee {
        position_id: u32,
    },
    WithdrawProtocolFee(PoolKey),
}

Output

Entrypoint return messages are variants of InvariantEvent enum.

pub enum InvariantEvent {
    ProtocolFeeChanged(Percentage),
    PositionCreatedReturn(Position),
    PositionCreatedEvent {
        block_timestamp: u64,
        address: ActorId,
        pool_key: PoolKey,
        liquidity_delta: Liquidity,
        lower_tick: i32,
        upper_tick: i32,
        current_sqrt_price: SqrtPrice,
    },
    PositionRemovedReturn(TokenAmount, TokenAmount),
    PositionRemovedEvent {
        block_timestamp: u64,
        caller: ActorId,
        pool_key: PoolKey,
        liquidity: Liquidity,
        lower_tick_index: i32,
        upper_tick_index: i32,
        sqrt_price: SqrtPrice,
    },
    CrossTickEvent {
        timestamp: u64,
        address: ActorId,
        pool: PoolKey,
        indexes: Vec<i32>,
    },
    SwapEvent {
        timestamp: u64,
        address: ActorId,
        pool: PoolKey,
        amount_in: TokenAmount,
        amount_out: TokenAmount,
        fee: TokenAmount,
        start_sqrt_price: SqrtPrice,
        target_sqrt_price: SqrtPrice,
        x_to_y: bool,
    },
    SwapReturn(CalculateSwapResult),
    Quote(QuoteResult),
    ClaimFee(TokenAmount, TokenAmount),
    QuoteRoute(TokenAmount),
    ActionFailed(InvariantError),
}

Errors

Errors are returned through panic!

Invariant specific entrypoints

This section describes invariant specific entrypoints.

Protocol fee

Get protocol fee

This method retrieves the current protocol fee percentage.

Entrypoint

State

Input

InvariantStateQuery::GetProtocolFee

Output

InvariantStateReply::ProtocolFee(Percentage)

Output parameters

Type	Description
Percentage	The current protocol fee.

Withdraw protocol fee

This operation enables the withdrawal of protocol fees associated with a specific pool, based on the provided pool key. The withdrawn funds are sent to the fee receiver wallet. Please note that this action can only be performed by fee receiver.

Entrypoint

Handle

Input

InvariantAction::WithdrawProtocolFee(PoolKey)

Input parameters

Type	Description
PoolKey	The pool key that corresponds to the withdrawal of fees from the associated pool.

Errors

Code	Description
NotFeeReceiver	Reverts the call when the caller is unauthorized receiver.
TransferError	Fails if the allowance is insufficient or the user balance transfer fails
NotEnoughGasToExecute	Occurs when provided gas was too low to execute

External Contracts

• GRC-20

Change protocol fee

This function allows for the adjustment of the current protocol fee percentage. Note that this operation is restricted to administrators.

Entrypoint

Handle

Input

InvariantAction::ChangeProtocolFee(Percentage)

Output

InvariantEvent::ProtocolFeeChanged(Percentage)

Input parameters

Type	Description
Percentage	The new protocol fee percentage.

Output parameters

Type	Description
Percentage	Updated protocol fee percentage.

Errors

Code	Description
NotAdmin	Reverts the call when the caller is an unauthorized user.

Change fee receiver

This function allows for the modification of the fee receiver of a pool. Please note that this action is exclusively available to administrators.

Entrypoint

Handle

Input

InvariantAction::ChangeFeeReceiver(PoolKey, ActorId)

Input parameters

Type	Description
PoolKey	The pool key of the pool where the change is to be made.
ActorId	The new fee receiver's address of the pool.

Errors

Code	Description
NotAdmin	Reverts the call when the caller is unauthorized user.

Fee tier

Add fee tier

This function enables the addition of a new fee tier, which users can subsequently utilize when creating pools. Please note that this action is restricted to administrators.

Entrypoint

Handle

Input

InvariantAction::AddFeeTier(FeeTier)

Input parameters

Type	Description
FeeTier	The fee tier to be added.

Errors

Code	Description
NotAdmin	Fails if an unauthorized user attempts to create a fee tier.
InvalidTickSpacing	Fails if the tick spacing is invalid.
FeeTierAlreadyExist	Fails if the fee tier already exists.
InvalidFee	Fails if fee is invalid.

Fee Tier exist

This function is used to verify the existence of a specified fee tier.

Entrypoint

State

Input

InvariantStateQuery::FeeTierExist(FeeTier)

Output

InvariantStateReply::FeeTierExist(bool)

Input parameters

Type	Description
FeeTier	The key associated with the fee tier to be checked for existence.

Output parameters

Type	Description
bool	boolean indicating if the fee tier is added.

Get fee tiers

Retrieves available fee tiers.

Entrypoint

State

Input

InvariantStateQuery::GetFeeTiers

Output

InvariantStateReply::QueriedFeeTiers(Vec<FeeTier>)

Output parameters

Type	Description
Vec<FeeTier>	Vector containing all fee tiers added to specified pool

Remove fee tier

This function removes a fee tier based on the provided fee tier key. After removal, the fee tier will no longer be available for use in pool creation. It's important to note that existing pools with that fee tier will remain unaffected. This action is exclusively available to administrators.

Entrypoint

Handle

Input

InvariantAction::RemoveFeeTier(FeeTier)

Input parameters

Type	Description
FeeTier	The key associated with the fee tier to be removed.

Errors

Code	Description
NotAdmin	Fails if an unauthorized user attempts to create a fee tier.
FeeTierNotFound	Fails if fee tier does not exist.

Pools

Create pool

This function creates a pool based on a pair of tokens and the specified fee tier. The order of the tokens is irrelevant, and only one pool can exist with a specific combination of two tokens and a fee tier.

Entrypoint

Handle

Input

InvariantAction::CreatePool {
    token_0: ActorId,
    token_1: ActorId,
    fee_tier: FeeTier,
    init_sqrt_price: SqrtPrice,
    init_tick: i32,
}

Input parameters

Name	Type	Description
token_0	ActorId	Address of the first GRC-20 token in the pair.
token_1	ActorId	Address of the second GRC-20 token in the pair.
fee_tier	FeeTier	The fee tier to be applied.
init_sqrt_price	SqrtPrice	The square root of the price for the initial pool related to init_tick
init_tick	i32	The initial tick value for the pool.

Errors

Code	Description
FeeTierNotFound	Fails if the specified fee tier cannot be found.
TokensAreSame	Fails if the user attempts to create a pool for the same tokens.
PoolAlreadyExist	Fails if Pool with same tokens and fee tier already exist.
InvalidInitTick	Fails if the init tick is not divisible by the tick spacing.
InvalidInitSqrtPrice	Fails if the init sqrt price is not related to the init tick.

Get pool

This function retrieves a pool based on two tokens and the specified fee tier. It returns an error if the pool does not exist.

Entrypoint

State

Input

InvariantStateQuery::GetPool(ActorId, ActorId, FeeTier)

Output

InvariantStateReply::Pool(Pool)

Input parameters

Type	Description
ActorId	Address of the first token in the pair.
ActorId	Address of the second token in the pair.
FeeTier	The fee tier of the pool you want to retrieve.

Output parameters

Type	Description
Pool	A struct containing pool data.

Errors

Code	Description
PoolNotFound	Fails if there is no pool associated with created key.
TokensAreSame	Fails if the user attempts to create a pool for the same tokens.

Get pools

Entrypoint

State

Input

InvariantStateQuery::GetPools

Output

InvariantStateReply::Pools(Vec<PoolKey>)

This function retrieves a listed pool keys.

Output parameters

Type	Description
Vec<PoolKey>	Vector with pool keys that indicates all pools listed.

Position

Create position

This function creates a position based on the provided parameters. The amount of tokens specified in liquidity delta will be deducted from the user's token balances. Position creation will fail if the user does not have enough tokens or has not approved enough tokens.

Entrypoint

Handle

Input

InvariantAction::CreatePosition {
    pool_key: PoolKey,
    lower_tick: i32,
    upper_tick: i32,
    liquidity_delta: Liquidity,
    slippage_limit_lower: SqrtPrice,
    slippage_limit_upper: SqrtPrice,
}

Output

    PositionCreatedReturn(Position)

Input parameters

Name	Type	Description
pool_key	PoolKey	The pool key for which you want to create a position.
lower_tick	i32	The lower tick of your position.
upper_tick	i32	The upper tick of your position.
liquidity_delta	Liquidity	The liquidity you want to provide.
slippage_limit_lower	SqrtPrice	The lower square root of price fluctuation you are willing to accept.
slippage_limit_upper	SqrtPrice	The upper square root of price fluctuation you are willing to accept.

Output parameters

Type	Description
Position	The position that was created.

Errors

Code	Description
ZeroLiquidity	Fails if the user attempts to open a position with zero liquidity.
InvalidTickIndexOrTickSpacing	Fails if the user attempts to create a position with invalid tick indexes or tick spacing.
PriceLimitReached	Fails if the price has reached the slippage limit.
TransferError	Fails if the allowance is insufficient or the user balance transfer fails.
PoolNotFound	Fails if pool does not exist.
NotEnoughGasToExecute	Occurs when provided gas was too low to execute
NotEnoughGasToUpdate	Occurs when provided gas turned out to insufficient to update after transfer

External Contracts

• GRC-20

Transfer position

This function changes ownership of an existing position based on the position index in the user's position list. You can only change ownership of positions that you own; otherwise, it will return an error.

Entrypoint

Handle

Input

InvariantAction::TransferPosition {
    index: u32,
    receiver: ActorId,
}

Input parameters

Name	Type	Description
index	u32	Index of the position in the user's position list.
receiver	ActorId	Address of the user who will receive the position.

Remove position

This function removes a position from the user's position list and transfers the tokens used to create the position to the user's address.

Entrypoint

Handle

Input

InvariantAction::RemovePosition {
    position_id: u32,
}

Output

InvariantEvent::PositionRemovedReturn(TokenAmount, TokenAmount)

Input parameters

Name	Type	Description
index	u32	Index of the position in the user's position list.

Output parameters

Type	Description
TokenAmount	Amount of token X sent to the user's wallet address.
TokenAmount	Amount of token Y sent to the user's wallet address.

Errors

Code	Description
PositionNotFound	Fails if Position cannot be found.
TransferError	Fails if an error occurs on the side of any of the withdrawn tokens
NotEnoughGasToExecute	Occurs when provided gas was too low to execute

External Contracts

• GRC-20

Claim fee

Entrypoint

Handle

Input

InvariantAction::ClaimFee {
    position_id: u32,
}

Output

InvariantEvent::ClaimFee(TokenAmount, TokenAmount)

This function allows the user to claim fees from an existing position. Tokens will be sent to the user's address.

Input parameters

Name	Type	Description
index	u32	Index of the position in the user's position list.

Output parameters

Type	Description
TokenAmount	Amount of token X sent to the user's wallet address.
TokenAmount	Amount of token Y sent to the user's wallet address.

Errors

Code	Description
PositionNotFound	Fails if Position cannot be found.
TransferError	Fails if an error occurs on the side of any of the withdrawn tokens
NotEnoughGasToExecute	Occurs when provided gas was too low to execute

External Contracts

• GRC-20

Get position

This function returns an result that contains error if the position cannot be found or a position if it actually exists.

Entrypoint

State

Input

InvariantStateQuery::GetPosition(ActorId, u32)

Output

InvariantStateReply::Position(Position)

Input parameters

Type	Description
ActorId	An ActorId identifying the user who owns the position.
u32	Index of the position in the user's position list.

Output parameters

Type	Description
Position	Found position

Errors

Code	Description
PositionNotFound	Fails if Position cannot be found.

Get all positions

This function returns a list of positions owned by the caller. The list will be empty if you do not have any positions.

Entrypoint

State

Input

InvariantStateQuery::GetAllPositions(ActorId, u32)

Output

InvariantStateReply::Positions(Vec<Position>)

Input parameters

Type	Description
ActorId	An ActorId identifying the user who own the positions.

Output parameters

Type	Description
Vec<Position>	A list containing the user's positions.

Swap

Swap

This function executes a swap based on the provided parameters. It transfers tokens from the user's address to the contract's address and vice versa. The swap will fail if the user does not have enough tokens, has not approved enough tokens, or if there is insufficient liquidity.

Entrypoint

Handle

Input

InvariantAction::Swap {
    pool_key: PoolKey,
    x_to_y: bool,
    amount: TokenAmount,
    by_amount_in: bool,
    sqrt_price_limit: SqrtPrice,
}

Output

InvariantEvent::SwapReturn(CalculateSwapResult)

Input parameters

Name	Type	Description
pool_key	PoolKey	Pool key of the pool on which you wish to perform the swap.
x_to_y	bool	Specifies the direction of the swap.
amount	TokenAmount	Amount of tokens you want to receive or give.
by_amount_in	bool	Indicates whether the entered amount represents the tokens you wish to receive or give.
sqrt_price_limit	SqrtPrice	If the swap achieves this square root of the price, it will be canceled.

Output parameters

Type	Description
CalculateSwapResult	A struct containing the amount in and amount out with starting and target square root of price, taken fee, pool and vector of crossed ticks.

Errors

Code	Description
AmountIsZero	Fails if the user attempts to perform a swap with zero amounts.
PriceLimitReached	Fails if the price has reached the specified price limit (or price associated with specified square root of price).
NoGainSwap	Fails if the user would receive zero tokens.
TransferError	Fails if the allowance is insufficient or the user balance transfer fails.
PoolNotFound	Fails if pool does not exist.
NotEnoughGasToUpdate	Occurs when provided gas was too low to perform a state update after calculation

External Contracts

• GRC-20

Quote

This function performs a simulation of a swap based on the provided parameters and returns the simulation results. It does not involve any actual token transfers.

Entrypoints

Handle

Input

InvariantAction::Quote {
    pool_key: PoolKey,
    x_to_y: bool,
    amount: TokenAmount,
    by_amount_in: bool,
    sqrt_price_limit: SqrtPrice,
}

Output

InvariantEvent::Quote(QuoteResult)

Name	Type	Description
pool_key	PoolKey	Pool key of the pool on which you wish to perform the swap.
x_to_y	bool	Specifies the direction of the swap.
amount	TokenAmount	Amount of tokens you want to receive or give.
by_amount_in	bool	Indicates whether the entered amount represents the tokens you wish to receive or give.
sqrt_price_limit	SqrtPrice	If the swap achieves this square root of the price, it will be canceled.

Output parameters

Type	Description
QuoteResult	A struct containing amount of tokens received, amount of tokens given, square root of price after the simulated swap and list of ticks that has been crossed durning the simulation

Errors

Code	Description
AmountIsZero	Fails if the user attempts to perform a swap with zero amounts.
PriceLimitReached	Fails if the price has reached the specified price limit (or price associated with specified square root of price).
NoGainSwap	Fails if the user would receive zero tokens.
PoolNotFound	Fails if pool does not exist.

Quote Route

Entrypoints

Handle

Input

InvariantAction::QuoteRoute {
    amount_in: TokenAmount,
    swaps: Vec<SwapHop>,
}

Output

InvariantEvent::QuoteRoute(TokenAmount)

This function performs a simulation of multiple swaps based on the provided parameters and returns the simulation results. It does not involve any actual token transfers.

Input parameters

Name	Type	Description
amount_in	TokenAmount	Amount of tokens you want to swap.
swaps	Vec<SwapHop>	A vector containing all parameters needed to identify separate swap steps.

Output parameters

Type	Description
TokenAmount	Amount of tokens received in the simulation.

Errors

Code	Description
AmountIsZero	Fails if the user attempts to perform a swap with zero amounts.
PriceLimitReached	Fails if the price has reached the specified price limit (or price associated with specified square root of price).
NoGainSwap	Fails if the user would receive zero tokens.
PoolNotFound	Fails if pool does not exist.

Tick

Get tick

Retrieves information about a tick at a specified index.

Entrypoint

State

Input

InvariantStateQuery::GetTick(PoolKey, i32)

Output

InvariantStateReply::Tick(Tick)

Input parameters

Type	Description
PoolKey	A unique key that identifies the specified pool.
i32	The tick index in the tickmap.

Output parameters

Type	Description
Tick	A struct containing tick data.

Errors

Code	Description
TickNotFound	Fails if tick cannot be found.

Is tick initialized

Retrieves information about a tick at a specified index.

Entrypoint

State

Input

InvariantStateQuery::IsTickInitialized(PoolKey, i32)

Output

InvariantStateReply::IsTickInitialized(bool)

Input parameters

Type	Description
PoolKey	A unique key that identifies the specified pool.
i32	The tick index in the tickmap.

Output parameters

Type	Description
bool	boolean identifying if the tick is initialized in tickmap.