bytevec takes advantage of Rust's concise and stable type system to
serialize data objects to a byte vector (
Vec<u8>) and back.
Rust has a very powerful type system with predictable sizes for most types, starting with the primitive types, so it's fairly easy to convert any type to a collection of bytes and convert it back. This library intends to give the user the means of converting a given type instance to a byte vector and store it or send it through the wire to another device, with the possibility of getting the value back from the byte vector anytime using the library traits.
Of course, Rust isn't magical enough to implement the traits to serialize
the functions automatically, as every type has its quirks. This library
uses two traits to give a type the functionality it needs to do that:
A type that implements this trait is able to use the
encode method that
Vec<u8> byte sequence. Seems prone to failure right? Of course it is,
internally it uses
unsafe blocks to extract the bytes of a given type, so
it can be pretty unsafe. That's why it always checks for any possible error and
returns the vector wrapped around a
BVEncodeResult instance. If everything
Ok, we will be able to get a byte vector value that represents the
original data structure.
bytevec doesn't actually do a 1:1 conversion of the bytes of the original type instance, as not every Rust type is stored on the stack. For any type that wraps a heap stored value, it will give a representation of the underlying value.
ByteEncodable out of the box for the following types:
The integral types:
The floating point types:
Tuples with up to 12 elements
For collections and other structures, automatic implementation of bytevec
requires that all of its underlying elements implement the
bytevec doesn't follow any particular serialization format. It follows simple rules when translating some type value to bytes:
For a primitive type such as the integral types, floating points or char that have fixed size, it will just grab the bytes and put them on a
u8buffer of the same length as the size of the type through
std::mem::transmute. These types are converted to and from little endian on serialization and deserialization respectively.
String and str don't store their byte count, it's up to their container (if any) to store the size of the byte buffer of the string.
Complex data structures such as
structs, tuples and collections need to store the sizes of their underlying data fields. These sizes are stored as values of a generic integral type parameter
Sizethat should be provided in every call of the methods of the
ByteDecodabletraits. This type parameter is propagated to the serialization and deserialization operations of the contained data fields. The type parameter
Sizeis constrained by the
BVSizetrait. Currently the types that implement this trait are
u64. Users should select the type for the
Sizetype parameter according to the expected size of the byte buffer. If the expected size exceeds the 232 byte length limit of
For structures with defined fields such as a custom
structor a tuple, it will store the size of each field on a sequence of
Sizevalues at the start of the slice segment for the structure, followed by the actual bytes of the values of the fields.
For any collection with variable length, it will first store the length (in elements, not byte count) on a
Sizevalue, followed by the byte count (yes, of
Size) of each element, and then the actual values of the elements. All of this done in order, order is important, the same order of serialization is the order of deserialization.
All serializable values can be nested, so any structure that implements
String, or another structure that also implements
ByteEncodablewill be serialized along all its fields.
Given a byte vector retrieved from memory, a file, or maybe a TCP connection,
the user will be able to pass the vector to the
decode method of
a type that implements the
decode will do a few checks
on the byte vector and if the required sizes matches, it will yield a type instance wrapped
BVDecodeResult. If the size doesn't match, or if some other conversion problem
arises, it will yield a
ByteVecError detailing the failure.
Almost all of the out of the box implementations of
ByteDecodable, but some of them, particularly the slices and
the tuple references don't make sense when deserialized, as they can't
point to the original data they were referencing. This is usually a problem
that requires some tweaking, but bytevec allows data conversion from byte
buffers that were originally referenced data to a new instance of an owned data type,
as long as the size requirements are the same. This way, slice data can
be assigned to a
Vec instance for example, as long as they share the same
type of the underlying elements.
ByteDecodable trait also provides the
decode_max method, which like
accepts the byte buffer to deserialize, but additionally, this method also accepts
limit argument. This parameter is compared to the length of the
u8 buffer and
if the buffer length is greater than it, it will return a
otherwise it will return the result of
decode on the byte buffer.
let slice = &["Rust", "Is", "Awesome!"]; let bytes = slice.encode::<u32>().unwrap(); let vec = <Vec<String>>::decode::<u32>(&bytes).unwrap(); assert_eq!(vec, slice);
Declares the given structures and implements the byte serialization traits.
Implements the byte serialization traits for the given structures.
Represents the generic integral type of the structure size indicators
Provides deserialization functionality for the implementing types.
Provides serialization functionality for the implementing types.