//! Big5 encoding.

// Note that we need to recreate Encoder/Decoders in these functions due to this note in the

// encoding_rs documentation:

//

// > Once the stream has ended, the Decoder object must not be used anymore. That is, you need to

// > create another one to process another stream.

use encoding_rs::{DecoderResult, EncoderResult, BIG5};

        EncoderResult::InputEmpty => {

            }

        }

    }

/// Decodes a Big5 character into a Unicode char

    // Strictly speaking, the Big5 encoding contains only double-byte character set characters.

    // However, in practice, the Big5 codes are always used together with an unspecified,

    // system-dependent single-byte character set (ASCII, or an 8-bit character set such as code

    // page 437), so that you will find a mix of DBCS characters and single-byte characters in

    // Big5-encoded text. Bytes in the range 0x00 to 0x7f that are not part of a double-byte

    // character are assumed to be single-byte characters.

    //

    // — https://en.wikipedia.org/wiki/Big5

    //

    // encoding_rs::Decoder for Big5 returns 0 for single-byte codes, so we handle ASCII manually.

            // Safety: It is assumed that decode_to_utf8_without_replacement will yield valid utf-8

            // output in dst. Additionally because written is > 1 we assume chars will yield a char

            // thus it should always be valid utf-8.

        }

        DecoderResult::InputEmpty |

        DecoderResult::OutputFull | // should not happen

    }

#[cfg(test)]

mod tests {

    use super::*;

    #[test]

    fn ascii_to_big5() {

        for i in 0..128 {

            let u = char::from(i);

            assert_eq!(unicode_to_big5(u), Some(u16::from(i)));

        }

    }

    #[test]

    fn chinese_to_big5() {

        assert_eq!(unicode_to_big5('好'), Some(0xA66E));

    }

    #[test]

    fn greek_to_big5() {

        assert_eq!(unicode_to_big5('ε'), Some(0xA360));

    }

    #[test]

    fn hindi_to_big5() {

        assert_eq!(unicode_to_big5('म'), None);

    }

    #[test]

    fn big5_to_ascii() {

        for i in 0..128 {

            assert_eq!(big5_to_unicode(u16::from(i)), Some(char::from(i)));

        }

    }

    #[test]

    fn chinese_big5_to_unicode() {

        assert_eq!(big5_to_unicode(0xA66E), Some('好'));

    }

    #[test]

    fn greek_big5_to_unicode() {

        assert_eq!(big5_to_unicode(0xA360), Some('ε'));

    }

    #[test]

    fn graphical_big5_to_unicode() {

        assert_eq!(big5_to_unicode(0xA143), Some('。'));

    }

}