Move a few modules to util

src/util/units.rs

@@ -0,0 +1,45 @@
+//! This module contains common units.
+
+pub type Scalar = f64;
+
+/// Type alias for unit of time
+pub type Second = Scalar;
+
+/// Supported time units
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum Unit {
+    Second,
+    MilliSecond,
+}
+
+impl Unit {
+    /// The abbreviation of the Unit.
+    pub fn short_name(self) -> String {
+        match self {
+            Unit::Second => String::from("s"),
+            Unit::MilliSecond => String::from("ms"),
+        }
+    }
+
+    /// Returns the Second value formatted for the Unit.
+    pub fn format(self, value: Second) -> String {
+        match self {
+            Unit::Second => format!("{:.3}", value),
+            Unit::MilliSecond => format!("{:.1}", value * 1e3),
+        }
+    }
+}
+
+#[test]
+fn test_unit_short_name() {
+    assert_eq!("s", Unit::Second.short_name());
+    assert_eq!("ms", Unit::MilliSecond.short_name());
+}
+
+// Note - the values are rounded when formatted.
+#[test]
+fn test_unit_format() {
+    let value: Second = 123.456789;
+    assert_eq!("123.457", Unit::Second.format(value));
+    assert_eq!("123456.8", Unit::MilliSecond.format(value));
+}