Struct ByteView

#[repr(C)]
pub struct ByteView {
    pub length: u32,
    pub prefix: u32,
    pub buffer_index: u32,
    pub offset: u32,
}

Helper to access views of GenericByteViewArray (StringViewArray and BinaryViewArray) where the length is greater than 12 bytes.

See Also:

• GenericByteViewArray for more information on the layout of the views.
• validate_binary_view and validate_string_view to validate

Example: Create a new u128 view

// Create a view for a string of length 20
// first four bytes are "Rust"
// stored in buffer 3
// at offset 42
let prefix = "Rust";
let view = ByteView::new(20, prefix.as_bytes())
  .with_buffer_index(3)
  .with_offset(42);

// create the final u128
let v = view.as_u128();
assert_eq!(v, 0x2a000000037473755200000014);

Example: decode a u128 into its constituent fields

// Convert a u128 to a ByteView
// See validate_{string,binary}_view functions to validate
let v = ByteView::from(0x2a000000037473755200000014);

assert_eq!(v.length, 20);
assert_eq!(v.prefix, 0x74737552);
assert_eq!(v.buffer_index, 3);
assert_eq!(v.offset, 42);

Fields

length: u32

The length of the string/bytes.

prefix: u32

First 4 bytes of string/bytes data.

buffer_index: u32

The buffer index.

offset: u32

The offset into the buffer.

Implementations

impl ByteView

pub fn new(length: u32, prefix: &[u8]) -> ByteView

Construct a ByteView for data length of bytes with the specified prefix.

See example on ByteView docs

Notes:

• the length should always be greater than 12 (Data less than 12 bytes is stored as an inline view)
• buffer and offset are set to 0

Panics

If the prefix is not exactly 4 bytes

pub fn with_buffer_index(self, buffer_index: u32) -> ByteView

Set the Self::buffer_index field

pub fn with_offset(self, offset: u32) -> ByteView

Set the Self::offset field

pub fn as_u128(self) -> u128

Convert ByteView to u128 by concatenating the fields

Trait Implementations

impl Clone for ByteView

fn clone(&self) -> ByteView

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ByteView

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for ByteView

fn default() -> ByteView

Returns the “default value” for a type.

impl From<u128> for ByteView

fn from(value: u128) -> ByteView

Converts to this type from the input type.

impl Copy for ByteView