///pub mod diff {    use std::ops::Range;     use crate::{bstr::ByteSlice, object::blob::diff::line::Change};     /// A platform to keep temporary information to perform line diffs on modified blobs.    ///    pub struct Platform<'old, 'new> {        /// The previous version of the blob.        pub old: crate::Object<'old>,        /// The new version of the blob.        pub new: crate::Object<'new>,        /// The algorithm to use when calling [imara_diff::diff()][git_diff::blob::diff()].        /// This value is determined by the `diff.algorithm` configuration.        pub algo: git_diff::blob::Algorithm,    }     ///    pub mod init {        /// The error returned by [`Platform::from_ids()`][super::Platform::from_ids()].        #[derive(Debug, thiserror::Error)]        #[allow(missing_docs)]        pub enum Error {            #[error("Could not find the previous blob or the new blob to diff against")]            FindExisting(#[from] crate::object::find::existing::Error),            #[error("Could not obtain diff algorithm from configuration")]            DiffAlgorithm(#[from] crate::config::diff::algorithm::Error),        }    }     impl<'old, 'new> Platform<'old, 'new> {        /// Produce a platform for performing various diffs after obtaining the object data of `previous_id` and `new_id`.        ///        /// Note that these objects are treated as raw data and are assumed to be blobs.        pub fn from_ids(            previous_id: &crate::Id<'old>,            new_id: &crate::Id<'new>,        ) -> Result<Platform<'old, 'new>, init::Error> {            match previous_id                .object()                .and_then(|old| new_id.object().map(|new| (old, new)))            {                Ok((old, new)) => {                    let algo = match new_id.repo.config.diff_algorithm() {                        Ok(algo) => algo,                        Err(err) => return Err(err.into()),                    };                    Ok(Platform { old, new, algo })                }                Err(err) => Err(err.into()),            }        }    }     ///    pub mod line {        use crate::bstr::BStr;         /// A change to a hunk of lines.        pub enum Change<'a, 'data> {            /// Lines were added.            Addition {                /// The lines themselves without terminator.                lines: &'a [&'data BStr],            },            /// Lines were removed.            Deletion {                /// The lines themselves without terminator.                lines: &'a [&'data BStr],            },            /// Lines have been replaced.            Modification {                /// The replaced lines without terminator.                lines_before: &'a [&'data BStr],                /// The new lines without terminator.                lines_after: &'a [&'data BStr],            },        }    }     impl<'old, 'new> Platform<'old, 'new> {        /// Perform a diff on lines between the old and the new version of a blob, passing each hunk of lines to `process_hunk`.        /// The diffing algorithm is determined by the `diff.algorithm` configuration.        ///        /// Note that you can invoke the diff more flexibly as well.        // TODO: more tests (only tested insertion right now)        pub fn lines<FnH, E>(&self, mut process_hunk: FnH) -> Result<(), E>        where            FnH: FnMut(line::Change<'_, '_>) -> Result<(), E>,            E: std::error::Error,        {            let input = self.line_tokens();            let mut err = None;            let mut lines = Vec::new();            git_diff::blob::diff(self.algo, &input, |before: Range<u32>, after: Range<u32>| {                if err.is_some() {                    return;                }                lines.clear();                lines.extend(                    input.before[before.start as usize..before.end as usize]                        .iter()                        .map(|&line| input.interner[line].as_bstr()),                );                let end_of_before = lines.len();                lines.extend(                    input.after[after.start as usize..after.end as usize]                        .iter()                        .map(|&line| input.interner[line].as_bstr()),                );                let hunk_before = &lines[..end_of_before];                let hunk_after = &lines[end_of_before..];                if hunk_after.is_empty() {                    err = process_hunk(Change::Deletion { lines: hunk_before }).err();                } else if hunk_before.is_empty() {                    err = process_hunk(Change::Addition { lines: hunk_after }).err();                } else {                    err = process_hunk(Change::Modification {                        lines_before: hunk_before,                        lines_after: hunk_after,                    })                    .err();                }            });             match err {                Some(err) => Err(err),                None => Ok(()),            }        }         /// Count the amount of removed and inserted lines efficiently.        pub fn line_counts(&self) -> git_diff::blob::sink::Counter<()> {            let tokens = self.line_tokens();            git_diff::blob::diff(self.algo, &tokens, git_diff::blob::sink::Counter::default())        }         /// Return a tokenizer which treats lines as smallest unit for use in a [diff operation][git_diff::blob::diff()].        ///        /// The line separator is determined according to normal git rules and filters.        pub fn line_tokens(&self) -> git_diff::blob::intern::InternedInput<&[u8]> {            // TODO: make use of `core.eol` and/or filters to do line-counting correctly. It's probably            //       OK to just know how these objects are saved to know what constitutes a line.            git_diff::blob::intern::InternedInput::new(self.old.data.as_bytes(), self.new.data.as_bytes())        }    }}