comparison rust/hg-core/src/utils.rs @ 46742:91ab5190a3de

rhg: Add support for environment variables in config include paths

Some tests rely on this.

Differential Revision: https://phab.mercurial-scm.org/D10140

46741:25e3dac511f0

pub fn current_exe() -> Result<std::path::PathBuf, HgError> {
    std::env::current_exe().map_err(|error| HgError::IoError {
        error,
        context: IoErrorContext::CurrentExe,
    })
}

pub(crate) enum MergeResult<V> {
    UseLeftValue,
    UseRightValue,

46742:91ab5190a3de

pub fn current_exe() -> Result<std::path::PathBuf, HgError> {
    std::env::current_exe().map_err(|error| HgError::IoError {
        error,
        context: IoErrorContext::CurrentExe,
    })
}

/// Expand `$FOO` and `${FOO}` environment variables in the given byte string
pub fn expand_vars(s: &[u8]) -> std::borrow::Cow<[u8]> {
    lazy_static::lazy_static! {
        /// https://github.com/python/cpython/blob/3.9/Lib/posixpath.py#L301
        /// The `x` makes whitespace ignored.
        /// `-u` disables the Unicode flag, which makes `\w` like Python with the ASCII flag.
        static ref VAR_RE: regex::bytes::Regex =
            regex::bytes::Regex::new(r"(?x-u)
                \$
                (?:
                    (\w+)
                    |
                    \{
                        ([^}]*)
                    \}
                )
            ").unwrap();
    }
    VAR_RE.replace_all(s, |captures: &regex::bytes::Captures| {
        let var_name = files::get_os_str_from_bytes(
            captures
                .get(1)
                .or_else(|| captures.get(2))
                .expect("either side of `|` must participate in match")
                .as_bytes(),
        );
        std::env::var_os(var_name)
            .map(files::get_bytes_from_os_str)
            .unwrap_or_else(|| {
                // Referencing an environment variable that does not exist.
                // Leave the $FOO reference as-is.
                captures[0].to_owned()
            })
    })
}

#[test]
fn test_expand_vars() {
    // Modifying process-global state in a test isn’t great,
    // but hopefully this won’t collide with anything.
    std::env::set_var("TEST_EXPAND_VAR", "1");
    assert_eq!(
        expand_vars(b"before/$TEST_EXPAND_VAR/after"),
        &b"before/1/after"[..]
    );
    assert_eq!(
        expand_vars(b"before${TEST_EXPAND_VAR}${TEST_EXPAND_VAR}${TEST_EXPAND_VAR}after"),
        &b"before111after"[..]
    );
    let s = b"before $SOME_LONG_NAME_THAT_WE_ASSUME_IS_NOT_AN_ACTUAL_ENV_VAR after";
    assert_eq!(expand_vars(s), &s[..]);
}

pub(crate) enum MergeResult<V> {
    UseLeftValue,
    UseRightValue,