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use ::{ Asn1DerError, std::mem };


/// A wrapper around a DER tag that is DER-(de-)serializable
#[repr(u8)] #[derive(Debug, Copy, Clone, Eq, PartialEq)] #[allow(non_camel_case_types)]
pub enum DerTag {
	// Well defined and supported types
	Boolean		= 0x01,
	Integer		= 0x02,
	OctetString	= 0x04,
	Null		= 0x05,
	Utf8String	= 0x0c,
	Sequence	= 0x30,
	
	// All possible remaining values in [0, 256) to allow a safe parsing from each `u8` value
	x00 = 0x00, /* Bool  */ /* Int   */ x03 = 0x03, /* OcStr */ /* Null  */ x06 = 0x06, x07 = 0x07,
	x08 = 0x08, x09 = 0x09, x0a = 0x0a, x0b = 0x0b, /* UTF-8 */ x0d = 0x0d, x0e = 0x0e, x0f = 0x0f,
	x10 = 0x10, x11 = 0x11, x12 = 0x12, x13 = 0x13, x14 = 0x14, x15 = 0x15, x16 = 0x16, x17 = 0x17,
	x18 = 0x18, x19 = 0x19, x1a = 0x1a, x1b = 0x1b, x1c = 0x1c, x1d = 0x1d, x1e = 0x1e, x1f = 0x1f,
	x20 = 0x20, x21 = 0x21, x22 = 0x22, x23 = 0x23, x24 = 0x24, x25 = 0x25, x26 = 0x26, x27 = 0x27,
	x28 = 0x28, x29 = 0x29, x2a = 0x2a, x2b = 0x2b, x2c = 0x2c, x2d = 0x2d, x2e = 0x2e, x2f = 0x2f,
	/* Seq   */ x31 = 0x31, x32 = 0x32, x33 = 0x33, x34 = 0x34, x35 = 0x35, x36 = 0x36, x37 = 0x37,
	x38 = 0x38, x39 = 0x39, x3a = 0x3a, x3b = 0x3b, x3c = 0x3c, x3d = 0x3d, x3e = 0x3e, x3f = 0x3f,
	x40 = 0x40, x41 = 0x41, x42 = 0x42, x43 = 0x43, x44 = 0x44, x45 = 0x45, x46 = 0x46, x47 = 0x47,
	x48 = 0x48, x49 = 0x49, x4a = 0x4a, x4b = 0x4b, x4c = 0x4c, x4d = 0x4d, x4e = 0x4e, x4f = 0x4f,
	x50 = 0x50, x51 = 0x51, x52 = 0x52, x53 = 0x53, x54 = 0x54, x55 = 0x55, x56 = 0x56, x57 = 0x57,
	x58 = 0x58, x59 = 0x59, x5a = 0x5a, x5b = 0x5b, x5c = 0x5c, x5d = 0x5d, x5e = 0x5e, x5f = 0x5f,
	x60 = 0x60, x61 = 0x61, x62 = 0x62, x63 = 0x63, x64 = 0x64, x65 = 0x65, x66 = 0x66, x67 = 0x67,
	x68 = 0x68, x69 = 0x69, x6a = 0x6a, x6b = 0x6b, x6c = 0x6c, x6d = 0x6d, x6e = 0x6e, x6f = 0x6f,
	x70 = 0x70, x71 = 0x71, x72 = 0x72, x73 = 0x73, x74 = 0x74, x75 = 0x75, x76 = 0x76, x77 = 0x77,
	x78 = 0x78, x79 = 0x79, x7a = 0x7a, x7b = 0x7b, x7c = 0x7c, x7d = 0x7d, x7e = 0x7e, x7f = 0x7f,
	x80 = 0x80, x81 = 0x81, x82 = 0x82, x83 = 0x83, x84 = 0x84, x85 = 0x85, x86 = 0x86, x87 = 0x87,
	x88 = 0x88, x89 = 0x89, x8a = 0x8a, x8b = 0x8b, x8c = 0x8c, x8d = 0x8d, x8e = 0x8e, x8f = 0x8f,
	x90 = 0x90, x91 = 0x91, x92 = 0x92, x93 = 0x93, x94 = 0x94, x95 = 0x95, x96 = 0x96, x97 = 0x97,
	x98 = 0x98, x99 = 0x99, x9a = 0x9a, x9b = 0x9b, x9c = 0x9c, x9d = 0x9d, x9e = 0x9e, x9f = 0x9f,
	xa0 = 0xa0, xa1 = 0xa1, xa2 = 0xa2, xa3 = 0xa3, xa4 = 0xa4, xa5 = 0xa5, xa6 = 0xa6, xa7 = 0xa7,
	xa8 = 0xa8, xa9 = 0xa9, xaa = 0xaa, xab = 0xab, xac = 0xac, xad = 0xad, xae = 0xae, xaf = 0xaf,
	xb0 = 0xb0, xb1 = 0xb1, xb2 = 0xb2, xb3 = 0xb3, xb4 = 0xb4, xb5 = 0xb5, xb6 = 0xb6, xb7 = 0xb7,
	xb8 = 0xb8, xb9 = 0xb9, xba = 0xba, xbb = 0xbb, xbc = 0xbc, xbd = 0xbd, xbe = 0xbe, xbf = 0xbf,
	xc0 = 0xc0, xc1 = 0xc1, xc2 = 0xc2, xc3 = 0xc3, xc4 = 0xc4, xc5 = 0xc5, xc6 = 0xc6, xc7 = 0xc7,
	xc8 = 0xc8, xc9 = 0xc9, xca = 0xca, xcb = 0xcb, xcc = 0xcc, xcd = 0xcd, xce = 0xce, xcf = 0xcf,
	xd0 = 0xd0, xd1 = 0xd1, xd2 = 0xd2, xd3 = 0xd3, xd4 = 0xd4, xd5 = 0xd5, xd6 = 0xd6, xd7 = 0xd7,
	xd8 = 0xd8, xd9 = 0xd9, xda = 0xda, xdb = 0xdb, xdc = 0xdc, xdd = 0xdd, xde = 0xde, xdf = 0xdf,
	xe0 = 0xe0, xe1 = 0xe1, xe2 = 0xe2, xe3 = 0xe3, xe4 = 0xe4, xe5 = 0xe5, xe6 = 0xe6, xe7 = 0xe7,
	xe8 = 0xe8, xe9 = 0xe9, xea = 0xea, xeb = 0xeb, xec = 0xec, xed = 0xed, xee = 0xee, xef = 0xef,
	xf0 = 0xf0, xf1 = 0xf1, xf2 = 0xf2, xf3 = 0xf3, xf4 = 0xf4, xf5 = 0xf5, xf6 = 0xf6, xf7 = 0xf7,
	xf8 = 0xf8, xf9 = 0xf9, xfa = 0xfa, xfb = 0xfb, xfc = 0xfc, xfd = 0xfd, xfe = 0xfe, xff = 0xff
}
impl DerTag {
	/// DER-deserializes a tag from `source`
	pub fn deserialize<'a>(mut source: impl Iterator<Item = &'a u8>) -> Result<Self, Asn1DerError> {
		Ok((*source.next().ok_or(Asn1DerError::LengthMismatch)?).into())
	}
	
	/// The length of the DER-serialized representation of `self`
	pub fn serialized_len(&self) -> usize {
		1
	}
	/// DER-serializes `self` into `buf` and returns the amount of bytes written
	pub fn serialize<'a>(&self, mut buf: impl Iterator<Item = &'a mut u8>)
		-> Result<usize, Asn1DerError>
	{
		*buf.next().ok_or(Asn1DerError::LengthMismatch)? = (*self).into();
		Ok(1)
	}
	
	/// Efficiently computes the length of the DER-serialized representation of a tag
	pub fn compute_serialized_len() -> usize {
		1
	}
}
impl From<u8> for DerTag {
	fn from(tag: u8) -> Self {
		// Safe because our enum contains all values from [0, 256)
		unsafe{ mem::transmute::<u8, DerTag>(tag) }
	}
}
impl From<DerTag> for u8 {
	fn from(tag: DerTag) -> Self {
		tag as u8
	}
}