@subsection TokenSwap

Token swap interface that can fit token escrow purposes aswell as token swap contracts.

Optionally may define a @code{defaultToken}, that may among other things be used for @code{withdraw()} calls without an @code{inToken}.

An explicit @emph{ERC20 approval} of the balance to be transacted will usually be required for the implementing contract.

If the value 0 is passed as argument to @code{deposit} or @code{withdraw}, implementers can choose one of two possible outcomes:

@itemize
@item Noop. 0 @emph{must} be returned.
@item Use @emph{balance} or the max available @emph{allowance}. The actual (spent) value @emph{must} be returned.
@end itemize

@subsubsection ERC165 Interface identifier

@include ../../build/TokenSwap.interface

@subsubsection Solidity interface definition

@include ../../build/contract_TokenSwap.texi

@subsubsection Reference implementations

@itemize
@item
@uref{git://holbrook.no/erc20-pool.git,}
@end itemize


@subsubsection Handling deposits

The implementation is free to decide whether deposits can be recovered directly, or if they will be locked in the smart contract - temporarily or permanently.

For the duration deposits are locked, they are part of the smart contract's swap liquidity. During this time, locked deposits may only be withdrawn in exchange for other tokens accepted by the contract.

Deposits that are not locked should be withdrawable using the @code{withdraw(address,uint256)} (@code{0xf3fef3a3}) method signature.

Of course, as with most swap contracts, the tokens available for withdrawal by the holder may not necessarily match the tokens that were deposited by the holder.