use bstr::BString;use smallvec::SmallVec; const MIN_SIZE: usize = 4 /* signature */ + 4 /* size */; pub type Signature = [u8; 4]; pub struct Iter<'a> {    data: &'a [u8],    pub consumed: usize,} /// A structure to associate object ids of a tree with sections in the index entries list.////// It allows to more quickly build trees by avoiding as it can quickly re-use portions of the index and its associated tree ids/// if there was no change to them. Portions of this tree are invalidated as the index is changed.pub struct Tree {    name: SmallVec<[u8; 23]>,    /// Only set if there are any entries in the index we are associated with.    id: Option<tree::NodeId>,    children: Vec<Tree>,} pub struct Link {    pub shared_index_checksum: git_hash::ObjectId,    pub bitmaps: Option<link::Bitmaps>,} pub struct UntrackedCache {    /// Something identifying the location and machine that this cache is for.    /// Should the repository be copied to a different machine, the entire cache can immediately be invalidated.    identifier: BString,    /// Stat for the .git/info/exclude file    info_exclude: Option<untracked_cache::OidStat>,    /// Stat for the `core.excludesfile`    excludes_file: Option<untracked_cache::OidStat>,    /// Usually `.gitignore`    exclude_filename_per_dir: BString,    dir_flags: u32,     /// A list of directories and sub-directories, with `directories[0]` being the root.    directories: Vec<untracked_cache::Directory>,} pub struct FsMonitor {    token: fs_monitor::Token,    /// if a bit is true, the resepctive entry is NOT valid as per the fs monitor.    entry_dirty: git_bitmap::ewah::Vec,} mod iter; pub(crate) mod fs_monitor {    use bstr::BString;     use crate::{        extension::{FsMonitor, Signature},        util::{read_u32, read_u64, split_at_byte_exclusive},    };     pub enum Token {        V1 { nanos_since_1970: u64 },        V2 { token: BString },    }     pub const SIGNATURE: Signature = *b"FSMN";     pub fn decode(data: &[u8]) -> Option<FsMonitor> {        let (version, data) = read_u32(data)?;        let (token, data) = match version {            1 => {                let (nanos_since_1970, data) = read_u64(data)?;                (Token::V1 { nanos_since_1970 }, data)            }            2 => {                let (token, data) = split_at_byte_exclusive(data, 0)?;                (Token::V2 { token: token.into() }, data)            }            _ => return None,        };         let (ewah_size, data) = read_u32(data)?;        let (entry_dirty, data) = git_bitmap::ewah::decode(&data[..ewah_size as usize]).ok()?;         if !data.is_empty() {            return None;        }         FsMonitor { token, entry_dirty }.into()    }} pub(crate) mod decode; pub(crate) mod tree; pub(crate) mod end_of_index_entry; pub(crate) mod index_entry_offset_table; pub mod link; pub(crate) mod resolve_undo; pub mod untracked_cache; pub mod sparse {    use crate::extension::Signature;     /// Only used as an indicator    pub const SIGNATURE: Signature = *b"sdir";}