# x_user_defined.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/encoding_rs-0.8.28/src/x_user_defined.rs`.
Keywords: rust, rustlang, rust-lang

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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::handles::*;
    use crate::variant::*;

    cfg_if! {
        if #[cfg(feature = "simd-accel")] {
            use simd_funcs::*;
            use packed_simd::u16x8;

            #[inline(always)]
            fn shift_upper(unpacked: u16x8) -> u16x8 {
                let highest_ascii = u16x8::splat(0x7F);
                unpacked + unpacked.gt(highest_ascii).select(u16x8::splat(0xF700), u16x8::splat(0))        }
        } else {
        }
    }

    pub struct UserDefinedDecoder;

    impl UserDefinedDecoder {
        pub fn new() -> VariantDecoder {
            VariantDecoder::UserDefined(UserDefinedDecoder)
        }

        pub fn max_utf16_buffer_length(&self, byte_length: usize) -> Option<usize> {
            Some(byte_length)
        }

        pub fn max_utf8_buffer_length_without_replacement(&self, byte_length: usize) -> Option<usize> {
            byte_length.checked_mul(3)
        }

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

        decoder_function!(
            {},
            {},
            {},
            {
                if b < 0x80 {
                    // ASCII run not optimized, because binary data expected
                    destination_handle.write_ascii(b);
                    continue;
                }
                destination_handle.write_upper_bmp(u16::from(b) + 0xF700);
                continue;
            },
            self,
            src_consumed,
            dest,
            source,
            b,
            destination_handle,
            _unread_handle,
            check_space_bmp,
            decode_to_utf8_raw,
            u8,
            Utf8Destination
        );

        #[cfg(not(feature = "simd-accel"))]
        pub fn decode_to_utf16_raw(
            &mut self,
            src: &[u8],
            dst: &mut [u16],
            _last: bool,
        ) -> (DecoderResult, usize, usize) {
            let (pending, length) = if dst.len() < src.len() {
                (DecoderResult::OutputFull, dst.len())
            } else {
                (DecoderResult::InputEmpty, src.len())
            };
            let src_trim = &src[..length];
            let dst_trim = &mut dst[..length];
            src_trim
                .iter()
                .zip(dst_trim.iter_mut())
                .for_each(|(from, to)| {
                    *to = {
                        let unit = *from;
                        if unit < 0x80 {
                            u16::from(unit)
                        } else {
                            u16::from(unit) + 0xF700
                        }
                    }
                });
            (pending, length, length)
        }

        #[cfg(feature = "simd-accel")]
        pub fn decode_to_utf16_raw(
            &mut self,
            src: &[u8],
            dst: &mut [u16],
            _last: bool,
        ) -> (DecoderResult, usize, usize) {
            let (pending, length) = if dst.len() < src.len() {
                (DecoderResult::OutputFull, dst.len())
            } else {
                (DecoderResult::InputEmpty, src.len())
            };
            // Not bothering with alignment
            let tail_start = length & !0xF;
            let simd_iterations = length >> 4;
            let src_ptr = src.as_ptr();
            let dst_ptr = dst.as_mut_ptr();
            for i in 0..simd_iterations {
                let input = unsafe { load16_unaligned(src_ptr.add(i * 16)) };
                let (first, second) = simd_unpack(input);
                unsafe {
                    store8_unaligned(dst_ptr.add(i * 16), shift_upper(first));
                    store8_unaligned(dst_ptr.add((i * 16) + 8), shift_upper(second));
                }
            }
            let src_tail = &src[tail_start..length];
            let dst_tail = &mut dst[tail_start..length];
            src_tail
                .iter()
                .zip(dst_tail.iter_mut())
                .for_each(|(from, to)| {
                    *to = {
                        let unit = *from;
                        if unit < 0x80 {
                            u16::from(unit)
                        } else {
                            u16::from(unit) + 0xF700
                        }
                    }
                });
            (pending, length, length)
        }
    }

    pub struct UserDefinedEncoder;

    impl UserDefinedEncoder {
        pub fn new(encoding: &'static Encoding) -> Encoder {
            Encoder::new(encoding, VariantEncoder::UserDefined(UserDefinedEncoder))
        }

        pub fn max_buffer_length_from_utf16_without_replacement(
            &self,
            u16_length: usize,
        ) -> Option<usize> {
            Some(u16_length)
        }

        pub fn max_buffer_length_from_utf8_without_replacement(
            &self,
            byte_length: usize,
        ) -> Option<usize> {
            Some(byte_length)
        }

        encoder_functions!(
            {},
            {
                if c <= '\u{7F}' {
                    // TODO optimize ASCII run
                    destination_handle.write_one(c as u8);
                    continue;
                }
                if c < '\u{F780}' || c > '\u{F7FF}' {
                    return (
                        EncoderResult::Unmappable(c),
                        unread_handle.consumed(),
                        destination_handle.written(),
                    );
                }
                destination_handle.write_one((u32::from(c) - 0xF700) as u8);
                continue;
            },
            self,
            src_consumed,
            source,
            dest,
            c,
            destination_handle,
            unread_handle,
            check_space_one
        );
    }

    // 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_x_user_defined(bytes: &[u8], expect: &str) {
            decode(X_USER_DEFINED, bytes, expect);
        }

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

        #[test]
        fn test_x_user_defined_decode() {
            // Empty
            decode_x_user_defined(b"", "");

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

            decode_x_user_defined(b"\x80\xFF", "\u{F780}\u{F7FF}");
            decode_x_user_defined(b"\x80\xFF\x61\x62\x80\xFF\x61\x62\x80\xFF\x61\x62\x80\xFF\x61\x62\x80\xFF\x61\x62", "\u{F780}\u{F7FF}\u{0061}\u{0062}\u{F780}\u{F7FF}\u{0061}\u{0062}\u{F780}\u{F7FF}\u{0061}\u{0062}\u{F780}\u{F7FF}\u{0061}\u{0062}\u{F780}\u{F7FF}\u{0061}\u{0062}");
        }

        #[test]
        fn test_x_user_defined_encode() {
            // Empty
            encode_x_user_defined("", b"");

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

            encode_x_user_defined("\u{F780}\u{F7FF}", b"\x80\xFF");
            encode_x_user_defined("\u{F77F}\u{F800}", b"&#63359;&#63488;");
        }

        #[test]
        fn test_x_user_defined_from_two_low_surrogates() {
            let expectation = b"&#65533;&#65533;";
            let mut output = [0u8; 40];
            let mut encoder = X_USER_DEFINED.new_encoder();
            let (result, read, written, had_errors) =
                encoder.encode_from_utf16(&[0xDC00u16, 0xDEDEu16], &mut output[..], true);
            assert_eq!(result, CoderResult::InputEmpty);
            assert_eq!(read, 2);
            assert_eq!(written, expectation.len());
            assert!(had_errors);
            assert_eq!(&output[..written], expectation);
        }
    }