rust: Move config value parsing functions to a new module
Differential Revision: https://phab.mercurial-scm.org/D10021
//! Parsing functions for various type of configuration values.
//!
//! Returning `None` indicates a syntax error. Using a `Result` would be more
//! correct but would take more boilerplate for converting between error types,
//! compared to using `.ok()` on inner results of various error types to
//! convert them all to options. The `Config::get_parse` method later converts
//! those options to results with `ConfigValueParseError`, which contains
//! details about where the value came from (but omits details of what’s
//! invalid inside the value).
pub(super) fn parse_bool(v: &[u8]) -> Option<bool> {
match v.to_ascii_lowercase().as_slice() {
b"1" | b"yes" | b"true" | b"on" | b"always" => Some(true),
b"0" | b"no" | b"false" | b"off" | b"never" => Some(false),
_ => None,
}
}
pub(super) fn parse_byte_size(value: &[u8]) -> Option<u64> {
let value = std::str::from_utf8(value).ok()?.to_ascii_lowercase();
const UNITS: &[(&str, u64)] = &[
("g", 1 << 30),
("gb", 1 << 30),
("m", 1 << 20),
("mb", 1 << 20),
("k", 1 << 10),
("kb", 1 << 10),
("b", 1 << 0), // Needs to be last
];
for &(unit, multiplier) in UNITS {
// TODO: use `value.strip_suffix(unit)` when we require Rust 1.45+
if value.ends_with(unit) {
let value_before_unit = &value[..value.len() - unit.len()];
let float: f64 = value_before_unit.trim().parse().ok()?;
if float >= 0.0 {
return Some((float * multiplier as f64).round() as u64);
} else {
return None;
}
}
}
value.parse().ok()
}