diff rust/hg-core/src/config/values.rs @ 46602:a687a7f27951

rust: Move config value parsing functions to a new module

Differential Revision: https://phab.mercurial-scm.org/D10021

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/rust/hg-core/src/config/values.rs	Wed Feb 17 20:24:04 2021 +0100
@@ -0,0 +1,43 @@
+//! 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()
+}