All contracts can be found in src, structured as follow:
src
├── config
│ ├── constants.sol
│ ├── enums.sol
│ ├── errors.sol
│ └── types.sol
├── core
│ ├── Grappa.sol
│ ├── CashOptionToken.sol
│ ├── CashOptionTokenDescriptor.sol
│ ├── engines
│ │ ├── BaseEngine.sol
│ │ └── mixins/...
│ └── oracles
│ ├── ChainlinkOracle.sol
│ └── ...
├── interfaces
├── libraries
└── test
All shared types, constant, enums and errors are defined in config.
We also separate each contract's error into each folder. All errors are prefixed with the contract name.
Shared abstract engine are located in src/core/engines, and each engines have their own repo. Margin engines are the most important part of the system as they decide the "rule of margining".
Currently, because there are lots of similarities between the 3 engines we implemented, we have a abstract contract called BaseEngine that everyone inherits from.
Engines are the entry point for option sellers (to create the option token out of the system). We're using a execute function for users to pass in array of operations they want to do for a given subAccount*. For example
note: subAccount*: In the current shared engine design (inherited from BaseEngine), we use a subAccount address to map ID to a specific account data structure designed by each engine. A subAccount is "controllable" by an address if only the last 1 bytes are different from the address. This mean each address can control 256 subAccounts. This design is inspired by Euler, it enables cheaper auth process without defining a owner for each ID.
(You don't have to follow this access control design to be compatible with Grappa)