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    // Copyright 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 super::*;
    use crate::data::*;
    use crate::handles::*;
    use crate::variant::*;
    // Rust 1.14.0 requires the following despite the asterisk above.
    use super::in_inclusive_range16;
    use super::in_range16;

    enum Gb18030Pending {
        None,
        One(u8),
        Two(u8, u8),
        Three(u8, u8, u8),
    }

    impl Gb18030Pending {
        fn is_none(&self) -> bool {
            match *self {
                Gb18030Pending::None => true,
                _ => false,
            }
        }

        fn count(&self) -> usize {
            match *self {
                Gb18030Pending::None => 0,
                Gb18030Pending::One(_) => 1,
                Gb18030Pending::Two(_, _) => 2,
                Gb18030Pending::Three(_, _, _) => 3,
            }
        }
    }

    pub struct Gb18030Decoder {
        first: Option<u8>,
        second: Option<u8>,
        third: Option<u8>,
        pending: Gb18030Pending,
        pending_ascii: Option<u8>,
    }

    impl Gb18030Decoder {
        pub fn new() -> VariantDecoder {
            VariantDecoder::Gb18030(Gb18030Decoder {
                first: None,
                second: None,
                third: None,
                pending: Gb18030Pending::None,
                pending_ascii: None,
            })
        }

        pub fn in_neutral_state(&self) -> bool {
            self.first.is_none()
                && self.second.is_none()
                && self.third.is_none()
                && self.pending.is_none()
                && self.pending_ascii.is_none()
        }

        fn extra_from_state(&self, byte_length: usize) -> Option<usize> {
            byte_length.checked_add(
                self.pending.count()
                    + match self.first {
                        None => 0,
                        Some(_) => 1,
                    }
                    + match self.second {
                        None => 0,
                        Some(_) => 1,
                    }
                    + match self.third {
                        None => 0,
                        Some(_) => 1,
                    }
                    + match self.pending_ascii {
                        None => 0,
                        Some(_) => 1,
                    },
            )
        }

        pub fn max_utf16_buffer_length(&self, byte_length: usize) -> Option<usize> {
            // ASCII: 1 to 1 (worst case)
            // gbk: 2 to 1
            // ranges: 4 to 1 or 4 to 2
            checked_add(1, self.extra_from_state(byte_length))
        }

        pub fn max_utf8_buffer_length_without_replacement(&self, byte_length: usize) -> Option<usize> {
            // ASCII: 1 to 1
            // gbk: 2 to 2 or 2 to 3
            // ranges: 4 to 2, 4 to 3 or 4 to 4
            // 0x80: 1 to 3 (worst case)
            self.max_utf8_buffer_length(byte_length)
        }

        pub fn max_utf8_buffer_length(&self, byte_length: usize) -> Option<usize> {
            checked_add(1, checked_mul(3, self.extra_from_state(byte_length)))
        }

        gb18030_decoder_functions!(
            {
                // If first is between 0x81 and 0xFE, inclusive,
                // subtract offset 0x81.
                let non_ascii_minus_offset = non_ascii.wrapping_sub(0x81);
                if non_ascii_minus_offset > (0xFE - 0x81) {
                    if non_ascii == 0x80 {
                        handle.write_upper_bmp(0x20ACu16);
                        continue 'outermost;
                    }
                    return (DecoderResult::Malformed(1, 0),
                            source.consumed(),
                            handle.written());
                }
                non_ascii_minus_offset
            },
            {
                // Two-byte (or error)
                if first_minus_offset >= 0x20 {
                    // Not the gbk ideograph range above GB2312
                    let trail_minus_offset = second.wrapping_sub(0xA1);
                    if trail_minus_offset <= (0xFE - 0xA1) {
                        // GB2312
                        let hanzi_lead = first_minus_offset.wrapping_sub(0x2F);
                        if hanzi_lead < (0x77 - 0x2F) {
                            // Level 1 Hanzi, Level 2 Hanzi
                            // or one of the 5 PUA code
                            // points in between.
                            let hanzi_pointer = mul_94(hanzi_lead) + trail_minus_offset as usize;
                            let upper_bmp = GB2312_HANZI[hanzi_pointer];
                            handle.write_upper_bmp(upper_bmp)
                        } else if first_minus_offset == 0x20 {
                            // Symbols (starting with ideographic space)
                            let bmp = GB2312_SYMBOLS[trail_minus_offset as usize];
                            handle.write_bmp_excl_ascii(bmp)
                        } else if first_minus_offset == 0x25 && ((trail_minus_offset.wrapping_sub(63) as usize) < GB2312_SYMBOLS_AFTER_GREEK.len()) {
                            handle.write_bmp_excl_ascii(GB2312_SYMBOLS_AFTER_GREEK[trail_minus_offset.wrapping_sub(63) as usize])
                        } else if first_minus_offset == 0x27 && (trail_minus_offset as usize) < GB2312_PINYIN.len() {
                            handle.write_bmp_excl_ascii(GB2312_PINYIN[trail_minus_offset as usize])
                        } else if first_minus_offset > 0x76 {
                            // Bottom PUA
                            let pua = (0xE234 + mul_94(first_minus_offset - 0x77) + trail_minus_offset as usize) as u16;
                            handle.write_upper_bmp(pua)
                        } else {
                            let bmp = gb2312_other_decode((mul_94(first_minus_offset - 0x21) + (trail_minus_offset as usize)) as u16);
                            handle.write_bmp_excl_ascii(bmp)
                        }
                    } else {
                        // gbk range on the left
                        let mut trail_minus_offset = second.wrapping_sub(0x40);
                        if trail_minus_offset > (0x7E - 0x40) {
                            let trail_minus_range_start = second.wrapping_sub(0x80);
                            if trail_minus_range_start > (0xA0 - 0x80) {
                                if second < 0x80 {
                                    return (DecoderResult::Malformed(1, 0),
                                            unread_handle_second.unread(),
                                            handle.written());
                                }
                                return (DecoderResult::Malformed(2, 0),
                                        unread_handle_second.consumed(),
                                        handle.written());
                            }
                            trail_minus_offset = second - 0x41;
                        }
                        // Zero-base lead
                        let left_lead = first_minus_offset - 0x20;
                        let left_pointer = left_lead as usize * (190 - 94) +
                                           trail_minus_offset as usize;
                        let gbk_left_ideograph_pointer = left_pointer.wrapping_sub((0x29 - 0x20) * (190 - 94));
                        if gbk_left_ideograph_pointer < (((0x7D - 0x29) * (190 - 94)) - 5) {
                            let upper_bmp = gbk_left_ideograph_decode(gbk_left_ideograph_pointer as u16);
                            handle.write_upper_bmp(upper_bmp)
                        } else if left_pointer < ((0x29 - 0x20) * (190 - 94)) {
                            let bmp = gbk_other_decode(left_pointer as u16);
                            handle.write_bmp_excl_ascii(bmp)
                        } else {
                            let bottom_pointer = left_pointer - (((0x7D - 0x20) * (190 - 94)) - 5);
                            let upper_bmp = GBK_BOTTOM[bottom_pointer];
                            handle.write_upper_bmp(upper_bmp)
                        }
                    }
                } else {
                    // gbk ideograph range above GB2312
                    let mut trail_minus_offset = second.wrapping_sub(0x40);
                    if trail_minus_offset > (0x7E - 0x40) {
                        let trail_minus_range_start = second.wrapping_sub(0x80);
                        if trail_minus_range_start > (0xFE - 0x80) {
                            if second < 0x80 {
                                return (DecoderResult::Malformed(1, 0),
                                        unread_handle_second.unread(),
                                        handle.written());
                            }
                            return (DecoderResult::Malformed(2, 0),
                                    unread_handle_second.consumed(),
                                    handle.written());
                        }
                        trail_minus_offset = second - 0x41;
                    }
                    let pointer = first_minus_offset as usize * 190usize +
                                  trail_minus_offset as usize;
                    let upper_bmp = gbk_top_ideograph_decode(pointer as u16);
                    handle.write_upper_bmp(upper_bmp)
                }
            },
            {
                // If third is between 0x81 and 0xFE, inclusive,
                // subtract offset 0x81.
                let third_minus_offset = third.wrapping_sub(0x81);
                if third_minus_offset > (0xFE - 0x81) {
                    // We have an error. Let's inline what's going
                    // to happen when `second` is
                    // reprocessed. (`third` gets unread.)
                    // `second` is guaranteed ASCII, so let's
                    // put it in `pending_ascii`. Recompute
                    // `second` from `second_minus_offset`.
                    self.pending_ascii = Some(second_minus_offset + 0x30);
                    // Now unread `third` and designate the previous
                    // `first` as being in error.
                    return (DecoderResult::Malformed(1, 1),
                            unread_handle_third.unread(),
                            handle.written());
                }
                third_minus_offset
            },
            {
                // If fourth is between 0x30 and 0x39, inclusive,
                // subtract offset 0x30.
                //
                // If we have an error, we'll inline what's going
                // to happen when `second` and `third` are
                // reprocessed. (`fourth` gets unread.)
                // `second` is guaranteed ASCII, so let's
                // put it in `pending_ascii`. Recompute
                // `second` from `second_minus_offset` to
                // make this block reusable when `second`
                // is not in scope.
                //
                // `third` is guaranteed to be in the range
                // that makes it become the new `self.first`.
                //
                // `fourth` gets unread and the previous
                // `first` gets designates as being in error.
                let fourth_minus_offset = fourth.wrapping_sub(0x30);
                if fourth_minus_offset > (0x39 - 0x30) {
                    self.pending_ascii = Some(second_minus_offset + 0x30);
                    self.pending = Gb18030Pending::One(third_minus_offset);
                    return (DecoderResult::Malformed(1, 2),
                            unread_handle_fourth.unread(),
                            handle.written());
                }
                let pointer = (first_minus_offset as usize * (10 * 126 * 10)) +
                              (second_minus_offset as usize * (10 * 126)) +
                              (third_minus_offset as usize * 10) +
                              fourth_minus_offset as usize;
                if pointer <= 39419 {
                    // BMP
                    if pointer == 7457 {
                        handle.write_upper_bmp(0xE7C7)
                    } else {
                        handle.write_bmp_excl_ascii(gb18030_range_decode(pointer as u16))
                    }
                } else if pointer >= 189_000 && pointer <= 1_237_575 {
                    // Astral
                    handle.write_astral((pointer - (189_000usize - 0x1_0000usize)) as u32)
                } else {
                    return (DecoderResult::Malformed(4, 0),
                            unread_handle_fourth.consumed(),
                            handle.written());
                }
            },
            self,
            non_ascii,
            first_minus_offset,
            second,
            second_minus_offset,
            unread_handle_second,
            third,
            third_minus_offset,
            unread_handle_third,
            fourth,
            fourth_minus_offset,
            unread_handle_fourth,
            source,
            handle,
            'outermost);
    }

    // XXX Experiment with inline directives
    fn gbk_encode_non_unified(bmp: u16) -> Option<(usize, usize)> {
        // Try ideographic punctuation first as it's the most likely case.
        // Throwing in the check for full-width currencies and tilde is probably
        // more size-efficient here than elsewhere.
        if in_inclusive_range16(bmp, 0x2014, 0x3017) || in_inclusive_range16(bmp, 0xFF04, 0xFFE1) {
            if let Some(pos) = position(&GB2312_SYMBOLS[..], bmp) {
                return Some((0xA1, pos + 0xA1));
            }
        }
        // Ext A
        if in_range16(bmp, 0x3400, 0x4E00) {
            return position(&GBK_BOTTOM[21..100], bmp).map(|pos| {
                (
                    0xFE,
                    pos + if pos < (0x3F - 16) {
                        0x40 + 16
                    } else {
                        0x41 + 16
                    },
                )
            });
        }
        // Compatibility ideographs
        if in_range16(bmp, 0xF900, 0xFB00) {
            return position(&GBK_BOTTOM[0..21], bmp).map(|pos| {
                if pos < 5 {
                    // end of second to last row
                    (0xFD, pos + (190 - 94 - 5 + 0x41))
                } else {
                    // last row
                    (0xFE, pos + (0x40 - 5))
                }
            });
        }
        // Handle everything below U+02CA, which is in GBK_OTHER.
        if bmp < 0x02CA {
            if in_range16(bmp, 0x00E0, 0x0262) && bmp != 0x00F7 {
                // Pinyin except U+1E3F
                if let Some(pos) = position(&GB2312_PINYIN[..], bmp) {
                    return Some((0xA8, pos + 0xA1));
                }
            } else if in_inclusive_range16(bmp, 0x00A4, 0x00F7)
                || in_inclusive_range16(bmp, 0x02C7, 0x02C9)
            {
                // Diacritics and Latin 1 symbols
                if let Some(pos) = position(&GB2312_SYMBOLS[3..(0xAC - 0x60)], bmp) {
                    return Some((0xA1, pos + 0xA1 + 3));
                }
            }
            return None;
        }
        if bmp >= 0xE794 {
            // Various brackets, all in PUA or full-width regions
            if let Some(pos) = position(&GB2312_SYMBOLS_AFTER_GREEK[..], bmp) {
                return Some((0xA6, pos + (0x9F - 0x60 + 0xA1)));
            }
        } else if bmp == 0x1E3F {
            // The one Pinyin placed elsewhere on the BMP
            return Some((0xA8, 0x7B - 0x60 + 0xA1));
        } else if in_range16(bmp, 0xA000, 0xD800) {
            // Since Korean has usage in China, let's spend a branch to fast-track
            // Hangul.
            return None;
        }
        // GB2312 other (except bottom PUA and PUA between Hanzi levels).
        if let Some(other_pointer) = gb2312_other_encode(bmp) {
            let other_lead = other_pointer as usize / 94;
            let other_trail = other_pointer as usize % 94;
            return Some((0xA2 + other_lead, 0xA1 + other_trail));
        }
        // At this point, we've handled all mappable characters above U+02D9 but
        // below U+2010. Let's check for that range in order to let lower BMP
        // characters used for minority languages in China avoid the subsequent
        // search that deals mainly with various symbols.
        if in_range16(bmp, 0x02DA, 0x2010) {
            return None;
        }
        // GBK other (except radicals and PUA in GBK_BOTTOM).
        if let Some(other_pointer) = gbk_other_encode(bmp) {
            let other_lead = other_pointer as usize / (190 - 94);
            let other_trail = other_pointer as usize % (190 - 94);
            let offset = if other_trail < 0x3F { 0x40 } else { 0x41 };
            return Some((other_lead + (0x81 + 0x20), other_trail + offset));
        }
        // CJK Radicals Supplement or PUA in GBK_BOTTOM
        if in_inclusive_range16(bmp, 0x2E81, 0x2ECA) || in_inclusive_range16(bmp, 0xE816, 0xE864) {
            if let Some(pos) = position(&GBK_BOTTOM[21..], bmp) {
                let trail = pos + 16;
                let offset = if trail < 0x3F { 0x40 } else { 0x41 };
                return Some((0xFE, trail + offset));
            }
        }
        // GB2312 bottom PUA
        let bmp_minus_gb2312_bottom_pua = bmp.wrapping_sub(0xE234);
        if bmp_minus_gb2312_bottom_pua <= (0xE4C5 - 0xE234) {
            let pua_lead = bmp_minus_gb2312_bottom_pua as usize / 94;
            let pua_trail = bmp_minus_gb2312_bottom_pua as usize % 94;
            return Some((0x81 + 0x77 + pua_lead, 0xA1 + pua_trail));
        }
        // PUA between Hanzi Levels
        let bmp_minus_pua_between_hanzi = bmp.wrapping_sub(0xE810);
        if bmp_minus_pua_between_hanzi < 5 {
            return Some((0x81 + 0x56, 0xFF - 5 + bmp_minus_pua_between_hanzi as usize));
        }
        None
    }

    #[cfg(not(feature = "fast-gb-hanzi-encode"))]
    #[inline(always)]
    fn encode_hanzi(bmp: u16, _: u16) -> (u8, u8) {
        if let Some((lead, trail)) = gb2312_level1_hanzi_encode(bmp) {
            (lead, trail)
        } else if let Some(hanzi_pointer) = gb2312_level2_hanzi_encode(bmp) {
            let hanzi_lead = (hanzi_pointer / 94) + (0xD8);
            let hanzi_trail = (hanzi_pointer % 94) + 0xA1;
            (hanzi_lead as u8, hanzi_trail as u8)
        } else {
            let (lead, gbk_trail) = if bmp < 0x72DC {
                // Above GB2312
                let pointer = gbk_top_ideograph_encode(bmp) as usize;
                let lead = (pointer / 190) + 0x81;
                let gbk_trail = pointer % 190;
                (lead, gbk_trail)
            } else {
                // To the left of GB2312
                let gbk_left_ideograph_pointer = gbk_left_ideograph_encode(bmp) as usize;
                let lead = (gbk_left_ideograph_pointer / (190 - 94)) + (0x81 + 0x29);
                let gbk_trail = gbk_left_ideograph_pointer % (190 - 94);
                (lead, gbk_trail)
            };
            let offset = if gbk_trail < 0x3F { 0x40 } else { 0x41 };
            (lead as u8, (gbk_trail + offset) as u8)
        }
    }

    #[cfg(feature = "fast-gb-hanzi-encode")]
    #[inline(always)]
    fn encode_hanzi(_: u16, bmp_minus_unified_start: u16) -> (u8, u8) {
        gbk_hanzi_encode(bmp_minus_unified_start)
    }

    pub struct Gb18030Encoder {
        extended: bool,
    }

    impl Gb18030Encoder {
        pub fn new(encoding: &'static Encoding, extended_range: bool) -> Encoder {
            Encoder::new(
                encoding,
                VariantEncoder::Gb18030(Gb18030Encoder {
                    extended: extended_range,
                }),
            )
        }

        pub fn max_buffer_length_from_utf16_without_replacement(
            &self,
            u16_length: usize,
        ) -> Option<usize> {
            if self.extended {
                u16_length.checked_mul(4)
            } else {
                // Need to add, because space check is done with the four-byte
                // assumption.
                checked_add(2, u16_length.checked_mul(2))
            }
        }

        pub fn max_buffer_length_from_utf8_without_replacement(
            &self,
            byte_length: usize,
        ) -> Option<usize> {
            if self.extended {
                // 1 to 1
                // 2 to 2
                // 3 to 2
                // 2 to 4 (worst)
                // 3 to 4
                // 4 to 4
                checked_add(2, byte_length.checked_mul(2))
            } else {
                // 1 to 1
                // 2 to 2
                // 3 to 2
                // Need to add, because space check is done with the four-byte
                // assumption.
                byte_length.checked_add(3)
            }
        }

        ascii_compatible_encoder_functions!(
            {
                let bmp_minus_unified_start = bmp.wrapping_sub(0x4E00);
                if bmp_minus_unified_start < (0x9FA6 - 0x4E00) {
                    // CJK Unified Ideographs
                    // Can't fail now, since all are
                    // mapped.
                    let (lead, trail) = encode_hanzi(bmp, bmp_minus_unified_start);
                    handle.write_two(lead, trail)
                } else if bmp == 0xE5E5 {
                    // It's not optimal to check for the unmappable
                    // and for euro at this stage, but getting
                    // the out of the way makes the rest of the
                    // code less messy.
                    return (
                        EncoderResult::unmappable_from_bmp(bmp),
                        source.consumed(),
                        handle.written(),
                    );
                } else if bmp == 0x20AC && !self.extended {
                    handle.write_one(0x80u8)
                } else {
                    match gbk_encode_non_unified(bmp) {
                        Some((lead, trail)) => handle.write_two(lead as u8, trail as u8),
                        None => {
                            if !self.extended {
                                return (
                                    EncoderResult::unmappable_from_bmp(bmp),
                                    source.consumed(),
                                    handle.written(),
                                );
                            }
                            let range_pointer = gb18030_range_encode(bmp);
                            let first = range_pointer / (10 * 126 * 10);
                            let rem_first = range_pointer % (10 * 126 * 10);
                            let second = rem_first / (10 * 126);
                            let rem_second = rem_first % (10 * 126);
                            let third = rem_second / 10;
                            let fourth = rem_second % 10;
                            handle.write_four(
                                (first + 0x81) as u8,
                                (second + 0x30) as u8,
                                (third + 0x81) as u8,
                                (fourth + 0x30) as u8,
                            )
                        }
                    }
                }
            },
            {
                if !self.extended {
                    return (
                        EncoderResult::Unmappable(astral),
                        source.consumed(),
                        handle.written(),
                    );
                }
                let range_pointer = astral as usize + (189_000usize - 0x1_0000usize);
                let first = range_pointer / (10 * 126 * 10);
                let rem_first = range_pointer % (10 * 126 * 10);
                let second = rem_first / (10 * 126);
                let rem_second = rem_first % (10 * 126);
                let third = rem_second / 10;
                let fourth = rem_second % 10;
                handle.write_four(
                    (first + 0x81) as u8,
                    (second + 0x30) as u8,
                    (third + 0x81) as u8,
                    (fourth + 0x30) as u8,
                )
            },
            bmp,
            astral,
            self,
            source,
            handle,
            copy_ascii_to_check_space_four,
            check_space_four,
            false
        );
    }

    // 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::super::testing::*;
        use super::super::*;

        fn decode_gb18030(bytes: &[u8], expect: &str) {
            decode(GB18030, bytes, expect);
        }

        fn encode_gb18030(string: &str, expect: &[u8]) {
            encode(GB18030, string, expect);
        }

        fn encode_gbk(string: &str, expect: &[u8]) {
            encode(GBK, string, expect);
        }

        #[test]
        fn test_gb18030_decode() {
            // Empty
            decode_gb18030(b"", &"");

            // ASCII
            decode_gb18030(b"\x61\x62", "\u{0061}\u{0062}");

            // euro
            decode_gb18030(b"\x80", "\u{20AC}");
            decode_gb18030(b"\xA2\xE3", "\u{20AC}");

            // two bytes
            decode_gb18030(b"\x81\x40", "\u{4E02}");
            decode_gb18030(b"\x81\x7E", "\u{4E8A}");
            decode_gb18030(b"\x81\x7F", "\u{FFFD}\u{007F}");
            decode_gb18030(b"\x81\x80", "\u{4E90}");
            decode_gb18030(b"\x81\xFE", "\u{4FA2}");
            decode_gb18030(b"\xFE\x40", "\u{FA0C}");
            decode_gb18030(b"\xFE\x7E", "\u{E843}");
            decode_gb18030(b"\xFE\x7F", "\u{FFFD}\u{007F}");
            decode_gb18030(b"\xFE\x80", "\u{4723}");
            decode_gb18030(b"\xFE\xFE", "\u{E4C5}");

            // The difference from the original GB18030
            decode_gb18030(b"\xA3\xA0", "\u{3000}");
            decode_gb18030(b"\xA1\xA1", "\u{3000}");

            // 0xFF
            decode_gb18030(b"\xFF\x40", "\u{FFFD}\u{0040}");
            decode_gb18030(b"\xE3\xFF\x9A\x33", "\u{FFFD}\u{FFFD}"); // not \u{FFFD}\u{FFFD}\u{0033} !
            decode_gb18030(b"\xFF\x32\x9A\x33", "\u{FFFD}\u{0032}\u{FFFD}"); // not \u{FFFD}\u{0032}\u{FFFD}\u{0033} !
            decode_gb18030(b"\xFF\x40\x00", "\u{FFFD}\u{0040}\u{0000}");
            decode_gb18030(b"\xE3\xFF\x9A\x33\x00", "\u{FFFD}\u{FFFD}\u{0033}\u{0000}");
            decode_gb18030(
                b"\xFF\x32\x9A\x33\x00",
                "\u{FFFD}\u{0032}\u{FFFD}\u{0033}\u{0000}",
            );

            // Four bytes
            decode_gb18030(b"\x81\x30\x81\x30", "\u{0080}");
            decode_gb18030(b"\x81\x35\xF4\x37", "\u{E7C7}");
            decode_gb18030(b"\x81\x37\xA3\x30", "\u{2603}");
            decode_gb18030(b"\x94\x39\xDA\x33", "\u{1F4A9}");
            decode_gb18030(b"\xE3\x32\x9A\x35", "\u{10FFFF}");
            decode_gb18030(b"\xE3\x32\x9A\x36\x81\x30", "\u{FFFD}\u{FFFD}");
            decode_gb18030(b"\xE3\x32\x9A\x36\x81\x40", "\u{FFFD}\u{4E02}");
            decode_gb18030(b"\xE3\x32\x9A", "\u{FFFD}"); // not \u{FFFD}\u{0032}\u{FFFD} !
            decode_gb18030(b"\xE3\x32\x9A\x00", "\u{FFFD}\u{0032}\u{FFFD}\u{0000}");
        }

        #[test]
        fn test_gb18030_encode() {
            // Empty
            encode_gb18030("", b"");

            // ASCII
            encode_gb18030("\u{0061}\u{0062}", b"\x61\x62");

            // euro
            encode_gb18030("\u{20AC}", b"\xA2\xE3");

            // two bytes
            encode_gb18030("\u{4E02}", b"\x81\x40");
            encode_gb18030("\u{4E8A}", b"\x81\x7E");
            if !cfg!(miri) {
                // Miri is too slow
                encode_gb18030("\u{4E90}", b"\x81\x80");
                encode_gb18030("\u{4FA2}", b"\x81\xFE");
                encode_gb18030("\u{FA0C}", b"\xFE\x40");
                encode_gb18030("\u{E843}", b"\xFE\x7E");
                encode_gb18030("\u{4723}", b"\xFE\x80");
                encode_gb18030("\u{E4C5}", b"\xFE\xFE");
            }

            // The difference from the original GB18030
            encode_gb18030("\u{E5E5}", b"&#58853;");
            encode_gb18030("\u{3000}", b"\xA1\xA1");

            // Four bytes
            encode_gb18030("\u{0080}", b"\x81\x30\x81\x30");
            encode_gb18030("\u{E7C7}", b"\x81\x35\xF4\x37");
            if !cfg!(miri) {
                // Miri is too slow
                encode_gb18030("\u{2603}", b"\x81\x37\xA3\x30");
                encode_gb18030("\u{1F4A9}", b"\x94\x39\xDA\x33");
                encode_gb18030("\u{10FFFF}", b"\xE3\x32\x9A\x35");
            }

            // Edge cases
            encode_gb18030("\u{00F7}", b"\xA1\xC2");
        }

        #[test]
        fn test_gbk_encode() {
            // Empty
            encode_gbk("", b"");

            // ASCII
            encode_gbk("\u{0061}\u{0062}", b"\x61\x62");

            // euro
            encode_gbk("\u{20AC}", b"\x80");

            // two bytes
            encode_gbk("\u{4E02}", b"\x81\x40");
            encode_gbk("\u{4E8A}", b"\x81\x7E");
            if !cfg!(miri) {
                // Miri is too slow
                encode_gbk("\u{4E90}", b"\x81\x80");
                encode_gbk("\u{4FA2}", b"\x81\xFE");
                encode_gbk("\u{FA0C}", b"\xFE\x40");
                encode_gbk("\u{E843}", b"\xFE\x7E");
                encode_gbk("\u{4723}", b"\xFE\x80");
                encode_gbk("\u{E4C5}", b"\xFE\xFE");
            }

            // The difference from the original gb18030
            encode_gbk("\u{E5E5}", b"&#58853;");
            encode_gbk("\u{3000}", b"\xA1\xA1");

            // Four bytes
            encode_gbk("\u{0080}", b"&#128;");
            encode_gbk("\u{E7C7}", b"&#59335;");
            if !cfg!(miri) {
                // Miri is too slow
                encode_gbk("\u{2603}", b"&#9731;");
                encode_gbk("\u{1F4A9}", b"&#128169;");
                encode_gbk("\u{10FFFF}", b"&#1114111;");
            }

            // Edge cases
            encode_gbk("\u{00F7}", b"\xA1\xC2");
        }

        #[test]
        #[cfg_attr(miri, ignore)] // Miri is too slow
        fn test_gb18030_decode_all() {
            let input = include_bytes!("test_data/gb18030_in.txt");
            let expectation = include_str!("test_data/gb18030_in_ref.txt");
            let (cow, had_errors) = GB18030.decode_without_bom_handling(input);
            assert!(!had_errors, "Should not have had errors.");
            assert_eq!(&cow[..], expectation);
        }

        #[test]
        #[cfg_attr(miri, ignore)] // Miri is too slow
        fn test_gb18030_encode_all() {
            let input = include_str!("test_data/gb18030_out.txt");
            let expectation = include_bytes!("test_data/gb18030_out_ref.txt");
            let (cow, encoding, had_errors) = GB18030.encode(input);
            assert!(!had_errors, "Should not have had errors.");
            assert_eq!(encoding, GB18030);
            assert_eq!(&cow[..], &expectation[..]);
        }

        #[test]
        fn test_gb18030_encode_from_utf16_max_length() {
            let mut output = [0u8; 20];
            let mut encoder = GB18030.new_encoder();
            {
                let needed = encoder
                    .max_buffer_length_from_utf16_without_replacement(1)
                    .unwrap();
                let (result, read, written) = encoder.encode_from_utf16_without_replacement(
                    &[0x3000],
                    &mut output[..needed],
                    true,
                );
                assert_eq!(result, EncoderResult::InputEmpty);
                assert_eq!(read, 1);
                assert_eq!(written, 2);
                assert_eq!(output[0], 0xA1);
                assert_eq!(output[1], 0xA1);
            }
        }
    }