pub trait BitWrite<E: Endianness> {
// Required method
fn write(&self, stream: &mut BitWriteStream<'_, E>) -> Result<()>;
}Expand description
Trait for types that can be written to a stream without requiring the size to be configured
The BitWrite 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 BitWrite or BitWriteSized
The struct is written field by field in the order they are defined in, if the size for a field is set stream.write_sized()
will be used, otherwise write_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
§Examples
#[derive(BitWrite)]
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 = "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 BitWrite or BitWriteSized
The enum is written by first writing a set number of bits as the discriminant of the enum, then the variant written.
For details about setting the input size for fields implementing BitWriteSized 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(BitWrite)]
#[discriminant_bits = 2]
enum TestBareEnum {
Foo,
Bar,
Asd = 3, // manually set the discriminant value for a field
}#[derive(BitWrite)]
#[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 write(&self, stream: &mut BitWriteStream<'_, E>) -> Result<()>
fn write(&self, stream: &mut BitWriteStream<'_, E>) -> Result<()>
Write the type to stream