use std::io; use bstr::ByteSlice; use crate::{encode, encode::NL, Commit, CommitRef, Kind}; impl crate::WriteTo for Commit {    /// Serializes this instance to `out` in the git serialization format.    fn write_to(&self, mut out: impl io::Write) -> io::Result<()> {        encode::trusted_header_id(b"tree", &self.tree, &mut out)?;        for parent in &self.parents {            encode::trusted_header_id(b"parent", parent, &mut out)?;        }        encode::trusted_header_signature(b"author", &self.author.to_ref(), &mut out)?;        encode::trusted_header_signature(b"committer", &self.committer.to_ref(), &mut out)?;        if let Some(encoding) = self.encoding.as_ref() {            encode::header_field(b"encoding", encoding, &mut out)?;        }        for (name, value) in &self.extra_headers {            encode::header_field_multi_line(name, value, &mut out)?;        }        out.write_all(NL)?;        out.write_all(&self.message)    }     fn kind(&self) -> Kind {        Kind::Commit    }     fn size(&self) -> usize {        let hash_in_hex = self.tree.kind().len_in_hex();        b"tree".len() + 1 /*space*/ + hash_in_hex + 1 /* nl */        + self.parents.iter().count() * (b"parent".len() + 1 + hash_in_hex + 1)            + b"author".len() + 1 /* space */ + self.author.size() + 1 /* nl */            + b"committer".len() + 1 /* space */ + self.committer.size() + 1 /* nl */            + self                .encoding                .as_ref()                .map_or(0, |e| b"encoding".len() + 1 /* space */ + e.len() + 1 /* nl */)            + self                .extra_headers                .iter()                .map(|(name, value)| {                    // each header *value* is preceded by a space and followed by a newline                    name.len() + value.split_str("\n").map(|s| s.len() + 2).sum::<usize>()                })                .sum::<usize>()            + 1 /* nl */            + self.message.len()    }} impl<'a> crate::WriteTo for CommitRef<'a> {    /// Serializes this instance to `out` in the git serialization format.    fn write_to(&self, mut out: impl io::Write) -> io::Result<()> {        encode::trusted_header_id(b"tree", &self.tree(), &mut out)?;        for parent in self.parents() {            encode::trusted_header_id(b"parent", &parent, &mut out)?;        }        encode::trusted_header_signature(b"author", &self.author, &mut out)?;        encode::trusted_header_signature(b"committer", &self.committer, &mut out)?;        if let Some(encoding) = self.encoding.as_ref() {            encode::header_field(b"encoding", encoding, &mut out)?;        }        for (name, value) in &self.extra_headers {            encode::header_field_multi_line(name, value, &mut out)?;        }        out.write_all(NL)?;        out.write_all(self.message)    }     fn kind(&self) -> Kind {        Kind::Commit    }     fn size(&self) -> usize {        let hash_in_hex = self.tree().kind().len_in_hex();        b"tree".len() + 1 /* space */ + hash_in_hex + 1 /* nl */            + self.parents.iter().count() * (b"parent".len() + 1 /* space */ + hash_in_hex + 1 /* nl */)            + b"author".len() + 1 /* space */ + self.author.size() + 1 /* nl */            + b"committer".len() + 1 /* space */ + self.committer.size() + 1 /* nl */            + self                .encoding                .as_ref()                .map_or(0, |e| b"encoding".len() + 1 /* space */ + e.len() + 1 /* nl */)            + self                .extra_headers                .iter()                .map(|(name, value)| {                    // each header *value* is preceded by a space and followed by a newline                    name.len() + value.split_str("\n").map(|s| s.len() + 2).sum::<usize>()                })                .sum::<usize>()            + 1 /* nl */            + self.message.len()    }}