use std::borrow::Cow; use smallvec::SmallVec;use winnow::{    combinator::{alt, eof, opt, preceded, repeat, terminated},    error::{AddContext, ParserError, StrContext},    prelude::*,    token::{rest, take_till},}; use crate::{parse, parse::NL, BStr, ByteSlice, CommitRef}; pub fn message<'a, E: ParserError<&'a [u8]> + AddContext<&'a [u8], StrContext>>(    i: &mut &'a [u8],) -> ModalResult<&'a BStr, E> {    if i.is_empty() {        // newline + [message]        let start = i.checkpoint();        return Err(winnow::error::ErrMode::from_input(i).add_context(            i,            &start,            StrContext::Expected("newline + <message>".into()),        ));    }    preceded(NL, rest.map(ByteSlice::as_bstr))        .context(StrContext::Expected(            "a newline separates headers from the message".into(),        ))        .parse_next(i)} pub fn commit<'a, E: ParserError<&'a [u8]> + AddContext<&'a [u8], StrContext>>(    i: &mut &'a [u8],) -> ModalResult<CommitRef<'a>, E> {    (        (|i: &mut _| parse::header_field(i, b"tree", parse::hex_hash))            .context(StrContext::Expected("tree <40 lowercase hex char>".into())),        repeat(0.., |i: &mut _| parse::header_field(i, b"parent", parse::hex_hash))            .map(|p: Vec<_>| p)            .context(StrContext::Expected(                "zero or more 'parent <40 lowercase hex char>'".into(),            )),        (|i: &mut _| parse::header_field(i, b"author", parse::signature_and_consumed).map(|(_signature, raw)| raw))            .context(StrContext::Expected("author <signature>".into())),        (|i: &mut _| parse::header_field(i, b"committer", parse::signature_and_consumed).map(|(_signature, raw)| raw))            .context(StrContext::Expected("committer <signature>".into())),        opt(|i: &mut _| parse::header_field(i, b"encoding", take_till(0.., NL)))            .context(StrContext::Expected("encoding <encoding>".into())),        repeat(            0..,            alt((                parse::any_header_field_multi_line.map(|(k, o)| (k.as_bstr(), Cow::Owned(o))),                |i: &mut _| {                    parse::any_header_field(i, take_till(0.., NL))                        .map(|(k, o)| (k.as_bstr(), Cow::Borrowed(o.as_bstr())))                },            )),        )        .context(StrContext::Expected("<field> <single-line|multi-line>".into())),        terminated(message, eof),    )        .map(            |(tree, parents, author, committer, encoding, extra_headers, message)| CommitRef {                tree,                parents: SmallVec::from(parents),                author,                committer,                encoding: encoding.map(ByteSlice::as_bstr),                message,                extra_headers,            },        )        .parse_next(i)}