Rust
Need help with rust-encoding?
Click the “chat” button below for chat support from the developer who created it, or find similar developers for support.
lifthrasiir

Description

Character encoding support for Rust

217 Stars 57 Forks MIT License 329 Commits 32 Opened issues

Services available

Need anything else?

Encoding 0.3.0-dev

Encoding on Travis CI

Character encoding support for Rust. (also known as

rust-encoding
) It is based on WHATWG Encoding Standard, and also provides an advanced interface for error detection and recovery.

This documentation is for the development version (0.3). Please see the stable documentation for 0.2.x versions.

Complete Documentation (stable)

Usage

Put this in your

Cargo.toml
:
[dependencies]
encoding = "0.3"

Then put this in your crate root:

extern crate encoding;

Data Table

By default, Encoding comes with ~480 KB of data table ("indices"). This allows Encoding to encode and decode legacy encodings efficiently, but this might not be desirable for some applications.

Encoding provides the

no-optimized-legacy-encoding
Cargo feature to reduce the size of encoding tables (to ~185 KB) at the expense of encoding performance (typically 5x to 20x slower). The decoding performance remains identical. This feature is strongly intended for end users. Do not try to enable this feature from library crates, ever.

For finer-tuned optimization, see

src/index/gen_index.py
for custom table generation.

Overview

To encode a string:

use encoding::{Encoding, EncoderTrap};
use encoding::all::ISO_8859_1;

assert_eq!(ISO_8859_1.encode("caf\u{e9}", EncoderTrap::Strict), Ok(vec![99,97,102,233]));

To encode a string with unrepresentable characters:

use encoding::{Encoding, EncoderTrap};
use encoding::all::ISO_8859_2;

assert!(ISO_8859_2.encode("Acme\u{a9}", EncoderTrap::Strict).is_err()); assert_eq!(ISO_8859_2.encode("Acme\u{a9}", EncoderTrap::Replace), Ok(vec![65,99,109,101,63])); assert_eq!(ISO_8859_2.encode("Acme\u{a9}", EncoderTrap::Ignore), Ok(vec![65,99,109,101])); assert_eq!(ISO_8859_2.encode("Acme\u{a9}", EncoderTrap::NcrEscape), Ok(vec![65,99,109,101,38,35,49,54,57,59]));

To decode a byte sequence:

use encoding::{Encoding, DecoderTrap};
use encoding::all::ISO_8859_1;

assert_eq!(ISO_8859_1.decode(&[99,97,102,233], DecoderTrap::Strict), Ok("caf\u{e9}".to_string()));

To decode a byte sequence with invalid sequences:

use encoding::{Encoding, DecoderTrap};
use encoding::all::ISO_8859_6;

assert!(ISO_8859_6.decode(&[65,99,109,101,169], DecoderTrap::Strict).is_err()); assert_eq!(ISO_8859_6.decode(&[65,99,109,101,169], DecoderTrap::Replace), Ok("Acme\u{fffd}".to_string())); assert_eq!(ISO_8859_6.decode(&[65,99,109,101,169], DecoderTrap::Ignore), Ok("Acme".to_string()));

To encode or decode the input into the already allocated buffer:

use encoding::{Encoding, EncoderTrap, DecoderTrap};
use encoding::all::{ISO_8859_2, ISO_8859_6};

let mut bytes = Vec::new(); let mut chars = String::new();

assert!(ISO_8859_2.encode_to("Acme\u{a9}", EncoderTrap::Ignore, &mut bytes).is_ok()); assert!(ISO_8859_6.decode_to(&[65,99,109,101,169], DecoderTrap::Replace, &mut chars).is_ok());

assert_eq!(bytes, [65,99,109,101]); assert_eq!(chars, "Acme\u{fffd}");

A practical example of custom encoder traps:

use encoding::{Encoding, ByteWriter, EncoderTrap, DecoderTrap};
use encoding::types::RawEncoder;
use encoding::all::ASCII;

// hexadecimal numeric character reference replacement fn hex_ncr_escape(_encoder: &mut RawEncoder, input: &str, output: &mut ByteWriter) -> bool { let escapes: Vec = input.chars().map(|ch| format!("{:x};", ch as isize)).collect(); let escapes = escapes.concat(); output.write_bytes(escapes.as_bytes()); true } static HEX_NCR_ESCAPE: EncoderTrap = EncoderTrap::Call(hex_ncr_escape);

let orig = "Hello, 世界!".to_string(); let encoded = ASCII.encode(&orig, HEX_NCR_ESCAPE).unwrap(); assert_eq!(ASCII.decode(&encoded, DecoderTrap::Strict), Ok("Hello, 世界!".to_string()));

Getting the encoding from the string label, as specified in WHATWG Encoding standard:

use encoding::{Encoding, DecoderTrap};
use encoding::label::encoding_from_whatwg_label;
use encoding::all::WINDOWS_949;

let euckr = encoding_from_whatwg_label("euc-kr").unwrap(); assert_eq!(euckr.name(), "windows-949"); assert_eq!(euckr.whatwg_name(), Some("euc-kr")); // for the sake of compatibility let broken = &[0xbf, 0xec, 0xbf, 0xcd, 0xff, 0xbe, 0xd3]; assert_eq!(euckr.decode(broken, DecoderTrap::Replace), Ok("\u{c6b0}\u{c640}\u{fffd}\u{c559}".to_string()));

// corresponding Encoding native API: assert_eq!(WINDOWS_949.decode(broken, DecoderTrap::Replace), Ok("\u{c6b0}\u{c640}\u{fffd}\u{c559}".to_string()));

Types and Stuffs

There are three main entry points to Encoding.

Encoding
is a single character encoding. It contains

encode
and
decode
methods for converting
String
to
Vec
and vice versa. For the error handling, they receive traps (
EncoderTrap
and
DecoderTrap
respectively) which replace any error with some string (e.g.
U+FFFD
) or sequence (e.g.
?
). You can also use
EncoderTrap::Strict
and
DecoderTrap::Strict
traps to stop on an error.

There are two ways to get

Encoding
:
  • encoding::all
    has static items for every supported encoding. You should use them when the encoding would not change or only handful of them are required. Combined with link-time optimization, any unused encoding would be discarded from the binary.
  • encoding::label
    has functions to dynamically get an encoding from given string ("label"). They will return a static reference to the encoding, which type is also known as
    EncodingRef
    . It is useful when a list of required encodings is not available in advance, but it will result in the larger binary and missed optimization opportunities.

RawEncoder
is an experimental incremental encoder. At each step of

raw_feed
, it receives a slice of string and emits any encoded bytes to a generic
ByteWriter
(normally
Vec
). It will stop at the first error if any, and would return a
CodecError
struct in that case. The caller is responsible for calling
raw_finish
at the end of encoding process.

RawDecoder
is an experimental incremental decoder. At each step of

raw_feed
, it receives a slice of byte sequence and emits any decoded characters to a generic
StringWriter
(normally
String
). Otherwise it is identical to
RawEncoder
s.

One should prefer

Encoding::{encode,decode}
as a primary interface.
RawEncoder
and
RawDecoder
is experimental and can change substantially. See the additional documents on
encoding::types
module for more information on them.

Supported Encodings

Encoding covers all encodings specified by WHATWG Encoding Standard and some more:

  • 7-bit strict ASCII (
    ascii
    )
  • UTF-8 (
    utf-8
    )
  • UTF-16 in little endian (
    utf-16
    or
    utf-16le
    ) and big endian (
    utf-16be
    )
  • All single byte encoding in WHATWG Encoding Standard:
    • IBM code page 866
    • ISO 8859-{2,3,4,5,6,7,8,10,13,14,15,16}
    • KOI8-R, KOI8-U
    • MacRoman (
      macintosh
      ), Macintosh Cyrillic encoding (
      x-mac-cyrillic
      )
    • Windows code pages 874, 1250, 1251, 1252 (instead of ISO 8859-1), 1253, 1254 (instead of ISO 8859-9), 1255, 1256, 1257, 1258
  • All multi byte encodings in WHATWG Encoding Standard:
    • Windows code page 949 (
      euc-kr
      , since the strict EUC-KR is hardly used)
    • EUC-JP and Windows code page 932 (
      shift_jis
      , since it's the most widespread extension to Shift_JIS)
    • ISO-2022-JP with asymmetric JIS X 0212 support (Note: this is not yet up to date to the current standard)
    • GBK
    • GB 18030
    • Big5-2003 with HKSCS-2008 extensions
  • Encodings that were originally specified by WHATWG Encoding Standard:
    • HZ
  • ISO 8859-1 (distinct from Windows code page 1252)

Parenthesized names refer to the encoding's primary name assigned by WHATWG Encoding Standard.

Many legacy character encodings lack the proper specification, and even those that have a specification are highly dependent of the actual implementation. Consequently one should be careful when picking a desired character encoding. The only standards reliable in this regard are WHATWG Encoding Standard and vendor-provided mappings from the Unicode consortium. Whenever in doubt, look at the source code and specifications for detailed explanations.

We use cookies. If you continue to browse the site, you agree to the use of cookies. For more information on our use of cookies please see our Privacy Policy.