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#![warn(clippy::all)]
use git2::Oid;
use std::collections::HashMap;
use std::path::{Path, PathBuf};
/// Track file changes for a file - renames and deletes
#[derive(Debug, Clone)]
pub struct GitFileFutureRegistry {
rev_changes: HashMap<Oid, RevChange>,
}
#[derive(Debug, Clone)]
struct RevChange {
files: HashMap<PathBuf, FileNameChange>,
/// first child is generally used only, it is the main branch - don't divert into other branches!
children: Vec<Oid>,
}
#[derive(Debug, Clone)]
pub enum FileNameChange {
Renamed(PathBuf),
Deleted(),
}
impl RevChange {
pub fn new() -> Self {
RevChange {
files: HashMap::new(),
children: Vec::new(),
}
}
}
impl GitFileFutureRegistry {
pub fn new() -> Self {
GitFileFutureRegistry {
rev_changes: HashMap::new(),
}
}
pub fn register(
&mut self,
id: &Oid,
parent_ids: &[Oid],
file_changes: &[(PathBuf, FileNameChange)],
) {
let entry = self.rev_changes.entry(*id).or_insert_with(RevChange::new);
(*entry).files.extend(file_changes.iter().cloned());
for parent_id in parent_ids {
let pentry = self
.rev_changes
.entry(*parent_id)
.or_insert_with(RevChange::new);
(*pentry).children.push(*id);
}
}
/// what is this called in the final revision?
/// returns None if it is deleted, or Some(final name)
pub fn final_name(&self, ref_id: &Oid, file: &Path) -> Option<PathBuf> {
let mut current_name: &PathBuf = &file.to_path_buf();
let mut current_ref: Oid = *ref_id;
loop {
let current_change = self.rev_changes.get(¤t_ref).unwrap();
match current_change.files.get(current_name) {
Some(FileNameChange::Renamed(new_name)) => {
current_name = new_name;
}
Some(FileNameChange::Deleted()) => return None,
None => (),
}
if let Some(first_child) = current_change.children.get(0) {
current_ref = *first_child;
// and loop will continue
} else {
// no children, so finished looking into the future
return Some(current_name.to_path_buf());
}
}
}
}
#[cfg(test)]
mod test {
use super::*;
use failure::Error;
use pretty_assertions::assert_eq;
fn pb(name: &str) -> PathBuf {
PathBuf::from(name)
}
#[test]
fn trivial_repo_returns_original_name() -> Result<(), Error> {
let mut registry = GitFileFutureRegistry::new();
let my_id = Oid::from_str("01")?;
registry.register(&my_id, &[], &[]);
assert_eq!(
registry.final_name(&my_id, &pb("foo.txt")),
Some(pb("foo.txt"))
);
Ok(())
}
#[test]
fn simple_rename_returns_old_name() -> Result<(), Error> {
let mut registry = GitFileFutureRegistry::new();
let my_id = Oid::from_str("01")?;
registry.register(
&my_id,
&[],
&[(pb("foo.txt"), FileNameChange::Renamed(pb("bar.txt")))],
);
assert_eq!(
registry.final_name(&my_id, &pb("foo.txt")),
Some(pb("bar.txt"))
);
Ok(())
}
#[test]
fn renames_and_deletes_applied_across_history() -> Result<(), Error> {
// my bad - this should be a few isolated tests not one big test-all test.
// classic how my standards slip for side projects!
let mut registry = GitFileFutureRegistry::new();
/*
+-----+
|01 |
|add a|
|add z|
+--+--+
|
+------v------+
|02 |
|rename a to b|
|delete z |
+-------------+
| |
+------v------+ +----v--------+
|04 | |05 |
|rename b to c| |rename b to d|
+--------------+--------------+
|
+--------v---------+
|06 merge |
|rename c to afinal|
|create new z |
+------------------+
*/
let id_1 = Oid::from_str("01")?;
let id_2 = Oid::from_str("02")?;
let id_4 = Oid::from_str("04")?;
let id_5 = Oid::from_str("05")?;
let id_6 = Oid::from_str("06")?;
registry.register(
&id_6,
&[id_4, id_5],
&[(pb("c"), FileNameChange::Renamed(pb("afinal")))],
);
// NOTE: topological order should (I think?) register rev 4 before rev 5 as it's first
registry.register(
&id_4,
&[id_2],
&[(pb("b"), FileNameChange::Renamed(pb("c")))],
);
registry.register(
&id_5,
&[id_2],
&[(pb("b"), FileNameChange::Renamed(pb("d")))],
);
registry.register(
&id_2,
&[id_1],
&[
(pb("a"), FileNameChange::Renamed(pb("b"))),
(pb("z"), FileNameChange::Deleted()),
],
);
registry.register(&id_1, &[], &[]);
// original a is afinal
// original z is gone
assert_eq!(registry.final_name(&id_1, &pb("a")), Some(pb("afinal")));
assert_eq!(registry.final_name(&id_1, &pb("z")), None);
// from the perspective of the filesystem after node 2, we know nothing of a any more, only b
assert_eq!(registry.final_name(&id_2, &pb("b")), Some(pb("afinal")));
Ok(())
}
}