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use std::io;
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use std::path::Path;
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#[derive(Debug)]
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pub enum RequirementsError {
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// TODO: include a path?
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Io(io::Error),
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/// The `requires` file is corrupted
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Corrupted,
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/// The repository requires a feature that we don't support
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Unsupported {
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feature: String,
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},
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}
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fn parse(bytes: &[u8]) -> Result<Vec<String>, ()> {
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// The Python code reading this file uses `str.splitlines`
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// which looks for a number of line separators (even including a couple of
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// non-ASCII ones), but Python code writing it always uses `\n`.
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let lines = bytes.split(|&byte| byte == b'\n');
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lines
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.filter(|line| !line.is_empty())
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.map(|line| {
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// Python uses Unicode `str.isalnum` but feature names are all
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// ASCII
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if line[0].is_ascii_alphanumeric() && line.is_ascii() {
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Ok(String::from_utf8(line.into()).unwrap())
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} else {
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Err(())
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}
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})
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.collect()
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}
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pub fn load(repo_root: &Path) -> Result<Vec<String>, RequirementsError> {
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match std::fs::read(repo_root.join(".hg").join("requires")) {
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Ok(bytes) => parse(&bytes).map_err(|()| RequirementsError::Corrupted),
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// Treat a missing file the same as an empty file.
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// From `mercurial/localrepo.py`:
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// > requires file contains a newline-delimited list of
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// > features/capabilities the opener (us) must have in order to use
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// > the repository. This file was introduced in Mercurial 0.9.2,
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// > which means very old repositories may not have one. We assume
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// > a missing file translates to no requirements.
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Err(error) if error.kind() == std::io::ErrorKind::NotFound => {
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Ok(Vec::new())
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}
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Err(error) => Err(RequirementsError::Io(error))?,
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}
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}
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pub fn check(repo_root: &Path) -> Result<(), RequirementsError> {
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for feature in load(repo_root)? {
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if !SUPPORTED.contains(&&*feature) {
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return Err(RequirementsError::Unsupported { feature });
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}
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}
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Ok(())
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}
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// TODO: set this to actually-supported features
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const SUPPORTED: &[&str] = &[
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"dotencode",
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"fncache",
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"generaldelta",
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"revlogv1",
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"sparserevlog",
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"store",
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// As of this writing everything rhg does is read-only.
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// When it starts writing to the repository, it’ll need to either keep the
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// persistent nodemap up to date or remove this entry:
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"persistent-nodemap",
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];
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