use crate::OutputFormat; /// A general purpose context for many operations provided herepub struct Context<W1: std::io::Write, W2: std::io::Write> {    /// A stream to which to output errors    pub err: W2,    /// A stream to which to output operation results    pub out: W1,    pub output_statistics: Option<OutputFormat>,} impl Default for Context<Vec<u8>, Vec<u8>> {    fn default() -> Self {        Context {            err: Vec::new(),            out: Vec::new(),            output_statistics: None,        }    }} pub(crate) mod function {    use std::{io, path::Path};     use anyhow::{Context as AnyhowContext, Result};    use gix::commitgraph::{verify::Outcome, Graph};     use crate::OutputFormat;     pub fn verify<W1, W2>(        path: impl AsRef<Path>,        super::Context {            err: _err,            mut out,            output_statistics,        }: super::Context<W1, W2>,    ) -> Result<gix::commitgraph::verify::Outcome>    where        W1: io::Write,        W2: io::Write,    {        let g = Graph::at(path.as_ref()).with_context(|| "Could not open commit graph")?;         #[allow(clippy::unnecessary_wraps, unknown_lints)]        fn noop_processor(_commit: &gix::commitgraph::file::Commit<'_>) -> std::result::Result<(), std::fmt::Error> {            Ok(())        }        let stats = g            .verify_integrity(noop_processor)            .with_context(|| "Verification failure")?;         #[cfg_attr(not(feature = "serde"), allow(clippy::single_match))]        match output_statistics {            Some(OutputFormat::Human) => drop(print_human_output(&mut out, &stats)),            #[cfg(feature = "serde")]            Some(OutputFormat::Json) => serde_json::to_writer_pretty(out, &stats)?,            _ => {}        }         Ok(stats)    }     fn print_human_output(out: &mut impl io::Write, stats: &Outcome) -> io::Result<()> {        writeln!(out, "number of commits with the given number of parents")?;        let mut parent_counts: Vec<_> = stats.parent_counts.iter().map(|(a, b)| (*a, *b)).collect();        parent_counts.sort_by_key(|e| e.0);        for (parent_count, commit_count) in parent_counts.into_iter() {            writeln!(out, "\t{parent_count:>2}: {commit_count}")?;        }        writeln!(out, "\t->: {}", stats.num_commits)?;         write!(out, "\nlongest path length between two commits: ")?;        if let Some(n) = stats.longest_path_length {            writeln!(out, "{n}")?;        } else {            writeln!(out, "unknown")?;        }         Ok(())    }}