Struct bitstream_io::write::BitWriter

pub struct BitWriter<W: Write, E: Endianness> { /* private fields */ }

For writing bit values to an underlying stream in a given endianness.

Because this only writes whole bytes to the underlying stream, it is important that output is byte-aligned before the bitstream writer’s lifetime ends. Partial bytes will be lost if the writer is disposed of before they can be written.

Implementations

impl<W: Write, E: Endianness> BitWriter<W, E>

pub fn new(writer: W) -> BitWriter<W, E>

Wraps a BitWriter around something that implements Write

pub fn endian(writer: W, _endian: E) -> BitWriter<W, E>

Wraps a BitWriter around something that implements Write with the given endianness.

pub fn into_writer(self) -> W

Unwraps internal writer and disposes of BitWriter.

Warning

Any unwritten partial bits are discarded.

pub fn writer(&mut self) -> Option<&mut W>

If stream is byte-aligned, provides mutable reference to internal writer. Otherwise returns None

pub fn into_bytewriter(self) -> ByteWriter<W, E>

Converts BitWriter to ByteWriter in the same endianness.

Warning

Any written partial bits are discarded.

pub fn bytewriter(&mut self) -> Option<ByteWriter<&mut W, E>>

If stream is byte-aligned, provides temporary ByteWriter in the same endianness. Otherwise returns None

Warning

Any unwritten bits left over when ByteWriter is dropped are lost.

pub fn into_unwritten(self) -> (u32, u8)

Consumes writer and returns any un-written partial byte as a (bits, value) tuple.

Examples

use std::io::Write;
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut data = Vec::new();
let (bits, value) = {
    let mut writer = BitWriter::endian(&mut data, BigEndian);
    writer.write(15, 0b1010_0101_0101_101).unwrap();
    writer.into_unwritten()
};
assert_eq!(data, [0b1010_0101]);
assert_eq!(bits, 7);
assert_eq!(value, 0b0101_101);

use std::io::Write;
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut data = Vec::new();
let (bits, value) = {
    let mut writer = BitWriter::endian(&mut data, BigEndian);
    writer.write(8, 0b1010_0101).unwrap();
    writer.into_unwritten()
};
assert_eq!(data, [0b1010_0101]);
assert_eq!(bits, 0);
assert_eq!(value, 0);

pub fn flush(&mut self) -> Result<()>

Flushes output stream to disk, if necessary. Any partial bytes are not flushed.

Errors

Passes along any errors from the underlying stream.

Trait Implementations

impl<W: Write, E: Endianness> BitWrite for BitWriter<W, E>

fn write_bit(&mut self, bit: bool) -> Result<()>

Examples

use std::io::Write;
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(Vec::new(), BigEndian);
writer.write_bit(true).unwrap();
writer.write_bit(false).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(false).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(true).unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);

use std::io::Write;
use bitstream_io::{LittleEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(Vec::new(), LittleEndian);
writer.write_bit(true).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(false).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(true).unwrap();
writer.write_bit(false).unwrap();
writer.write_bit(true).unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);

fn write<U>(&mut self, bits: u32, value: U) -> Result<()>

where U: Numeric,

Examples

use std::io::Write;
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(Vec::new(), BigEndian);
writer.write(1, 0b1).unwrap();
writer.write(2, 0b01).unwrap();
writer.write(5, 0b10111).unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);

use std::io::Write;
use bitstream_io::{LittleEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(Vec::new(), LittleEndian);
writer.write(1, 0b1).unwrap();
writer.write(2, 0b11).unwrap();
writer.write(5, 0b10110).unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);

use std::io::{Write, sink};
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut w = BitWriter::endian(sink(), BigEndian);
assert!(w.write(9, 0u8).is_err());    // can't write  u8 in 9 bits
assert!(w.write(17, 0u16).is_err());  // can't write u16 in 17 bits
assert!(w.write(33, 0u32).is_err());  // can't write u32 in 33 bits
assert!(w.write(65, 0u64).is_err());  // can't write u64 in 65 bits
assert!(w.write(1, 2).is_err());      // can't write   2 in 1 bit
assert!(w.write(2, 4).is_err());      // can't write   4 in 2 bits
assert!(w.write(3, 8).is_err());      // can't write   8 in 3 bits
assert!(w.write(4, 16).is_err());     // can't write  16 in 4 bits

fn write_signed<S>(&mut self, bits: u32, value: S) -> Result<()>

where S: SignedNumeric,

Examples

use std::io::Write;
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(Vec::new(), BigEndian);
writer.write_signed(4, -5).unwrap();
writer.write_signed(4, 7).unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);

use std::io::Write;
use bitstream_io::{LittleEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(Vec::new(), LittleEndian);
writer.write_signed(4, 7).unwrap();
writer.write_signed(4, -5).unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);

fn byte_aligned(&self) -> bool

Example

use std::io::{Write, sink};
use bitstream_io::{BigEndian, BitWriter, BitWrite};
let mut writer = BitWriter::endian(sink(), BigEndian);
assert_eq!(writer.byte_aligned(), true);
writer.write(1, 0).unwrap();
assert_eq!(writer.byte_aligned(), false);
writer.write(7, 0).unwrap();
assert_eq!(writer.byte_aligned(), true);

fn write_from<V>(&mut self, value: V) -> Result<()>

where V: Primitive,

Writes whole value to the stream whose size in bits is equal to its type’s size.

fn write_bytes(&mut self, buf: &[u8]) -> Result<()>

Writes the entirety of a byte buffer to the stream.

fn write_unary0(&mut self, value: u32) -> Result<()>

Writes value number of 1 bits to the stream and then writes a 0 bit. This field is variably-sized.

fn write_unary1(&mut self, value: u32) -> Result<()>

Writes value number of 0 bits to the stream and then writes a 1 bit. This field is variably-sized.

fn build<T: ToBitStream>(&mut self, build: &T) -> Result<(), T::Error>

Builds and writes complex type

fn build_with<T: ToBitStreamWith>( &mut self, build: &T, context: &T::Context ) -> Result<(), T::Error>

Builds and writes complex type with context

fn byte_align(&mut self) -> Result<()>

Pads the stream with 0 bits until it is aligned at a whole byte. Does nothing if the stream is already aligned.

impl<W: Write, E: Endianness> HuffmanWrite<E> for BitWriter<W, E>

fn write_huffman<T>( &mut self, tree: &WriteHuffmanTree<E, T>, symbol: T ) -> Result<()>

where T: Ord + Copy,

Example

use std::io::Write;
use bitstream_io::{BigEndian, BitWriter, HuffmanWrite};
use bitstream_io::huffman::compile_write_tree;
let tree = compile_write_tree(
    vec![('a', vec![0]),
         ('b', vec![1, 0]),
         ('c', vec![1, 1, 0]),
         ('d', vec![1, 1, 1])]).unwrap();
let mut writer = BitWriter::endian(Vec::new(), BigEndian);
writer.write_huffman(&tree, 'b').unwrap();
writer.write_huffman(&tree, 'c').unwrap();
writer.write_huffman(&tree, 'd').unwrap();
assert_eq!(writer.into_writer(), [0b10110111]);