use std::io; use bstr::BStr;use gix_date::parse::TimeBuf; use crate::{Kind, Tag, TagRef, encode, encode::NL}; /// An Error used in [`Tag::write_to()`][crate::WriteTo::write_to()].#[derive(Debug, thiserror::Error)]#[expect(missing_docs)]pub enum Error {    #[error("Tags must not start with a dash: '-'")]    StartsWithDash,    #[error("The tag name was no valid reference name")]    InvalidRefName(#[from] gix_validate::tag::name::Error),} impl From<Error> for io::Error {    fn from(err: Error) -> Self {        io::Error::other(err)    }} impl crate::WriteTo for Tag {    fn write_to(&self, out: &mut dyn io::Write) -> io::Result<()> {        encode::trusted_header_id(b"object", &self.target, out)?;        encode::trusted_header_field(b"type", self.target_kind.as_bytes(), out)?;        encode::header_field(b"tag", validated_name(self.name.as_ref())?, out)?;        if let Some(tagger) = &self.tagger {            let mut buf = TimeBuf::default();            encode::trusted_header_signature(b"tagger", &tagger.to_ref(&mut buf), out)?;        }         if !self.message.iter().all(|b| *b == b'\n') {            out.write_all(NL)?;        }        out.write_all(self.message.as_ref())?;        if let Some(message) = &self.pgp_signature {            out.write_all(NL)?;            out.write_all(message.as_ref())?;        }        Ok(())    }     fn kind(&self) -> Kind {        Kind::Tag    }     fn size(&self) -> u64 {        (b"object".len() + 1 /* space */ + self.target.kind().len_in_hex() + 1 /* nl */            + b"type".len() + 1 /* space */ + self.target_kind.as_bytes().len() + 1 /* nl */            + b"tag".len() + 1 /* space */ + self.name.len() + 1 /* nl */            + self            .tagger            .as_ref()            .map_or(0, |t| b"tagger".len() + 1 /* space */ + t.size() + 1 /* nl */)            + if self.message.iter().all(|b| *b == b'\n') { 0 } else { 1 /* nl */ } + self.message.len()            + self.pgp_signature.as_ref().map_or(0, |m| 1 /* nl */ + m.len())) as u64    }} impl crate::WriteTo for TagRef<'_> {    fn write_to(&self, mut out: &mut dyn io::Write) -> io::Result<()> {        encode::trusted_header_field(b"object", self.target, &mut out)?;        encode::trusted_header_field(b"type", self.target_kind.as_bytes(), &mut out)?;        encode::header_field(b"tag", validated_name(self.name)?, &mut out)?;        if let Some(tagger) = self.tagger {            encode::trusted_header_field(b"tagger", tagger.as_ref(), &mut out)?;        }         if !self.message.iter().all(|b| *b == b'\n') {            out.write_all(NL)?;        }        out.write_all(self.message)?;        if let Some(message) = self.pgp_signature {            out.write_all(NL)?;            out.write_all(message)?;        }        Ok(())    }     fn kind(&self) -> Kind {        Kind::Tag    }     fn size(&self) -> u64 {        (b"object".len() + 1 /* space */ + self.target().kind().len_in_hex() + 1 /* nl */            + b"type".len() + 1 /* space */ + self.target_kind.as_bytes().len() + 1 /* nl */            + b"tag".len() + 1 /* space */ + self.name.len() + 1 /* nl */            + self                .tagger                .map_or(0, |raw| b"tagger".len() + 1 /* space */ + raw.len() + 1 /* nl */)            + if self.message.iter().all(|b| *b == b'\n') { 0 } else { 1 /* nl */ } + self.message.len()            + self.pgp_signature.as_ref().map_or(0, |m| 1 /* nl */ + m.len())) as u64    }} fn validated_name(name: &BStr) -> Result<&BStr, Error> {    gix_validate::tag::name(name)?;    if name[0] == b'-' {        return Err(Error::StartsWithDash);    }    Ok(name)} #[cfg(test)]mod tests;