Crate hg_parser

source ·
Expand description

§hg-parser

Mercurial repository parser written in the Rust programming language.

§Basic usage

§Add dependency to Cargo.toml

[dependencies]
hg-parser = "0.8"

§Use case - Analyse revision log and export to git fast-import format

use hg_parser::{file_content, FileType, ManifestEntryDetails, MercurialRepository, Revision};

use std::env::args;
use std::io::Write;
use std::path::{Path, PathBuf};
use std::string::ParseError;
use std::time::Instant;

fn main() -> Result<(), Error> {
    let path: PathBuf = args().nth(1).expect("path not provided").parse()?;
    export_repo(path)
}

fn export_repo<P: AsRef<Path>>(path: P) -> Result<(), Error> {
    let start = Instant::now();
    let repo = MercurialRepository::open(path)?;

    let stdout = std::io::stdout();
    let mut writer = stdout.lock();

    for changeset in &repo {
        let revision = changeset.revision;
        eprintln!("rev: {:?}", revision);

        let header = &changeset.header;
        let mut branch = None;
        let mut closed = false;
        for (key, value) in &header.extra {
            if key == b"branch" {
                branch = Some(value.as_slice());
            }

            if key == b"close" && value == b"1" {
                closed = true;
            }
        }

        let mut branch: Vec<_> = branch.unwrap_or(b"master").into();
        for b in branch.iter_mut() {
            if *b == b' ' {
                *b = b'-';
            }
        }

        let user = String::from_utf8_lossy(&header.user);
        let desc = String::from_utf8_lossy(&header.comment);

        let time = header.time.timestamp_secs();
        let timezone = header.time.tz_offset_secs();
        let tz = format!("{:+03}{:02}", -timezone / 3600, ((-timezone % 3600) / 60));

        write!(writer, "reset refs/heads/")?;
        writer.write_all(&branch)?;
        write!(writer, "\ncommit refs/heads/")?;
        writer.write_all(&branch)?;
        writeln!(writer, "\nmark :{}", mark(revision))?;

        writeln!(writer, "author {} {} {}", user, time, tz)?;
        writeln!(writer, "committer {} {} {}", user, time, tz)?;
        writeln!(writer, "data {}", desc.len() + 1)?;
        writeln!(writer, "{}\n", desc)?;

        match (header.p1, header.p2) {
            (Some(p1), Some(p2)) => {
                writeln!(writer, "from :{}", mark(p1))?;
                writeln!(writer, "merge :{}", mark(p2))?;
            }
            (Some(p), None) | (None, Some(p)) => {
                writeln!(writer, "from :{}", mark(p))?;
            }
            _ => (),
        }

        for file in changeset.files {
            match (file.data, file.manifest_entry) {
                (None, None) => {
                    write!(writer, "D ")?;
                    writer.write_all(&file.path)?;
                    writeln!(writer)?;
                }
                (Some(data), Some(manifest_entry)) => {
                    write!(
                        writer,
                        "M {} inline ",
                        match manifest_entry.details {
                            ManifestEntryDetails::File(FileType::Symlink) => "120000",
                            ManifestEntryDetails::File(FileType::Executable) => "100755",
                            ManifestEntryDetails::Tree
                            | ManifestEntryDetails::File(FileType::Regular) => "100644",
                        }
                    )?;
                    writer.write_all(&file.path)?;
                    let data = file_content(&data);
                    writeln!(writer, "\ndata {}", data.len())?;
                    writer.write_all(data)?;
                }
                _ => panic!("Wrong file data!"),
            }
        }

        if closed {
            write!(writer, "reset refs/tags/archive/")?;
            writer.write_all(&branch)?;
            writeln!(writer, "\nfrom :{}\n", mark(revision))?;

            write!(writer, "reset refs/heads/")?;
            writer.write_all(&branch)?;
            writeln!(writer, "\nfrom 0000000000000000000000000000000000000000\n")?;
        }
    }

    for (rev, tag) in repo.tags().unwrap() {
        eprintln!("export tag {}", tag.name);
        writeln!(writer, "reset refs/tags/{}", tag.name).unwrap();
        writeln!(writer, "from :{}", mark(rev)).unwrap();
        writeln!(writer).unwrap();
    }

    eprintln!("Done. Elapsed: {:?}", start.elapsed());
    Ok(())
}

fn mark<R: Into<Revision>>(rev: R) -> usize {
    (rev.into() + 1).0 as usize
}

#[derive(Debug)]
#[allow(dead_code)]
enum Error {
    MercurialRepoException(hg_parser::ErrorKind),
    Parse(ParseError),
    IO(std::io::Error),
}

impl From<ParseError> for Error {
    fn from(value: ParseError) -> Self {
        Error::Parse(value)
    }
}

impl From<std::io::Error> for Error {
    fn from(value: std::io::Error) -> Self {
        Error::IO(value)
    }
}

impl From<hg_parser::ErrorKind> for Error {
    fn from(value: hg_parser::ErrorKind) -> Self {
        Error::MercurialRepoException(value)
    }
}

§Implementation details

hg-parser is based on repository parse code from mononoke project. Which basically based on original Mercurial source code. Version has some simplifications which may not work for you.

Structs§

Enums§

Functions§

  • file_content
    Extract blob data (raw file content) from internal Mercurial representation. This representation is by default returned by ChangesetIter iterator.