#![allow(unused)] use std::path::{Path, PathBuf}; use memmap2::Mmap; use crate::{decode, extension, File, State}; mod error {     /// The error returned by [File::at()][super::File::at()].    #[derive(Debug, thiserror::Error)]    #[allow(missing_docs)]    pub enum Error {        #[error("An IO error occurred while opening the index")]        Io(#[from] std::io::Error),        #[error(transparent)]        Decode(#[from] crate::decode::Error),        #[error(transparent)]        LinkExtension(#[from] crate::extension::link::decode::Error),    }} pub use error::Error; /// Initializationimpl File {    /// Try to open the index file at `path` with `options`, assuming `object_hash` is used throughout the file, or create a new    /// index that merely exists in memory and is empty.    ///    /// Note that the `path` will not be written if it doesn't exist.    pub fn at_or_default(        path: impl Into<PathBuf>,        object_hash: git_hash::Kind,        options: decode::Options,    ) -> Result<Self, Error> {        let path = path.into();        Ok(match Self::at(&path, object_hash, options) {            Ok(f) => f,            Err(Error::Io(err)) if err.kind() == std::io::ErrorKind::NotFound => {                File::from_state(State::new(object_hash), path)            }            Err(err) => return Err(err),        })    }     /// Open an index file at `path` with `options`, assuming `object_hash` is used throughout the file.    pub fn at(path: impl Into<PathBuf>, object_hash: git_hash::Kind, options: decode::Options) -> Result<Self, Error> {        let path = path.into();        let (data, mtime) = {            // SAFETY: we have to take the risk of somebody changing the file underneath. Git never writes into the same file.            let file = std::fs::File::open(&path)?;            #[allow(unsafe_code)]            let data = unsafe { Mmap::map(&file)? };            (data, filetime::FileTime::from_last_modification_time(&file.metadata()?))        };         let (state, checksum) = State::from_bytes(&data, mtime, object_hash, options)?;        let mut file = File {            state,            path,            checksum: Some(checksum),        };        if let Some(mut link) = file.link.take() {            link.dissolve_into(&mut file, object_hash, options)?;        }         Ok(file)    }     /// Consume `state` and pretend it was read from `path`, setting our checksum to `null`.    ///    /// `File` instances created like that should be written to disk to set the correct checksum via `[File::write()]`.    pub fn from_state(state: crate::State, path: impl Into<PathBuf>) -> Self {        File {            state,            path: path.into(),            checksum: None,        }    }}