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3c51e3dad1
Add addVaultAssets, removeVaultAssets (two overloads: plain accountSend and doWithdraw-based), clawbackVaultAssets, and moveVaultAssets as the single points through which a Vault's sfAssetsTotal/sfAssetsAvailable are mutated and funds move to/from its pseudo-account: - addVaultAssets increases both fields and transfers in from a sender. - removeVaultAssets/clawbackVaultAssets decrease both fields equally and transfer out; a FinalRemoval flag hard-resets both fields to exactly zero on a Vault's last withdrawal, since the discounted exchange-rate formula can produce values with more precision than the asset can canonically represent, and subtracting such a value would leave a non-canonical residual instead of an exact zero. - moveVaultAssets decreases only sfAssetsAvailable, for disbursements (e.g. a loan's principal and origination fee) where sfAssetsTotal independently grows via accrued interest. Also consolidate getAssetsTotalScale into VaultHelpers::getVaultScale, and move isRounded from LendingHelpers into STAmount.h alongside the other rounding utilities.
protocol
Classes and functions for handling data and values associated with the XRP Ledger protocol.
Serialized Objects
Objects transmitted over the network must be serialized into a canonical format. The prefix "ST" refers to classes that deal with the serialized format.
The term "Tx" or "tx" is an abbreviation for "Transaction", a commonly occurring object type.
Optional Fields
Our serialized fields have some "type magic" to make optional fields easier to read:
- The operation
x[sfFoo]means "return the value of 'Foo' if it exists, or the default value if it doesn't." - The operation
x[~sfFoo]means "return the value of 'Foo' if it exists, or nothing if it doesn't." This usage of the tilde/bitwise NOT operator is not standard outside of thexrpldcodebase.- As a consequence of this,
x[~sfFoo] = y[~sfFoo]assigns the value of Foo from y to x, including omitting Foo from x if it doesn't exist in y.
- As a consequence of this,
Typically, for things that are guaranteed to exist, you use
x[sfFoo] and avoid having to deal with a container that may
or may not hold a value. For things not guaranteed to exist,
you use x[~sfFoo] because you want such a container. It
avoids having to look something up twice, once just to see if
it exists and a second time to get/set its value.
(Real example)
The source of this "type magic" is in SField.h.