This is an implementation of the BigBit standard, used for representing arbitrarily large numbers and strings in a compact way. The only implementation provided by the author is a Node.js implementation — this crate aims to implement the functionality presented there with idiomatic Rust code.
In short, the specification describes 3 formats: - Head Byte (HB), used for storing extremely large (but still finitely large) signed integers and decimal fractions without losing precision - Extended Head Byte (EHB), used for storing arbitrarily large signed integers and decimal fractions without losing precision as long as sufficent storage space is provided. - Linked Bytes (LB), used for storing arbitrarily large unsigned integers, mainly used directly inside the Extended Head Byte format to store the exponent and the number of additional coefficient bytes, but also useful for storing strings better than both UTF-8 and UTF-16.
Since this is a format parser, #![no_std] is enabled by default, meaning that alloc is the only dependency, allowing you to use this in a freestanding environment.
Currently, not the entire BigBit standard is implemented. Here's a list of what's already done:
- Head Byte number storage
- Linked Bytes number storage
- Linked Bytes addition and subtraction (Add/AddAssign and Sub/SubAssign)
And here's a list of what's not finished just yet:
- Borrowed Linked Bytes (required for EHB) — a Linked Bytes number which doesn't own its contents and is a slice into an EHB number (will be added in 0.0.x)
- Creating HB/LB numbers from primitive integers and f32/f64 (most likely will be added in 0.1.0)
- The Extended Header Byte format (will be added in 0.0.x)
- Arithmetic operations (addition, subtraction, multiplication and division are all defined by the BigBit standard), except for LB addition, which is already implemented; the main issue is dealing with the exponents (will mark the 1.0.0 release, might be partially added over the course of 0.x.x releases)
- Strings encoded using Linked Bytes (will be added in 0.0.x)
- Debug and Display formatting (i.e. converting the numbers either into a debugging-friendly representation as an array of bytes or a string representing the number in decimal scientific notation or full notation, as well as other numeric notations; simple Debug and Display decimal formatting will be added in 0.1.0 while the rest is planned for 1.0.0)
- Tests (planned for 0.1.0 but might be partially added earlier)
0.0.3 are yanked, these had a minor LB addition bug, so please upgrade if you haven't already.