pub trait BitRead<'a, E: Endianness>: Sized {
// Required method
fn read(stream: &mut BitReadStream<'a, E>) -> Result<Self>;
// Provided methods
fn skip(stream: &mut BitReadStream<'a, E>) -> Result<()> { ... }
fn bit_size() -> Option<usize> { ... }
}Expand description
Trait for types that can be read from a stream without requiring the size to be configured
The BitRead trait can be used with #[derive] on structs and enums
§Structs
The implementation can be derived for a struct as long as every field in the struct implements BitRead or BitReadSized
The struct is read field by field in the order they are defined in, if the size for a field is set stream.read_sized()
will be used, otherwise stream_read() will be used.
The size for a field can be set using 3 different methods
- set the size as an integer using the
sizeattribute, - use a previously defined field as the size using the
sizeattribute - read a set number of bits as an integer, using the resulting value as size using the
size_bitsattribute
§Examples
#[derive(BitRead)]
struct TestStruct {
foo: u8,
str: String,
#[size = 2] // when `size` is set, the attributed will be read using `read_sized`
truncated: String,
bar: u16,
float: f32,
#[size = 3]
asd: u8,
#[size_bits = 2] // first read 2 bits as unsigned integer, then use the resulting value as size for the read
dynamic_length: u8,
#[size = "asd"] // use a previously defined field as size
previous_field: u8,
}§Enums
The implementation can be derived for an enum as long as every variant of the enum either has no field, or an unnamed field that implements BitRead or BitReadSized
The enum is read by first reading a set number of bits as the discriminant of the enum, then the variant for the read discriminant is read.
For details about setting the input size for fields implementing BitReadSized see the block about size in the Structs section above.
The discriminant for the variants defaults to incrementing by one for every field, starting with 0.
You can overwrite the discriminant for a field, which will also change the discriminant for every following field.
§Examples
#[derive(BitRead)]
#[discriminant_bits = 2]
enum TestBareEnum {
Foo,
Bar,
Asd = 3, // manually set the discriminant value for a field
}#[derive(BitRead)]
#[discriminant_bits = 2]
enum TestUnnamedFieldEnum {
#[size = 5]
Foo(i8),
Bar(bool),
#[discriminant = 3] // since rust only allows setting the discriminant on field-less enums, you can use an attribute instead
Asd(u8),
}Required Methods§
Sourcefn read(stream: &mut BitReadStream<'a, E>) -> Result<Self>
fn read(stream: &mut BitReadStream<'a, E>) -> Result<Self>
Read the type from stream
Provided Methods§
Sourcefn skip(stream: &mut BitReadStream<'a, E>) -> Result<()>
fn skip(stream: &mut BitReadStream<'a, E>) -> Result<()>
Skip the type
This might be faster than reading it if the size is known beforehand
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.
Implementations on Foreign Types§
Source§impl BitRead<'_, LittleEndian> for Option<NonZeroU16>
impl BitRead<'_, LittleEndian> for Option<NonZeroU16>
Source§impl BitRead<'_, LittleEndian> for Option<NonZeroU32>
impl BitRead<'_, LittleEndian> for Option<NonZeroU32>
Source§impl BitRead<'_, LittleEndian> for Option<NonZeroU64>
impl BitRead<'_, LittleEndian> for Option<NonZeroU64>
Source§impl BitRead<'_, LittleEndian> for Option<NonZeroU128>
impl BitRead<'_, LittleEndian> for Option<NonZeroU128>
Source§impl<'a, E: Endianness, T1: BitRead<'a, E>, T2: BitRead<'a, E>, T3: BitRead<'a, E>> BitRead<'a, E> for (T1, T2, T3)
impl<'a, E: Endianness, T1: BitRead<'a, E>, T2: BitRead<'a, E>, T3: BitRead<'a, E>> BitRead<'a, E> for (T1, T2, T3)
Source§impl<'a, E: Endianness, T1: BitRead<'a, E>, T2: BitRead<'a, E>, T3: BitRead<'a, E>, T4: BitRead<'a, E>> BitRead<'a, E> for (T1, T2, T3, T4)
impl<'a, E: Endianness, T1: BitRead<'a, E>, T2: BitRead<'a, E>, T3: BitRead<'a, E>, T4: BitRead<'a, E>> BitRead<'a, E> for (T1, T2, T3, T4)
Source§impl<'a, E: Endianness, T: BitRead<'a, E>> BitRead<'a, E> for Option<T>
Read a boolean, if true, read T, else return None
impl<'a, E: Endianness, T: BitRead<'a, E>> BitRead<'a, E> for Option<T>
Read a boolean, if true, read T, else return None