Variable Len Reader

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Description

A Rust crate to read variable length data based on varint format.

Features

• Reading and writing.
• Both synchronous and asynchronous implementations.
• Support bytes and tokio crates.
• Long chunk version for varint implementations. (But not recommended to use because it's stupid.)
• Support signed and unsigned value. (Using zigzag encoding.)
• Support usize/isize directly or convert from/to u128/i128. (with the ap suffix.)
• Support extra type of f32, f64, vec<u8> and string.
• Built-in implementation of std::io::Read, std::io::Write and tokio::io::AsyncRead, tokio::io::AsyncWrite.
• Chaining bytes::Buf support.
• no-std support.

Usage

Add this to your Cargo.toml:

[dependencies]
variable-len-reader = "^3.2"

Example

Directly use in tcp stream:

use std::net::{TcpListener, TcpStream};
use anyhow::Result;
use variable_len_reader::{VariableReader, VariableWriter};

fn main() -> Result<()> {
    let server = TcpListener::bind("localhost:0")?;
    let mut client = TcpStream::connect(server.local_addr()?)?;
    let mut server = server.incoming().next().unwrap()?;

    // Write
    client.write_string(&"Hello world!")?;

    // Read
    let message = server.read_string()?;
    assert_eq!("Hello world!", message);
    
    Ok(())
}

Use with bytes crate:

use bytes::{Buf, BufMut, BytesMut};
use variable_len_reader::{VariableReader, VariableWriter};

fn main() {
    let message = "Hello world!";
    let mut writer = BytesMut::new().writer();

    // Write
    writer.write_string(message).unwrap();

    let bytes = writer.into_inner();
    assert_eq!(message.len() as u8, bytes[0]);
    assert_eq!(message.as_bytes(), &bytes[1..]);
    let mut reader = bytes.reader();

    // Read
    let string = reader.read_string().unwrap();
    assert_eq!(message, string);
}

Async mode with tokio crate: (Require 'async_default' feature)

use anyhow::Result;
use tokio::net::{TcpListener, TcpStream};
use variable_len_reader::{AsyncVariableReader, AsyncVariableWriter};
use variable_len_reader::helper::{AsyncReaderHelper, AsyncWriterHelper};

#[tokio::main]
async fn main() -> Result<()> {
    let server = TcpListener::bind("localhost:0").await?;
    let mut client = TcpStream::connect(server.local_addr()?).await?;
    let (mut server, _) = server.accept().await?;

    // Write
    AsyncWriterHelper(&mut client).help_write_string(&"Hello tokio!").await?;

    // Read
    let message = AsyncReaderHelper(&mut server).help_read_string().await?;
    assert_eq!("Hello tokio!", message);
    
    Ok(())
}