TokenExtension

TokenExtension

This shouldn’t be used directly, it should be extended by child contracts

This contract setups the base of every Token Extension contract. It defines a set data structure for holding important information about the current Extension registration instance. This includes the extension supported token standards, function signatures, supported interfaces, deployer address and extension version.

The TokenExtension also defines three functions that allow extensions to register callbacks to specific events: _listenForTokenTransfers, _listenForTokenBeforeTransfers, _listenForTokenApprovals

The ExtensionBase also provides several function modifiers to restrict function invokation

onlyOwner()

A function modifier to only allow the token owner to execute this function

onlyTokenOrOwner()

A function modifier to only allow the token owner or the address that registered the extension to execute this function

constructor() (internal)

Invoke TokenExtension constructor and set the deployer as well as register the packageHash

_setVersion(uint256 __version) (internal)

Sets the package version. Can only be called within the constructor

_setPackageName(string package) (internal)

Sets the package name. Can only be called within the constructor

_supportsTokenStandard(enum TokenStandard tokenStandard) (internal)

Sets token standard as supported. Can only be called within the constructor. Valid token standards referenced in the TokenStandards enum

_setInterfaceLabel(string interfaceLabel_) (internal)

Sets the interface label of the extension. Can only be called within the constructor and should be called for every extension.

_supportsAllTokenStandards() (internal)

Sets all valid token standard as supported. Can only be called within the constructor.

extensionDeployer() → address (external)

Gets the extension deployer address

packageHash() → bytes32 (external)

Gets the package hash (generated using the package name and deployer address)

version() → uint256 (external)

Gets the package version

isTokenStandardSupported(enum TokenStandard standard) → bool (external)

Checks if token standard is supported by the extension

_requireRole(bytes32 roleId) (internal)

Specify a token role Id that this extension requires. For example if an extension needs to mint tokens then it should require TOKEN_MINTER_ROLE. Can only be called within the constructor.

_supportInterface(bytes4 interfaceId) (internal)

Specify a specific interface label that this extension supports. Can only be called within the constructor.

_registerFunctionName(string selector) (internal)

Same as _registerFunction(bytes4), however lets you specify a function by its function signature. Can only be called within the constructor.

_registerFunction(bytes4 selector) (internal)

Register a function selector to be added to the token. If this function is invoked on the token, then this extension instance will be invoked. Can only be called within the constructor.

externalFunctions() → bytes4[] (external)

An array of function signatures registered by the extension

This function is used by the TokenProxy to determine what function selectors to add to the TokenProxy

requiredRoles() → bytes32[] (external)

Gets the list of required roles required to call the extension

_isInsideConstructorCall() → bool (internal)

Checks if execution context is within the contract constructor

interfaceLabel() → string (external)

The ERC1820 interface label the extension will be registered as in the ERC1820 registry

_isTokenOwner(address addr) → bool (internal)

Checks if address is the token owner

_erc20Token() → contract IERC20Extendable (internal)

Explicit method for erc20 tokens. I returns an erc20 proxy contract interface

_tokenOwner() → address (internal)

Get the current owner address of the registered token

_buildTransfer(address from, address to, uint256 amountOrTokenId) → struct TransferData (internal)

Creates a TransferData structure, to be used as an argument for tokenTransfer function. Also it is relevant to point out that TransferData supports all token standards available in this enum TokenStandard

_tokenTransfer(struct TransferData tdata) → bool (internal)

Perform a transfer given a TransferData struct. Only addresses with the token controllers role should be able to invoke this function.

_listenForTokenTransfers(function (struct TransferData) external returns (bool) callback) (internal)

Listen for token transfers and invoke the provided callback function. When the callback is invoked, the transfer has already occured. It is important that the callback has the onlyToken modifier in order to ensure that only the token can execute the callback function.

_listenForTokenBeforeTransfers(function (struct TransferData) external returns (bool) callback) (internal)

Listen for token approvals and invoke the provided callback function. When the callback is invoked, the approval has already occured. It is important that the callback has the onlyToken modifier in order to ensure that only the token can execute the callback function.

_listenForTokenApprovals(function (struct TransferData) external returns (bool) callback) (internal)

Listen for token transfers and invoke the provided callback function. The callback is invoked right before the transfer occurs. It is important that the callback has the onlyToken modifier in order to ensure that only the token can execute the callback function