aave-tokens on Aptos

This documentation covers the tokenization modules in the Aave protocol implementation on Aptos. Similar to Aave on EVM chains, the Aptos implementation uses specialized tokens to represent user positions in the protocol.

The a_token_factory module manages the creation and operations of aTokens, which represent user supply positions in the Aave protocol. aTokens are interest-bearing tokens that automatically accrue interest to their holders.

public(friend) fun create_token(    signer: &signer,    name: String,    symbol: String,    decimals: u8,    icon_uri: String,    project_uri: String,    incentives_controller: Option<address>,    underlying_asset: address,    treasury: address): address

Creates a new aToken for a specific underlying asset.

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public(friend) fun mint(    caller: address,    on_behalf_of: address,    amount: u256,    index: u256,    metadata_address: address): bool

Mints aTokens to a user.

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public(friend) fun burn(    from: address,    receiver_of_underlying: address,    amount: u256,    index: u256,    metadata_address: address)

Burns aTokens from a user and sends the equivalent amount of underlying to the receiver.

In some instances, a mint event could be emitted from a burn transaction if the amount to burn is less than the interest that the user accrued.

public(friend) fun mint_to_treasury(    amount: u256,    index: u256,    metadata_address: address)

Mints aTokens to the reserve treasury.

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public(friend) fun transfer_on_liquidation(    from: address,    to: address,    amount: u256,    index: u256,    metadata_address: address)

Transfers aTokens in the event of a borrow being liquidated, in case the liquidator reclaims the aToken.

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public fun handle_repayment(    _user: address,    _on_behalf_of: address,    _amount: u256,    _metadata_address: address)

Handles the underlying received by the aToken after the transfer has been completed.

The default implementation is empty as with standard tokens, nothing needs to be done after the transfer is concluded. However, in the future there may be aTokens that allow for example to stake the underlying to receive LM rewards. In that case, handle_repayment() would perform the staking of the underlying asset.

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public(friend) fun drop_token(metadata_address: address)

Drops the aToken associated data.

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public fun get_underlying_asset_address(    metadata_address: address): address

Returns the address of the underlying asset of this aToken.

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public fun get_previous_index(    user: address,    metadata_address: address): u256

Returns the last index interest was accrued to the user's balance.

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public fun get_scaled_user_balance_and_supply(    owner: address,    metadata_address: address): (u256, u256)

Returns the scaled balance of the user and the scaled total supply.

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public fun scaled_balance_of(    owner: address,    metadata_address: address): u256

Returns the scaled balance of the user.

The scaled balance is the sum of all the updated stored balance divided by the reserve's liquidity index at the moment of the update.

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public fun scaled_total_supply(    metadata_address: address): u256

Returns the scaled total supply of the aToken.

The scaled total supply is the sum of all scaled balances of the users.

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public fun decimals(metadata_address: address): u8

Returns the decimals of the aToken.

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The variable_debt_token_factory module manages the creation and operations of variable debt tokens in the Aave protocol on Aptos. Variable debt tokens represent user borrowing positions with a variable interest rate.

public(friend) fun create_token(    signer: &signer,    name: String,    symbol: String,    decimals: u8,    icon_uri: String,    project_uri: String,    incentives_controller: Option<address>,    underlying_asset: address): address

Creates a new variable debt token for a specific underlying asset.

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public(friend) fun mint(    caller: address,    on_behalf_of: address,    amount: u256,    index: u256,    metadata_address: address): bool

Mints debt tokens to the on_behalf_of address.

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public(friend) fun burn(    from: address,    amount: u256,    index: u256,    metadata_address: address)

Burns debt tokens from a user.

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public(friend) fun drop_token(metadata_address: address)

Drops the variable debt token associated data.

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public fun get_underlying_asset_address(    metadata_address: address): address

Returns the address of the underlying asset of this variable debt token.

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public fun get_previous_index(    user: address,    metadata_address: address): u256

Returns the last index interest was accrued to the user's balance.

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public fun get_scaled_user_balance_and_supply(    owner: address,    metadata_address: address): (u256, u256)

Returns the scaled balance of the user and the scaled total supply.

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public fun scaled_balance_of(    owner: address,    metadata_address: address): u256

Returns the scaled balance of the user.

The scaled balance is the sum of all the updated stored balance divided by the reserve's variable debt index at the moment of the update.

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public fun scaled_total_supply(    metadata_address: address): u256

Returns the scaled total supply of the variable debt token.

The scaled total supply is the sum of all scaled balances of the users with debt.

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public fun name(metadata_address: address): String

Returns the name of the variable debt token.

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public fun symbol(metadata_address: address): String

Returns the symbol of the variable debt token.

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public fun decimals(metadata_address: address): u8

Returns the decimals of the variable debt token.

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The variable debt token implementation in Aptos follows similar principles to the Ethereum implementation but is adapted to the Move language and Aptos blockchain architecture:

The variable debt tokens in Aave on Aptos serve the same purpose as in the Ethereum implementation: they represent a user's variable-rate debt position in the protocol and automatically accrue interest over time based on the variable interest rate of the corresponding reserve.