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head.rs
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head.rs
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//!
use std::convert::TryInto;
use git_hash::ObjectId;
use git_ref::FullNameRef;
use crate::{
ext::{ObjectIdExt, ReferenceExt},
Head,
};
/// Represents the kind of `HEAD` reference.
pub enum Kind {
/// The existing reference the symbolic HEAD points to.
///
/// This is the common case.
Symbolic(git_ref::Reference),
/// The yet-to-be-created reference the symbolic HEAD refers to.
///
/// This is the case in a newly initialized repository.
Unborn(git_ref::FullName),
/// The head points to an object directly, not to a symbolic reference.
///
/// This state is less common and can occur when checking out commits directly.
Detached {
/// The object to which the head points to
target: ObjectId,
/// Possibly the final destination of `target` after following the object chain from tag objects to commits.
peeled: Option<ObjectId>,
},
}
impl Kind {
/// Attach this instance to a `repo` to produce a [`Head`].
pub fn attach(self, repo: &crate::Repository) -> Head<'_> {
Head { kind: self, repo }
}
}
impl<'repo> Head<'repo> {
/// Returns the name of this references, always `HEAD`.
pub fn name(&self) -> &'static FullNameRef {
// TODO: use a statically checked version of this when available.
"HEAD".try_into().expect("HEAD is valid")
}
/// Returns the full reference name of this head if it is not detached, or `None` otherwise.
pub fn referent_name(&self) -> Option<&FullNameRef> {
Some(match &self.kind {
Kind::Symbolic(r) => r.name.as_ref(),
Kind::Unborn(name) => name.as_ref(),
Kind::Detached { .. } => return None,
})
}
/// Returns true if this instance is detached, and points to an object directly.
pub fn is_detached(&self) -> bool {
matches!(self.kind, Kind::Detached { .. })
}
// TODO: tests
/// Returns the id the head points to, which isn't possible on unborn heads.
pub fn id(&self) -> Option<crate::Id<'repo>> {
match &self.kind {
Kind::Symbolic(r) => r.target.try_id().map(|oid| oid.to_owned().attach(self.repo)),
Kind::Detached { peeled, target } => {
(*peeled).unwrap_or_else(|| target.to_owned()).attach(self.repo).into()
}
Kind::Unborn(_) => None,
}
}
/// Force transforming this instance into the symbolic reference that it points to, or panic if it is unborn or detached.
///
/// # Panics
///
/// If this isn't actually a head pointing to a symbolic reference.
pub fn into_referent(self) -> crate::Reference<'repo> {
match self.kind {
Kind::Symbolic(r) => r.attach(self.repo),
_ => panic!("BUG: Expected head to be a born symbolic reference"),
}
}
}
///
pub mod log {
use std::convert::TryInto;
use crate::Head;
impl<'repo> Head<'repo> {
/// Return a platform for obtaining iterators on the reference log associated with the `HEAD` reference.
pub fn log_iter(&self) -> git_ref::file::log::iter::Platform<'static, 'repo> {
git_ref::file::log::iter::Platform {
store: &self.repo.refs,
name: "HEAD".try_into().expect("HEAD is always valid"),
buf: Vec::new(),
}
}
}
}
///
pub mod peel {
use crate::{
ext::{ObjectIdExt, ReferenceExt},
Head,
};
mod error {
use crate::{object, reference};
/// The error returned by [Head::peel_to_id_in_place()][super::Head::peel_to_id_in_place()] and [Head::into_fully_peeled_id()][super::Head::into_fully_peeled_id()].
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error(transparent)]
FindExistingObject(#[from] object::find::existing::OdbError),
#[error(transparent)]
PeelReference(#[from] reference::peel::Error),
}
}
pub use error::Error;
use crate::head::Kind;
///
pub mod to_commit {
use crate::object;
/// The error returned by [Head::peel_to_commit_in_place()][super::Head::peel_to_commit_in_place()].
#[derive(Debug, thiserror::Error)]
#[allow(missing_docs)]
pub enum Error {
#[error(transparent)]
Peel(#[from] super::Error),
#[error("Branch '{name}' does not have any commits")]
Unborn { name: git_ref::FullName },
#[error(transparent)]
ObjectKind(#[from] object::try_into::Error),
}
}
impl<'repo> Head<'repo> {
// TODO: tests
/// Peel this instance to make obtaining its final target id possible, while returning an error on unborn heads.
pub fn peeled(mut self) -> Result<Self, Error> {
self.peel_to_id_in_place().transpose()?;
Ok(self)
}
// TODO: tests
/// Follow the symbolic reference of this head until its target object and peel it by following tag objects until there is no
/// more object to follow, and return that object id.
///
/// Returns `None` if the head is unborn.
pub fn peel_to_id_in_place(&mut self) -> Option<Result<crate::Id<'repo>, Error>> {
Some(match &mut self.kind {
Kind::Unborn(_name) => return None,
Kind::Detached {
peeled: Some(peeled), ..
} => Ok((*peeled).attach(self.repo)),
Kind::Detached { peeled: None, target } => {
match target
.attach(self.repo)
.object()
.map_err(Into::into)
.and_then(|obj| obj.peel_tags_to_end().map_err(Into::into))
.map(|peeled| peeled.id)
{
Ok(peeled) => {
self.kind = Kind::Detached {
peeled: Some(peeled),
target: *target,
};
Ok(peeled.attach(self.repo))
}
Err(err) => Err(err),
}
}
Kind::Symbolic(r) => {
let mut nr = r.clone().attach(self.repo);
let peeled = nr.peel_to_id_in_place().map_err(Into::into);
*r = nr.detach();
peeled
}
})
}
// TODO: tests
// TODO: something similar in `crate::Reference`
/// Follow the symbolic reference of this head until its target object and peel it by following tag objects until there is no
/// more object to follow, transform the id into a commit if possible and return that.
///
/// Returns an error if the head is unborn or if it doesn't point to a commit.
pub fn peel_to_commit_in_place(&mut self) -> Result<crate::Commit<'repo>, to_commit::Error> {
let id = self.peel_to_id_in_place().ok_or_else(|| to_commit::Error::Unborn {
name: self.referent_name().expect("unborn").to_owned(),
})??;
id.object()
.map_err(|err| to_commit::Error::Peel(Error::FindExistingObject(err)))
.and_then(|object| object.try_into_commit().map_err(Into::into))
}
/// Consume this instance and transform it into the final object that it points to, or `None` if the `HEAD`
/// reference is yet to be born.
pub fn into_fully_peeled_id(self) -> Option<Result<crate::Id<'repo>, Error>> {
Some(match self.kind {
Kind::Unborn(_name) => return None,
Kind::Detached {
peeled: Some(peeled), ..
} => Ok(peeled.attach(self.repo)),
Kind::Detached { peeled: None, target } => target
.attach(self.repo)
.object()
.map_err(Into::into)
.and_then(|obj| obj.peel_tags_to_end().map_err(Into::into))
.map(|obj| obj.id.attach(self.repo)),
Kind::Symbolic(r) => r.attach(self.repo).peel_to_id_in_place().map_err(Into::into),
})
}
}
}