use crate::loose;use flate2::Decompress;use git_object as object;use object::borrowed;use smallvec::SmallVec;use std::{io::Read, path::PathBuf}; /// Returned by [`loose::Object::decode()`] and [`loose::Object::stream()`]#[derive(thiserror::Error, Debug)]#[allow(missing_docs)]pub enum Error {    #[error("decompression of object data failed")]    Decompress(#[from] flate2::DecompressError),    #[error(transparent)]    Parse(#[from] borrowed::Error),    #[error("Could not {action} data at '{path}'")]    Io {        source: std::io::Error,        action: &'static str,        path: PathBuf,    },} // Decoding and streamingimpl loose::Object {    /// Decode the object to make it's fields accessible in case of Trees, Tags and Commits.    ///    /// This is a zero-copy operation with data read from disk if needed and stored in memory.    /// The returned [`borrowed::Object`] references this data where possible.    ///    /// **Note**: Blobs are also loaded into memory and are made available that way.    /// Consider using `stream()` if large Blobs are expected.    pub fn decode(&mut self) -> Result<borrowed::Object<'_>, Error> {        self.decompress_all()?;        let bytes = &self.decompressed_data[self.header_size..];        Ok(borrowed::Object::from_bytes(self.kind, bytes)?)    }     /// Returns an implementation of [`std::io::Read`], which decompresses the objects data on the fly.    ///    /// **Note**: This is most useful for big blobs as these won't be read into memory in full. Use [`decode()`][loose::Object::decode()] for    /// Trees, Tags and Commits instead for convenient access to their payload.    pub fn stream(&mut self) -> Result<loose::object::stream::Reader<'_>, Error> {        match &self.path {            Some(path) => Ok(loose::object::stream::Reader::from_file(                self.header_size,                std::fs::File::open(path).map_err(|source| Error::Io {                    source,                    action: "open",                    path: path.to_owned(),                })?,            )),            None => {                self.decompress_all()?;                Ok(loose::object::stream::Reader::from_data(                    self.header_size,                    &self.decompressed_data.as_slice(),                ))            }        }    }     pub(crate) fn decompress_all(&mut self) -> Result<(), Error> {        if self.decompression_complete {            debug_assert!(                self.size + self.header_size == self.decompressed_data.len(),                "when decompression is done, we have stored everything in memory"            );            return Ok(());        }        let total_size = self.header_size + self.size;        if let Some(path) = self.path.take() {            // NOTE: For now we just re-read everything from the beginning without seeking, as our buffer            // is small so the seek might be more expensive than just reading everything.            let mut file = std::fs::File::open(&path).map_err(|source| Error::Io {                source,                action: "open",                path: path.clone(),            })?;            let file_size = file                .metadata()                .map_err(|source| Error::Io {                    source,                    action: "read metadata",                    path: path.clone(),                })?                .len() as usize;            let mut buf = Vec::with_capacity(file_size);            file.read_to_end(&mut buf).map_err(|source| Error::Io {                source,                action: "read",                path,            })?;            self.compressed_data = SmallVec::from(buf);        }        let mut vec = Vec::with_capacity(std::cmp::min(self.compressed_data.len() * 2, usize::MAX));        Decompress::new(true).decompress_vec(&self.compressed_data[..], &mut vec, flate2::FlushDecompress::None)?;        self.decompressed_data = SmallVec::from(vec);        self.compressed_data = Default::default();        self.decompressed_data.shrink_to_fit();        assert!(self.decompressed_data.len() == total_size);        self.decompression_complete = true;        Ok(())    }}