diff options
Diffstat (limited to 'third_party/rust/shift_or_euc')
| -rw-r--r-- | third_party/rust/shift_or_euc/.cargo-checksum.json | 1 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/CONTRIBUTING.md | 38 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/COPYRIGHT | 9 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/Cargo.toml | 30 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/LICENSE-APACHE | 202 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/LICENSE-MIT | 25 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/README.md | 73 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/examples/detect.rs | 56 | ||||
| -rw-r--r-- | third_party/rust/shift_or_euc/src/lib.rs | 278 |
9 files changed, 712 insertions, 0 deletions
diff --git a/third_party/rust/shift_or_euc/.cargo-checksum.json b/third_party/rust/shift_or_euc/.cargo-checksum.json new file mode 100644 index 0000000000..cc5816349a --- /dev/null +++ b/third_party/rust/shift_or_euc/.cargo-checksum.json @@ -0,0 +1 @@ +{"files":{"CONTRIBUTING.md":"0e64fb3dd5a00e3fd528de6442de3f2ca851bd718c45cca0871aaf4eedac9ee1","COPYRIGHT":"3a7313aa2f19bf7095a2fd731c3d5e76f38d5e4640bd2a115d53032f24b2aa6c","Cargo.toml":"f9f41b76ecbe257a312ab09ed1208189b8dc9952d12d17a216fe2846d1d471c8","LICENSE-APACHE":"cfc7749b96f63bd31c3c42b5c471bf756814053e847c10f3eb003417bc523d30","LICENSE-MIT":"dac4dde23582d18b01701032860d8f8a1979fb2cf626060ca8de77e081a2a3d5","README.md":"b7148745a7ef59788e76fbe638d4b41c54dcaa1313a809f4630a020645f892a8","examples/detect.rs":"eb7239ccc802290ef24331db600ca1226198801dd86df86876b4b738ef4b8470","src/lib.rs":"f2a83db125d553af5c6fabae0487ef211aad62f2d93c4418dc510cbd425d472a"},"package":"f930dea4685b9803954b9d74cdc175c6d946a22f2eafe5aa2e9a58cdcae7da8c"}
\ No newline at end of file diff --git a/third_party/rust/shift_or_euc/CONTRIBUTING.md b/third_party/rust/shift_or_euc/CONTRIBUTING.md new file mode 100644 index 0000000000..1d41d4c60e --- /dev/null +++ b/third_party/rust/shift_or_euc/CONTRIBUTING.md @@ -0,0 +1,38 @@ +If you send a pull request / patch, please observe the following. + +## Licensing + +Since this crate is dual-licensed, +[section 5 of the Apache License 2.0](https://www.apache.org/licenses/LICENSE-2.0#contributions) +is considered to apply in the sense of Contributions being automatically +under the Apache License 2.0 or MIT dual license (see the `COPYRIGHT` file). +That is, by the act of offering a Contribution, you place your Contribution +under the Apache License 2.0 or MIT dual license stated in the `COPYRIGHT` +file. Please do not contribute if you aren't willing or allowed to license your +contributions in this manner. + +You are encouraged to dedicate test code that you contribute to the Public +Domain using the CC0 dedication. If you contribute test code that is not +dedicated to the Public Domain, please be sure not to put it in a part of +source code that the comments designate as being dedicated to the Public +Domain. + +## Copyright Notices + +If you require the addition of your copyright notice, it's up to you to edit in +your notice as part of your Contribution. Not adding a copyright notice is +taken as a waiver of copyright notice. + +## Compatibility with Stable Rust + +Please ensure that your Contribution compiles with the latest stable-channel +rustc. + +## rustfmt + +The `rustfmt` version used for this code is `rustfmt-nightly`. Please either +use that version or avoid using `rustfmt` (so as not to reformat all the code). + +## Unit tests + +Please ensure that `cargo test` succeeds. diff --git a/third_party/rust/shift_or_euc/COPYRIGHT b/third_party/rust/shift_or_euc/COPYRIGHT new file mode 100644 index 0000000000..1cacb3eb05 --- /dev/null +++ b/third_party/rust/shift_or_euc/COPYRIGHT @@ -0,0 +1,9 @@ +shift_or_euc is copyright 2018 Mozilla Foundation. + +Licensed under the Apache License, Version 2.0 +<LICENSE-APACHE or +https://www.apache.org/licenses/LICENSE-2.0> or the MIT +license <LICENSE-MIT or https://opensource.org/licenses/MIT>, +at your option. All files in the project carrying such +notice may not be copied, modified, or distributed except +according to those terms. diff --git a/third_party/rust/shift_or_euc/Cargo.toml b/third_party/rust/shift_or_euc/Cargo.toml new file mode 100644 index 0000000000..b28ae619a2 --- /dev/null +++ b/third_party/rust/shift_or_euc/Cargo.toml @@ -0,0 +1,30 @@ +# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO +# +# When uploading crates to the registry Cargo will automatically +# "normalize" Cargo.toml files for maximal compatibility +# with all versions of Cargo and also rewrite `path` dependencies +# to registry (e.g., crates.io) dependencies +# +# If you believe there's an error in this file please file an +# issue against the rust-lang/cargo repository. If you're +# editing this file be aware that the upstream Cargo.toml +# will likely look very different (and much more reasonable) + +[package] +edition = "2018" +name = "shift_or_euc" +version = "0.1.0" +authors = ["Henri Sivonen <hsivonen@hsivonen.fi>"] +description = "Detects among the Japanese legacy encodings" +homepage = "https://docs.rs/shift_or_euc/" +documentation = "https://docs.rs/shift_or_euc/" +readme = "README.md" +keywords = ["encoding", "web", "charset"] +categories = ["text-processing", "encoding", "web-programming", "internationalization"] +license = "MIT/Apache-2.0" +repository = "https://github.com/hsivonen/shift_or_euc" +[dependencies.encoding_rs] +version = "0.8.17" + +[dependencies.memchr] +version = "2.2.0" diff --git a/third_party/rust/shift_or_euc/LICENSE-APACHE b/third_party/rust/shift_or_euc/LICENSE-APACHE new file mode 100644 index 0000000000..d645695673 --- /dev/null +++ b/third_party/rust/shift_or_euc/LICENSE-APACHE @@ -0,0 +1,202 @@ + + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + + TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + + 1. 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IN NO EVENT +SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY +CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION +OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR +IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER +DEALINGS IN THE SOFTWARE. diff --git a/third_party/rust/shift_or_euc/README.md b/third_party/rust/shift_or_euc/README.md new file mode 100644 index 0000000000..e0c77d6fcc --- /dev/null +++ b/third_party/rust/shift_or_euc/README.md @@ -0,0 +1,73 @@ +# shift_or_euc + +[](https://github.com/hsivonen/shift_or_euc/blob/master/COPYRIGHT) + +A Japanese legacy encoding detector for detecting between Shift_JIS, EUC-JP, +and, optionally, ISO-2022-JP _given_ the assumption that the encoding is one +of those. + +This detector is generally more accurate (but see below about the failure +mode on half-width katakana) and decides much sooner than machine +learning-based detectors. To decide EUC-JP, machine learning-based detectors +try to gain confidence that the input looks like EUC-JP. To decide EUC-JP, +this detector instead looks for two simple rule-based signs of the input not +being Shift_JIS. + +As a consequence of not containing machine learning tables, the binary size +footprint that this crate adds on top of +[`encoding_rs`](https://docs.rs/crate/encoding_rs) is tiny. + +## Documentation + +[API documentation on docs.rs](https://docs.rs/crate/shift_or_euc) + +## Licensing + +See the file named [COPYRIGHT](https://github.com/hsivonen/shift_or_euc/blob/master/COPYRIGHT). + +## Sample Program Usage + +1. [Install Rust](https://rustup.rs/) +2. `git clone https://github.com/hsivonen/shift_or_euc` +3. `cd shift_or_euc` +4. `cargo run --example detect PATH_TO_FILE` + +The program prints one of: + +* Shift_JIS +* EUC-JP +* ISO-2022-JP +* Undecided + +## Principle of Operation + +The detector is based on two observations: + +1. The ISO-2022-JP escape sequences don't normally occur in Shift_JIS or +EUC-JP, so encountering such an escape sequence (before non-ASCII has been +encountered) can be taken as indication of ISO-2022-JP. +2. When normal (full-with) kana or common kanji encoded as Shift_JIS is +decoded as EUC-JP, or vice versa, the result is either an error or half-width +katakana, and it's very uncommon for Japanese HTML to have half-width katakana +character before a normal kana or common kanji character. Therefore, if +decoding as Shift_JIS results in error or have-width katakana, the detector +decides that the content is EUC-JP, and vice versa. + +## Failure Modes + +The detector gives the wrong answer if the text has a half-width katakana +character before normal kana or common kanji. Some uncommon kanji are +undecidable. (All JIS X 0208 Level 1 kanji are decidable.) + +The half-width katakana issue is mainly relevant for old 8-bit JIS X 0201-only +text files that would decode correctly as Shift_JIS but that the detector +detects as EUC-JP. + +The undecidable kanji issue does not realistically show up when a full +document is fed to the detector, because, realistically, in a full document, +there is at least one kana or common kanji. It can occur, though, if the +detector is only run on a prefix of a document and the prefix only contains +the title of the document. It is possible for document title to consist +entirely of undecidable kanji. (Indeed, Japanese Wikipedia has articles with +such titles.) If the detector is undecided, falling back to Shift_JIS is +typically the Web oriented better guess.
\ No newline at end of file diff --git a/third_party/rust/shift_or_euc/examples/detect.rs b/third_party/rust/shift_or_euc/examples/detect.rs new file mode 100644 index 0000000000..9ab21a3561 --- /dev/null +++ b/third_party/rust/shift_or_euc/examples/detect.rs @@ -0,0 +1,56 @@ +// Copyright 2018 Mozilla Foundation. See the COPYRIGHT +// file at the top-level directory of this distribution. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +use std::fs::File; +use std::io::Read; + +use shift_or_euc::Detector; + +fn main() { + let mut args = std::env::args_os(); + if args.next().is_none() { + eprintln!("Error: Program name missing from arguments."); + std::process::exit(-1); + } + if let Some(path) = args.next() { + if args.next().is_some() { + eprintln!("Error: Too many arguments."); + std::process::exit(-3); + } + if let Ok(mut file) = File::open(path) { + let mut buffer = [0u8; 4096]; + let mut detector = Detector::new(true); + loop { + if let Ok(num_read) = file.read(&mut buffer[..]) { + let opt_enc = if num_read == 0 { + detector.feed(b"", true) + } else { + detector.feed(&buffer[..num_read], false) + }; + if let Some(encoding) = opt_enc { + println!("{}", encoding.name()); + return; + } else if num_read == 0 { + println!("Undecided"); + return; + } + } else { + eprintln!("Error: Error reading file."); + std::process::exit(-5); + } + } + } else { + eprintln!("Error: Could not open file."); + std::process::exit(-4); + } + } else { + eprintln!("Error: One path argument needed."); + std::process::exit(-2); + } +} diff --git a/third_party/rust/shift_or_euc/src/lib.rs b/third_party/rust/shift_or_euc/src/lib.rs new file mode 100644 index 0000000000..978fc7f27e --- /dev/null +++ b/third_party/rust/shift_or_euc/src/lib.rs @@ -0,0 +1,278 @@ +// Copyright 2018 Mozilla Foundation. See the COPYRIGHT +// file at the top-level directory of this distribution. +// +// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or +// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +#![doc(html_root_url = "https://docs.rs/shift_or_euc/0.1.0")] + +//! A Japanese legacy encoding detector for detecting between Shift_JIS, +//! EUC-JP, and, optionally, ISO-2022-JP _given_ the assumption that the +//! encoding is one of those. +//! +//! This detector is generally more accurate (but see below about the failure +//! mode on half-width katakana) and decides much sooner than machine +//! learning-based detectors. To decide EUC-JP, machine learning-based +//! detectors try to gain confidence that the input looks like EUC-JP. To +//! decide EUC-JP, this detector instead looks for two simple rule-based +//! signs of the input not being Shift_JIS. +//! +//! As a consequence of not containing machine learning tables, the binary +//! size footprint that this crate adds on top of +//! [`encoding_rs`](https://docs.rs/crate/encoding_rs) is tiny. +//! +//! # Licensing +//! +//! See the file named [COPYRIGHT](https://github.com/hsivonen/shift_or_euc/blob/master/COPYRIGHT). +//! +//! # Principle of Operation +//! +//! The detector is based on two observations: +//! +//! 1. The ISO-2022-JP escape sequences don't normally occur in Shift_JIS or +//! EUC-JP, so encountering such an escape sequence (before non-ASCII has been +//! encountered) can be taken as indication of ISO-2022-JP. +//! 2. When normal (full-with) kana or common kanji encoded as Shift_JIS is +//! decoded as EUC-JP, or vice versa, the result is either an error or +//! half-width katakana, and it's very uncommon for Japanese HTML to have +//! half-width katakana character before a normal kana or common kanji +//! character. Therefore, if decoding as Shift_JIS results in error or +//! have-width katakana, the detector decides that the content is EUC-JP, and +//! vice versa. +//! +//! # Failure Modes +//! +//! The detector gives the wrong answer if the text has a half-width katakana +//! character before normal kana or common kanji. Some uncommon kanji are +//! undecidable. (All JIS X 0208 Level 1 kanji are decidable.) +//! +//! The half-width katakana issue is mainly relevant for old 8-bit JIS X +//! 0201-only text files that would decode correctly as Shift_JIS but that the +//! detector detects as EUC-JP. +//! +//! The undecidable kanji issue does not realistically show up when a full +//! document is fed to the detector, because, realistically, in a full +//! document, there is at least one kana or common kanji. It can occur, +//! though, if the detector is only run on a prefix of a document and the +//! prefix only contains the title of the document. It is possible for +//! document title to consist entirely of undecidable kanji. (Indeed, +//! Japanese Wikipedia has articles with such titles.) If the detector is +//! undecided, falling back to Shift_JIS is typically the Web oriented better +//! guess. + +use encoding_rs::Decoder; +use encoding_rs::DecoderResult; +use encoding_rs::Encoding; +use encoding_rs::EUC_JP; +use encoding_rs::ISO_2022_JP; +use encoding_rs::SHIFT_JIS; + +/// Returns the index of the first non-ASCII byte or the first +/// 0x1B, whichever comes first, or the length of the buffer +/// if neither is found. +fn find_non_ascii_or_escape(buffer: &[u8]) -> usize { + let ascii_up_to = Encoding::ascii_valid_up_to(buffer); + if let Some(escape) = memchr::memchr(0x1B, &buffer[..ascii_up_to]) { + escape + } else { + ascii_up_to + } +} + +/// Feed decoder with one byte (if `last` is `false`) or EOF (if `last` is +/// `true`). `byte` is ignored if `last` is `true`. +/// Returns `true` if there was no rejection or `false` upon rejecting the +/// encoding hypothesis represented by this decoder. +#[inline(always)] +fn feed_decoder(decoder: &mut Decoder, byte: u8, last: bool) -> bool { + let mut output = [0u16; 1]; + let input = [byte]; + let (result, _read, written) = decoder.decode_to_utf16_without_replacement( + if last { b"" } else { &input }, + &mut output, + last, + ); + match result { + DecoderResult::InputEmpty => { + if written == 1 { + match output[0] { + 0xFF61...0xFF9F => { + return false; + } + _ => {} + } + } + } + DecoderResult::Malformed(_, _) => { + return false; + } + DecoderResult::OutputFull => { + unreachable!(); + } + } + true +} + +/// A detector for detecting the character encoding of input on the +/// precondition that the encoding is a Japanese legacy encoding. +pub struct Detector { + shift_jis_decoder: Decoder, + euc_jp_decoder: Decoder, + second_byte_in_escape: u8, + iso_2022_jp_disqualified: bool, + escape_seen: bool, + finished: bool, +} + +impl Detector { + /// Instantiates the detector. If `allow_2022` is `true` the possible + /// guesses are Shift_JIS, EUC-JP, ISO-2022-JP, and undecided. If + /// `allow_2022` is `false`, the possible guesses are Shift_JIS, EUC-JP, + /// and undecided. + pub fn new(allow_2022: bool) -> Self { + Detector { + shift_jis_decoder: SHIFT_JIS.new_decoder_without_bom_handling(), + euc_jp_decoder: EUC_JP.new_decoder_without_bom_handling(), + second_byte_in_escape: 0, + iso_2022_jp_disqualified: !allow_2022, + escape_seen: false, + finished: false, + } + } + + /// Feeds bytes to the detector. If `last` is `true` the end of the stream + /// is considered to occur immediately after the end of `buffer`. + /// Otherwise, the stream is expected to continue. `buffer` may be empty. + /// + /// If you're running the detector only on a prefix of a complete + /// document, _do not_ pass `last` as `true` after the prefix if the + /// stream as a whole still contains more content. + /// + /// Returns `Some(encoding_rs::SHIFT_JIS)` if the detector guessed + /// Shift_JIS. Returns `Some(encoding_rs::EUC_JP)` if the detector + /// guessed EUC-JP. Returns `Some(encoding_rs::ISO_2022_JP)` if the + /// detector guessed ISO-2022-JP (only possible if `true` was passed as + /// `allow_2022` when instantiating the detector). Returns `None` if the + /// detector is undecided. If `None` is returned even when passing `true` + /// as `last`, falling back to Shift_JIS is the best guess for Web + /// purposes. + /// + /// Do not call again after the method has returned `Some(_)` or after + /// the method has been called with `true` as `last`. + /// + /// # Panics + /// + /// If called after the method has returned `Some(_)` or after the method + /// has been called with `true` as `last`. + pub fn feed(&mut self, buffer: &[u8], last: bool) -> Option<&'static Encoding> { + assert!( + !self.finished, + "Tried to used a detector that has finished." + ); + self.finished = true; // Will change back to false unless we return early + let mut i = 0; + if !self.iso_2022_jp_disqualified { + if !self.escape_seen { + i = find_non_ascii_or_escape(buffer); + } + while i < buffer.len() { + let byte = buffer[i]; + if byte > 0x7F { + self.iso_2022_jp_disqualified = true; + break; + } + if !self.escape_seen && byte == 0x1B { + self.escape_seen = true; + i += 1; + continue; + } + if self.escape_seen && self.second_byte_in_escape == 0 { + self.second_byte_in_escape = byte; + i += 1; + continue; + } + match (self.second_byte_in_escape, byte) { + (0x28, 0x42) | (0x28, 0x4A) | (0x28, 0x49) | (0x24, 0x40) | (0x24, 0x42) => { + return Some(ISO_2022_JP); + } + _ => {} + } + if self.escape_seen { + self.iso_2022_jp_disqualified = true; + break; + } + i += 1; + } + } + for &byte in &buffer[i..] { + if !feed_decoder(&mut self.euc_jp_decoder, byte, false) { + return Some(SHIFT_JIS); + } + if !feed_decoder(&mut self.shift_jis_decoder, byte, false) { + return Some(EUC_JP); + } + } + if last { + if !feed_decoder(&mut self.euc_jp_decoder, 0, true) { + return Some(SHIFT_JIS); + } + if !feed_decoder(&mut self.shift_jis_decoder, 0, true) { + return Some(EUC_JP); + } + return None; + } + self.finished = false; + None + } +} + +// Any copyright to the test code below this comment is dedicated to the +// Public Domain. http://creativecommons.org/publicdomain/zero/1.0/ + +#[cfg(test)] +mod tests { + use super::*; + #[test] + fn test_iso_2022_jp() { + let mut detector = Detector::new(true); + assert_eq!( + detector.feed(b"abc\x1B\x28\x42\xFF", true), + Some(ISO_2022_JP) + ); + } + + #[test] + fn test_error_precedence() { + let mut detector = Detector::new(true); + assert_eq!(detector.feed(b"abc\xFF", true), Some(SHIFT_JIS)); + } + + #[test] + fn test_invalid_euc_jp() { + let mut detector = Detector::new(true); + assert_eq!(detector.feed(b"abc\x81\x40", true), Some(SHIFT_JIS)); + } + + #[test] + fn test_invalid_shift_jis() { + let mut detector = Detector::new(true); + assert_eq!(detector.feed(b"abc\xEB\xA8", true), Some(EUC_JP)); + } + + #[test] + fn test_invalid_shift_jis_before_invalid_euc_jp() { + let mut detector = Detector::new(true); + assert_eq!(detector.feed(b"abc\xEB\xA8\x81\x40", true), Some(EUC_JP)); + } + + #[test] + fn test_undecided() { + let mut detector = Detector::new(true); + assert_eq!(detector.feed(b"abc", false), None); + assert_eq!(detector.feed(b"abc", false), None); + } + +} |