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/*! BaseNC ====== Encoding and decoding of Base-N encodings, `#[no_std]` compatible. Encoding trait -------------- The hero of the show is [`Encoding`](trait.Encoding.html), defining the entry point for encoding and decoding for an encoding. The trait is implemented by unit structs, eg. `Base64Std`, allowing type inference to help out. The hero has two sidekicks: [`Encoder`](trait.Encoder.html) and [`Decoder`](trait.Decoder.html) providing access to the encoding's iterator adapters. Buffer to buffer ---------------- When you have an input buffer, `&[u8]` or `&str`, and want to encode or decode respectively to a new buffer can be done conveniently using the [`encode`](fn.encode.html) and [`decode`](fn.decode.html) free functions. They are ensured to be implemented efficiently and avoid code bloat. ### Buffers A side note about buffers, they are types implementing the [`EncodeBuf`](trait.EncodeBuf.html) and [`DecodeBuf`](trait.DecodeBuf.html) traits. Under `#[no_std]` they are only implemented by `&mut [u8]` acting as a fixed size buffer. Otherwise `EncodeBuf` is implemented by `String` for convenience and `&mut String` and `&mut Vec<u8>` for efficient buffer reuse. `DecodeBuf` is implemented by `Vec<u8>` for convenience and `&mut Vec<u8>` for efficient buffer reuse. Iterator adapters ----------------- For maximum flexibility the encoding and decoding can be pipelined as an iterator adapter. The trait [`Encode`](trait.Encode.html) adapts an iterator over bytes given an encoding into an iterator over chars of the encoded input. The trait [`Decode`](trait.Decode.html) adapts an iterator over chars given an encoding into an iterator over the resulting bytes of the decoded input. */ #![no_std] #[cfg(any(test, feature = "std"))] #[macro_use] extern crate std; #[cfg(feature = "unstable")] pub mod details; #[cfg(not(feature = "unstable"))] mod details; mod buf; pub use buf::{EncodeBuf, DecodeBuf}; //---------------------------------------------------------------- /// Decoding error. /// /// Note that encoding can never fail. #[derive(Copy, Clone, Debug, Eq, PartialEq)] pub enum Error { /// Not a valid character in the alphabet. InvalidChar(char), /// Input has incorrect length or is not padded to the required length. BadLength, /// Input is not canonical. /// /// Unused padding MUST consist of zero bits. Denormal, } use ::core::fmt; impl fmt::Display for Error { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match *self { Error::InvalidChar(chr) => write!(f, "invalid char: {}", chr), Error::BadLength => write!(f, "bad length"), Error::Denormal => write!(f, "denormal"), } } } #[cfg(any(test, feature = "std"))] impl ::std::error::Error for Error { fn description(&self) -> &str { match *self { Error::InvalidChar(_) => "invalid char", Error::BadLength => "bad length", Error::Denormal => "denormal", } } } //---------------------------------------------------------------- /// Data encoding. /// /// Use the free-standing functions to avoid having to drag in this trait. pub trait Encoding { /// Returns the encoding's alphabet. /// /// # Examples /// /// ``` /// use basenc::{Encoding}; /// /// assert_eq!( /// basenc::LowerHex.alphabet(), /// "0123456789abcdef" /// ); /// ``` fn alphabet(self) -> &'static str; /// Directly encode into an encode buffer. /// /// Use [`encode`](fn.encode.html) for convenience. fn encode<B: EncodeBuf>(self, bytes: &[u8], buffer: B) -> B::Output; /// Directly decode into a decode buffer. /// /// Use [`decode`](fn.decode.html) for convenience. fn decode<B: DecodeBuf>(self, string: &str, buffer: B) -> Result<B::Output, Error>; } /// Directly encode into an encode buffer. /// /// Convenient as it doesn't require the [`Encoding`](trait.Encoding.html) trait to be imported. /// /// Note that encoding can never fail. /// /// # Examples /// /// ``` /// assert_eq!( /// basenc::encode(b"hello world", basenc::Base64Std, String::new()), /// "aGVsbG8gd29ybGQ=" /// ); /// ``` /// /// Convenience, appends to a by-value buffer and returns that buffer. /// /// ``` /// let mut str_buf = String::from("output: "); /// assert_eq!( /// basenc::encode(b"BuFfEr ReUsE!", basenc::Base64Url, &mut str_buf), /// "QnVGZkVyIFJlVXNFIQ" /// ); /// assert_eq!(str_buf, "output: QnVGZkVyIFJlVXNFIQ"); /// ``` /// /// Appends to an existing buffer, returns a reference to the encoded input. /// /// ``` /// let mut stack_buf = [0u8; 16]; /// assert_eq!( /// basenc::encode(b"\x00\x80\xFF\xDC", basenc::LowerHex, &mut stack_buf[..]), /// "0080ffdc" /// ); /// ``` /// /// Uses fixed-size arrays on the stack as a buffer, available with `#[no_std]`. /// /// Panics if the buffer is too small to fit the output. pub fn encode<C: Encoding, B: EncodeBuf>(bytes: &[u8], encoding: C, buffer: B) -> B::Output { encoding.encode(bytes, buffer) } /// Directly decode into a decode buffer. /// /// Convenient as it doesn't require the [`Encoding`](trait.Encoding.html) trait to be imported. /// /// Decoding may fail and produce an [`Error`](enum.Error.html) instead. /// /// # Examples /// /// ``` /// assert_eq!( /// basenc::decode("aGVsbG8gd29ybGQ=", basenc::Base64Std, Vec::new()), /// Ok(b"hello world"[..].to_vec()) /// ); /// // Note that the buffer is swallowed on error /// assert_eq!( /// basenc::decode("&'nv@l!d", basenc::Base64Std, Vec::new()), /// Err(basenc::Error::InvalidChar('&')) /// ); /// ``` /// /// Convenience, appends to a by-value buffer and returns that buffer. /// /// ``` /// let mut byte_buf = vec![0x11, 0x22, 0x33]; /// assert_eq!( /// basenc::decode("QnVGZkVyIFJlVXNFIQ", basenc::Base64Url, &mut byte_buf), /// Ok(&b"BuFfEr ReUsE!"[..]) /// ); /// assert_eq!(byte_buf, b"\x11\x22\x33BuFfEr ReUsE!"); /// ``` /// /// Appends to an existing buffer, returns a reference to the decoded input. /// /// ``` /// let mut stack_buf = [0u8; 16]; /// assert_eq!( /// basenc::decode("0080FFDC", basenc::UpperHex, &mut stack_buf[..]), /// Ok(&b"\x00\x80\xFF\xDC"[..]) /// ); /// ``` /// /// Uses fixed-size arrays on the stack as a buffer, available with `#[no_std]`. /// /// Panics if the buffer is too small to fit the output. pub fn decode<C: Encoding, B: DecodeBuf>(string: &str, encoding: C, buffer: B) -> Result<B::Output, Error> { encoding.decode(string, buffer) } //---------------------------------------------------------------- /// Create an encoder adapter for an encoding given an `Iterator<Item = u8>`. /// /// Helper for [`Encode`](trait.Encode.html), should be merged into [`Encoding`](trait.Encoding.html) but can't be due to HKT reasons. pub trait Encoder<I: Iterator<Item = u8>>: Encoding { type Encoder: Iterator<Item = char>; fn encoder(self, iter: I) -> Self::Encoder; } /// Byte iterator adapter to an encoder. /// /// Adapts any `Iterator<Item = u8>` into an iterator over the encoded chars. /// /// Beware of code bloat! The entire decode logic may get inlined at the invocation site. /// /// # Examples /// /// ``` /// use basenc::Encode; /// /// assert!( /// "hello".bytes() /// .encode(basenc::UpperHex) /// .eq("68656C6C6F".chars()) /// ); /// /// assert!( /// b"\xadapters\xff"[..].iter().cloned() /// .encode(basenc::Base64Url) /// .eq("rWFwdGVyc_8".chars()) /// ); /// /// assert!( /// "STRingS".bytes() /// .encode(basenc::LowerHex) /// .eq("535452696e6753".chars()) /// ); /// ``` pub trait Encode<I: Iterator<Item = u8>, R: Encoder<I>> { fn encode(self, encoding: R) -> R::Encoder; } impl<I: Iterator<Item = u8>, R: Encoder<I>> Encode<I, R> for I { fn encode(self, encoding: R) -> R::Encoder { encoding.encoder(self) } } /// Create a decoder adapter for an encoding given an `Iterator<Item = char>`. /// /// Helper for [`Decode`](trait.Decode.html), should be merged into [`Encoding`](trait.Encoding.html) but can't be due to HKT reasons. pub trait Decoder<I: Iterator<Item = char>>: Encoding { type Decoder: Iterator<Item = Result<u8, Error>>; fn decoder(self, iter: I) -> Self::Decoder; } /// Char iterator adapter to a decoder. /// /// Adapts any `Iterator<Item = char>` into an iterator over a result of the decoded bytes. /// /// Beware of code bloat! The entire decode logic may get inlined at the invocation site. /// /// # Examples /// /// ``` /// use basenc::Decode; /// /// assert!( /// "68656c6c6F".chars() /// .decode(basenc::AnyHex) /// .eq("hello".bytes().map(Ok)) /// ); /// ``` pub trait Decode<I: Iterator<Item = char>, R: Decoder<I>> { fn decode(self, encoding: R) -> R::Decoder; } impl<I: Iterator<Item = char>, R: Decoder<I>> Decode<I, R> for I { fn decode(self, encoding: R) -> R::Decoder { encoding.decoder(self) } } //---------------------------------------------------------------- pub use details::base64::{Base64Std, Base64Url}; pub use details::hex::{LowerHex, UpperHex, AnyHex};