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#[derive(Clone,Copy,Eq,PartialEq,Hash)]
pub struct UUID(u64,u64);
impl std::fmt::Debug for UUID {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let raw = self.format_raw();
        f.write_str(unsafe{std::str::from_utf8_unchecked(&raw[..])})
    }
}
impl std::fmt::Display for UUID {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let raw = self.format_raw();
        f.write_str(unsafe{std::str::from_utf8_unchecked(&raw[..])})
    }
}
// TODO: https://github.com/Theaninova/lightning-fast-hex-parser
fn stupid_hex(f: u64) -> u32 {
    let t = f & 0x4040_4040_4040_4040;
    let mut s = (f & 0xF0F0F0F0F0F0F0F) + ((t >> 3) | (t >> 6));
    s = ((s << 4) | (s >> 8)) & 0x00FF00FF00FF00FF;
    s |= s << 24;
    return ((s & 0xFFFF0000FFFF0000) | (s >> 48)) as u32
}
impl UUID {
    pub fn from_bytes(exa: &[u8]) -> Option<UUID> {
        let bytes: &[u8;36] = exa.try_into().ok()?;
        //no validate
        let mut p0 = (stupid_hex(u64::from_le_bytes(bytes[0..8].try_into().unwrap())) as u64) << 32;
        let op = u32::from_le_bytes(bytes[9..13].try_into().unwrap()) as u64
            | ((u32::from_le_bytes(bytes[14..18].try_into().unwrap()) as u64) << 32);
        p0 |= stupid_hex(op) as u64;
        let op = u32::from_le_bytes(bytes[19..23].try_into().unwrap()) as u64
            | ((u32::from_le_bytes(bytes[24..28].try_into().unwrap()) as u64) << 32);
        let mut p1 = (stupid_hex(op) as u64) << 32;
        p1 |= stupid_hex(u64::from_le_bytes(bytes[28..36].try_into().unwrap())) as u64;
        Some(UUID(p0,p1))
    }
    pub fn format_raw(&self) -> [u8;36] {
        const ALPHA: [u8;16] = *b"0123456789abcdef";
        let mut ai = 16;
        let mut bi = 16;
        let mut q = || { ai -= 1; ALPHA[((self.0>>(ai*4))&0b1111u64) as usize] };
        let mut p = || { bi -= 1; ALPHA[((self.1>>(bi*4))&0b1111u64) as usize] };
        [
            q(), q(), q(), q(),
            q(), q(), q(), q(), b'-',
            q(), q(), q(), q(), b'-',
            q(), q(), q(), q(), b'-',
            p(), p(), p(), p(), b'-',
            p(), p(), p(), p(),
            p(), p(), p(), p(),
            p(), p(), p(), p()
        ]
    }
}
use serde::de::{Deserializer, Unexpected, Visitor};
use serde::{Deserialize, Serialize, Serializer};

struct UUIDVisitor {}
impl<'de> Visitor<'de> for UUIDVisitor {
    type Value = UUID;

    fn expecting(&self, formatter: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(
            formatter,
            "Invalid Word Length <=15 length"
        )
    }

    fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
    where
        E: serde::de::Error,
    {
        if let Some(word) = UUID::from_bytes(s.as_bytes()) {
            Ok(word)
        } else {
            Err(serde::de::Error::invalid_value(
                Unexpected::Other("Invalid UUID"),
                &self,
            ))
        }
    }
}

impl Serialize for UUID {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
    where
        S: Serializer,
    {
        let buf = self.format_raw();
        serializer.serialize_str(unsafe {
            std::str::from_utf8_unchecked(&buf[..])
        })
    }
}

impl<'de> Deserialize<'de> for UUID {
    fn deserialize<D>(deserializer: D) -> Result<UUID, D::Error>
    where
        D: Deserializer<'de>,
    {
        deserializer.deserialize_any( UUIDVisitor{})
    }
}