use crate::file::{self, commit::Commit, File, COMMIT_DATA_ENTRY_SIZE};use git_object::{borrowed, HashKind, SHA1_SIZE};use std::{    convert::{TryFrom, TryInto},    fmt::{Debug, Formatter},    path::Path,}; /// Accessimpl File {    /// Returns the commit data for the commit located at the given lexigraphical position.    ///    /// `pos` must range from 0 to self.num_commits().    ///    /// # Panics    ///    /// Panics if `pos` is out of bounds.    pub fn commit_at(&self, pos: file::Position) -> Commit<'_> {        Commit::new(self, pos)    }     pub fn hash_kind(&self) -> HashKind {        HashKind::Sha1    }     /// Returns 20 bytes sha1 at the given index in our list of (sorted) sha1 hashes.    /// The position ranges from 0 to self.num_commits()    // copied from git-odb/src/pack/index/access.rs    pub fn id_at(&self, pos: file::Position) -> borrowed::Id<'_> {        assert!(            pos.0 < self.num_commits(),            "expected lexigraphical position less than {}, got {}",            self.num_commits(),            pos.0        );        let pos: usize = pos            .0            .try_into()            .expect("an architecture able to hold 32 bits of integer");        let start = self.oid_lookup_offset + (pos * SHA1_SIZE);        borrowed::Id::try_from(&self.data[start..start + SHA1_SIZE]).expect("20 bytes SHA1 to be alright")    }     pub fn iter_base_graph_ids(&self) -> impl Iterator<Item = borrowed::Id<'_>> {        let base_graphs_list = match self.base_graphs_list_offset {            Some(v) => &self.data[v..v + (SHA1_SIZE * self.base_graph_count as usize)],            None => &[],        };        base_graphs_list            .chunks_exact(SHA1_SIZE)            .map(|bytes| borrowed::Id::try_from(bytes).expect("20 bytes SHA1 to be alright"))    }     pub fn iter_commits(&self) -> impl Iterator<Item = Commit<'_>> {        (0..self.num_commits()).map(move |i| self.commit_at(file::Position(i)))    }     pub fn iter_ids(&self) -> impl Iterator<Item = borrowed::Id<'_>> {        (0..self.num_commits()).map(move |i| self.id_at(file::Position(i)))    }     // copied from git-odb/src/pack/index/access.rs    pub fn lookup(&self, id: borrowed::Id<'_>) -> Option<file::Position> {        let first_byte = id.first_byte() as usize;        let mut upper_bound = self.fan[first_byte];        let mut lower_bound = if first_byte != 0 { self.fan[first_byte - 1] } else { 0 };         // Bisect using indices        // TODO: Performance of V2 could possibly be better if we would be able to do a binary search        // on 20 byte chunks directly, but doing so requires transmuting and that is unsafe, even though        // it should not be if the bytes match up and the type has no destructor.        while lower_bound < upper_bound {            let mid = (lower_bound + upper_bound) / 2;            let mid_sha = self.id_at(file::Position(mid));             use std::cmp::Ordering::*;            match id.cmp(&mid_sha) {                Less => upper_bound = mid,                Equal => return Some(file::Position(mid)),                Greater => lower_bound = mid + 1,            }        }        None    }     /// Returns the number of commits in this graph file.    ///    /// The maximum valid `file::Position` that can be used with this file is one less than    /// `num_commits()`.    pub fn num_commits(&self) -> u32 {        self.fan[255]    }     pub fn path(&self) -> &Path {        &self.path    }} impl File {    /// Returns the byte slice for the given commit in this file's Commit Data (CDAT) chunk.    pub(crate) fn commit_data_bytes(&self, pos: file::Position) -> &[u8] {        assert!(            pos.0 < self.num_commits(),            "expected lexigraphical position less than {}, got {}",            self.num_commits(),            pos.0        );        let pos: usize = pos            .0            .try_into()            .expect("an architecture able to hold 32 bits of integer");        let start = self.commit_data_offset + (pos * COMMIT_DATA_ENTRY_SIZE);        &self.data[start..start + COMMIT_DATA_ENTRY_SIZE]    }     /// Returns the byte slice for this file's entire Extra Edge List (EDGE) chunk.    pub(crate) fn extra_edges_data(&self) -> Option<&[u8]> {        Some(&self.data[self.extra_edges_list_range.clone()?])    }} impl Debug for File {    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {        write!(f, r#"File("{:?}")"#, self.path.display())    }}