use std::collections::VecDeque; use git_hash::ObjectId;use git_object::{    bstr::{BStr, BString, ByteSlice, ByteVec},    tree,}; use crate::tree::visit; /// A Change as observed by a call to [`visit(…)`][visit::Visit::visit()], enhanced with the path affected by the change./// Its similar to [visit::Change] but includes the path that changed.#[derive(Clone, Debug, PartialEq, Eq)]#[allow(missing_docs)]pub enum Change {    Addition {        entry_mode: tree::EntryMode,        oid: ObjectId,        path: BString,    },    Deletion {        entry_mode: tree::EntryMode,        oid: ObjectId,        path: BString,    },    Modification {        previous_entry_mode: tree::EntryMode,        previous_oid: ObjectId,         entry_mode: tree::EntryMode,        oid: ObjectId,         path: BString,    },} /// A [Visit][visit::Visit] implementation to record every observed change and keep track of the changed paths.#[derive(Clone, Debug, Default)]pub struct Recorder {    path_deque: VecDeque<BString>,    path: BString,    /// The observed changes.    pub records: Vec<Change>,} impl Recorder {    fn pop_element(&mut self) {        if let Some(pos) = self.path.rfind_byte(b'/') {            self.path.resize(pos, 0);        } else {            self.path.clear();        }    }     fn push_element(&mut self, name: &BStr) {        if !self.path.is_empty() {            self.path.push(b'/');        }        self.path.push_str(name);    }     fn path_clone(&self) -> BString {        self.path.clone()    }} impl visit::Visit for Recorder {    fn pop_front_tracked_path_and_set_current(&mut self) {        self.path = self.path_deque.pop_front().expect("every parent is set only once");    }     fn push_back_tracked_path_component(&mut self, component: &BStr) {        self.push_element(component);        self.path_deque.push_back(self.path.clone());    }     fn push_path_component(&mut self, component: &BStr) {        self.push_element(component);    }     fn pop_path_component(&mut self) {        self.pop_element();    }     fn visit(&mut self, change: visit::Change) -> visit::Action {        use visit::Change::*;        self.records.push(match change {            Deletion { entry_mode, oid } => Change::Deletion {                entry_mode,                oid,                path: self.path_clone(),            },            Addition { entry_mode, oid } => Change::Addition {                entry_mode,                oid,                path: self.path_clone(),            },            Modification {                previous_entry_mode,                previous_oid,                entry_mode,                oid,            } => Change::Modification {                previous_entry_mode,                previous_oid,                entry_mode,                oid,                path: self.path_clone(),            },        });        visit::Action::Continue    }}