chisel-decoders

Overview

This crate contains a very simple, lean implementation of a decoder that will consume u8 bytes from a given Read implementation, and decode into the Rust internal char type using UTF-8 . This is an offshoot lib from an ongoing toy parser project, and is used as the first stage of the scanning/lexing phase of the parser in order avoid unnecessary allocations during the u8 sequence -> char conversion.

Note that the implementation is pretty fast and loose, and under the covers utilises some bit-twiddlin' in conjunction with the unsafe transmute function to do the conversions. No string allocations are used during conversion. There is minimal checking (other than bit-masking) of the inbound bytes - it is not intended to be a full-blown UTF8 validation library, although improved/feature-flagged validation may be added at a later date.

Usage

Usage is very simple, provided you have something that implements Read in order to source some bytes:

Create from a slice

Just wrap your array in a mut reader, and then plug it into a new instance of Utf8Decoder:

```rust # use std::io::BufReader; # use chisel_decoders::utf8::Utf8Decoder;

let buffer: &[u8] = &[0x10, 0x12, 0x23, 0x12];
let mut reader = BufReader::new(buffer);
let _decoder = Utf8Decoder::new(&mut reader);

```

Create from a file

Just crack open your file, wrap in a Read instance and then plug into a new instance of Utf8Decoder:

```rust # use std::fs::File; # use std::io::BufReader; # use std::path::PathBuf; # use chisel_decoders::utf8::Utf8Decoder;

let path = PathBuf::from("./Cargo.toml");
let f = File::open(path);
let mut reader = BufReader::new(f.unwrap());
let _decoder = Utf8Decoder::new(&mut reader);

```

Consuming chars

You can either pull out new chars from the decoder wrapped inside a Result type:

```rust # use std::fs::File; # use std::io::BufReader; # use std::path::PathBuf; # use chisel_decoders::utf8::Utf8Decoder;

let path = PathBuf::from("./Cargo.toml");
let f = File::open(path);
let mut reader = BufReader::new(f.unwrap());
let mut decoder = Utf8Decoder::new(&mut reader);
loop {
    let result = decoder.decode_next();
    if result.is_err() {
        break;
    }
}

`` Alternatively, you can just use theUtf8Decoderas anIterator`:

```rust # use std::fs::File; # use std::io::BufReader; # use std::path::PathBuf; # use chisel_decoders::utf8::Utf8Decoder;

let path = PathBuf::from("./Cargo.toml");
let f = File::open(path);
let mut reader = BufReader::new(f.unwrap());
let decoder = Utf8Decoder::new(&mut reader);
for c in decoder {
   println!("char: {}", c)
}

```

Building and Testing

As you would expect, just cargo build in order to build the crate.

Suggestions and Requests

If you have any suggestions, requests or even just comments relating to this crate, then please just add an issue and I'll try and take a look when I get change. Please feel free to fork this repo if you want to utilise/modify this code in any of your own work.