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54e052d8bb
The exponent bounds check appeared verbatim in both normalize() and IOUAmount(Number const&). Extract it into a private enforceExponentBounds() and call it from both. Named "enforce" rather than "check" because the function acts on the value as well as inspecting it: it throws above the range and truncates to zero below it. That matches the codebase precedent of requireAuth (a pure predicate) versus enforceMPTokenAuthorization (which mutates). Defined out of line because a header inline would need STAmount's offset constants, and STAmount.h already includes IOUAmount.h. No behavior change: the extracted body is identical to both original blocks, and the Number constructor still applies it after delegating construction completes.
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.