use crate::compound;use std::{fs, io, path::PathBuf}; pub mod parse;pub mod unquote; #[derive(thiserror::Error, Debug)]pub enum Error {    #[error(transparent)]    Io(#[from] io::Error),    #[error(transparent)]    Parse(#[from] parse::Error),    #[error(transparent)]    Init(#[from] compound::init::Error),    #[error("Alternates form a cycle: {} -> {}", .0.iter().map(|p| format!("'{}'", p.display())).collect::<Vec<_>>().join(" -> "), .0.first().expect("more than one directories").display())]    Cycle(Vec<PathBuf>),} pub fn resolve(objects_directory: impl Into<PathBuf>) -> Result<Vec<compound::Db>, Error> {    let relative_base = objects_directory.into();    let mut dirs = vec![(0, relative_base.clone())];    let mut out = Vec::new();    let mut seen = vec![relative_base.canonicalize()?];    while let Some((depth, dir)) = dirs.pop() {        match fs::read(dir.join("info").join("alternates")) {            Ok(input) => {                for path in parse::content(&input)?.into_iter() {                    let path = relative_base.join(path);                    let path_canonicalized = path.canonicalize()?;                    if seen.contains(&path_canonicalized) {                        continue;                    }                    seen.push(path_canonicalized);                    dirs.push((depth + 1, path));                }            }            Err(err) if err.kind() == io::ErrorKind::NotFound => {                // Only resolve for repositories with at least one link, otherwise the line below causes infinite recursion                if depth != 0 {                    // The tail of a chain doesn't have alternates, and thus is the real deal                    out.push(compound::Db::at(dir)?);                }            }            Err(err) => return Err(err.into()),        };    }     if out.is_empty() && seen.len() > 1 {        return Err(Error::Cycle(seen));    }    Ok(out)}