BalancerAdapter

The BalancerAdapter is designed to interact with the Balancer v2 Protocol.

This adapter enables users to harness the power of Balancer's v2 AMM features and integrate them into their financial strategies.

Enums

SwapOperation

Defines the actions available with respect to Swap Operations:

SWAP: Perform a swap against a single pool
BATCH_SWAP: Perform a series of swaps against one or multiple pools

enum SwapOperation {SWAP, BATCH_SWAP}

Structs

GeneralExtraData

Defines the necessary data required for performing deposit-wise & withdrawl-wise actions such as:

Join pools
Exit pools

struct GeneralExtraData {
    bytes32 poolId;
    bytes userData;
    bool fromToInternalBalance;
}

Members

Name	Type	Description
`poolId`	`bytes32`	The ID of the target pool
`userData`	`bytes`	ABI encoded specific use case data to pass to the target pool. Check the following for more info: Pool Join userData, Pool Exit userData
`fromToInternalBalance`	`bool`	A flag, which in the context of:-`deposit`: If true, the sender's Internal Balance (Vault's bookkeeping) will be preferred, performing an ERC20 transfer for the difference between the requested amount and the user's Internal Balance (if any); if false, an ERC20 transfer will be performed for the whole requested amount. -`withdraw`: If true, tokens will be deposited to recipient's Internal Balance (Vault's bookkeeping) instead of transferred; if false, an ERC20 transfer will be performed.

SingleSwapData

Defines the necessary data for invoking the Vault's swap function. It encapsulates the necessary data for performing a swap against a single pool.

Note: This structure serves as the non-encoded operation data within the broader SwapExtraData struct.

struct SingleSwapData {
    bytes32 poolId;
    IVault.SwapKind kind;
    bool fromInternalBalance;
    bool toInternalBalance;
    bytes userData;
    uint256 limit;
    uint256 deadline;
}

Members

Name	Type	Description
`poolId`	`bytes32`	The ID of the target pool
`kind`	`IVault.SwapKind`	The swap kind (GIVEN_IN, or GIVEN_OUT)
`fromInternalBalance`	`bool`	If true the sender's Internal Balance (Vault's bookkeeping) will be preferred, performing an ERC20 transfer for the difference between the requested amount and the user's Internal Balance (if any). If false, an ERC20 transfer will be performed for the whole requested amount.
`toInternalBalance`	`bool`	If true, tokens will be deposited to recipient's Internal Balance (Vault's bookkeeping) instead of transferred; if false, an ERC20 transfer will be performed.
`userData`	`bytes`	ABI encoded specific use case data to pass to the target pool
`limit`	`uint256`	Limit for the swap that depends on the swap kind:`GIVEN_IN`: The amount of tokens taken from the pool must be greater than or equal to `limitGIVEN_OUT`: The amount of tokens sent to the pool must be less than or equal to `limit`
`deadline`	`uint256`	The deadline epoch timestamp (in seconds) until which the swap can be executed

BatchSwapData

Defines the necessary data for invoking the Vault's batchSwap function. It encapsulates the necessary data for performing a series of swaps against one or multiple pools.

Note: This structure serves as the non-encoded operation data within the broader SwapExtraData struct.

struct BatchSwapData {
    IVault.BatchSwapStep[] swaps;
    IAsset[] assets;
    IVault.SwapKind kind;
    bool fromInternalBalance;
    bool toInternalBalance;
    int256[] limits;
    uint256 deadline;
    uint256 nativeTokenAmount;
}

Members

Name	Type	Description
`swaps`	`IVault.BatchSwapStep[]`	Data for each individual swap executed
`assets`	`IAsset[]`	Array of assets' addresses to be used in the swaps. ETH is specified with the zero address (sentinel value)
`kind`	`IVault.SwapKind`	The swap kind (GIVEN_IN, or GIVEN_OUT)
`fromInternalBalance`	`bool`	If true the sender's Internal Balance (Vault's bookkeeping) will be preferred, performing ERC20 transfers for the difference between the requested amount and the user's Internal Balance (if any). If false, an ERC20 transfer will be performed for the whole requested amount.
`toInternalBalance`	`bool`	If true, tokens will be deposited to recipient's Internal Balance (Vault's bookkeeping) instead of transferred; if false, an ERC20 transfer will be performed.
`limits`	`int256[]`	Array of limits for each token involved in the batch swap. In the context of swap kind:`GIVEN_IN`: The amount for each token taken from the pool must be greater than or equal to the respective specified `limitGIVEN_OUT`: The amount of each token sent to the pool must be less than or equal to the repsective specified `limit`
`deadline`	`uint256`	The deadline epoch timestamp (in seconds) until which the batch swap can be executed
`nativeTokenAmount`	`uint256`	The amount of native token to be sent to the poolNote: Pools never interact with ETH directly; it will be wrapped to, or unwrapped from WETH by the Vault

SwapExtraData

Used to indicate the appropriate action of a Swap Operation.

struct SwapExtraData {
    SwapOperation swapOperation;
    bytes extraSwapData;
}

Members

Name	Type	Description
`swapOperation`	`SwapOperation`	The action to conduct (SWAP, or BATCH_SWAP)
`extraSwapData`	`bytes`	Additional ABI encoded data related to the operation ( a , b )

Layout

Used to store crucial data for the Adapter's functionality in a specific storage slot.

struct Layout {
    IVault vault;
    address nativeToken;
}

Members

Name	Type	Description
`vault`	`IVault`	The interface representing the Vault contract instance
`nativeToken`	`address`	The address of the wrapped native token address

State Variables

STORAGE_SLOT

Unique identifier for the storage slot where the Layout struct is stored.

bytes32 internal immutable STORAGE_SLOT;

Constructor

Sets the value of the STORAGE_SLOT state variable.

The value is computed as the keccak256 hash of the abi encoding of:

The Nexera-FI.BalancerAdapter string literal
The address of this contract (BalancerAdapter)

constructor();

Functions

initialize

Initializes the Adapter.

function initialize(bytes calldata initData_) external override;

Parameters

Name	Type	Description
`initData_`	`bytes`	The ABI encoded Layout data

_deposit

Internal function for handling Deposit Operations.

This function is responsible for depositing specified assets into a target Balancer pool.

Called by executeAction function.

function _deposit(
    IAdapter.TokenAmount[] calldata out,
    IAdapter.TokenAmount[] calldata expectedIn,
    bytes calldata extraData
) internal override;

Parameters

Name	Type	Description
`out`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the token compositions to send. The array must contain the tokens (addresss & amount fields) to be deposited in the order of the target pool tokens.
`expectedIn`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the expected token compositions to receive (BPT token). The array's length must equal 1 and contain the address of the target pool's BPT token (the amount field is ignored).
`extraData`	`bytes`	ABI encoded data of type `GeneralExtraData` required for the action.

_withdraw

Internal function for handling Withdraw Operations.

This function is responsible for withdrawing specified assets from a target Balancer pool.

Called by executeAction function.

function _withdraw(
    IAdapter.TokenAmount[] calldata out,
    IAdapter.TokenAmount[] calldata expectedIn,
    bytes calldata extraData
) internal override;

Parameters

Name	Type	Description
`out`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the token compositions to send. The array's length must equal 1 and contain the address of the target pool's BPT token (the amount field is ignored).
`expectedIn`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the expected token compositions to receive. The array must contain the tokens (addresss & amount fields) to be withdrawn in the order of the target pool tokens.Note: amount fields must be 0 if `toInternalBalance == true`
`extraData`	`bytes`	ABI encoded data of type `GeneralExtraData` required for the action.

_swap

Internal function for handling Swap Operations.

This function facilitates the swapping (either SWAP, or BATCH_SWAP) of assets against a target Balancer pool.

Called by executeAction function.

function _swap(
    IAdapter.TokenAmount[] calldata out,
    IAdapter.TokenAmount[] calldata expectedIn,
    bytes calldata extraData
) internal virtual override;

Parameters

Name	Type	Description
`out`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the token compositions to send. In the context of: swap: The array's length must equal 1 and contain the token (address & amount field) to be provided to the pool. batch swap: The `out` parameter is ignored as all data needed are included in the extraData parameterNote: amount fields must be 0 if `toInternalBalance == true`
`expectedIn`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the expected token compositions to receive. In the context of: swap: The array's length must equal 1 and contain the token (address & amount field) to be received from the pool. batch swap: The `out` parameter is ignored as all data needed are included in the extraData parameterNote: amount fields must be 0 if `toInternalBalance == true`
`extraData`	`bytes`	ABI encoded data of type `SwapExtraData` required for the action.

_operate

This function always raises the OPERATION_NOT_SUPPORTED error, as Operate is not an action supported within the Balancer's Vault.

Called by executeAction function.

function _operate(
    IAdapter.TokenAmount[] calldata,
    IAdapter.TokenAmount[] calldata,
    bytes calldata
) internal virtual override;

_collect

This function always raises the OPERATION_NOT_SUPPORTED error, as Collect is not an action supported within the Balancer's Vault.

Called by executeAction function.

function _collect(
    IAdapter.TokenAmount[] calldata,
    IAdapter.TokenAmount[] calldata,
    bytes calldata
) internal virtual override;

_singleSwap

Performs a swap against a single Balancer pool.

Called by _swap function.

function _singleSwap(
    IAdapter.TokenAmount calldata out,
    IAdapter.TokenAmount calldata expectedIn,
    bytes memory extraSwapData
) internal virtual;

Parameters

Name	Type	Description
`out`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the token compositions to send.The array's length must equal 1 and contain the token (address & amount field) to be provided to the pool
`expectedIn`	`IAdapter.TokenAmount[]`	Array of `TokenAmount` structs defining the token compositions to receive.The array's length must equal 1 and contain the token (address & amount field) to be received from the pool
`extraSwapData`	`bytes`	ABI encoded data of type `SingleSwapData`.Note: The repsective amount fields must be 0 within `out` and/or `expectedIn` if: `fromInternalBalance == true` and/or `toInternalBalance == true` respectively.

_batchSwap

Performs a series of swaps against one or multiple Balancer pools.

Called by _swap function.

function _batchSwap(
    bytes memory extraSwapData
) internal virtual;

Parameters

Name	Type	Description
extraSwapData	bytes	ABI encoded data of type `BatchSwapData` that encapsulates all the required data

_validatePool

Internal helper function to validate that the specified token corresponds to the BPT (Balancer Pool Token) of the target pool specified by poolId. It reverts if the validation fails.

It invokes the Vault's getPool method to retrieve the address of the target pool's BPT to validate against.

Called by _deposit and _withdraw functions.

function _validatePool(bytes32 poolId, address token) internal view;

Parameters

Name	Type	Description
poolId	bytes32	The ID of the target pool
token	address	The token to be validated as the BPT of the target pool

layout

Retrieves a reference to the Layout struct stored at a specified storage slot.

function layout() internal view returns (Layout storage l);

BalancerAdapter

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