Mercurial > hg
view rust/hg-core/src/revlog/filelog.rs @ 48237:027ebad952ac
rhg: internally, return a structured representation from hg cat
The purpose of this change is to make it possible to support limited templating in `hg cat`, so we could print separators between files etc.
The templating itself is not implemented yet, so this functionality is unused in `rhg cat`.
However, in our fork of hg we're implementing a slightly different command `hg jscat` which makes use of this.
So accepting this change will let us minimize the size of the patch we're maintaining on our side.
Differential Revision: https://phab.mercurial-scm.org/D11679
author | Arseniy Alekseyev <aalekseyev@janestreet.com> |
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date | Fri, 15 Oct 2021 14:05:20 +0100 |
parents | 87e3f878e65f |
children | e9faae0f445c |
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use crate::errors::HgError; use crate::repo::Repo; use crate::revlog::path_encode::path_encode; use crate::revlog::revlog::{Revlog, RevlogError}; use crate::revlog::NodePrefix; use crate::revlog::Revision; use crate::utils::files::get_path_from_bytes; use crate::utils::hg_path::HgPath; use crate::utils::SliceExt; use std::path::PathBuf; /// A specialized `Revlog` to work with file data logs. pub struct Filelog { /// The generic `revlog` format. revlog: Revlog, } impl Filelog { pub fn open(repo: &Repo, file_path: &HgPath) -> Result<Self, HgError> { let index_path = store_path(file_path, b".i"); let data_path = store_path(file_path, b".d"); let revlog = Revlog::open(repo, index_path, Some(&data_path))?; Ok(Self { revlog }) } /// The given node ID is that of the file as found in a manifest, not of a /// changeset. pub fn data_for_node( &self, file_node: impl Into<NodePrefix>, ) -> Result<FilelogEntry, RevlogError> { let file_rev = self.revlog.rev_from_node(file_node.into())?; self.data_for_rev(file_rev) } /// The given revision is that of the file as found in a manifest, not of a /// changeset. pub fn data_for_rev( &self, file_rev: Revision, ) -> Result<FilelogEntry, RevlogError> { let data: Vec<u8> = self.revlog.get_rev_data(file_rev)?; Ok(FilelogEntry(data.into())) } } fn store_path(hg_path: &HgPath, suffix: &[u8]) -> PathBuf { let encoded_bytes = path_encode(&[b"data/", hg_path.as_bytes(), suffix].concat()); get_path_from_bytes(&encoded_bytes).into() } pub struct FilelogEntry(Vec<u8>); impl FilelogEntry { /// Split into metadata and data /// Returns None if there is no metadata, so the entire entry is data. fn split_metadata(&self) -> Result<Option<(&[u8], &[u8])>, HgError> { const DELIMITER: &[u8; 2] = &[b'\x01', b'\n']; if let Some(rest) = self.0.drop_prefix(DELIMITER) { if let Some((metadata, data)) = rest.split_2_by_slice(DELIMITER) { Ok(Some((metadata, data))) } else { Err(HgError::corrupted( "Missing metadata end delimiter in filelog entry", )) } } else { Ok(None) } } /// Split into metadata and data pub fn split(&self) -> Result<(Option<&[u8]>, &[u8]), HgError> { if let Some((metadata, data)) = self.split_metadata()? { Ok((Some(metadata), data)) } else { Ok((None, &self.0)) } } /// Returns the file contents at this revision, stripped of any metadata pub fn data(&self) -> Result<&[u8], HgError> { let (_metadata, data) = self.split()?; Ok(data) } /// Consume the entry, and convert it into data, discarding any metadata, /// if present. pub fn into_data(self) -> Result<Vec<u8>, HgError> { if let Some((_metadata, data)) = self.split_metadata()? { Ok(data.to_owned()) } else { Ok(self.0) } } }